Books

Sustainable Production of Platform and Drop-in Chemicals from Biomass and Wastes: Opportunities and Challenges

Kalyan Gayen, Sunil K. maity  and Tridib Kumar Bhowmick

CRC Press (Taylor & Francis Group), 2026

Our society demands sustainable sourcing of commodity products and energy to overcome the futuristic challenges of petroleum scarcity. Circumventing carbon emissions from petroleum industries is equally essential for maintaining the earth’s habitable environmental conditions. On the other hand, organic carbon-rich wastes streaming from agriculture, municipality, and industry pose serious environmental threats. These wastes could be potential wealth if they are utilized for producing chemicals or energy, simultaneously solving the problem of their management/disposal and associated environmental consequences. Currently, the petrochemical sector meets the soaring demand for commodity products, including polymer, rubber, fibre, fertilizer, dyes and paints, detergent, and so on. These products are derived via three petrochemical building blocks: olefins, aromatics, and synthesis gas. However, the non-renewability and negative environmental impact of petroleum demand sustainable sources of petrochemical products. Biomass/waste is an inexhaustible renewable carbon resource with a diverse chemical composition and is formed through atmospheric carbon capture. Biomass/waste thus presents a tremendous opportunity to meet the demands of commodity products in a sustainable manner in an integrated biorefinery approach. The US Department of Energy thus identified a list of biomass-derived oxygenated chemicals, completely different from petrochemical building blocks, known as platform chemicals. These platform chemicals have the potential to produce commodities that are currently derived from petroleum. The transition from petrochemicals to bio-based products can contribute to sustainability, simultaneously curbing carbon emissions. This book thus provides the comprehensive and up-to-date status for sustainable production of platform and drop-in chemicals from renewable biomass and waste streams, circumventing the negative impacts arising from waste management and disposal, dependency on fossil fuels, and greenhouse gas (GHG) emissions. This book covers three major areas for the conversion of biomass and waste into platform/drop-in chemicals. Section I introduces the concept of petrochemical building block chemicals and platform/drop-in chemicals in biorefinery approaches, with an overview of their applications and production methods. Section II covers the detailed status of producing individual platform/drop-in chemicals from biomass and wastes by chemo-catalytic approaches. Section III includes the current state-of-the-art biochemical conversion of biomass and wastes into specific platform/drop-in chemicals. This book further covers commercial status, economic benefits, and life cycle analysis of various processes. The chapters provide comprehensive and up-to-date information about the current state-of-the-art research and commercial initiatives in their field. This information will provide the foundation for future researchers and investors for possible investments. This book will ultimately boost fundamental and applied research in this area, eventually promoting the development of commercially sustainable processes for bio-based chemicals. 

Hydrocarbon Biorefinery

Sustainable Processing of Biomass for Hydrocarbon Biofuels

Sunil K. Maity, Kalyan Gayen, Tridib Kumar Bhowmick

Elsevier 2021.

Sustainable production of hydrocarbon biofuels from biomass, fuels that are fully compatible with existing internal combustion engines, will allow the global transport economy to transition to a sustainable energy source without the need for capital-intensive new infrastructures. Hydrocarbon Biorefinery: Sustainable Processing of Biomass for Hydrocarbon Biofuels presents a comprehensive and easy to understand consolidation of existing knowledge for the production of hydrocarbon biofuels from biomass. Three major areas for the conversion of biomass to hydrocarbon biofuels are addressed: i) Chemical and thermochemical conversion processes, ii) Biological and biochemical conversion processes, and iii) Conversion processes of biomass-derived compounds. Additionally, the book includes process design, life cycle analysis of various processes, reaction engineering, catalysts, process conditions and process concepts, and is supported with detailed case studies. The economic viability of each process is specifically addressed to provide a clear guide for the economic development of future hydrocarbon biofuels.  Hydrocarbon Biorefinery: Sustainable Processing of Biomass for Hydrocarbon Biofuels offers an all-in-one resource for researchers, graduate students, and industry professionals working in the area of bioenergy and will be of interest to energy engineers, chemical engineers, bioengineers, chemists, agricultural researchers, and mechanical engineers. Furthermore, this book provides structured foundational content on biorefineries for undergraduate and graduate students. 

Sustainable Downstream Processing of Microalgae for Industrial Application

Kalyan Gayen, Tridib Kumar Bhowmick, Sunil K. Maity

CRC Press, 2019.

Microalgae can be future resource for industrial biotechnology. In current energy crisis era, microalgae are under tremendous research focus for the production of biodiesel due to their high photosynthetic efficiency, growth rate and high lipid content compared to territorial plants. However, the large-scale production of algal biomass and downstream processing of harvested algae towards bio-fuels are facing several challenges from economic viability perspective. Apart from bio-fuels, the microalgae synthesize number of bio-molecules such as pigments (e.g., chlorophyll, carotenoid), protein (e.g., lectin, phycobiliprotein), and carbohydrates (e.g., agar, carrageenan, alginate, fucodian) which are available in the various forms of microalgal products. Therefore, developing a strategy for large-scale production and use of algal biomass for the co-production of these value-added macromolecules is thus imperative for the improvement of the economics of algal biorefinery.

In the above context, this book covers three major areas (i) commercial-scale production of bio-molecules from microalgae, (ii) sustainable approach for industrial-scale operation, and (iii) optimization of downstream processes. Each of these sections is composed of several chapters written by the renowned academicians/industry experts. Furthermore, in this book, a significant weightage is given to the industry experts (around 50%) to enrich the industrial perspectives.

We hope that amalgamate of fundamental knowledge from academicians and applied research information from industry experts will be useful for forthcoming implementation of a sustainable integrated microalgal biorefinery. This book highlights following.

• Explores biomolecules from microalgae and their applications

• Discusses microalgae cultivations and harvesting

• Examines downstream processing of biomolecules

• Explores sustainable integrated approaches for industrial scale operations

• Examines purification techniques specific for microalgal proteins, Omega 3 fatty Acids, carbohydrates, and pigments

Nanobiotechnology Applications of Nanomaterials in Biotechnology, Medicine and Healthcare

Tridib Kumar Bhowmick, Kaylan Gayen, Sunil Kumar Maity

CRC Press 2024. ISBN 9781032303871 , https://doi.org/10.1201/9781003305583

This book covers topics related to drug delivery, biomaterials, drug design, formulation development, nanoscience, and nanotechnology. It describes the fundamental concepts in nanotechnology and their different applications in biotechnology to solve engineering challenges and generate new areas of technological development. Nanobiotechnology: Applications of Nanomaterials in Biotechnology, Medicine, and Healthcare covers vast application areas that include medical science, material science, pharmaceutical science, and environmental science. Section 1 presents recent research updates on the different nanomaterials, which are promising in different medical and biotechnological applications. Applications of nanomaterials as bone replacement orthopedic implants have revolutionized the treatment of orthopedic surgery. Nanostructured polymeric materials have gained immense research attention as therapeutic carriers for the precise delivery of drugs at targeted sites. Nanocellulose is recognized as a promising green nanomaterial due to its renewability and abundance in nature. Scientific topics on the most recent scientific and technological advances and applications of different nanostructured materials are presented in this section. Section 2 focuses on the novel synthesis methods that are used extensively and promising for large-scale production of inorganic and nanostructured materials. Section 3 covers the applications of nanotools in the treatment of  different diseases, including cancers and genetic diseases. The increasing use of nanotechnology will bring changes in the manufacturing processes of nanomaterials. The applications of nanomaterials in the field of medical imaging and molecular detection are presented in section 4. This book will be useful for students, researchers, scientists, academicians, and industrial manufacturers to understand the importance and applicability of nanomaterials in the field of biotechnology and medical science. 

Book Chapters

An introduction to building blocks, platform, and drop-in chemicals: A sustainability approach

 Sunil K. maity, Kalyan Gayen, Tridib Kumar Bhowmick

CRC Press 2026. 

The building-block chemicals derived from petroleum and natural gas are the foundation of organic chemicals, commodity products, polymers, and fertilisers. However, the current geopolitical situation is creating a dwindling global crude oil supply, driving prices to unaffordable levels. Therefore, sourcing these products from carbon-neutral renewable biomass and waste is essential for stable global economic growth and the long-term sustainability of human civilization. Integrated biorefinery concepts are thus developed to complement these products, in addition to biofuels, from biomass and wastes through a range of chemical intermediates, known as platform and drop-in chemicals. This chapter thus provides an overview of the production of synthesis gas, olefinic, and aromatic building-block chemicals from petroleum, along with their product opportunities and applications. The chapter then covers various platforms and drop-in chemicals, with an emphasis on their manufacturing via different conversion approaches. These platform and drop-in chemicals can produce a diverse range of organic chemicals, currently derived from building-block chemicals, to meet the growing demand for a wide range of commodity products. The chapter concludes with a discussion of current challenges and future directions. 

Importance of Nanomaterials for Biological Applications

Bhabatush Biswas, Kalyan Gayen, Sunil K. Maity, Tarun Kanti Bandyopadhyay, and Tridib Kumar Bhowmick

In: Tridib Kumar Bhowmick, Kaylan Gayen, Sunil Kumar Maity (eds), Nanobiotechnology Applications of Nanomaterials in Biotechnology, Medicine and Healthcare. 

CRC Press 2024. ISBN 9781032303871 , https://doi.org/10.1201/9781003305583

Nanomaterials are unique materials whose dimension ranges from 1 to 100 nm. Nanomaterials have been the cardinal research focus in medical and biological applications due to their unique properties. These features led to unprecedented developments in the applications of nanomaterials in disease targeting, therapeutics delivery, gene delivery, and healthcare diagnostic functions. Several nanostructures exhibited great potential due to their multifaceted properties, including high surface area-to-volume ratio, electroactivity, low toxicity, biocompatibility, doping ability, scalable and economical manufacturing process, and fluorescence and functionalization properties. Particulate matters in the form of minerals, herbs, metals, animal, and chemical products have been used in traditional medicine (Ayurveda, Siddha, Unani, and Traditional Chinese medicine) from ancient times. This chapter thus discusses the efficacy of these traditional medicines in light of the emerging scientific understanding of the role of nanomaterials in the delivery of therapeutics and related applications. The chapter also highlights varieties of nanomaterials (carbon, metal, polymeric, ceramic, lipid, etc.), which are under current research focus for their application in the biomedical field. This chapter further presents their significance in therapeutic delivery, gene therapy, disease targeting, photodynamic/photothermal therapy, bioimaging, biosensors, and tissue engineering applications. 

Technological advancements in the production of green diesel from biomass 

Sudhakara R. Yenumala, Baishakhi Sarkhel, and Sunil K. Maity 

In: Aslam, M., Shivaji Maktedar, S., Sarma, A.K. (eds) Green Diesel: An Alternative to Biodiesel and Petrodiesel. Advances in Sustainability Science and Technology. Springer Nature 219–248, 2022. https://doi.org/10.1007/978-981-19-2235-0_7 

Diesel-range hydrocarbons derived from biomass have similar chemical compositions and physicochemical properties with petroleum-derived diesel, known as green diesel. Green diesel also meets the American Society for Testing and Materials (ASTM) specification ASTM D975. Green diesel is thus compatible with existing petroleum pipelines, storage tanks, fuelling stations, and diesel engines. Currently, green diesel is produced from non-edible tree-born oils and lignocellulose biomass. Hydroprocessing of oils and fats, biomass-to-liquid, and a combination of fast pyrolysis and hydrodeoxygenation of bio-oil, are some of the thermochemical processes used to produce green diesel. While commercial technologies are available for producing green diesel from oils and fats, these technologies are suffering from the challenges of the dearth and high cost of feedstock. On the contrary, lignocellulosic biomass is abundant and inexpensive. However, the technologies for converting lignocellulosic biomass to green diesel are in the developing stage. This chapter presents the existing and upcoming hydropyrolysis technologies for converting lignocellulosic biomass to green diesel.

Keywords: Hydroprocessing; Green diesel; Pyrolysis; Hydrodeoxygenation; Non-edible oils; and Biomass.

Hydrocarbon biorefinery: A sustainable approach

Alekhya Kunamalla, Swarnalatha Mailaram, Bhushan S. Shrirame, P Kumar, SK. Maity 

Academic Press, Elsevier 2022, 1-44. 

A sustainable hydrocarbon biorefinery is crucial to reduce dependency on petroleum. This chapter presents different types of biomass with their availability and chemical structure, various biorefinery approaches, and a diverse range of biofuels. The sugar and starch, triglycerides, and lignocellulose are traditional biorefineries. These biorefineries produce a vast range of oxygenated biofuels (biodiesel, bioethanol, biobutanol, and dimethyl ether) and fuel-additives (γ-valerolactone, alkyl levulinates, furanic compounds, and glycerol acetals). On the other hand, a hydrocarbon biorefinery produces biofuels similar to current transportation fuels, known as hydrocarbon biofuels. These biofuels are compatible with existing refinery facilities. This biorefinery is thus vital to circumvent huge capital investment. This chapter presents a comprehensive overview of three different routes of hydrocarbon biorefinery: chemical and thermochemical, biological and biochemical, and conversion of biomass-derived compounds. This chapter further provides an overview of the role of heterogeneous catalysis in the hydrocarbon biorefinery.

Keywords: Biomass; Biorefinery; Hydrocarbon biorefinery; Hydrocarbon biofuels; Heterogeneous catalysis

Hydrodeoxygenation of triglycerides for the production of green diesel: Role of heterogeneous catalysis

Pankaj Kumar, Deepak Verma, Malayil Gopalan Sibi, Paresh Butolia, Sunil K. Maity 

Academic Press, Elsevier 2022, 97-126.

Catalytic hydrodeoxygenation of triglycerides is a prominent technology in hydrocarbon biorefinery for producing diesel-range biofuels, named green diesel. The triglycerides are fatty ester of glycerol associated with three long-chain fatty acids. While the triglycerides are generally composed of C8-C24 fatty acids, the majority of the fatty acids are in the diesel range (C16 and C18). The removal of oxygen from triglycerides thus produces green diesel. Therefore, the present chapter provides an overview of the hydrodeoxygenation of triglycerides. The process involves a combination of hydrogenation, hydrodeoxygenation, and decarbonylation reactions. This chapter also covers the impact of metal-based catalysts and process conditions on the reaction mechanism and composition, fuel properties, and yield of green diesel. The fuel characteristics of green diesel demonstrate that it can be used directly in an unmodified combustion engine. This chapter further covers the commercial status and economic viability of this technology.

Keywords: Biomass; Green diesel; HDO; Heterogeneous catalysts; Hydrocarbon biorefinery

Advances in the conversion of methanol to gasoline 

Jyoti Prasad Chakraborty, Satyansh Singha, Sunil K. Maity 

Academic Press, Elsevier 2022, 177-200. 

Methanol-to-gasoline (MTG) process is a sustainable approach for producing gasoline-range hydrocarbon biofuels. It can also mitigate the challenges associated with crude oil, such as environmental pollution, scarcity and cost of fossil-derived fuels, and political instability in major crude oil-producing countries. MTG process starts with the production of syngas, followed by conversion of syngas to methanol and production of gasoline from methanol. This chapter summarized the various feedstock used for producing methanol, including biomass and carbon dioxide. MTG process started way back in 1978 when the first plant was installed in New Zealand. Since then, significant technological advancement has been witnessed in the MTG process. This chapter thus presents progress in the MTG process. Specifically, the effect of characteristic features of zeolites and various process variables on the MTG process are elaborated. The reaction mechanism and industrial processes are also discussed briefly.

Keywords: Biomass; Methanol; Gasoline; ZSM-5 catalyst; Reaction mechanism

Biomass, Biorefinery, and Biofuels

S Mailaram, Pankaj Kumar, Alekhya Kunamalla, Palkesh Saklecha, SK Maity 

Academic Press, Elsevier 2021, 51-87.

