Comparison of One and Two Step Methods for Producing Jet Fuel Building Blocks From Cellulosic Biomass: Hemicellulose Release and Levulinic Acid Production From Maple Wood

Xylose and levulinic acid are important building blocks for making jet fuel from cellulosic biomass. Although hemicellulose can be easily released by hot water or dilute acid pretreatment, levulinic acid is traditionally produced by reacting biomass directly with concentrated acid, degrading much of the hemicellulose sugars in very costly equipment. In this study, a two-step process was developed to increase yields of xylose and levulinic acid with less acid by releasing hemicellulose sugars before introducing dilute acid to produce levulinic acid from the resulting cellulose/lignin residue. This integrated process increased levulinic acid yields by up to ~15% compared with direct reaction with acid in a single step. In addition, yields of levulinic acid, xylose, xylose degradation products, total soluble carbon, and total organic carbon were followed throughout the process to compare with the traditional one step method. Furthermore, product yields and distributions were compared for use of sulfuric and hydrochloride acids over a range of acid concentrations, temperatures, and reaction times.