Techno-Economic Assessment of Mixed-Furan Production from Diverse Biomass Hydrolysates

Abstract

We present techno-economic analyses of high-yield production of furans [5-hydroxymethylfurfural (HMF) and furfural] from mixed-sugar hydrolysates via a novel hybrid enzyme-chemo-catalytic process. In this process, glucose and xylose in biomass hydrolysates are first isomerized to corresponding ketoses (i.e., fructose and xylulose) using immobilized glucose–xylose isomerase. This enzymatic step is closely integrated with selective extraction of the keto-sugars into a water–immiscible octanol phase containing aryl boronic acids that have a selective affinity for keto-sugars. As a result, isomerization and extraction occur simultaneously and drive the isomerization equilibrium toward the formation of the ketose isomers—a process termed simultaneous isomerization and reactive extraction (SIRE). Then, the keto-sugars in the octanol phase are back-extracted into an acidic ionic liquid (IL) that is uniquely suited for sugar dehydration reactions—a process step termed back extraction (BE). Thereafter, the ketose-rich sugar mixture undergoes dehydration to furans in the IL, which is part of a biphasic reaction medium with tetrahydrofuran (THF) that facilitates extraction and stabilization of the furans as they are formed. Finally, the furans are recovered from THF. Overall, the SIRE–BE–dehydration process provides a pathway for high-yield conversion of lignocellulosic mixed-sugar hydrolysates to HMF and furfural. We performed the chemical process design for a furan production facility operating at a feed rate of 1000 MT/day of biomass hydrolysate sugars (dry basis) via the SIRE–BE–dehydration pathway. The process design corresponded closely with experiments and included integration of novel and energy-efficient product and chemical recovery methods. We estimated the minimum furan selling price (MFSP) to be $1.42/kg—a promising price point for industrially important chemical products. Sensitivity analyses identified feedstock sugar cost and overall furan yield as the dominant contributors to the selling price, and modest improvements of 10% in both parameters could reduce the MFSP to $1.23/kg, a price which is competitive for fuel and polymer precursor applications.