Biomass is the only carbon-neutral renewable resource for the sustainable production of biofuels. There are three types of biofuels: traditional, hydrocarbon, and fuel additives. Traditional biofuels, such as biodiesel, bio-ethanol, and bio-butanol, contain oxygen in their structure and are therefore limited to mixing with transportation fuels. Hydrocarbon biofuels are similar to existing transportation fuels and well-suited with unmodified combustion engines. This chapter covers various routes for the production of the hydrocarbon biofuels, such as hydrodeoxygenation (HDO) of triglycerides, fast pyrolysis followed by HDO of bio-oil, Fischer–Tropsch synthesis, oligomerization of bio-olefins, and HDO of condensed products from C–C bond forming reactions. Several biomass-derived compounds are also suitable for mixing with transportation fuels to a certain extent, known as fuel additives: γ-valerolactone, furanic compounds, 5-ethoxymethylfurfural, alkyl levulinates, glycerol acetal, and dimethyl ether. This chapter describes the production of these fuel additives from methanol and platform chemicals.

Keywords. Bio-ethanol; bio-butanol; biodiesel; hydrocarbon biofuel; fuel additive

Biofuels from triglycerides: A review

S Mailaram, P Kumar, SK Maity

Nova Science Publishers, Inc., New York 2020, 1-27. ISBN: 978-1-53618-134-0

This chapter gives an overview of the various thermochemical routes for the conversion of triglycerides to biofuels. The transesterification, thermal and catalytic cracking, and hydrodeoxygenation are the main thermochemical processes for manufacturing biofuels from triglycerides. The transesterification of triglycerides with methanol produces fatty acid methyl esters, known as biodiesel. The thermal and catalytic cracking of triglycerides produces hydrocarbons in the range of gasoline, jet fuel, and diesel. The cracking routes are, however, associated with the drawback of low yield of biofuel and catalyst deactivation due to the coke deposition on the catalyst. The hydrodeoxygenation is the most potential route to convert triglycerides to diesel-range hydrocarbons, known as green diesel. In this route, the oxygen is eliminated as water and CO. The green diesel is also fully compatible with the existing diesel engine. This chapter provides a detailed description of these processes, including operating conditions, reaction mechanism, catalysts, and techno-economic feasibility.

 Keywords: Biodiesel; Green diesel; Transesterification; Hydrodeoxygenation.

Biorefinery Polyutilization Systems: Production of green transportation fuels from biomass

P Kumar, M Varkolu, S Mailaram, A Kunamalla, SK Maity

Academic Press, Elsevier 2019, 373-407. 

The green transportation fuels (green gasoline, green diesel, and green jet fuel) (GTF) derived from biomass are quite similar to the petroleum-derived transportation fuels and compatible with existing petroleum refinery infrastructures and combustion engines. The present chapter provides an outline of the various routes for the production of GTF from biomass. In general, the biomass is converted to GTF through thermochemical, chemical, biochemical, and platform chemical-based routes. The current chapter presents an outline of thermochemical conversion processes such as biomass gasification, liquefaction, and pyrolysis and chemical conversion process such as hydrodeoxygenation of triglycerides. The ethanol to gasoline and butanol to gasoline are two important biochemical conversion processes for the production of GTF and discussed in the present chapter. The present chapter also provides an outline of the production of GTF and fuel additives from the platform chemicals such as 5-hydroxymethylfurfural, furfural, and levulinic acid.

Keywords: Hydrocarbon biorefinery; Green transportation fuels; Fast pyrolysis; Hydrodeoxygenation of triglycerides; Ethanol to gasoline; Butanol to gasoline; Platform chemicals

Integrated approach for the sustainable extraction of carbohydrates and proteins from microalgae

S Sarkar, MS Manna, SK Maity, TK Bhowmik, K Gayen

CRC Press, Taylor & Francis Group 2019, 27 pages

Microalgae possess plenty of useful metabolites (broadly carbohydrate, proteins, pigments, and lipids) that can be converted into commercially useful products. Microalgal cells contain a large quantity of structural and functional carbohydrates, as well as bio-functional proteins and peptides. Downstream processing of these individual metabolites from microalgae, however, incurs higher costs compared to other sources. Hence, an integrated extraction approach is becoming essential for commercialization. The microalgae possess a thick cell wall and thus require an additional pre-treatment prior to extraction. The cell disruption of microalgae is an energy-intensive process and thus influences the economics of the overall process significantly. On the other hand, proteins are prone to denaturation under severe conditions, for example, high temperature, extreme pH, and high shear. Therefore, the cell-disruption method should be carried out under mild conditions to retain the native functionality and structure of the proteins. The merits and demerits of different mild cell-disruption methods for integrated processes such as bead milling, ultrasonication, pulse electric field, and enzymatic treatment are discussed in this chapter. Selective extraction of individual metabolites in a sequential manner from the biomass has been demonstrated as a useful approach. Both proteins and carbohydrates are soluble in polar solvents. Consequently, both of these are extracted by aqueous solvents, simultaneously followed by their separation into different fractions. Aqueous two-phase separation and three-phase partitioning are the efficient liquid–liquid extraction techniques to obtain proteins and carbohydrates from the microalgal biomass. Integration of membrane separation with aqueous co-extraction of carbohydrates and proteins is another potential approach for this purpose.

Process development for hydrolysate optimization from lignocellulosic biomass towards biofuel production

A Mazumder, SK Maity, D Sen, K Gayen

Nova Science Publishers, Inc., New York 2014, 41-76. ISBN: 978-1-63463-187-7.

The renewable biofuels derived from lignocellulosic biomass (LCB) through hydrolysis is a promising alternative of fossil fuel and it creates carbon balance of the ecosystem by recycling the emitted CO2 into biomass production. LCB mainly comprises of cellulose, hemicellulose and lignin with a small percentage of pectin, protein, extractive and ash. Prior to hydrolysis of LCB, pretreatment can be performed by different methods namely physical (e.g. mechanical reduction, pyrolysis and extrusion), chemical (e.g. acid, alkaline, oxidative pretreatment and ozonolysis), physiochemical (e.g. steam pretreatment and ammonia fiber explosion (AFEX)) and biological pretreatment. The pretreatment process is one key step to remove lignin and hemicellulose attributing to an improvement in the LCB hydrolysis efficiency. Enzymatic hydrolysis is preferred over acid hydrolysis that produces inhibitory products (e.g. furfural, hydroxymethylfurfural (HMF), acetic acid, formic acid and levulinic acid) of subsequent fermentation process. Different detoxification methods (physical, chemical and biological) are employed to remove the inhibitors. However, enzymatic hydrolysis rate and yield depend on several factors such as concentration and quality of substrate, pretreatment methods, cellulase enzymes and reaction conditions (e.g. temperature, pH and mixing). Upcoming amalgamated techniques with both hydrolysis and fermentation, such as separate enzymatic hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), non isothermal simultaneous saccharification and fermentation (NSSF), simultaneous saccharification and co-fermentation (SSCF), simultaneous saccharification, filtration and fermentation (SSFF), two chamber bioreactor separated by a membrane filter, and consolidated bioprocessing are the key areas that require detailed analysis for further technology improvement prior to commercialization of hydrolysis process.

Publications

Production of Sustainable Aviation Fuel Precursor from Furanics Using High Surface Area Ordered Mesoporous Sulfonic Acid Functionalized Silica

Bhushan S. Shrirame, Sunil K. Maity

Industrial & Engineering Chemistry Research 2026, 65 (6), 3094–3105. https://doi.org/10.1021/acs.iecr.5c03691

The present work demonstrated the efficacy of high surface area ordered mesoporous sulfonic acid functionalized silica (SO3H-SiO2) as a solid-acid catalyst for the furfural-2-methylfuran hydroxyalkylation–alkylation reaction to obtain a branched-chain C15 sustainable aviation fuel precursor. Bare silica and SO3H-SiO2 with up to 15 mol % −SO3H loading showed an ordered mesoporous structure. Brønsted acidity and acid density proliferated with enhanced −SO3H loadings, upholding consistent Lewis acidity. The catalytic efficacy of SO3H-SiO2 was thus enhanced at elevated −SO3H loadings. The SO3H-SiO2 also exhibited promising regeneration and reusability with minimal leaching of acidic functionality. The 2-methylfuran conversion was 78.4% at 300 min under optimum reaction conditions (323 K and 2:1 2-methylfuran/furfural mole ratio) using SO3H-SiO2 with 15 mol % −SO3H. An empirical second order kinetic model was developed to correlate 2-methylfuran conversion with an activation energy of 45.5 kJ/mol. The 2-methylfuran/furfural mole ratio results were used to validate the kinetic model. 

Biological production of muconic acid from renewable biomass: Advances in metabolic engineering and lignin valorisation

Vinod Kumar, Satish Kumar Ainala, Vivek Kumar Gaur, Samuel Jacob, Yuheng Lin, Ponnusami Venkatachalam, Sunil K. Maity, Naseem A. Gaur, Gopalakrishnan Kumar, Vijai Kumar Gupta

Microbial Cell Factories 2026. https://doi.org/10.1186/s12934-026-03037-3

Muconic acid (MA) is characterized by two reactive carboxylic acid groups and two conjugated double bonds, making it a highly valuable industrial platform chemical with significant market potential. It serves as a key intermediate in the manufacturing of important commercial chemical products such as adipic acid and terephthalic acid. The finite fossil-based resources and climate issues due to CO2 emission have necessitated the microbial routes for the production of MA, a potential alternative to fossil-based synthesis. This review provides a comprehensive overview of recent progress in the biological production of MA. The article begins with an outline of the present catalytic routes and known biochemical pathways for MA biosynthesis. The review then focuses on metabolic engineering strategies employed in various microbial hosts including Escherichia coli, Corynebacterium glutamicum, and Pseudomonas putida to enhance MA production from diverse feedstocks such as sugars, aromatic compounds, and lignin-derived substrates. Special attention is given to pathway optimization, host tolerance, and strategies enabling efficient conversion of lignin-derived intermediates within integrated biorefinery frameworks. Key challenges associated with scaling up bio-based MA production to industrial levels are discussed, along with potential strategies for developing robust and efficient microbial cell factories. The review concludes with future perspectives and recommendations to accelerate research progress and development in this field. 

Food Waste Valorization: Guidance for Integrating Sustainable Management Strategies

Rendra Hakim Hafyan, Vinod Kumar, Sunil K. Maity, Jhuma Sadhukhan, Siddharth Gadkari

Applied Sciences 2026, 16 (11), 5349. https://doi.org/10.3390/app16115349

Food waste (FW) is a major global challenge with significant economic and environmental costs, yet its nutrient-rich composition also offers an opportunity for valorization into high-value biochemicals and biofuels within a circular bioeconomy. Effective FW management requires systematic frameworks that balance environmental performance, economic returns, and social acceptance, a challenge that is particularly difficult in developing countries where technical, financial, and participation barriers persist. This review proposes a strategic, step-by-step approach to enhance current FW management through the objective integration of biorefinery pathways producing biochemicals and biofuels products. Both biochemical and thermochemical conversion routes are evaluated against industrial yield benchmarks, market value, and end-use specifications to identify the products and processes most capable of enhancing sustainability. The review further presents a framework for multi-objective optimization (MOO) that simultaneously addresses economic, environmental, and social objectives, and for incorporating decision-maker preferences into the selection of optimum solutions. By coupling sustainability assessment with structured decision support, this review provides practical guidance for selecting FW management strategies that are economically viable, environmentally sound, and socially acceptable. 

Beets beyond sugar: Potential and limitations of sugar beet pulp as a feedstock for biorefineries

Kawinharsun Dhodduraj, Vivek Narisetty, Seyed Ali Nabavi, Roberto Parra Saldivar, Frederic Coulon, Deepti Agrawal, Sunil K. Maity, Venkatesh Balan, Vinod Kumar

Industrial Crops and Products 2026, 240, 122559. https://doi.org/10.1016/j.indcrop.2025.122559

Sugar beet (SB) is a major sugar crop in the European Union and the United States, primarily cultivated for the commercial production of table sugar. Post-extraction of sucrose, the fibrous fraction which remains is called sugar beet pulp (SBP). SBP is rich in structural carbohydrates such as cellulose, hemicellulose and pectin containing glucose, arabinose and galactouronic acid as their respective monomeric units. SBP is a renewable source of fermentable sugars that constitute about 85 % of total carbohydrates. Leveraging SBP as a substrate for a biorefinery supports circular bioeconomy principles by simultaneously reducing agricultural waste and enabling the sustainable production of value-added chemicals. This review highlights current advances in SBP valorization, beginning with an overview of SB processing and waste generation, followed by a critical assessment of pretreatment strategies that enhance carbohydrate accessibility. Particular attention is given to emerging routes for the bioconversion of arabinose and galacturonic acid, which together represent more than half of SBP’s fermentable fraction yet remain significantly underutilized in industrial biotechnology. Microbial pathways, metabolic engineering interventions, and fermentation approaches enabling the production of value-added compounds such as arabitol, 2,3-butanediol, ascorbic acid, mucic acid and prebiotics are examined in detail. The review concludes by addressing current challenges and identifying research gaps to unlock the full potential of SBP within integrated biorefinery systems. 

Forgotten Fibre Waste: Mycoremediation and Recycling of Used Absorbent Hygiene Products

Roberto Parra-Saldívar, Stephen J. Russell, Hafiz M.N. Iqbal, Mireya Navarro-Márquez, Guadalupe Gutiérrez-Soto, Vinod Kumar, Gopalakrishnan Kumar, Kumar Raja Vanapalli, Sunil K. Maity

Resources, Conservation & Recycling 2026, 226, 108673. https://doi.org/10.1016/j.resconrec.2025.108673 

Beyond clothing, end-of-life technical textiles and nonwoven products are an additional source of fibre-based waste and environmental impact. Absorbent Hygiene Products (AHPs), i.e. single use, disposable diapers (nappies), adult incontinence and menstrual products, play an important role in supporting the personal hygiene and wellbeing of millions of people worldwide, but their disposal presents considerable waste management and environmental challenges due to their biological contamination, as well as mixed fibre and polymer composition. Despite high rates of consumption, used AHPs remain one of the hardest waste streams to recycle, and most are incinerated or landfilled. Internationally, very little used AHP recycling infrastructure exists, and generating high-value outputs from such waste is highly challenging, mainly due to its multifaceted nature. This review evaluates the potential for an alternative biotechnological approach to recycling based on mycoremediation and biocatalysis of used AHPs (containing cellulose, superabsorbent polymers and synthetic polymers) harnessing fungi to valorise the cellulosic and plastic components of the waste. We focus on the synergistic integration of mycoremediation and precision fermentation techniques as part of a biorefinery model to yield valuable material outputs from used AHPs, such as industrial chemicals and fibre-forming biodegradable polymers for industrial applications, as a basis for new circular economies. 

Sustainable Aviation Fuel: A Greener Future for Aviation Industry

Bhushan S. Shrirame, Sunil K. Maity, Santi Chuetor

Applied Science and Engineering Progress Applied Science and Engineering Progress 2026, 19 (2), 7893. https://doi.org/10.14416/j.asep.2025.07.006  

The aviation industry has been experiencing exponential growth due to rising economic progress and global connectivity. This sector is instrumental in the national and international economy and plays a vital role in modern society [1]. In 2018, the aviation industry transported around 64 million tons of freight and 4.3 billion travelers. This activity generated USD 6.7 trillion worth and 65 million employments [1], [2]. However, aviation fuels (C9-C16: n-/iso/cyclo-paraffin, aromatics, and naphthalene) are primarily obtained from non-renewable fossil-based resources. In 2005, the commercial airlines consumed 260 million cum of aviation fuels, and it was increased to 330 million cum in 2018. The growing air transportation poses severe environmental threats. The aviation sector emitted more than a gigaton of carbon worldwide in 2019. As the demand for aviation fuels is anticipated to increase 2-3 times by 2050 compared to 2019, it is essential to diminish the environmental impacts of this sector [3]. Sustainable aviation fuel (SAF) derived from renewable biomass is the only eco-friendly alternative to circumvent the dearth of fossil resources and climate change. Therefore, the net-zero emission policy has been adopted by many countries, and many more are expected to participate in this noble initiative. The SAF is projected to be the primary contributor to achieving this mission, offsetting carbon capture, infrastructure and operational improvement, and development of new aircraft technologies, which are 85% more proficient compared to the 1960s (Figure 1) [4]. In 2020, 0.1 billion liters of SAF were consumed in airlines, contributing less than 0.05% of aviation fuels [5]. However, the contribution of SAF to net-zero emissions is projected to be 65% by 2050 (Figure 1) [6]. Therefore, transitioning from conventional aviation fuels to SAF is essential for achieving carbon neutrality [7].

