Ringkasan Eksekutif

 Research Background

The Natuna Sea is Indonesia's largest natural gas resource, with 46 TSCF-proven reserves consisting of 71 mol% of CO2 and 28 mol% of CH4 [1]. Natural gas reserves in Indonesia and some of Indonesia's upstream gas projects can be seen in Figure 1. To date, the natural gas reserve in the Natuna Sea has not been utilized because of its higher CO2 content than other natural gas reserves [2,3]. Dry reforming of methane (DRM) is considered a promising technology for converting natural gas reserves into synthesis gas (syngas), as it utilizes methane and CO2 [4]. Syngas is an essential intermediate in the chemical industry because it is a source of hydrogen and raw material required to produce various chemical compounds [5–9]. Syngas produced from the DRM is supposed to have a H2/CO ratio close to 1, which is suitable for producing oxygenated chemicals and hydrocarbons through the Fischer-Tropsch process [10–13]. The syngas can then be converted into various products such as wax, olefin, alcohol, and dimethyl ether [14,15]. The primary reaction in the DRM is as follows:

 Research Problems

A few technical problems are arising in these processes, which cover carbon formation at 500 – 700°C, sintering of nickel catalyst at 700 – 800°C, time lag during start-up in Pd membrane, and Pd membrane deactivation.

Scientific Objective

This research aims to develop a novel Ni-based catalyst, which will be loaded into the fixed bed reactor and convert the natural gas to synthesis gas containing hydrogen. To increase hydrogen productivity while producing and separating, the Pd-based membrane reactor with Cu-ZnO/g-Al2O3 catalyst will be used. The membrane's Pd surface is a nanomaterial supported by alumina and will be used to separate hydrogen produced from the water gas shift reaction.

Technological Objective

The technological objective of this research is to develop the technology of fixed bed reactor containing Ni-based catalyst and the technology of nano-Pd based membrane reactor containing Cu-ZnO/Al2O3 catalyst. The process integration offers beneficial in terms of catalytic and separation processes.

Results and Discussion

The NiO@Al2O3 catalyst was synthesized using the chemical reduction and hydrolysis method of aluminum isopropoxide (AIP) with variations in the ratio of nickel and alumina (81%-wt Ni, 68%-wt Ni, and 58%-wt Ni) and calcination temperatures (600°C, 700°C, and 800°C). All synthetic catalysts contained crystalline NiO components (JCPDS 73–52) with a crystallite size range of 9.2–13.73 nm and belonged to the mesoporous material. Based on HRTEM analysis, the core-shell morphology formed with NiO distribution is relatively homogeneous. Hence, this morphology can inhibit sintering at high temperatures for the DRM process. The effect of nickel to alumina ratio and calcination temperature on performance, chemical characteristics, and carbon deposition on NiO@Al2O3 catalyst were studied. The results of H2-TPR on the catalyst showed that hydrogen consumption occurred in the temperature range of 300–840°C in the synthesized catalyst and commercial methanation catalysts. Based on the results of the performance test and characterization, the catalyst that had the best performance for 160 minutes at a temperature of 700°C, atmospheric pressure, and WHSV 18,000 mL g-1 h-1, was the 68%Ni-T700 catalyst which had CH4 and CO2 conversions of 85% and 54%, yields H2 and CO reached 49% and 42%, respectively, and the H2/CO ratio reached 1.2 with carbon deposition of 18.2% or around 0.185 gC/gcat. However, the performance of the Ni@Al2O3 catalyst indicates the presence of high carbon deposition even though the core-shell morphology has been formed. This fact was induced by sintering during catalyst reduction.

Another type of Ni-based catalyst was proposed with an additional promoter type on the activity and stability. The effect of base promoter addition on the amount of carbon deposition was investigated. The catalyst activity was tested in a fixed-bed reactor under atmospheric pressure at 700oC. Overall, all catalysts exhibited good stability for 240 minutes. Moreover, catalysts with Mg and Ca promoters showed the highest CH4 and CO2 conversion among all catalysts. Ni-Mg/MCM-41 catalyst yielded 72% CH4 and 54% CO2 conversions. Meanwhile, Ni-Ca/MCM-41 yielded 69% CH4 and 55% CO2 conversions. Furthermore, MCM-41-based catalysts with base promoter produced a small amount of carbon deposition.

In the third stage, a high thermal resistance catalyst was synthesized using zirconia and cerium. The results of catalyst performance for 240 minutes at a temperature of 700°C, atmospheric pressure, and WHSV 60,000 mL g-1 h-1 showed that the 10% Ni/CeZrO2 synthesis catalyst had the highest activity with an average conversion of CH4 and CO2 of each of 74% and 55%, the average yields of H2 and CO are 51% and 43%, respectively. The H2/CO ratio is 1.4. The performance of the 10% Ni/CeZrO2 catalyst also showed much better results than the core-shell catalyst, steam reforming catalyst, and commercial methanation. The conversion values of CH4 and CO2 per mass of the active center of 10% Ni/CeZrO2 catalyst were 2.2 and 2.1 times higher than commercial steam reforming catalysts, respectively. The amount of carbon formed for the test time of 4 hours on the steam reforming and commercial methanation catalysts, which is about 0.34 and 0.39 gC/gcat compared to the synthesis catalyst (< 0.01 gC/gcat) so that the carbon deposition in the whole synthesis catalyst can be ignored. This is because the components of the catalyst support have better oxygen storage and mobility properties in the de-coking process by CeO2 through the Boudouard reaction.

