Insights into Solvent Effects in Catalytic Reactions for Biomass Conversion

摘要

Biomass conversion into platform molecules and fuels has received increasing interest in our current transition to a sustainable source of chemicals and energy. Recently, the use of organic solvents has been shown to be beneficial in the chemical conversion of lignocellulosic biomass. One such solvent is gamma-valerolactone (GVL), which can be produced from both the hemicellulose and cellulose fractions of lignocellulosic biomass and is miscible with water, allowing for monophasic reaction systems. The use of GVL as a solvent for biomass conversion reactions has led to significant improvements in reaction performance compared to conversion in aqueous media, where increased catalytic activity and higher selectivity to desired reaction products have been demonstrated. Furthermore, we have recently reported that the simultaneous conversion of hemicellulose and cellulose can be achieved using GVL as a solvent in a single reactor, eliminating the need for pretreatment and/or separation steps. It was shown that GVL not only increases the selectivity to desired products, but it also solubilizes biomass and humins (i.e., biomass degradation products) at typical biomass processing conditions, thereby avoiding solids handling problems. More recently, we have taken advantage of accelerated rates of cellulose and hemicellulose deconstruction in GVL-H2O solvent mixtures to develop a processing strategy to produce concentrated streams of C5 and C6 sugars from biomass using only dilute concentrations of mineral acids without using enzymes or ionic liquids. More generally, other polar aprotic organic solvents, such as gamma-lactones and furans, have shown comparable benefits to GVL in biomass conversion processes.