Recent Advances in Catalytic Conversion of Bioethanol to 1,3-Butadiene: Reaction Mechanism, Catalyst Design, and Process Scalability

Abhishek R. Varma, Md Ziyaur Rahman, Siddharth Gadkari, Atthasit Tawai, Malinee Sriariyanun, Ao Xia, Vinod Kumar, Sunil K. Maity

ChemSusChem 2026, 19 (1), e202501926. https://doi.org/10.1002/cssc.202501926

1,3-Butadiene (BD), a symmetric C4 diene, is a primary precursor for numerous synthetic rubbers and is sourced largely from the naphtha cracking process. Sustainable BD production from renewable biomass is indispensable for preserving the environment through the circular economy. Ethanol-to-BD (ETB) has particularly witnessed a resurgence in recent years, following two different routes: one-step conversion and two-step process via acetaldehyde. The present review article critically examines the current state-of-the-art research progress of the ETB processes, in terms of historical perspective, reaction mechanism, kinetics, thermodynamics, multifunctional heterogeneous catalysts, reaction parameters, and economic-environmental impact analysis. The ETB processes encompass a complex sequence of reactions on different catalytic sites, including dehydrogenation, carbon–carbon coupling, and dehydration. However, the catalyst with the proper balance between acidic, basic, redox, and metal functionalities (e.g., metal/metal oxide-modified MgO–SiO2 and Zn–Zr mixed oxide), which are uniformly distributed and cooperative, remains a critical challenge in these processes. Despite notable advancements in understanding molecular mechanisms, the design of catalysts for high BD selectivity and process scalability remains the key obstacle to commercial success. The comprehensive summary of ETB process developments provides a foundation for researchers and industry practitioners to advance research and optimize the critical parameters for sustainable BD production. 

Life cycle assessment for circular biomanufacturing of lactic acid from sugarcane bagasse

Kumar Raja Vanapalli, Naseeba Parveen, Sunil K. Maity, Roberto Parra Saldivar, Samuel Jacob, Gopalakrishnan Kumar, Vinod Kumar

Sustainable Production and Consumption 2026, 64, 306-322. https://doi.org/10.1016/j.spc.2025.11.008

Lactic acid (LA) is a top platform chemical with diverse applications in various industrial sectors. Sugarcane bagasse (SCB) is a significant waste stream during sugarcane processing. Our previous work was focused on the biomanufacturing of LA using fermentable sugars from SCB and techno-economic analysis. The current study evaluated the life cycle assessment (LCA) of SCB-based LA manufacturing for three different routes using the process models based on industrial-scale biorefinery – acid pretreatment & fermentation integrated with reactive distillation (ARD), alkali pretreatment & fermentation integrated with reactive distillation (AkRD), and alkali pretreatment & fermentation integrated with distillation (AkD). The environmental impacts were evaluated using attributional and consequential life cycle assessment (aLCA and cLCA). While aLCA was used to identify process hotspots by proportionally allocating environmental impacts, long-term impacts were assessed through cLCA by accounting for avoided products and additional burdens resulting from the upstream and downstream consequences of the processes. The aLCA analysis indicated that ARD had a 30–36 % superior environmental performance compared to AkRD and AkD, based on midpoint & endpoint impacts. The cooling water (45–47 %) and steam (27–29.1 %) during distillation, along with chemicals (18.4–24.2 %) in pretreatment and fermentation, were identified as environmental hotspots, with the respective values representing their proportionate contributions to the midpoint impacts across all scenarios. The cLCA depicted that LA recovered from the processes could offset environmental impacts by 34–44.2 %, emphasizing the long-term benefits of replacing the conventional LA manufacturing process. Moreover, valorisation of CO2, gypsum, and steam as by-products could significantly reduce environmental impacts. The process heat integration pinch technology further reduced steam and cooling water demands, cutting the impact by 26–27.5 %. These findings emphasize the importance of water recycling and energy integration for improving the overall sustainability of SCB to LA valorisation. 

Simulation-based process design and preliminary techno-economic assessment of sulfonation-based pretreatment of sugarcane leaves under mild conditions

Chanin Panjapornpon, Apinya Kaoloun, Malinee Sriariyanun, Keerthi Katam, Sunil K. Maity, Atthasit Tawai

Waste and Biomass Valorization 2025, https://doi.org/10.1007/s12649-025-03428-4 

This study presents the process design and preliminary techno-economic assessment of a sulfonation-based pretreatment employing a methanesulfonic acid (MSA)–formic acid (FA) co-solvent system for lignocellulosic ethanol production from sugarcane leaves. A batch-resolved, simulation-based framework integrating experimentally validated solvent-recycling data was developed to capture the temporal evolution of mass and energy flows during pretreatment and hydrolysis, providing an alternative approach to conventional steady-state techno-economic analyses by incorporating process dynamics. Optimization using response surface methodology (RSM) and a genetic algorithm (GA) identified conditions yielding 29.40 mg g⁻1 and 30.49 mg g⁻1 reducing sugars with no statistically significant difference, though the optimal parameters differed substantially: 27.5 wt% FA at 81 °C for 102 min (RSM) versus 20 wt% FA at 89 °C for 177 min (GA). A 50% solvent recovery strategy, validated across five reuse cycles, maintained hydrolytic efficiency and confirmed the feasibility of partial solvent recycling. The validated data were incorporated into an Aspen Plus® simulation at a scale of 50 tons per batch to evaluate time-dependent mass and energy balances. Solvent recycling reduced chemical costs by approximately 45%, while the RSM-based configuration incurred 19.8% higher pretreatment cost due to greater reagent use and shorter duration. The developed framework provides a systematic basis for dynamic cost–performance evaluation and scalable biorefinery design. 

Synergistic Effects of Ultrasound and Deep Eutectic Solvent Pretreatment on Sugarcane Leaves Bioconversion to Ethanol

Sukunya Areeya, Diana Jose, Suksun Amornraksa, Atthasit Tawai, Prapakorn Tantayotai, Dillirani Nagarajan, Nagaraju Kottam, Sunil K. Maity, Malinee Sriariyanun

BioEnergy Research 2025, 18, 94. https://doi.org/10.1007/s12155-025-10901-4

The increasing accumulation of sugarcane agricultural waste poses a significant environmental challenge, highlighting the urgent need for innovative valorization strategies such as converting sugarcane leaves into bioethanol through efficient pretreatment technologies. Therefore, this study investigates the effect of pretreatment using a combination of ultrasonic and deep eutectic solvents (DESs), ethylene glycol: citric acid (EG/CA) and choline chloride: citric acid (ChCl/CA), on sugarcane leaves’ compositions and properties. DES-assisted pretreatment was conducted using a solid-to-liquid ratio of 1:5 (w/w) at 90 °C and 100 rpm stirring speed for 3.15 h. Ultrasound-assisted pretreatment was optimized for amplitude and duration. The reducing sugar concentration obtained after pretreatment increased by 2.89 times for EG/CA and 3.41 times for ChCl/CA compared to the untreated sample (3.75 g/L). However, combining EG/CA pretreatment with ultrasound at 40% amplitude for 30 min enhanced reducing sugar concentration to 8.49 g/L with the highest crystallinity index (CrI) of 50.09%. Applying ultrasonic pretreatment before DES effectively improved the sugar release, resulting in an ethanol yield of 17.14%. Additionally, Fourier-transform infrared spectroscopy (FT-IR) was employed to examine chemical structural modifications of the biomass, verifying the effectiveness of ultrasound-assisted DES pretreatment. These findings highlight the potential of ultrasound-assisted DES pretreatment as an effective alternative for lignocellulosic biomass processing. 

Optimization of sustainable bioprocessing for the production of high-value biomolecules (Chlorophylls and Proteins) using Desmodesmus subspicatus

Sreya Sarkar, Sambit Sarkar, Sunil K. Maity, Tridib Kumar Bhowmick, Kalyan Gayen

Preparative Biochemistry & Biotechnology 2025, 55(10), 1257–1272. https://doi.org/10.1080/10826068.2025.2502765

Traditional protein and pigment (e.g., chlorophyll) sources are becoming insufficient due to the rapid rise of the global population in modern civilization. Microalgae offer a promising solution for protein and chlorophyll sources due to their higher productivity than terrestrial plants. This study aims to optimize the cultivation conditions for Desmodesmus subspicatus, a microalgal strain containing ∼60% protein and 4% chlorophyll, to enhance biomass, protein and chlorophyll productivity. A Taguchi Orthogonal Array (TOA) was used for systematic optimization of BG-11 medium components. Further experiments assessed the effects of light intensity and different carbon and nitrogen sources. Under optimized BG-11 conditions, biomass increased 1.3-fold, with protein and chlorophyll productivity rising 2.25 and 1.92-fold, respectively. Supplementation with carbon and nitrogen sources under varying light (84–504 µmol m−2 s−1) further enhanced yields by 1.6-fold. Glycine proved to be the most effective nitrogen source, while cellulose as a carbon source resulted in 2.4-fold higher biomass, 7.3-fold higher protein, and 2.3-fold higher chlorophyll. Cytotoxicity assessment of the extracted chlorophyll revealed over 94% A549 cell viability at concentrations up to 100 µg/mL, confirming its biocompatibility. Therefore, Desmodesmus subspicatus has promise as a sustainable source of proteins and chlorophylls in the nutraceutical and food industries. 

Techno-economic assessment of edible fruit coating production from banana stem using pinch analysis

Puspita Dey, Tridib Kumar Bhowmick, Dev Kumar Yadav, Baby Zaithanpuii Hmar, Kalyan Gayen, Sunil K. Maity

Chemical Engineering Journal 2025, 513, 162974. https://doi.org/10.1016/j.cej.2025.162974

Fruits and vegetables are prone to damage during post-harvest storage, with substantial economic losses. Edible fruit coating is a sustainable approach to extending their self-life without harming human health. Cellulose is an abundant biopolymer and is often used for edible coating formulation. This study presents a comprehensive techno-economic feasibility analysis for manufacturing cellulose-based edible fruit coating from 10 and 100 MT wet banana stem (WBS) per day. The process involves cellulose extraction from WBS, followed by cellulose conversion into a coating matrix, carboxymethyl-cellulose. Hemicellulose is further utilized for biogas generation by anaerobic digestion, which saves around 14% steam consumption. Processes are integrated using the pinch method, which reduces about 50% utility demand, translating to savings of 1.38% and 2.46% production costs and 0.75–1.2% and 1.78–2.34% minimum selling prices for 10 and 100 MT WBS/day, respectively. Production cost is much lower for 100 MT WBS/day (0.257 US$/kg) than 10 MT WBS/day (0.462 US$/kg) due to economics-of-scale benefits. The minimum selling price demonstrates that the proposed process is more profitable than existing marketed products for 10 MT WBS/day (0.54–0.86 US$/kg) and 100 MT WBS/day (0.28–0.36 US$/kg). However, profitability parameters are the most attractive for 100 MT WBS/day with more than 300% internal rate of return, 450 million US$ net present value, and less than a year break-even point. These inspiring results are pivotal for entrepreneurs investing in profitable edible fruit and vegetable coating businesses from WBS. 

Techno-economics of sugarcane bagasse valorization to lactic acid using pinch technology: Distillation vs. reactive distillation

S.K. Maity, D. Agrawal, S. Gadkari, K.R. Vanapalli, Y. Yong, D. Zhu, C. Chen, V. Kumar

ACS Sustainable Chemistry & Engineering 2025, 13, 6538−6553. https://doi.org/10.1021/acssuschemeng.5c00223 

Sugar cane is one of the largest agricultural crops, and sugar cane bagasse (SCB), a major waste from sugar cane processing, is an abundant and inexpensive source of fermentable sugars for producing diverse platform chemicals. The present study evaluates the technoeconomic viability of L (+) lactic acid (LA) production from SCB with different stand-alone process scenarios modeled using the pinch method. It critically evaluates various cost-contributing factors when a sugar-rich hydrolysate is obtained via two different pretreatment methods: dilute acid and alkali. The cost–benefit of LA purification by conventional distillation (CD) is further compared to reactive distillation (RD). The pinch method cuts the LA manufacturing costs by 10–11%. Alkali pretreatment combined with RD involves a lower capital investment and utility consumption than the CD counterpart and slightly less LA manufacturing cost. However, LA production via dilute acid pretreatment and purification by RD emerges as the most profitable scenario due to capital investment, utility demand, and chemical consumption savings. This scenario offers the minimum LA selling price of 2.3 US$/kg for an 8.5% discount factor and a 5 year payback period. However, for a 20 year plant life and 2.5 US$/kg factory-gate LA selling price, the internal rate of return was 31% and the payback period was 4.4 years for an 8.5% discount factor. 

Sustainable aviation fuel range branched alkanes via hydrodeoxygenation of furfural-derived trifurylmethane over mesoporous NiW-ZrO2 composite catalysts

Bhushan S. Shrirame, Sunil K. Maity

 Biomass and Bioenergy 2025, 196, 107759. https://doi.org/10.1016/j.biombioe.2025.107759

Sustainable aviation fuel (SAF) is vital to carbon neutrality in the air transportation sector. Branched alkanes are the most desirable in SAF due to their superior combustion properties and higher density than linear paraffin. The present study demonstrates a two-step process for manufacturing SAF-range C9-C15 branched alkanes from biomass-derived furanics: (i) production of C15 trifurylmethane from furfural and 2-methylfuran by hydroxyalkylation-alkylation reaction, followed by (ii) hydrodeoxygenation of trifurylmethane over mesoporous NiW-ZrO2 composite catalysts. Trifurylmethane deoxygenation involves ring saturation and ring opening initial steps, followed by parallel hydrodeoxygenation, decarbonylation, and cracking reactions. The catalytic activity of NiW-ZrO2 is strongly influenced by the evolution of acidic W-O-Zr species, metallic Ni, and NiW alloy. This study thus enlightens the significance of calcination temperatures, WO3 doping, and NiO loading in forming these species, the structural properties of NiW-ZrO2, and their influence on catalytic efficacy. Catalytic activity proliferates up to 1023 K calcination temperature and 10 wt% WO3 doping due to strong Ni-W synergy, evolving NiW alloy and acidic species. However, 1073 K calcination temperature and 15 wt% WO3 doping deteriorate catalytic activity because of the evolution of crystalline WO3 species and reduction in acidity. Catalytic performance further improves by rising NiO doping up to 10 wt% and deteriorates somewhat at 15 wt% due to the evolution of bulk NiO. The decarbonylation mechanism dominates at moderate reaction temperatures up to 573 K, with C14 being major alkane. However, the high reaction temperature favours lighter alkanes because of enhanced cracking reactions. 

A Comparative Techno-Economic Feasibility of Hydrogen Production from Sugarcane Bagasse and Bread Waste

Rendra Hakim Hafyan, Jhuma Sadhukhan, Vinod Kumar, Sunil K. Maity, Siddharth Balkrishna Gadkari

Fuel 2025, 388, 134469. https://doi.org/10.1016/j.fuel.2025.134469

An increase in the emphasis on sustainable energy solutions underscores a vital need for hydrogen as a clean, decarbonizing, and efficient energy carrier. This necessity is driving extensive research into alternative feedstocks for hydrogen production. Promising resources like sugarcane bagasse and bread waste, valued for their abundance and high sugar content, can be a promising feedstock for hydrogen. Processes, such as steam reforming of ethanol and aqueous-phase reforming of xylitol, effectively utilize sugarcane bagasse and bread waste to produce hydrogen, supporting a circular bioeconomy and reducing dependence on fossil fuels. This study aims to investigate the process design and techno-economic feasibility of hydrogen production from sugarcane bagasse and bread waste. Results show that sugarcane bagasse-based feedstock requires higher capital investment and annual operational costs, at 68.3 M$ and 24.3 M$ per year compared to bread waste-based feedstock, which involves 49.8 M$ and 18.74 M$ per year, respectively. Profitability analysis indicated that bread waste-based hydrogen production was more economically viable, with a higher net present value of 36.45 M$ and a higher internal rate of return of 17 %, along with a payback period of 11 years. A sensitivity analysis revealed that the selling price of hydrogen and fixed capital investment were the most influential parameters affecting the net present value. These findings highlight the economic advantages of utilizing bread waste over sugarcane bagasse, suggesting that bread waste is a more cost-effective and sustainable option for hydrogen production. By prioritizing bread waste as a feedstock, it is possible to achieve significant economic benefits, making it a strategic choice for future hydrogen production initiatives and advancing renewable energy technologies. 

