Bio-oil production from individual and co-hydrothermal liquefaction of jute stalks and rice straw: Insights from kinetics study, product characterization, optimization and life cycle assessment

Hydrothermal liquefaction (HTL) is a promising process for the generation of biofuels and biochemical from lignocellulosic wastes. The article focuses on the HTL of jute stalks (JS) and rice straw (RS) and co-HTL of RS-JS mixtures in a temperature range of 240-360°C for 10-30 minutes in a batch reactor in the presence of water in a sub-critical condition. The lumped kinetics of hydrothermal liquefaction of JS and RS were determined. The fuel quality in terms of H/C and O/C ratios of bio-oil have been compared to petroleum crude, and those of hydrochar have been compared with lignite and peat using the Van Krevelen diagram. The maximum bio-oil yields of JS and RS are 33.81% and 30.34%, respectively. The hydro-char have been characterized using TGA, FTIR, XRD and FESEM. The optimum bio-oil yield obtained was 33.9% at 319.2°C for 26.3 minutes and 83.1% JS. At 319.2°C and 26.3 min, the higher heating values of bio-oil of JS-RS mixture (83.1% JS), RS and JS are 28.56, 25.70 and 28.70 MJ/kg, respectively. The phenolic compounds of 19.54%; 49.51%, 45.59%, aromatic compounds of 13.22%; 26.27%; 24.28%, cyclic compounds of 47.62%; 3.76%; 11.79% and aliphatic compounds of 0.16%; 0.02; 0.04% are present in bio-oils of RS, JS, and JS-RS mixture (83.1% JS) respectively. Life cycle assessments for individual and co-HTL have been conducted by midpoint analysis using SimaPro-V9-software. The findings are expected to be useful in the development of biorefineries, based on HTL of crop residues like rice, jute, their mixture, and other similar ones.