Enhanced yields of furfural and other products by simultaneous solvent extraction during thermochemical treatment of cellulosic biomass

Abstract

Furfural derived from pentose sugars is one of the key reactive intermediates for production of hydrocarbons from cellulosic biomass for use as drop-in fuels. Simultaneous extraction into a solvent immiscible in water can substantially enhance furfural yields by removing it from the aqueous environment where the yield would otherwise be limited by its rapid degradation to chars and other carbon rich compounds that are loosely termed humins. Thus, in this study, the effectiveness of the organic solvent methyl isobutyl ketone (MIBK) in improving furfural yields from maple wood was determined for reactions of 5 wt% solids in 0.1 M sulfuric or hydrochloric acid at 170 °C over a range of reaction times. For comparison, pure xylose, glucose, and Avicel cellulose were also reacted under the same conditions. Various process configurations based on simultaneous hydrolysis and dehydration were compared to acid hydrolysis followed by dehydration to furfural with and without simultaneous extraction. Without MIBK extraction, the maximum furfural yields were less than 65% when maple wood was reacted for about 40–45 min with either sulfuric or hydrochloric acid. However, the yield increased significantly to about 85.3% when MIBK extraction was employed in combination with sulfuric acid catalysis for 50 min, while combining MIBK extraction with hydrochloric acid catalysis only increased the yield to ∼67.0%. Simultaneous extraction with MIBK also improved yields of other products such as 5-HMF and levulinic acid, compared to results from the acids alone.