 A Comprehensive Review of Approaches in Carbon Capture, and Utilization to Reduce Greenhouse Gases

Ijlal Raheem, Atthasit Tawai, Suksun Amornraksa, Malinee Sriariyanun, Ankit Joshi, Madhulika Gupta, Wasinee Pongprayoon, Debraj Bhattacharyya, Sunil K. Maity

Applied Science and Engineering Progress 2025, 18(2), 7629. https://doi.org/10.14416/j.asep.2024.11.004

Addressing atmospheric CO2 levels is crucial for mitigating global warming and promoting sustainable fossil fuel use. This review explores various CO2 capture strategies, including pre-combustion, post-combustion, oxy-fuel combustion, direct air capture, chemical looping, and polymeric membranes. Each strategy is critically evaluated in terms of its advantages, limitations, and overall effectiveness. Additionally, this study discusses advanced separation techniques for captured CO2, emphasizing recent innovations in membrane technology integrated with cryogenic processes. This integration has the potential to economically extract CO2 from diverse industrial processes, offering significant benefits in terms of operational cost reduction and increased efficiency. A detailed market analysis is also presented to explore feasible CO2 utilization options, highlighting potential incentives and motivations for capturing CO2. Furthermore, the technological readiness level of various capture and separation techniques is assessed, offering insights into their development and progress over time. This comprehensive analysis aims to support the advancement of effective and economically viable CO2 management solutions, contributing to a more sustainable and climate-resilient future. 

Mechanism-Based Thermodynamic Analysis for One-Step and Two-Step Ethanol-to-1,3-Butadiene Conversion Processes

Md Ziyaur Rahman, Abhishek R. Varma, Siddharth Gadkari, Atthasit Tawai, Malinee Sriariyanun, Vinod Kumar, Sunil K. Maity

Industrial & Engineering Chemistry Research 2024, 63 (47), 20697–20713. https://doi.org/10.1021/acs.iecr.4c02681

Renewable 1,3-butadiene (BD) is essential for sustainability of the synthetic rubber sector. This work presents a comprehensive thermodynamic analysis for one- and two-step ethanol-to-BD conversion processes. The two-step process comprises ethanol dehydrogenation, followed by the condensation of acetaldehyde with another ethanol molecule into BD. The process involves a complex reaction network with a wide range of byproducts depending on the nature of the catalysts and operating conditions, lacking unique consensus on the C–C bond-forming mechanism. This study elucidates the temperature regime for the spontaneity of the reactions proposed in various mechanisms and side reactions based on the standard Gibbs free energy change. The equilibrium conversion and product selectivity were further calculated under a wide temperature and pressure range. The overall reaction in the one-step process is thermodynamically spontaneous above 417 K, while the first and second steps of the two-step process are spontaneous above 550 and 285 K, respectively. Excepting Prins condensation, other mechanisms lack the spontaneity of all reaction steps. The equilibrium BD selectivity is favorable at elevated temperatures and low pressures. The addition of acetaldehyde in the two-step process has a favorable impact with higher BD selectivity, the maximum being at a 1:1 molar ratio of ethanol/acetaldehyde. This study elucidates thermodynamic insights into existing mechanisms and drives the evolution of a feasible mechanism. This effort will eventually help design novel catalysts and optimized processes for sustainable biobased BD production using ethanol derived from renewable feedstocks, aligning with the global commitment to greener and resource-friendly chemical manufacturing. 

Hydrodeoxygenation of stearic acid to produce green diesel over alumina supported CoMo catalysts: Role of Co/Mo mole ratio

Pankaj Kumar, Sunil K. Maity, Debaprasad Shee

Renewable Energy 2024, 237, 121700. https://doi.org/10.1016/j.renene.2024.121700

Alumina-supported CoMo catalyst is a potential alternative to precious metal-based catalysts for hydrodeoxygenation (HDO) of stearic acid to diesel-range hydrocarbons. The molar proportion of individual metals in bimetallic catalysts plays a vital role in forming various catalytically active species. This study thus elucidates the impact of the Co/Mo mole ratio on the efficacy of CoMo catalysts. The CoMo catalysts showed superior catalytic activity compared to the Co catalysts due to the synergistic interaction due to CoMo alloy. The Mo, Co, and mixed metal oxide were observed in CoMo catalysts after calcination. For 4.1 mmol metals per g of alumina, Mo and Co oxides were increased with increasing Mo and Co content, respectively. However, CoMoO4 was increased by increasing Mo loading up to 2.4 mmol Mo. Conversely, the reduced CoMo catalysts were gradually enriched with CoMo alloy with increasing Co content of up to 2.4 mmol Co and slightly declined for 3.1 mmol Co. The reaction follows the HDO mechanism over CoMo alloy and Co oxide resulting C18 hydrocarbon formation. The CoMo catalysts displayed enhanced catalytic performance at elevated temperatures and metal loadings, with insignificant effect on the alkane selectivity. The experimental results were also correlated by a suitable kinetic model. 

Comprehensive techno-economic and environmental assessment for 2,3-butanediol production from bread waste

Bikash R Tiwari, Sunil K. Maity, Satinder K Brar, Kit Wayne Chen, Gopalakrishnan Kumar, Vinod Kumar 

Chemical Engineering Journal 2024, 500, 157003. https://doi.org/10.1016/j.cej.2024.157003

Bread waste (BW) is a common food waste in Europe and North America and has enormous potential as a biorefinery substrate for the sustainable synthesis of various platform chemicals. Our previous work made use of BW for the fermentative production of 2,3–butanediol (BDO). The present work evaluated the economic prospects and environmental consequences associated with the overall processes, handling 100 metric tons BW per day. The comprehensive process design using Aspen Plus and integrated techno-economic and environmental assessment was carried out for two different BW hydrolysis scenarios: acid and enzyme hydrolysis, followed by fermentation and extraction-based downstream BDO separation. The optimal heat exchanger network was designed using pinch analysis, which improved the energy efficiency of the process significantly, with about 10 % savings of BDO production costs. Despite this improvement, the BDO derived from BW was exorbitant (4.2–6.9 $/kg) compared to the market price (3.23 $/kg) due to relatively higher capital investment for the current plant capacity. Further, the process inventory was modelled in SimaPro v9.1.0 to estimate the environmental consequences of these production processes for impact categories, such as global warming (2.63 – 3.19 kg CO2 eq.), marine eutrophication (3.55 × 10-4 – 4.01 × 10-4 kg N eq.), terrestrial ecotoxicity (6.44 – 7.88 kg 1,4 − DCB), etc. Sensitivity and uncertainty analyses were also conducted to establish the reliability of the results. It was found that the enzyme hydrolysis was associated with lower environmental impacts than acid hydrolysis. This comprehensive study can be used as a guideline for developing sustainable BW-based biorefinery in the future. 

Comparative Life Cycle Assessment of Glycerol Valorization Routes to 1,2- and 1,3-Propanediol Based on Process Modeling

Kumar Raja Vanapalli, Lourembam Nongdren, Sunil K. Maity, Vinod Kumar

ACS Sustainable Chemistry & Engineering 2024, 12 (40), 14716–14731. https://doi.org/10.1021/acssuschemeng.4c04691 

Crude glycerol, a high-volume byproduct of the biodiesel industry, has seen a significant surplus due to the industry’s rapid growth. It can be a promising feedstock for a range of high-value products via chemical and biochemical routes. This study thus elucidates the relative environmental performance of two prominent glycerol valorization technologies, i.e., catalytic hydrogenolysis to 1,2-propanediol and microbial fermentation (batch and fed-batch) to 1,3-propanediol, using a cradle-to-gate life cycle assessment (LCA). The LCA was performed using an experimental data-driven comprehensive process model to represent an industrial-scale biorefinery, handling 20 833 kg/h of glycerol. The LCA results identified cooling water (18–35.5%) and steam (15.2–33.7%) consumption in the distillation and glycerol sourcing (33.3–68.1%) as the critical environmental hotspots, which should be focused on while designing the process. The fed-batch fermentation process was environmentally more benign, with significantly lower environmental impacts than hydrogenolysis (by 35.2%) and batch fermentation (by 48.2%). Integrating effective process heat recovery using pinch technology reduced the overall environmental impacts by 4.9–11.2%. The environmental performance of the overall processes varied substantially (2.4–62.1%) with changes in glycerol sourcing and production methods. Therefore, energy and material recycling with sustainable water and glycerol sourcing can improve the sustainability of the overall process. 

Effective deep eutectic solvent pretreatment in one-pot lignocellulose biorefinery for ethanol production

Diana Jose, S. Vasudevan, P. Venkatachalam, Sunil K Maity, A. A. Septevan, M. Gupta, P. Tantayotai, H. El Bari, Malinee Sriaryanun

 Industrial Crops & Products 2024, 222, 119626. https://doi.org/10.1016/j.indcrop.2024.119626 

Deep eutectic solvents (DES) mediated pretreatment is a promising approach to enhance biofuel yield in lignocellulose biorefinery. However, post-pretreatment DES residues act as inhibitors for enzymatic saccharification requiring biomass washing, leading to significant water and energy consumption. This research aims to develop a novel one-pot method (OP) that eliminates the washing step for the environmentally benign production of lignocellulosic bioethanol from Napier grass. The process involves DES pretreatment using Choline Chloride (ChCl):Sorbitol (1:2), ChCl:Urea (1:2), and ChCl:Lactic acid (1:4), followed by enzymatic saccharification and fermentation with Saccharomyces cerevisiae. By optimizing pretreatment conditions using the OFAT method, the highest sugar yields for ChCl:Sorbitol (ChCl:S), ChCl:Urea (ChCl:U), and ChCl:Lactic acid (ChCl:LA) were increased by 1.92-fold, 1.93-fold, and 1.87-fold, respectively, compared to untreated biomass (at 205.6 mg/g). The effect of different concentrations of DES (0–10 % v/v) on cellulase enzyme and kinetic parameters, Km and Vm, were determined to understand the pattern of inhibition. The study revealed that DES at 5 % v/v minimized uncompetitive inhibition during saccharification after 1 h. There was no inhibition of yeast culture, as evidenced by the absence of inhibition zones. Ethanol analysis revealed significantly higher yields in the OP compared to the conventional approach. Particularly, with ChCl:LA, the ethanol yield reached 0.483 g/g-pretreated biomass, marking a noteworthy 2.42-fold increase compared to the separate hydrolysis and fermentation (SHF). Understanding the impact of pretreatment chemical residues on enzymatic saccharification and fermentation offers opportunities to optimize one-pot processes, leading to advancement in time savings, and the overall efficiency of lignocellulosic bioethanol production. 

Hydrodeoxygenation of C15 furanic precursor over mesoporous NiMo-ZrO2 composite catalysts for the production of sustainable aviation fuel

Bhushan S. Shrirame and Sunil K. Maity

Catalysis Today 2024, 442, 114917. https://doi.org/10.1016/j.cattod.2024.114917

Sustainable aviation fuel (SAF) is essential for achieving carbon neutrality in the transportation sector. This study elucidates the production of SAF range C9-C15 branched alkanes by hydrodeoxygenation (HDO) of C15 furanic precursor derived from 2-methylfuran and furfural via hydroxyalkylation-alkylation reaction. HDO reaction was performed using high surface area mesoporous NiMo-ZrO2 composite catalysts that exhibited high selectivity to central SAF alkanes (C13-C14). Deoxygenation follows a complex reaction network involving furanic double bond saturation and furan-ring opening reactions in series, followed by the cascade of HDO, dehydroformylation, and C-C bond cleavage. The present investigation enlightens the impact of calcination temperatures and metal (Mo and Ni) contents on structural stability, physicochemical properties, and catalytic performance of NiMo-ZrO2. Both Ni and Mo stabilized the tetragonal ZrO2 phases with improved surface area. The catalytic activity proliferated with rising calcination temperature till 873 K due to the enrichment of Mo-O-Zr acidic species and deteriorated beyond this temperature owing to the generation of crystalline MoO3/Zr(MoO4)2 species. NiMo alloy formation was enhanced, and concurrently, acidity was reduced with increasing Mo content. 30 wt% MoO3-containing catalyst showed the best catalytic activity due to the proper balance between acidity and NiMo alloy. Oxygenate conversion was boosted by increasing NiO addition up to 15 wt% due to the enhanced Ni and NiMo alloy formation and decreased at 20 wt% owing to the evolution of catalytically inactive bulk metal oxide species. Catalytic cracking was prominent at elevated reaction temperatures, with significant amounts of C13 alkane. 

Techno-Economic Viability of Bio-Based Methyl Ethyl Ketone from Sugarcane Using Integrated Fermentative and Chemo-Catalytic Approach: Process Integration Using Pinch Technology

Abishek R. Varma, Bhushan Shrirame, Siddharth Gadkari, Kumar Raja Vanapalli, Vinod Kumar, Sunil K. Maity

Chemical Engineering Journal 2024, 489, 151297.  https://doi.org/10.1016/j.cej.2024.151297 

Butanediols are versatile platform chemicals that can be transformed into a spectrum of valuable products. This study examines the techno-commercial feasibility of an integrated biorefinery for fermentative production of 2,3-butanediol (BDO) from sucrose of sugarcane (SC), followed by chemo-catalytic upgrading of BDO to a carbon-conservative derivative, methyl ethyl ketone (MEK) with established commercial demand. The techno-economics of three process configurations are compared for downstream MEK separation from water and co-product, isobutyraldehyde (IBA): (I) heterogeneous azeotropic distillation of MEK-water and extractive separation of (II) MEK and (III) MEK-IBA from water using p-xylene as a solvent. The thermal efficiency of these manufacturing processes is further improved using pinch technology. The implementation of pinch technology reduces 8% of BDO and 9–10% of MEK production costs. Despite these improvements, raw material and utility costs remain substantial. The capital expenditure is notably higher for MEK production from SC than BDO alone due to additional processing steps. The extraction based MEK separation is the simplest process configuration despite marginally higher capital requirements and utility consumption with slightly higher production costs than MEK-water azeotropic distillation. Economic analysis suggests that bio-based BDO is cost-competitive with its petrochemical counterpart, with a minimum gross unitary selling price of US$ 1.54, assuming a 15% internal rate of return over five-year payback periods. However, renewable MEK is approximately 16–24% costlier than the petrochemical route. Future strategies must focus on reducing feedstock costs, improving BDO fermentation efficacy, and developing a low-cost downstream separation process to make renewable MEK commercially viable. 

Recent Advances in Bio-based Production of Top Platform Chemical, Succinic acid: An Alternative to Conventional Chemistry

Vinod Kumar, Pankaj Kumar, Sunil K. Maity, Deepti Agrawal, Vivek Narisetty, Samuel Jacob, Gopalakrishnan Kumar, Shashi Kant Bhatia, Dinesh Kumar, Vivekanand Vivekanand

Biotechnology for Biofuels and Bioproducts 2024, 17, 72. https://doi.org/10.1186/s13068-024-02508-2

Succinic acid (SA) is one of the top platform chemicals with huge applications in diverse sectors. The presence of two carboxylic acid groups on terminal carbon atoms makes SA a highly functional molecule than can be derivatized into a wide range of products. The biological SA production route is a cleaner, greener, and promising technological option with huge potential to sequester the potent greenhouse gas, carbon dioxide. The recycling of renewable carbon of biomass (an indirect form of CO2), along with fixing CO2 in the form of SA, offers a carbon-negative SA manufacturing route to reduce atmospheric CO2 load. These attractive attributes mandate a paradigm shift from fossil-based to microbial SA manufacturing, as evidenced by several commercial-scale production of bio-SA in the last decade. The current review article scrutinizes the existing knowledge and covers SA production by the most efficient SA producers, including several bacteria and yeast strains. The review starts with the biochemistry of the major pathways accumulating SA as an end product. It discusses the SA production from a variety of pure and crude renewable sources by native as well as engineered strains with details of pathway/metabolic, evolutionary, and process engineering approaches employed for enhancing TYP (titer, yield, and productivity) metrics. The review is then extended to recent progress on separation technologies to recover SA from fermentation broth. Thereafter, SA derivatization opportunities via chemo-catalysis are discussed for various high-value products, which are only a few steps away. The last two sections are devoted to the current scenario of industrial production of bio-SA and associated challenges, along with the author's perspective.