For the base promoter of the NiO/CeZrO2 catalyst, kinetic parameters and a bed reactor model were developed. Determination of the kinetic equation of 10% Ni/CeZrO2 catalyst followed the Langmuir-Hinshelwood mechanism with a rate-determining step, namely CH4 dissociation (activation of C–H bonds) in the nickel active center. The difference in model values and kinetic parameters with experimental data values has an error value of 5% and RMSE 0.046, so the model is valid for reactor modeling. The reactor modeling was carried out in a steady state involving gas (CH4, CO2, H2, CO, and H2O) and solid (carbon) components with a 1D quasi-homogeneous model. The modeling was carried out on the feed composition CH4:CO2 approaching the composition of the Natuna Gas Field, which is 30:70, having the results of CH4 conversion, CO2 conversion, and the H2/CO ratio obtained at an operating temperature of 700 °C which is around 92%, 28%, and 1.4, respectively.

Multidisciplinary Collaboration with University and Chemical Industry

To strengthen the research, a multidisciplinary research collaboration has been created, which includes:

• Osaka University: nanomaterials, zeolite

• Gifu University: Pd-based membrane

Universities in Indonesia are also involved, such as Universitas Diponegoro and Universitas Gadjah Mada. The industrial application will become an essential aspect in the future; therefore, collaboration with PT Pupuk Sriwidjaja has also been commenced.

Student Involvement

This research has involved various levels of the program: bachelor, master, and Ph.D. programs.

Bachelor students:

• Faisa Maheswari Millenianya

• Enrisha Rinindra Putri

• Fitri Az Zahra

• Wulan Reyhana

• Harisa Riski Amalia

• Hurin Aghniasari

• Agnes Regina Gracia Sianipar

• Aditya Megaria Napitupulu

• Rosemary Emmanuela Dame

• Dominikus Denis Dewantomo,

Master students:

• • Khadijah Sayyidatun Nisa

  • Hafsah

  • Abdul Rashid Bin Abdul Razak

  • Salma Liska

  • Raihan Annisa Fitri

  • Rawiyah Khairunida’ Shalihah

Ph.D. Students:

• Intan Clarissa Sophiana

• Gita Nur Sajida

• Yulia Tri Rahkadima

Paper and Proceeding

1. Yogi Wibisono Budhi, Hans Kristian Irawan, Raihan Annisa Fitri, Tareqh Al Syifa Elgi Wibisono, Elvi Restiawaty, Manabu Miyamoto, Shigeyuki Uemiya (2023). Effect of Co-Existing Gases  on Hydrogen Permeation through a Pd82-Ag18/α-Al2O3 Membrane during Transient Start-up. Heliyon, Volume 9, Issue 6, June 2023, e16979: https://doi.org/10.1016/j.heliyon.2023.e16979 (Q1)

2. Nisa K.S.; Suendo V.; Sophiana I.C.; Susanto H.; Kusumaatmaja A.; Nishiyama N.; Budhi Y.W. Effect of base promoter on activity of MCM-41-supported nickel catalyst for hydrogen production via dry reforming of methane (2022) International Journal of Hydrogen Energy, Volume 47, Issue 55, Pages 23201 – 23212, https://doi.org/10.1016/j.ijhydene.2022.05.081 (Q1)

3. Sophiana, I.C., Iskandar, F., Devianto, H., Nishiyama, N., Budhi, Y.W. Coke-resistant Ni/CeZrO2 Catalysts for Dry Reforming of Methane to Produce Hydrogen-rich Syngas (2022) Nanomaterials (Q1)

4. International conference: Dynamic Steam Modulation on Dry Reforming of Methane to Reduce the Carbon Formation Using a Fixed Bed Reactor. Hafsah, Intan Clarissa Sophiana, Yogi Wibisono Budhi (International Conference on Environment 2021 (ICENV2021) by School of Chemical Engineering, Universiti Sains Malaysia)

5. Rosemary Emmanuela Dame, Dominikus Denis Dewantomo, Raihan Annisa Fitri, Elvi Restiawaty, Manabu Miyamoto, Shigeyuki Uemiya and Yogi Wibisono Budhi, Hydrogen Separation from Dry Reformer Effluent Using Pd82-Ag18/α-Al2O3 Membrane During Transient Start-Up Period, Quality in Research, Bali, 2023

6. Yulia Tri Rahkadima, Raihan Annisa Fitri, Hafis Pratama Rendra Graha and Yogi Wibisono Budhi, High-Temperature Water Gas Shift: Thermodynamic and Reactor Modeling Study, Quality in Research, Bali, 2023

7. Gita Nur Sajida, Salma Liska, Wibawa Hendra Saputera, Haryo Pandu Winoto, and Yogi Wibisono Budhi, Study of The Water Gas Shift Reaction Thermodynamic, Kinetic, and Reactor Modelling, Quality in Research, Bali, 2023

8. Salma Liska, Hary Devianto, Gita Nur Sajida, Elvi Restiawaty, Manabu Miyamoto, Shigeyuki Uemiya, Norikazu Nishiyama, Yogi Wibisono Budhi, Strategy to Prevent Reverse Reactions in Water Gas Shift (WGS) through Cu/ZnO Nanocatalyst with MFI Type of Zeolite Support, Quality in Research, Bali, 2023

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