Generation of high value products from agriculture residue via hydrothermal liquefaction

Author: Bharath Kiran Maddipudi, Department of Chemical and Biological Engineering

Mentor: Dr. Rajesh Shende, Department of Chemical and Biological Engineering

South Dakota on an average generates about 9 million tons of agricultural residue per year. Corn stover and wheat straw are generally found in a major amount in the agricultural residue. In order to boost the bioeconomy, it is imperative to process this agricultural residue to produce high value products, which will generate additional revenue stream offsetting the biofuel cost. In this study, we investigated hydrothermal liquefaction (HTL) of the pre-processed corn stover/biochemically derived hydrolyzed solid (UHS) was carried out at temperatures and pressure of 225-300 ℃ and 600-2000 psi, respectively for 1-2 hours. HTL processing was aimed at producing four products/co-products, which included biochar, bio-oil, lactic acid and phenol under different set of experimental conditions. It is planned to develop a pilot scale HTL reactor system with the capability to handle 1 tpd throughput. HTL process resulted in gas, aqueous biocrude, heavy bio-oil (HBO) and solid char. The gas phase was analyzed by gas-chromatography, which revealed the presence of H₂, CH₄, CO₂, and CO whereas the biocrude liquid was characterized by TOC analyzer and gas-chromatography mass spectrometry (GC-MS) to understand extent of liquefied carbon and oxygenated hydrocarbons, respectively. Both solid biochar and HBO were analyzed by the elemental analyzer and the HHVs were estimated based on C, H, N and O content. Yield and quality of the high value products will be presented.

Keywords: Corn stover/UHS, integrated biorefinery (IBR), hydrothermal liquefaction, value-added products