AOPC-Based Control for Efficient Uncertainty Mitigation in UASB Wastewater Treatment with Multiple Manipulated Variables and Distributed Biomass Integration

Suksun Amornraksa, Chanin Panjapornpon, Sunil K Maity, Malinee Sriariyanun, Atthasit Tawai 

Computers & Chemical Engineering 2024, 108735.

https://doi.org/10.1016/j.compchemeng.2024.108735

This study proposes an adaptive optimal predictive control (AOPC) for the upflow anaerobic sludge blanket (UASB) reactor with recirculation, employing a PDE-ODE system. Effectively addressing complexity and uncertainties associated with Danckwerts-boundary conditions and biomass distribution, an analytical model predictive control scheme incorporates adaptive set points and compensators. By dynamically adjusting multiple manipulated inputs, including the feed flow rate and recirculation-to-feed ratio, the controller achieves precise effluent concentration control. The robustness of the control system is investigated through fluctuations in inlet concentrations (15–30 %) and variations in bacterial growth rates (10–30 %). The control performance index, ISE, indicates that the AOPC-based control system outperforms the PI controller by 28–150 times for inlet concentration variations and 3–84 times for growth rate changes. With a settling time of 1–3 days, the proposed system excels over the conventional controller, which consistently struggles to maintain the target, emphasizing its inherent robustness.  

Recent advances in fermentative production of C4 diols and their chemo-catalytic upgrading to high-value chemicals

Abhishek R Varma, Bhushan S Shrirame, Sunil K Maity, Deepti Agrawal, Naglis Malys, Leonardo Rios-Solis, Gopalakrishnan Kumar, Vinod Kumar

Chinese Journal of Catalysis 2023, 52, 99-126.

The current era is witnessing the transition from a fossil-dominated economy towards sustainable and low-carbon green manufacturing technologies at economical prices with reduced energy usage. The biological production of chemical building blocks from biomass using cell factories is a potential alternative to fossil-based synthesis. However, microbes have their own limitations in generating the whole spectrum of petrochemical products. Therefore, there is a growing interest in an integrated/hybrid approach where products containing active functional groups obtained by biological upgrading of biomass are converted via chemo-catalytic routes. The present review focuses on the biological production of three important structural isomers of C4 diols, 2,3-, 1,3-, and 1,4-butanediol, which are currently manufactured by petrochemical route to meet the soaring global market demand. The review starts with justifications for the integrated approach and summarizes the current status of the biological production of these diols, including the substrates, microorganisms, fermentation technology and metabolic/pathway engineering. This is followed by a comprehensive review of recent advances in catalytic upgrading of C4 diols to generate a range of products. The roles of various active sites in the catalyst on catalytic activity, product selectivity, and catalyst stability are discussed. The review also covers examples of integrated approaches, addresses challenges associated with developing end-to-end processes for bio-based production of C4 diols, and underlines existing limitations for their upgrading via direct catalytic conversion. Finally, the concluding remarks and prospects emphasise the need for an integrated biocatalytic and chemo-catalytic approach to broaden the spectrum of products from biomass. 

One-Step Conversion of n‑Butanol to Aromatics-free Gasoline over the HZSM‑5 Catalyst: Effect of Pressure, Catalyst Deactivation, and Fuel Properties as a Gasoline

Venkata Chandra Sekhar Palla, Debaprasad Shee, Sunil K. Maity, Srikanta Dinda

Acs Omega 2023, 8, 43739–43750.

Sustainable production of gasoline-range hydrocarbon fuels from biomass is critical in evading the upgradation of combustion engine infrastructures. The present work focuses on the selective transformation of n-butanol to gasoline-range hydrocarbons free from aromatics in a single step. Conversion of n-butanol was carried out in a down-flow fixed-bed reactor with the capability to operate at high pressures using the HZSM-5 catalyst. The selective transformation of n-butanol was carried out for a wide range of temperatures (523–563 K), pressures (1–40 bar), and weight hourly space velocities (0.75–14.96 h–1) to obtain the optimum operating conditions for the maximum yields of gasoline range (C5–C12) hydrocarbons. A C5–C12 hydrocarbons selectivity of ∼80% was achieved, with ∼11% and 9% selectivity to C3–C4 paraffin and C3–C4 olefins, respectively, under optimum operating conditions of 543 K, 0.75 h–1, and 20 bar. The hydrocarbon (C5–C12) product mixture was free from aromatics and primarily olefinic in nature. The distribution of these C5–C12 hydrocarbons depends strongly on the reaction pressure, temperature, and WHSV. These olefins were further hydrogenated to paraffins using a Ni/SiO2 catalyst. The fuel properties and distillation characteristics of virgin and hydrogenated hydrocarbons were evaluated and compared with those of gasoline to understand their suitability as a transportation fuel in an unmodified combustion engine. The present work further delineates the catalyst stability study for a long time-on-stream (TOS) and extensive characterization of spent catalysts to understand the nature of catalyst deactivation. 

Life cycle assessment of fermentative production of lactic acid from bread waste based on process modelling using pinch technology 

Kumar Raja Vanapalli, Rajarshi Bhar, Sunil K. Maity, Brajesh K. Dubey, Sandeep Kumar, Vinod Kumar 

Science of the Total Environment 2023, 905, 167051.

Bread waste (BW), a rich source of fermentable carbohydrates, has the potential to be a sustainable feedstock for the production of lactic acid (LA). In our previous work, the LA concentration of 155.4 g/L was achieved from BW via enzymatic hydrolysis, which was followed by a techno-economic analysis of the bioprocess. This work evaluates the relative environmental performance of two scenarios - neutral and low pH fermentation processes for polymer-grade LA production from BW using a cradle-to-gate life cycle assessment (LCA). The LCA was based on an industrial-scale biorefinery process handling 100 metric tons BW per day modelled using Aspen Plus. The LCA results depicted that wastewater from anaerobic digestion (AD) (42.3–51 %) and cooling water utility (34.6–39.5 %), majorly from esterification, were the critical environmental hotspots for LA production. Low pH fermentation yielded the best results compared to neutral pH fermentation, with 11.4–11.5 % reduction in the overall environmental footprint. Moreover, process integration by pinch technology, which enhanced thermal efficiency and heat recovery within the process, led to a further reduction in the impacts by 7.2–7.34 %. Scenario and sensitivity analyses depicted that substituting ultrapure water with completely softened water and sustainable management of AD wastewater could further improve the environmental performance of the processes.

Techno-commercial viability of glycerol valorization to 1,2- and 1,3-propanediol using pinch technology

Bhushan S. Shrirame, Abhishek R. Varma, Swagat Sabyasachi Sahoo, Kalyan Gayen, Sunil K. Maity

Biomass and Bioenergy 2023, 177, 106943

Glycerol is a low-value by-product in biodiesel industries and an important platform chemical in biorefinery with vast derivative potentials. 1,2- and 1,3-Propanediol (PDO) are vital polymer precursors. Valorizing glycerol to PDOs is thus a promising approach for producing renewable chemicals and improving the economics of biodiesel industries. Therefore, this work demonstrated the techno-economic feasibility of PDOs for 100–2000 metric tons per day glycerol feed rate. 1,2-PDO was produced by selective hydrogenolysis of glycerol, while microbial batch and fed-batch fermentation of glycerol was considered for manufacturing 1,3-PDO with the co-production of 2,3-butanediol and ethanol. Pinch analysis was applied for process integration that reduced utility demands by around 19% for 1,2-PDO and 12–16% for 1,3-PDO. However, utilities were still major operating costs in these processes. Besides, utility consumptions and capital expenditures were considerably higher for 1,3-PDO by batch fermentation than 1,2-PDO due to low glycerol concentration (50 g/L). 1,3-PDO production cost (USD 3.42/kg) by batch fermentation was thus much more than 1,2-PDO (USD 0.98/kg). The minimum unitary selling price was USD 1.15 for 1,2-PDO and USD 4.90 for 1,3-PDO (batch) for 8.5% rate of return and five years payback period. However, the microbial 1,3-PDO produced by fed-batch fermentation was economically viable, with USD 0.78 and USD 1.02 as unitary production costs and minimum selling price.

Lactic acid and biomethane production from bread waste: A techno-economic and profitability analysis using pinch technology

Swarnalatha Mailaram, Vivek Narisetty, Sunil K. Maity, Siddharth Gadkari, Vijay Kumar Thakur, Stephen Russell, Vinod Kumar 

Sustainable Energy & Fuels  7, 2023, 3034-3046. 

Lactic acid (LA) is a vital platform chemical with diverse applications, especially for biodegradable polylactic acid. Bread waste (BW) is sugar-rich waste biomass generated in large quantities in residential and commercial operations. Recently, we evaluated the potential of BW for LA production by Bacillus coagulans under non-sterile conditions. This work presents a techno-economic and profitability analysis for valorizing 100 metric tons of BW per day to alleviate environmental pollution with concurrent production of LA and biomethane. We compared two fermentation approaches: acid-neutral (Scenario I) and low pH (Scenario II). Traditional esterification with methanol, followed by hydrolysis of methyl lactate, was employed for downstream separation to obtain polymer-grade LA. High-pressure steam was generated from solid debris via anaerobic digestion to complement energy demands partly. Energy consumption was further attenuated by process integration using pinch technology, with around 15% and 11% utility cost savings for Scenario I and II, respectively. These processes were capital-intensive, with 42–46% of LA production cost stemming from direct and indirect costs. Utilities were the major cost-contributing factor (19–21%) due to energy-intensive water evaporation from dilute fermentation broth. Due to additional processing steps, capital investment and operating costs were slightly higher in Scenario I than in Scenario II. LA manufacturing cost was thus more for Scenario I ($2.07 per kg) than Scenario II ($1.82 per kg). The minimum LA selling price for Scenario I and II were $3.52 and $3.22 per kg, respectively, with five-year payback periods and 8.5% internal rates of return. LA was slightly more expensive for decentralized BW processing than the market price. 

Life Cycle Assessment of Microbial 2,3-Butanediol Production from Brewer’s Spent Grain Modeled on Pinch Technology

Bikash Ranjan Tiwari, Rajarshi Bhar, Brajesh Kumar Dubey, Sunil K. Maity, Satinder Kaur Brar, Gopalakrishnan Kumar, Vinod Kumar

ACS Sustainable Chemistry & Engineering 2023, 11 (22), 8271–8280.

Microbial production of 2,3-butanediol (BDO) has received considerable attention as a promising alternate to fossil-derived BDO. In our previous work, BDO concentration >100 g/L was accumulated using brewer’s spent grain (BSG) via microbial routes which was followed by techno-economic analysis of the bioprocess. In the present work, a life cycle assessment (LCA) was conducted for BDO production from the fermentation of BSG to identify the associated environmental impacts. The LCA was based on an industrial-scale biorefinery processing of 100 metric tons BSG per day modeled using ASPEN plus integrated with pinch technology, a tool for achieving maximum thermal efficiency and heat recovery from the process. For the cradle-to-gate LCA, the functional unit of 1 kg of BDO production was selected. One-hundred-year global warming potential of 7.25 kg CO2/kg BDO was estimated while including biogenic carbon emission. The pretreatment stage followed by the cultivation and fermentation contributed to the maximum adverse impacts. Sensitivity analysis revealed that a reduction in electricity consumption and transportation and an increase in BDO yield could reduce the adverse impacts associated with microbial BDO production. 

Techno-Economic Analysis of 2,3-Butanediol Production from Sugarcane Bagasse 

Siddharth Gadkari, Vivek Narisetty, Sunil K. Maity, Haresh Manyar, Kaustubha Mohanty, Rajesh Banu Jeyakumar, Kamal Kishore Pant, Vinod Kumar

ACS Sustainable Chemistry & Engineering 2023, 11(22), 8337–8349.

Sugarcane bagasse (SCB) is a significant agricultural residue generated by sugar mills based on sugarcane crop. Valorizing carbohydrate-rich SCB provides an opportunity to improve the profitability of sugar mills with simultaneous production of value-added chemicals, such as 2,3-butanediol (BDO). BDO is a prospective platform chemical with multitude of applications and huge derivative potential. This work presents the techno-economic and profitability analysis for fermentative production of BDO utilizing 96 MT of SCB per day. The study considers plant operation in five scenarios representing the biorefinery annexed to a sugar mill, centralized and decentralized units, and conversion of only xylose or total carbohydrates of SCB. Based on the analysis, the net unit production cost of BDO in the different scenarios ranged from 1.13 to 2.28 US$/kg, while the minimum selling price varied from 1.86 to 3.99 US$/kg. Use of the hemicellulose fraction alone was shown to result in an economically viable plant; however, this was dependent on the condition that the plant would be annexed to a sugar mill which could supply utilities and the feedstock free of cost. A standalone facility where the feedstock and utilities were procured was predicted to be economically feasible with a net present value of about 72 million US$, when both hemicellulose and cellulose fractions of SCB were utilized for BDO production. Sensitivity analysis was also conducted to highlight some key parameters affecting plant economics. 

Production of green jet fuel from furanics via hydroxyalkylation-alkylation over mesoporous MoO3-ZrO2 and hydrodeoxygenation over Co/γ-Al2O3: Role of calcination temperature and MoO3 content in MoO3-ZrO2

Alekhya Kunamalla, Sunil K.Maity 

Fuel 332, 2023, 125977

Green biofuels are equivalent to hydrocarbon-based motor fuels and compatible with existing refinery infrastructures and combustion engines. Therefore, sustainable production of green biofuels is essential to circumvent the construction of expensive biorefinery infrastructures. This study thus presents the production of green jet fuel from biomass-derived furanic compounds via hydroxyalkylation-alkylation (HAA) reaction coupled with hydrodeoxygenation (HDO) of the C15 biofuel precursor. MoO3-promoted ZrO2 is a promising solid acid catalyst with excellent thermal stability. The HAA reaction of 2-methylfuran with furfural was thus investigated over a novel MoO3-promoted mesoporous ZrO2 catalyst. This work elucidated the role of calcination temperature and MoO3 loading on the structural variation of MoO3-promoted mesoporous ZrO2 and the evolution of acid sites. The highest acid density and consequently best catalytic performance was observed at 873 K calcination temperature with 20 wt% MoO3 loading. About 85 % 2-methylfuran conversion was achieved over 1.25 g of this optimum catalyst at 2:1 2-methylfuran/furfural mole ratio, 323 K, and 5 h. The HAA reaction was further investigated at various reaction temperatures, catalyst loadings, and 2-methylfuran/furfural mole ratios to obtain optimum reaction conditions. HDO of biofuel precursor was examined over Co/γ-Al2O3 catalyst at various reaction temperatures, initial hydrogen pressure, and Co metal loading on γ-Al2O3 to understand the reaction mechanism and identify the optimum reaction conditions. HDO of biofuel precursor progressed through successive furan ring saturation and opening reactions, followed by a combination of HDO, decarbonylation, and cleavage of tertiary-carbon bonds. C9-C15 alkanes were observed as products, with C11 and C14 hydrocarbons being dominant at 573 K and 30 bar. The elevated hydrogen pressure and reaction temperature boosted the conversion of oxygen-containing intermediate compounds at the cost of CC cracking reactions. The conversion of oxygen-containing intermediate compounds was enhanced with rising Co metal loading on γ-Al2O3 up to 20 wt% due to the enhancement of metal dispersion.

Techno-economic analysis for the production of 2,3-butanediol (BDO) from brewers’ spent grain (BSG) using pinch technology

 Swarnalatha Mailaram, V. Narisetty, V.V. Ranade, V. Kumar, Sunil K. Maity*

Industrial & Engineering Chemistry Research 2022, 61(5), 2195-2205.

