This work is an improvement in yield rates of almost 50 percent over current commercial technologies and can thereby potentially reduce the cost of furfural production to within the range of current price of crude oil.
Green Chemistry, 2014; 16 (8): 3819.
Charles M. Cai, Nikhil Nagane, Rajeev Kumar, Charles E. Wyman.
Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California, Riverside, 1084 Columbia Avenue, Riverside, USA &
Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California, Riverside, 446 Winston Chung Hall, 900 University Ave., Riverside, USA
Metal halides are selective catalysts suitable for production of the fuel precursors furfural and 5-HMF from sugars derived from lignocellulosic biomass. However, they do not perform nearly as well when applied to biomass even in combination with immiscible extracting solvents or expensive ionic co-solvents. Here, we couple metal halides with a highly tunable co-solvent system employing renewable tetrahydrofuran (THF) to significantly enhance co-production of furfural and 5-HMF from biomass in a single phase reaction strategy capable of integrating biomass deconstruction with catalytic dehydration of sugars. Screening of several promising metal halide species at 170 °C in pH-controlled reactions with sugar solutions and larger 1 L reactions with maple wood and corn stover revealed how the interplay between relative Brønsted and Lewis acidities was responsible for enhancing catalytic performance in THF co-solvent. Combining FeCl3 with THF co-solvent was particularly effective, achieving one of the highest reported simultaneous yields of furfural (95%) and 5-HMF (51%) directly from biomass with minimal levulinic acid formation (6%). Furthermore, over 90% of the lignin from biomass was extracted by THF and recovered as a fine lignin powder. Tuning the volume ratio of THF to water from 4 : 1 to 1 : 1 preserved 10% to 31% of the reacted biomass as a glucan-rich solid suitable for further catalytic reaction, enzymatic digestion, or possible pulp and paper production.