EFFECT OF OPERATIONAL PARAMETERS ON SUPERCRITICAL CO₂ ASSISTED LIQUEFACTION OF PINEWOOD

With growing demand for sustainable aviation fuels (SAFs), development of viable and economic pathway for conversion of biomass resources into SAFs is of imminent necessity. Lignocellulosic biomass is an abundant bioresources that can be utilized for biofuel production. However, existing thermochemical methods to convert these feedstocks into biofuels are hindered by stability issues of bio-oil in fastpyrolysis, technoeconomic issues in gasification route, and high energy needs for water heating, and contaminated process water produced in hydrothermal liquefaction. Alternatively, we propose integrated near-critical liquefaction extraction utilizing supercritical CO2 (SCO2) as solvent for simultaneous liquefaction of biomass and extraction of higher quality biocrude using its solubility in SCO2. This includes thermochemical liquefaction of the biomass in the presence of SCO2 followed by SCO2-assisted solvent extraction of high-quality bio-oil components from the products. To understand this relatively new and novel process, the influence of near-critical liquefaction's operating conditions - CO2/biomass ratio, biomass loading, particle size, and catalyst loading on the quality and yield of biocrude, and overall conversion of liquefaction was investigated using 100 mL batch mode experiments. Taguchi method of design of experiments utilized to perform experiments towards ranking the importance of these process parameters. Temperature of 300 oC with residence time of 1 hour, pinewood as the biomass, and K2CO3 as the catalyst were tested. These results are of importance towards improving the liquefaction step and its further development and integration with extraction step for high-quality biocrude production. This higher quality biocrude can be further co-hydrotreated with petroleum crude to produce biogenic carbon fuels.