 2,3-Butanediol (BDO) is a versatile platform chemical with great potentials as the precursor for various value-added derivatives across different industrial sectors. This work thus presents a techno-economic feasibility study for microbial BDO production from C5 and C6 sugars derived from brewers’ spent grain (BSG). Water-soluble carbohydrates obtained from pretreatment were further utilized for the biogas generation. Besides, the solid residue generated after fermentation and biogas were used to generate high-pressure steam and electricity. The process integration was carried out using pinch technology for various BDO titers and plant capacities. The pinch analysis helped in the reduction of hot and cold utility consumption by about 34% and 18%, respectively. The minimum hot and cold utility consumption was 4.59 MW and 10.97 MW for 100 MT BSG per day with 100 g/L BDO titer, respectively. The cooling water consumption was decreased, and electricity generation was increased with increase in BDO titer while BDO production cost reduced marginally. For 100 MT BSG per day, the BDO production cost was US$1.84, US$1.76, and US$1.74/kg for BDO titers of 80, 100, and 120 g/L, respectively. However, the unitary BDO production cost was only US$1.07 for 2000 MT BSG per day. For 100 g/L BDO titer, the minimum selling price was US$3.63 and US$2.00/kg of BDO for 100 and 2000 MT BSG per day, respectively, with 8.5% return on investment and five years as the payback period.

Dual liquid–liquid extraction versus distillation for the production of bio-butanol from corn, sugarcane, and lignocellulose biomass: A techno-economic analysis using pinch technology

SwarnalathaMailaram and Sunil K.Maity*

Fuel 2022, 312, 122932.

n-Butanol has emerged as a potential biofuel and promising feedstock for organic chemicals. This study presents a techno-economic comparison of dual liquid–liquid extraction (LLE) with distillation for manufacturing 10,000 MT bio-butanol per annum from corn, sugarcane, and lignocellulose biomass using pinch technology. The energy consumption per kg of bio-butanol was lower in dual LLE than distillation. However, the dual LLE involves the complex recovery of extractants with high capital investment and utility consumption. The bio-butanol production cost was thus slightly higher for dual LLE than distillation. Despite the high capital investment, the bio-butanol production cost was much lower for lignocellulose biomass than corn and sugarcane due to cheaper feedstock and higher co-product credit. The production cost was, however, higher for corn compared to sugarcane due to higher feedstock cost, additional enzymatic hydrolysis step, and extra cost for enzymes and nutrients. The production cost per kg of bio-butanol from corn, sugarcane, and lignocellulose biomass was USD 1.50, USD 1.11, and USD 0.65 for distillation and USD 1.59, USD 1.19, and USD 0.74 for dual LLE, respectively. The feedstock contributed 53–70% of the production cost with ∼130%, ∼60%, and ∼40% contribution of co-product credit for lignocellulose biomass, sugarcane, and corn, respectively. The profitability analysis was further carried out to obtain the minimum bio-butanol selling price.

Production of jet fuel-range hydrocarbon biofuel by hydroxyalkylation-alkylation of furfural with 2-methylfuran and hydrodeoxygenation of C15 fuel precursor over Ni/γ-Al2O3 catalyst: A reaction mechanism

Alekhya Kunamalla,  Bhushan S. Shrirame and  Sunil K. Maity*  

Energy Adv., 2022, 1, 99-112.

This study presents manufacturing jet fuel-range (C9-C15) hydrocarbon biofuels from 2-methylfuran and furfural. The process involves hydroxyalkylation-alkylation reaction, followed by hydrodeoxygenation of the C15 fuel precursor. Hydroxyalkylation-alkylation reaction was investigated under various cation exchange resin loading, furfural/2-methylfuran molar ratio, and reaction temperatures. Hydroxyalkylation-alkylation reaction results were further corroborated by an appropriate kinetic model. Hydrodeoxygenation proceeds via the sequential furan ring-hydrogenation and ring-opening reactions, followed by the combination of dehydroformylation, hydrodeoxygenation, and cracking reactions. The dehydroformylation reaction was the leading pathway over Ni/γ-Al2O3 catalyst, forming mainly C14H30 alkane. The oxygenates conversion was boosted with rising hydrogen pressure, Ni metal content on γ-Al2O3, and reaction temperatures. Both hydrodeoxygenation and hydrogenation reactions proliferated at elevated hydrogen pressure with the enrichment of the C15 alkane and ring-opening and ring-hydrogenation products. The cracking, ring-opening, and ring-hydrogenation reactions were promoted at elevated reaction temperatures with a significant amount of lighter alkanes.

Role of CeO2/ZrO2 mole ratio and nickel loading for steam reforming of n-butanol using Ni–CeO2–ZrO2–SiO2 composite catalysts: A reaction mechanism

M Varkolu, Alekhya Kunamalla, SAK Jinnala, P Kumar, Sunil K Maity*, D Shee

International Journal of Hydrogen Energy 2021,46, 7320-7335.

This study presents steam reforming of n-butanol to synthesis gas using high surface area mesoporous Ni–CeO2–ZrO2–SiO2 composite catalysts. The reaction proceeds through a combination of dehydrogenation, dehydration, and cracking reactions with propanal, butanal, and C2–C4 hydrocarbons as intermediate compounds. The ceria forms a solid solution with zirconia, promotes dispersion of nickel, and enhances oxygen storage/release capacity. The carbon conversion to synthesis gas (CCSG) and hydrogen yield are thus enhanced with increasing CeO2/ZrO2 mole ratio up to 1:2 and decreased slightly for higher mole ratios. The CCSG and hydrogen yield are also boosted by increasing the amount of nickel in the catalyst up to 20 wt%. 1:2 CeO2/ZrO2 mole ratio and 20 wt% nickel content are thus deliberated as optimum. The optimum catalyst exhibits stable catalytic performance for about 30 h time-on-stream. The study further presents the effect of temperature and steam/carbon mole ratio on n-butanol steam reforming.

Keywords: Bio-butanol; Mesoporous Ni–CeO2–ZrO2–SiO2; Steam reforming; Synthesis gas

Techno-economic Analysis for Production of Biodiesel and Green Diesel from Microalgal Oil

S Mailaram, N Dobhal, SK Maity*

Springer Proceedings in Energy 2021, 1465-1475.

Microalgae has massive potential for the production of biofuels. Thermochemical conversion of microalgal oil is the potential route to produce diesel-range biofuels. This work provides the process design using Aspen Plus and economic analysis for transesterification and hydrodeoxygenation of microalgal oil to produce biodiesel and green diesel, respectively. In the present study, the microalgal oil derived from Nannochloropsis salina is considered as feedstock. Capital, operating expenses and the manufacturing cost of the biodiesel and green diesel have been estimated for various plant capacities ranging from 0.05 to 0.15 million metric ton microalgal oil per annum. The effect of plant capacity and different cost-contributing factors on the manufacturing cost of biodiesel and green diesel has also been studied. The manufacturing cost of diesel oil-equivalent biodiesel and green diesel was USD 4.425 and USD 4.294 per kg, respectively, for 0.125 million metric ton microalgal oil per annum.

Keywords:Techno-economic analysis Microalgal oil Biodiesel Green diesel

Production of Aromatics from n-Butanol over HZSM-5, H-β, and γ-Al2O3: Role of Silica/Alumina Mole Ratio and Effect of Pressure

VCS Palla, D Shee, and SK Maity

ACS Sustainable Chem. Eng. 2020, 8, 40, 15230–15242.

The production of aromatics from biomass is very much essential to address the sustainability issue of human civilization. The present work proposed a novel process for aromatics production from n-butanol (BTA) using various solid acid catalysts (HZSM-5, H-β, and γ-Al2O3) in a high-pressure fixed-bed reactor. γ-Al2O3 is associated with Lewis acid sites only and hence selective toward butylenes. H-β showed lower selectivity toward aromatics and benzene–toluene–ethylbenzene–xylene (BTEX) compared to HZSM-5 because of rapid catalyst deactivation. The selectivity to aromatics was strongly dependent on the silica/alumina (Si/Al) mole ratio of HZSM-5. The highest selectivity to aromatics was observed over HZSM-5 (Si/Al = 55) because of the presence of an optimum quantity of Brønsted acid sites and organic radicals. The aromatics and BTEX selectivity improved with increasing operating pressure up to 20 bar and reduced slightly at higher pressure. The aromatics and BTEX selectivity, however, declined with increasing weight hourly space velocity (WHSV) and enhanced with increasing temperature up to 623 K. The maximum aromatics selectivity was 49.2% with 29.4% BTEX over HZSM-5 (Si/Al = 55) under optimum reaction conditions: 20 bar, 623 K, and 0.75 h–1 WHSV. A comprehensive reaction mechanism was further delineated correlating variation of product distribution obtained over a broad range of process conditions.

Hydrodeoxygenation of karanja oil using ordered mesoporous nickel-alumina composite catalysts

SR Yenumala, P Kumar, SK Maity*, D Shee

Catalysis Today 348, 2020, 45-54.

This study presents a systematic investigation of hydrodeoxygenation (HDO) of karanja oil over ordered mesoporous nickel-alumina composite catalysts. These catalysts were prepared by the evaporation-induced self-assembly method. The catalysts showed the ordered mesoporous structure up to 15 wt% nickel content in the catalyst. The mesoporous structure, however, became disorder beyond this nickel content. The catalysts were associated with catalytically active dispersed tetrahedral (or octahedral) coordinated nickel aluminate with strong interaction with alumina and a negligible amount of catalytically poor extra-framework nickel. The mesoporous nickel-alumina composite catalysts thus demonstrated superior catalytic activity compared to mesoporous alumina and γ-Al2O3 supported nickel catalysts. Wide ranges of linear paraffins (C14-C22) were formed in the reaction with C17 alkane as the main product. The conversion of oxygenates was enhanced with the rise in initial hydrogen pressure and nickel content in the catalyst without affecting product distribution much. The cracking of heavy hydrocarbons was, however, significant at elevated reaction temperatures, resulting in high selectivity to C17 alkane. For the optimum nickel loading of 20 wt%, the conversion of oxygenates was almost 100% with about 70 wt% C17 alkane and 15 wt% each lower and higher than C17 alkanes at 633 K and 2 h reaction time.

Keywords: Mesoporous nickel-alumina catalyst; Evaporation-induced self-assembly method; Composite catalyst; Hydrodeoxygenation; Karanja oil; Green diesel

Hydrodeoxygenation of stearic acid using Mo modified Ni and Co/alumina catalysts: Effect of calcination temperature

Pankaj Kumar, Sunil K. Maity*, D Shee

Chemical Engineering Communications 207, 2020, 904-919.

The calcination temperature (Cal-Temp) plays a vital role in the performance of supported metal catalysts. In this work, the alumina supported Ni, NiMo, Co, and CoMo catalysts were prepared at different Cal-Temp. The catalysts were characterized by various techniques to identify the catalytically active different surface species to correlate their role in the hydrodeoxygenation of stearic acid. With increasing Cal-Temp, the metal dispersion was increased for Ni, NiMo, and CoMo catalyst (up to 973 K) and decreased for Co catalyst. With increasing Cal-Temp, the catalytic activity was thus increased for Ni and NiMo catalyst and decreased for Co catalyst. The activity of CoMo catalyst was, however, enhanced with rising Cal-Temp up to 973 K and declined slightly after that. The optimum Cal-Temp for Ni, NiMo, Co, and CoMo catalyst was found to be 1023 K, 973 K, 773 K, and 973 K. The reaction followed the decarbonylation route over active metallic centers (Ni and Co) and the HDO route over oxophilic M2+⋅MoO2 (M = Ni/Co) and reducible cobalt oxide species. The C17 alkane was thus the principal product over Ni catalyst, whereas C18 alkane was the primary product over CoMo and NiMo catalyst. In contrast, both C17 and C18 alkanes were significant over Co catalyst.

Keywords: Calcination temperature; Green diesel; Hydrodeoxygenation; Ni, NiMo, Co and CoMo catalyst; Stearic acid

Production of green diesel from karanja oil (Pongamia pinnata) using mesoporous NiMo-alumina composite catalysts

Sudhakara Reddy Yenumala, Pankaj Kumar, Sunil K Maity*, D Shee

Bioresource Technology Reports 7, 2019, 100288.

NiMo-alumina catalysts with a small quantity of Mo showed ordered mesoporous structure. For 4.3 mmol total metals content, mesoporous structure, however, became disorder for 1.7 mmol and higher Mo content. The C18 alkane was the leading product among hydrocarbons (C15–C22) formed during hydrodeoxygenation of karanja oil. The catalytically active NiMo complex and Mo oxide species with lower oxidation states were substantial in NiMo catalysts with the modest quantity of both Mo and Ni and relatively small for the other two extremes. The catalytic activity and selectivity to C18 alkane were thus enhanced with the rise in Mo content up to 3.4 mmol. The catalytic activity was also improved with growing total metals content and temperature. The optimum catalyst (0.9 mmol Ni and 3.4 mmol Mo) showed the complete conversion of oxygenates with 13 wt% < C18, 75 wt% C18, and 12 wt% > C18 alkanes at 340 °C and 4 h reaction.

Keywords: Green diesel; Hydrodeoxygenation; Karanja Oil; NiMo-alumina; Mesoporous catalysts

Near-Room-Temperature Synthesis of Sulfonated Carbon Nanoplates and Their Catalytic Application

Devarakonda Damodar, Alekhya Kunamalla, Mohan Varkolu, Sunil K. Maity, and Atul S. Deshpande

ACS Sustainable Chem. Eng. 2019, 7, 15, 12707–12717.

We demonstrate a unique one-pot synthesis approach to obtain sulfonated carbon nanoplates having elongated hexagonal morphology (S-ECN). The S-ECN was synthesized by dehydration of recrystallized sucrose and sodium chloride mixed crystals with concentrated sulfuric acid under ambient conditions. No additional heat treatment or elaborate experimental setup was necessary to obtain graphitic carbon nanoplates. Scanning electron microscopy (SEM) studies showed that the presence of NaCl and recrystallization conditions played a crucial role in crystal habit modification of sucrose during recrystallization. Consequently, initial morphology of sucrose crystals was largely preserved in resultant carbon nanostructures. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy studies showed that S-ECN was partially graphitic with wider interplanar spacing compared to standard graphite. The elemental analysis (CHNS) and Fourier transform infrared (FTIR) spectroscopic studies confirm the presence of sulfur in the form of −SO3H group. The catalytic performance of the S-ECN was studied for hydroxyalkylation–alkylation (HAA) reaction of 2-methylfuran with furfural to produce C15 oxygenated hydrocarbon. The S-ECN showed up to 90% conversion of 2-methylfuran. Additionally, an empirical kinetic model was developed to obtain rate constant of HAA reaction and to correlate 2-methylfuran conversion under various reaction conditions. The experimental results matched reasonably well with the calculated 2-methylfuran conversion.

Keywords: Sucrose, Recrystallization, Dehydration, Sulfonated carbon nanoplates, Catalytic activity

Techno-economic evaluation of two alternative processes for production of green diesel from karanja oil: A pinch analysis approach

Swarnalatha Mailaram and Sunil K. Maity*

Journal of Renewable and Sustainable Energy 11, 2019, 025906.

Hydrodeoxygenation (HDO) of vegetable oil is a potential technology for the production of green diesel for direct application in unmodified combustion engines. This study provides the conceptual process design for HDO of karanja oils by two different routes: (i) direct HDO of vegetable oils (direct HDO) and (ii) HDO of fatty acids derived from hydrolysis of vegetable oils (two-step HDO). Pinch analysis was carried out to obtain energy targets and the maximum level of heat recovery and to design the heat exchange network. An economic analysis was then performed using USD 0.5 per kg as the retail price of karanja oil. The production costs of green diesel were estimated as USD 0.84 per kg and USD 0.798 per kg for direct and two-step HDO, respectively, for an optimum plant capacity of 0.12 × 106 metric ton per annum of karanja oil. The analysis was further extended to understand various cost-contributing factors and the effect of feedstock and the price of co-products on the manufacturing costs of green diesel. A discounted cash flow analysis was carried out to determine the minimum selling price of green diesel.

Role of NiMo alloy and Ni species in the performance of NiMo/alumina catalysts for hydrodeoxygenation of stearic acid: a kinetic study

Pankaj Kumar, Sunil K Maity, Debaprasad Shee

ACS omega 2019, 4, 2833-2843.

