Process synthesis and analysis of catalytic biofuel production from separate conversion of hemicellulose and cellulose using lignin-derived alkylphenol solvents

Abstract

We develop a process in which the cellulose and hemicellulose fractions of lignocellulosic biomass are converted separately to jet fuel-range liquid hydrocarbon fuels(butene oligomers(BO)) while alkylphenol solvents (propyl guaiacol (PG) and propyl syringol (PS)) are produced from the lignin fraction through catalytic conversion subsystems. In this process dilute sulfuric acid (SA)-catalyzed pretreatment fractionates the biomass into insoluble cellulose and soluble hemicellulose-derived xylose, and they then are converted separately to levulinic acid (LA) using 2-sec-butylphenol (SBP) and lignin-derived alkylphenol solvents (LDS), respectively. The LA is converted catalytically to BO, passing through γ-valerolactone (GVL) and butene platforms. This process leads to a high biomass-to-fuels yield (34.8 mol%) at low concentrations of biomass derivatives using large volumes of solvents. Therefore, we design separation subsystems for recovering the alkylphenol solvents and biomass derivatives to be combined with the catalytic conversion subsystems of hemicellulose, cellulose and lignin. We then show a heat exchanger network (HEN) design to satisfy total energy requirements of the process from combustion of biomass degradation products. Finally, our economic analysis shows that the process design using corn stover feedstock leads to a minimum selling price of $3.37 per gallon of gasoline equivalent for jet fuel-range liquid hydrocarbon fuels, which suggests that it is an economically competitive alternative to current biofuels production approaches as a result of iterative experimental and computational efforts.