The hydrodeoxygenation (HDO) of vegetable oil and fatty acid is extremely important for the sustainable production of diesel-range hydrocarbons. The present work depicts the role of Ni/Mo (mole) in the performance of alumina-supported NiMo catalysts for the HDO of stearic acid. Both Ni and NiMo alloy coexist in the NiMo catalysts depending on the Ni and Mo content. With increasing Ni/Mo (mole), the NiMo alloy content in the catalyst increases with the simultaneous decrease in the Ni content. The activity of NiMo catalysts thus enhances with increasing Ni/Mo (mole). The reaction follows a decarbonylation route over Ni sites and a HDO route over NiMo alloy species. C17 and C18 alkanes are thus observed as the dominating hydrocarbon product over Ni and NiMo alloy-rich catalysts, respectively. The activity of the NiMo catalyst further enhances with increasing reaction temperature and metal (Ni + Mo) loading. The selectivity to alkanes was, however, not affected by metal loading. A suitable kinetic model was further established based on the reaction mechanism to relate the kinetic data. 

Reaction mechanism and kinetic modeling for the hydrodeoxygenation of triglycerides over alumina supported nickel catalyst

Sudhakara Reddy Yenumala, Sunil K. Maity*, D Shee

Reaction Kinetics, Mechanisms and Catalysis 120, 2017, 09–128.

The present work provides a systematic study to delineate the reaction mechanism and develop a mechanistic kinetic model for the hydrodeoxygenation (HDO) of triglycerides (TG) over alumina supported nickel catalyst. The HDO of 1:2 molar mixtures of tripalmitin and tristearin was studied in a batch reactor over a wide range of process conditions. The results showed that TG instantaneously converted to respective fatty acids. The fatty acids further converted to the fatty aldehydes. The fatty aldehydes, then, rapidly converted to alkanes by two parallel reaction pathways. The decarbonylation of fatty aldehyde (RP-I) was the dominating route compared to the reduction of the fatty aldehyde to fatty alcohol followed by its dehydration and hydrogenation (RP-II). A mechanistic kinetic model was developed based on the observed reaction pathway to correlate the experimental results. The rate constants for the conversion of palmitic acid and stearic acid to alkanes were matched closely with each other thereby demonstrating that HDO is independent of fatty acid chain length. The developed kinetic model was further validated using experimental data at various hydrogen-to-nitrogen mole ratios in the gas phase. Furthermore, the rate constants obtained for various catalyst loadings were correlated by a linear equation with zero intercept.

Keywords:Triglyceride; Hydrodeoxygenation; Reaction mechanism; Kinetics; Nickel-alumina

Etherification of Glycerol with Ethanol over Solid Acid Catalysts: Kinetic Study Using Cation Exchange Resin

Vishnu P. Yadav, Sunil K. Maity*, D Shee

Indian Chemical Engineer 59(2), 2017, 117-135.

The etherification of glycerol with ethanol is a novel process to utilise low-value by-product (glycerol) of the biodiesel industry to produce ethers of glycerol suitable for use as fuel additive or solvent. The etherification of glycerol with ethanol was investigated under the liquid phase in a high pressure batch reactor using two different types of commercial solid acid catalyst (zeolites and strongly acidic cation exchange resin (CER)). The CER showed superior catalytic activity over H-beta zeolite. The diethyl ether was observed as major product at high ethanol-to-glycerol mole ratio. The product selectivity diverted towards ethers of glycerol with decreasing ethanol-to-glycerol mole ratio. Among ethers of glycerol, glycerol monoethyl ether was the major product of the reaction. The reaction mechanism for etherification of glycerol with ethanol was delineated based on experimental observations. The reaction rate increased with increasing catalyst loading and temperature without affecting selectivity to the products significantly. The apparent activation energy of glycerol and ethanol was 25.1 and 26.6 kcal/mol, respectively. An empirical kinetic model was developed to correlate experimental data at different temperatures. The conversion of the reactants calculated from the kinetic model matched reasonably with experimental data.

Conversion of n-butanol to gasoline range hydrocarbons, butylenes and aromatics

Venkata Chandra Sekhar Palla, D Shee, Sunil K Maity

Applied Catalysis A: General 526, 2016, 28-36.

Sustainable production of hydrocarbon transportation fuels and building-block chemicals from biomass is extremely important to circumvent the development of capital-intensive new infrastructures for automobile sector and petrochemical industry. The present investigation is thus focused on selective conversion of n-butanol to gasoline range transportation fuel, and butylenes and aromatics building blocks in single step. Systematic investigation was carried out in a fixed-bed reactor over HZSM-5 catalyst at atmospheric pressure for clear identification of temperature and weight hourly space velocity (WHSV) window to maximize the yield of various products. The present article additionally provides the mechanistic insights for the formation of various products from n-butanol.

Keywords: n-Butanol; Gasoline; Aromatics; Butylenes; HZSM-5.

Hydrodeoxygenation of Karanja Oil over Supported Nickel Catalysts: Influence of Support and Nickel Loading

Sudhakara Reddy Yenumala, Sunil K. Maity*, D Shee

Catalysis Science & Technology 6, 2016, 3156-3165.

Abstract. Production of hydrocarbon transportation fuels from triglycerides is extremely important to reduce dependency on limited fossil fuels. The present article provides a systematic examination of hydrodeoxygenation (HDO) of karanja oil (KO) in a semi-batch reactor over supported (γ-Al2O3, SiO2, and HZSM-5) nickel catalysts. The catalysts were associated with both dispersed and bulk nickel/nickel oxide depending on the extent of nickel loading and nature of the support. Virgin KO is composed of ~76 wt% C18 fatty acids with ~15 wt% oxygen. HDO of KO resulted in a wide range of alkanes (C10–C22) with n-heptadecane being the major one. Transformation of KO into alkanes proceeds through three distinct routes: HDO, catalytic cracking, thermal cracking, or their combination. Highly acidic catalysts (HZSM-5 and Ni/HZSM-5) promote catalytic cracking leading to formation of a large amount of lighter alkanes. The cracking reaction becomes significant over the γ-Al2O3 supported nickel catalyst with ≤15 wt% nickel loading at elevated temperatures. A strong metal–support interaction favored the HDO pathway over the γ-Al2O3 supported nickel catalyst with ≥20 wt% nickel loading. About 80 wt% of KO was converted to the liquid product with physicochemical properties comparable with light diesel oil.

Roles of supports (γ-Al2O3, SiO2, ZrO2) and performance of metals (Ni, Co, Mo) in steam reforming of isobutanol

Vimala Dhanala, Sunil K. Maity*, D Shee

RSC Advances 5, 2015, 52522–52532.

The production of synthesis gas from bio-isobutanol in an integrated biorefinery is a novel approach for its downstream conversion to hydrocarbon fuels and organic chemicals. The present article provides a systematic examination of the structure–activity correlation of various supported transition metal catalysts, xMS (x mmol metal, M (Ni, Co, and Mo) supported on S (Al, Si, and Zr for γ-Al2O3, SiO2, and ZrO2 respectively)) for steam reforming (SR) of bio-isobutanol. The activity of the catalyst was strongly influenced by metal-support interaction as reflected by metal dispersion, metal crystallite size, and extent of bulk metal/metal oxide. The catalytic activity increased in the order of 4.3NiZr < 4.3NiSi < 4.3NiAl and 4.3MoAl < 4.3CoAl < 4.3NiAl. 7.3CoAl exhibited consistent catalytic activity up to 12 h of time-on-stream. The hydrogen yield was boosted with rise of temperature and steam-to-carbon mole ratio (SCMR) with concurrent drop of selectivity to methane. The selectivity to CO reduced with increasing SCMR and decreasing temperature. Furthermore, spent catalysts were characterized to elucidate the effect of metal and support on the nature of coke formed and chemical transformation of the catalyst during SR.

Oxidative Steam Reforming of Isobutanol over Ni/γ-Al2O3 Catalysts: A Comparison with Thermodynamic Equilibrium Analysis

Vimala Dhanala, Sunil K. Maity*, and D Shee

Journal of Industrial and Engineering Chemistry 27, 2015, 27, 153-163.

Present work provides a systematic investigation of oxidative steam reforming (OSR) and comparisons with steam reforming (SR) of isobutanol over γ-Al2O3 supported nickel catalysts. Catalysts characterization results demonstrated that majority of nickel oxide was present as dispersed NiAl2O4. The hydrogen yield and selectivity to CO and methane were somewhat lesser for OSR compared to SR. The H2/CO mole ratio in the range of 8–10 was observed under the experimental conditions. The experimental results were matched well with equilibrium products compositions. The spent catalysts were further characterized to elucidate chemical and morphological changes of the catalysts during SR and OSR.

Keywords: Oxidative steam reforming; Thermodynamic equilibrium analysis; Bio-butanol; Synthesis gas; Ni/γ-Al2O3

Opportunities, recent trends and challenges of integrated biorefinery: Part I

Sunil K. Maity*

Renewable and Sustainable Energy Reviews 43, 2015, 1427-1445.

Sustainable production of energy, fuels, organic chemicals and polymers from biomass in an integrated biorefinery is extremely important to reduce enslavement on limited fossil fuels. In the present article, the biomass was classified into four general types based on their origin: energy crops, agricultural residues and waste, forestry waste and residues and industrial and municipal wastes. The article further elucidates the chemistry of various types of biomass used in the biorefinery. The biorefinery was classified into three broad categories based on the chemistry of biomass: triglyceride, sugar and starchy and lignocellulosic. The article further presents a comprehensive outlines of opportunities and recent trends of each type of biorefinery. A brief overview of original and revised list of platform chemicals, their sources from biomass and derivative potentials were also articulated. The article also provides comparisons of different types of biorefinery, broad challenges and availability of biomass. Furthermore, the article provides an overview of hydrocarbon biorefinery for production of hydrocarbon fuels and building block chemicals from biomass.

Keywords: Biorefinery; Biomass; Bio-fuels; Platform chemical; Lignocellulose; Starch

Opportunities, recent trends and challenges of integrated biorefinery: Part II

Sunil K. Maity*

Renewable and Sustainable Energy Reviews 43, 2015, 1446-1466.

Availability of cost-competitive biomass conversion technologies plays crucial role for successful realization of biorefinery for sustainable production of fuels and organic chemicals from biomass. The present article provides an outline of opportunities and socio-techno-economic challenges of various biomass processing technologies. The biomass processing technologies were classified into three broad categories: thermochemical, chemical and biochemical. This review article presents an overview of two potential thermochemical conversion processes, gasification and fast pyrolysis, for direct conversion of lignocellulosic biomass. The article further provides a brief review of chemical conversion of triglycerides by transesterification with methanol for production of biodiesel. The highly productive microalgae as an abundant source of triglycerides for biodiesel and various other fuels products were also reviewed. The present article also provides an outline of various steps involved in biochemical conversion of carbohydrates to alcoholic bio-fuels, bio-ethanol and bio-butanols and conversion of nature׳s most abundant aromatic polymer, lignin, to value-added fuels and chemicals. Furthermore, an overview of production of hydrocarbon fuels through various biomass processing technologies such as hydrodeoxygenation of triglycerides, biosynthetic pathways and aqueous phase catalysis in hydrocarbon biorefinery were highlighted. The present article additionally provides economic comparisons of various biomass conversion technologies.

Keywords: Biorefinery; Bio-fuel; Pyrolysis; Microalgae; Bio-butanol; Green diesel

Kinetics of Hydrodeoxygenation of Octanol over Supported Nickel Catalysts: A Mechanistic Aspect

Venkata Chandra Sekhar Palla, D Shee, Sunil K. Maity

RSC Advances 4, 2014, 41612-41621.

Abstract. The hydrodeoxygenation (HDO) of 1-octanol as a model aliphatic alcohol of bio-oil was investigated in a continuous down-flow fixed-bed reactor over γ-Al2O3, SiO2, and HZSM-5 supported nickel catalysts in the temperature range of 488–533 K. The supported nickel catalysts were prepared by incipient wetness impregnation method and characterized by BET, XRD, TPR, TPD, H2 pulse chemisorption, and UV-vis spectroscopy. Characterization of supported nickel (or nickel oxide) catalysts revealed existence of dispersed as well as bulk nickel (or nickel oxide) depending on the extent of nickel loading and the nature of the support. The acidity of γ-Al2O3 supported nickel catalysts decreased with increasing the nickel loading on γ-Al2O3. n-Heptane, n-octane, di-n-octyl ether, 1-octanal, isomers of heptene and octene, tetradecane, and hexadecane were identified as products of HDO of 1-octanol. The C7 hydrocarbons were observed as primary products for catalysts with active metal sites such as γ-Al2O3 and SiO2 supported nickel catalysts. However, C8 hydrocarbons were primarily formed over acidic catalysts such as pure HZSM-5 and HZSM-5 supported nickel catalyst. The 1-octanol conversion increased with increasing nickel loading on γ-Al2O3, and temperature and decreasing pressure and WHSV. The selectivity to products was strongly influenced by temperature, nickel loading on γ-Al2O3, pressure, and types of carrier gases (nitrogen and hydrogen). The selectivity to C7 hydrocarbons was favoured over catalysts with increased nickel loading on γ-Al2O3 at elevated temperature and lower pressure. A comprehensive reaction mechanism of HDO of 1-octanol was delineated based on product distribution under various process conditions over different catalysts.

Kinetics of Hydrodeoxygenation of Stearic Acid Using Supported Nickel Catalysts: Effects of Supports

Pankaj Kumar, Sudhakara Reddy Yenumala, Sunil K. Maity*, D Shee

Applied Catalysis A: General 471, 2014, 28– 38.

The hydrodeoxygenation of fatty acids derived from vegetable and microalgal oils is a novel process for production of liquid hydrocarbon fuels well-suited with existing internal combustion engines. The hydrodeoxygenation of stearic acid was investigated in a high pressure batch reactor using n-dodecane as solvent over nickel metal catalysts supported on SiO2, γ-Al2O3, and HZSM-5 in the temperature range of 533–563 K. Several supported nickel oxide catalysts with nickel loading up to 25 wt.% were prepared by incipient wetness impregnation method and reduced using hydrogen. The catalysts were then characterized by BET, TPR, H2 pulse chemisorption, TPD, XRD, and ICP-AES. Characterization studies revealed that only dispersed nickel oxide was present up to 15 wt.% nickel loading on γ-Al2O3. The acidity of the supports depends on nickel loading of oxidized catalysts and increases with increasing nickel loading up to 15 wt.%. n-Pentadecane, n-hexadecane, n-heptadecane, n-octadecane, and l-octadecanol were identified as products of hydrodeoxygenation of stearic acid with n-heptadecane being primary product. The catalytic activity and selectivity to products for hydrodeoxygenation of stearic acid depends strongly on acidity of the supports. The maximum selectivity to n-heptadecane was observed with nickel supported γ-Al2O3 catalyst. A suitable reaction mechanism of hydrodeoxygenation of stearic acid was delineated based on products distribution. The conversion of stearic acid was increased with increasing reaction time, nickel loading on γ-Al2O3, temperature, and catalyst loading. Complete conversion of stearic acid was accomplished with more than 80% selectivity to n-heptadecane at reasonable reaction temperature of 563 K after 240 min of reaction using 15 wt.% Ni/γ-Al2O3 catalyst. An empirical kinetic model was also developed to correlate the experimental data.

Keywords: Hydrodeoxygenation; Stearic acid; Green diesel; Ni/γ-Al2O3; Modeling

Steam Reforming of Isobutanol for Production of Synthesis Gas over Ni/γ-Al2O3 Catalysts

Vimala Dhanala, Sunil K. Maity*, Debaprasad Shee

RSC Advances 3, 2013, 24521–24529.

Abstract. Bio-isobutanol has received widespread attention as a bio-fuel and a source of chemicals and synthesis gas as part of an integrated biorefinery approach. The production of synthesis gas by steam reforming (SR) of isobutanol was investigated in a down-flow stainless steel fixed-bed reactor (FBR) over Ni/γ-Al2O3 catalysts in the temperature range of 723–923 K. The NiO/γ-Al2O3 catalysts were prepared by the wet impregnation method and reduced in the FBR prior to the reaction. The surface area, metal dispersion, crystalline phase, and reducibility of the prepared catalysts were determined using BET, chemisorption, XRD and TPR, respectively. From the TPR studies, the maximum hydrogen consumption was observed in the temperature range of 748–823 K for all the catalysts. The presence of nickel species was confirmed through the characterization of the catalysts using powder XRD. The time-on-stream (TOS) studies showed that the catalysts remained fairly stable for more than 10 h of TOS. The conversion of carbon to gaseous products (CCGP) was increased by increasing the nickel loading on γ-Al2O3 and the temperature and by decreasing the weight hourly space velocity (WHSV). The hydrogen yield was increased by increasing the nickel loading on γ-Al2O3, the WHSV, the steam-to-carbon mole ratio (SCMR), and the temperature. The selectivity to methane decreased at high reaction temperatures and SCMRs. The selectivity to CO decreased with increasing SCMRs and decreasing temperatures. The work was further extended to the thermodynamic equilibrium analysis of the SR of isobutanol under experimental conditions using Aspen Plus, and the equilibrium results were then compared to the experimental results. A reasonably good agreement was observed between the trends in the equilibrium and the experimental results.

Thermodynamic Evaluation of Dry Reforming of Vegetable Oil for Production of Synthesis Gas

Sudhakara Reddy Yenumala, Sunil K. Maity*

Journal of Renewable and Sustainable Energy 4, 2012, 043120.

Abstract. The dry reforming (DR) is a promising technology for utilization of greenhouse gas, carbon dioxide, to produce synthesis gas for downstream synthesis of valuable chemicals and fuels. In this study, equilibrium of DR and autothermal dry reforming (ATDR) of vegetable oils was investigated by Gibbs free energy minimization method. The effects of various process variables of DR and ATDR of vegetable oils such as temperature (673–1273 K), carbon dioxide-to-carbon mole ratio (CCMR) (0.5–3.0), and oxygen-to-carbon mole ratio (OCMR) (0–1.0) were studied to obtain equilibrium products composition, thermodynamically promising operating conditions, and thermoneutral conditions of the process. The study revealed that insignificant amount of coke and compounds containing two or more carbon atoms were formed for both DR and ATDR of vegetable oils. The hydrogen yield was found to increase with increase in temperatures for DR of vegetable oil. At temperature 983 K and above, the hydrogen yield was found to increase with CCMR, reach maxima, and then decrease with further increase in CCMR. The carbon dioxide conversion and yield of CO and water were increased and yield of methane was decreased with increase in temperature. The yield of CO and water were increased and the conversion of carbon dioxide and yield of methane were decreased with increase of CCMR. For ATDR of vegetable oils, the reduced yield of CO and methane and enhanced yield of water and hydrogen (up to temperature of maximum hydrogen yield) were observed compared to that of DR. From critical analysis of the results of DR and ATDR of vegetable oil, the optimum conditions for maximum yield of hydrogen with very low yield of methane were determined as 1000–1050 K, CCMR of about 1, and oxygen-to-carbon mole ratio of 0.6–0.7. It was observed that about 80% hydrogen yield with 78–83 moles of CO and 0.2–0.6 moles of methane per mole of vegetable oil could be obtained under the optimum conditions.

Correlation of Solubility of Single Gases/Hydrocarbons in Polyethylene Using PC-SAFT

Sunil K. Maity*

Asia-Pacific Journal of Chemical Engineering 7, 2012, 406-417.

Abstract. The knowledge of solubility of gases and hydrocarbons in polymer has enormous importance in the design and development of reactor, polymer foaming, and membrane separation processes. In this work, the solubility of gases and hydrocarbons in polyethylene was correlated using a thermodynamic model based on perturbed‐chain statistical associating fluid theory (PC‐SAFT). The experimental solubility data of various gases such as ethylene, carbon dioxide, nitrogen, methane, and hydrocarbons of up to chain length of seven in both molten and semicrystalline polyethylene has been reviewed and the suitability of the developed model based on PC‐SAFT was then tested using the available solubility data in literatures for various gases and hydrocarbons. Furthermore, the optimum values of adjustable solvents‐solute binary interaction parameters (Kij) of PC‐SAFT at different temperatures have been estimated by regression of the PC‐SAFT model using experimental solubility isotherms. A suitable correlation of Kij with temperature was then developed using the estimated Kij at different temperatures. The solubility calculated from the developed model using the estimated Kij was then compared to the experimental results and a reasonably good correlation was observed.

Kinetics of Esterification of Ethylene Glycol with Acetic Acid using Cation Exchange Resin Catalyst

Vishnu P. Yadav, Sunil K. Maity*, Prakash Biswas, Raghubansha K. Singh

Chemical and Biochemical Engineering Quarterly 25(3), 2011, 359-366.

Abstract. The esterification of ethylene glycol with acetic acid was investigated in a batch reactor in presence of a strongly acidic cation exchange resin, seralite SRC-120, as catalyst in the temperature range of 333 to 363 K. The detailed kinetic study was performed to understand the effect of various process variables such as catalyst loading, ethylene glycol to acetic acid mole ratio, and temperature on conversion of reactants and selectivity to products. Further, two different kinetic models, empirical and kinetic model based on Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach, were developed to correlate the experimental concentration versus time data. The kinetic parameters of the developed models were then estimated at different temperatures using non-linear regression technique based on modified Levenberg-Marquardt algorithm. The calculated results based on the estimated kinetic and equilibrium constants at different temperatures were then compared with the experimental values and LHHW-based model was found to fit the experimental data reasonably better compared to empirical kinetic model. The estimated rate constants at different temperatures of LHHW-based model were then used to estimate the activation energy and frequency factor of the rate constants. 

Reforming of Vegetable Oil for Production of Hydrogen: A Thermodynamic Analysis

Sudhakara Reddy Yenumala, Sunil K. Maity*

International Journal of Hydrogen Energy 36, 2011, 36, 11666-11675.

Abstract. The vegetable oils are one of the promising renewable feedstock for production of hydrogen suitable for application in hydrogen based fuel cells for electrical power generation. In the present work, a thermodynamic equilibrium analysis of steam reforming (SR) and autothermal steam reforming (ATSR) of vegetable oils to synthesis gas was investigated by Gibbs free energy minimization method. The thermodynamic equilibrium analysis was performed considering the vegetable oils as a mixture of triglycerides containing three same fatty acid groups in the structure. The property method used for equilibrium analysis was first regressed using available physical and chemical properties of the considered triglycerides. The regressed property method was then used to calculate the equilibrium products composition. The effects of various parameters of SR of vegetable oils, temperature and steam-to-carbon ratio (SCR), on hydrogen yield and selectivity of CO and methane was studied in a broad range of temperature (573–1273 K) and SCRs (1–6). The optimum conditions for SR of vegetable oils were then determined for maximum hydrogen yield with very low selectivity of methane. The thermodynamic equilibrium analysis of ATSR of vegetable oils was then performed at different oxygen-to-carbon ratios and thermoneutral conditions were then determined for various operating conditions.

Keywords: Hydrogen; Vegetable oils;Thermodynamic analysis; Steam reforming; Autothermal steam reforming 

Previous publications

1. Sunil K. Maity, Sujit Sen, Narayan C. Pradhan, A new mechanistic model for liquid–liquid phase transfer catalysis: Reaction of benzyl chloride with aqueous ammonium sulfide. Chemical Engineering Science 2009, 64(21), 4365-4374.

2. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Reduction of p-Nitrotoluene by Aqueous Ammonium Sulfide: Anion Exchange Resin as a Triphasic Catalyst. Chemical Engineering Journal 2008, 141, 187–193. 

3. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Kinetics of Phase Transfer Catalyzed Reduction of Nitrochlorobenzenes by Aqueous Ammonium Sulfide: Utilization of Hydrotreater Off-gas for the Production of Value-Added Chemicals. Applied Catalysis B: Environmental 2008, 77, 418–426.

4. Sujit Sen, Sunil K. Maity, Narayan C. Pradhan and Anand V. Patwardhan, Utilization of Hydrogen Sulphide for the Synthesis of Dibenzyl Sulphide: Effects of Process Parameters on Conversion and Selectivity. International Journal of Chemical Sciences 2007, 5(4), 1569-1578.

5. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Reduction of o-Nitroanisole to o-Anisidine by H2S-rich Aqueous Diethanolamine: A Novel Process for Utilization of H2S-laden Gas Streams. Chemical Engineering Science 2007, 62, 805-813.

6. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Kinetics of Reduction of Nitrotoluenes by H2S-rich Aqueous Ethanolamine. Industrial & Engineering Chemistry Research 2006, 45, 7767-7774.

7. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Reaction of benzyl chloride with ammonium sulfide under liquid–liquid phase transfer catalysis: Reaction mechanism and kinetics. Journal of Molecular Catalysis A: Chemical 2006, 250, 114–121.

8. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Kinetics of the Reduction of Nitrotoluenes by Aqueous Ammonium Sulfide under Liquid-Liquid Phase Transfer Catalysis. Applied Catalysis A: General 2006, 301, 251–258. 

9. Sanghamitra Barman, Sunil K. Maity, Narayan C. Pradhan, Alkylation of Toluene with Isopropyl alcohol catalyzed by Ce-exchanged NaX Zeolite. Chemical Engineering Journal 2005, 114, 39–45. 

10. Ruchi Agarwal, Durga Prasad, Sunil Maity, Kalyan Gayen, Saibal Ganguly, Experimental Measurement and Model Based Inferencing of Solubility of Polyethylene in Xylene. Journal of Chemical Engineering of Japan 2004, 37 (12), 1427-1435.

Conference Presentations

1. Sunil  K. Maity,  Kalyan Gayen, Sirshendu De, Saibal Ganguly, Modeling and Simulation of Solid-Liquid Equilibrium: Model Validation Using Solubility Data and Sensitivity Study for Polyethylene System. 1st national Conference of Research Scholar and Young Scientists, Indian Institute of Technology, Kharagpur, India, 2004, P 28-34. PDF

2. Sunil K. Maity, Anand V. Patwardhan and Narayan C. Pradhan, Reaction of Benzyl Chloride with Aqueous Ammonium Sulfide under Liquid–Liquid Phase Transfer Catalysis. CHEMCON, Indian Institute of Technology, New Delhi, 2005. PDF

3. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Phase Transfer Catalyzed Reduction of Nitrotoluenes by Aqueous Ammonium Sulfide: Kinetic Study. SCHEMCON, Indian Institute of Technology, Guwahati, 2005. PDF

4. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Reduction of Nitrotoluenes by H2S-rich Aqueous Ethanolamine Solution: A Viable Alternative to Claus Process. 19th Canadian Symposium on Catalysis, May 14-17, 2006, Saskatoon, SK, Canada. PDF

5. Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Kinetics of Reduction of Nitrochlorobenzenes by Aqueous Ammonium Sulfide under Liquid–Liquid Phase Transfer Catalysis. CHEMCON, Ankleshwar, Gujarat, India, page-23, 2006. PDF

6. K. Ganapathi S. Naidu, Sunil K. Maity, Narayan C. Pradhan, Anand V. Patwardhan, Kinetics of Vapor-Phase Alkylation of Benzene with Isopropyl Alcohol over Commercial H-Mordenite Catalyst. CHEMCON, Ankleshwar, Gujarat, India, page-23, 2006. PDF

7. Sunil K. Maity, CH. Seetaram, Narayan C. Pradhan, Kinetics of Transalkylation of Diisopropylbenzenes with Benzene. CHEMCON, Ankleshwar, Gujarat, India, page-33, 2006. PDF

8. Sujit Sen, Sunil K. Maity, Narayan C. Pradhan and Anand V. Patwardhan, Utilization of Hydrogen Sulphide for the Synthesis of Dibenzyl Sulphide: Effects of Process Parameters on Conversion and Selectivity. National Conference on Frontiers in Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati, India, 2007.

9. Vishnu P. Yadav, Rudra Palash Mukherjee, Kandi Bantraj, Sunil K. Maity,* Kinetic Modeling of Esterification of Ethylene Glycol with Acetic Acid. International Conference On Modeling, Optimization, And Computing (ICMOC 2010), West Bengal, (India), 28–30 October 2010.

10. Sudhakara Reddy Yenumala, Sunil K. Maity*, Thermodynamic Analysis of Steam Reforming of Vegetable Oil. International Conference on Recent trends in Renewable energy Resources,  Indian Institute of Chemical Technology, Uppal Road, Hyderabad - 500 607, AP, INDIA, January 2011.

11. Vishnu P. Yadav, Sunil K. Maity, Debaprasad Shee, Etherification of Glycerol with Ethanol Using Cation Exchange Resin. CHEMCON, Dr. B.R. Ambedkar National Institute of Technology, Punjab, India, 27-30 December, 2012.

12. Vimala Dhanala, Sunil K. Maity, Debaprasad Shee, Vinod M. Janardhanan, Steam Reforming of Isobutanol for the Production of Synthesis Gas over Ni/Al2O3 Catalyst. CHEMCON, Dr. B.R. Ambedkar National Institute of Technology, Punjab, India, 27-30 December, 2012.

13. Pankaj Kumar, Sudhakara Reddy Yenumala, Sunil K. Maity, Debaprasad Shee Hydrodeoxygenation of Stearic Acid Using Supported Nickel Alumina Catalysts. CHEMCON, Dr. B.R. Ambedkar National Institute of Technology, Punjab, India, 27-30 December, 2012.

14. P.V. Chandra Sekhar, Debaprasad Shee, Sunil Kumar Maity, Hydrodeoxygenation of 1-Octanol. CHEMCON, Dr. B.R. Ambedkar National Institute of Technology, Punjab, India, 27-30 December, 2012.

15. Sudhakara Reddy Yenumala, Sunil K. Maity, Reforming of Vegetable Oil: A thermodynamic Equilibrium Analysis. International Conference on Advances in Chemical Engineering (ACE 2013), February 22-24, 2013, IIT Roorkee, India.

16. Vishnu P. Yadav, Sunil K. Maity, Debaprasad Shee, Utilization of glycerol: etherification with ethanol. International Conference on Advances in Chemical Engineering (ACE 2013), February 22-24, 2013, IIT Roorkee, India.

17. Vimala Dhanala, Sunil K. Maity*, Debaprasad Shee, Steam reforming of isobutanol for production of synthesis gas: Effects of metals. World Congress on Petrochemistry and Chemical Engineering, Hilton San Antonio Airport, United States 78216, November 18-20, 2013.

18. Vimala Dhanala, Sunil K. Maity*, Debaprasad Shee, Cobalt supported g-Al2O3 catalyst for steam reforming of isobutanol for production of synthesis gas. Seventh Tokyo Conference on Advanced Catalytic Science and Technology (TOCAT7) at Kyoto, Japan, June 1-6, 2014.

19. Venkata Chandra Sekhar Palla, Debaprasad Shee*, Sunil K. Maity, Hydrodeoxygenation of 1-Octanol over Supported Nickel Catalysts. Seventh Tokyo Conference on Advanced Catalytic Science and Technology (TOCAT7) at Kyoto, Japan, June 1-6, 2014.

20. SR Yenumala, SK Maity, D Shee, Hydrodeoxygenation of karanja oil for the production of green diesel. 64th Canadian Chemical Engineering Conference, Canada, October 19-22, 2014. 

21. M Varkolu, SAK Jinnala, A Kunamalla, SK Maity, D Shee, Mesoporous Ni-CeO2-ZrO2-SiO2 composite catalyst for steam reforming of n-butanol. International Hydrogen & Fuel Cell Conference, Jodhpur, Rajasthan, India, December 9-11, 2018. 

22. M Varkolu, SAK Jinnala, A Kunamalla, SK Maity, D Shee, Steam reforming of bio-butanol over mesoporous Ni-CeO2-ZrO2-SiO2 composite catalysts. International Conference on Catalysis Science, Engineering & Technology, Stockholm, Sweden, November 04-07, 2018. 

23. P Kumar, SK Maity and D Shee, Hydrodeoxygenation of stearic acid over NiMo/γ-Al2O3 catalyst. 255th American Chemical Society Meeting, New Orleans LA, 18-22 March, 2018. 

24. S Mailaram, SK Maity, Hydrodeoxygenation of karanja oil for the production of green diesel: process design with heat integration and economic analysis. AIChE Annual Meeting, Pittsburg, PA, October 28 - November 2, 2018. 

25. SR Yenumala, SK Maity, D Shee, Production of green diesel from karanja oil using ordered mesoporous nickel-alumina composite catalyst. Applied Catalysis & Chemical Engineering, Dubai, UAE, April 08 - 10, 2019.

26. S Mailaram, N Dobhal and Sunil K. Maity*, Techno-economic Analysis for Production of Biodiesel and Green diesel from Microalgal oil. Conference: 7th International Conference on Advances in Energy Research (ICAER 2019), IIT Mumbai, India, 10 - 12 December 2019