Researchers at Concordia University (Canada) have developed a new one-pot system for the catalytic conversion of cellulosic biomass into alkyl levulinates and other esters and subsequent product extraction. The obtained liquid fractions (light and heavy fractions) could be used, after drying and removal of unused alcohol, for blending into gasoline or diesel/biodiesel.
The team used two different conversion procedures: ethanolysis (direct acid-catalyzed conversion in ethanol medium) and a sequential procedure, the latter consisting of acid hydrolysis followed by the esterification of resulting acids with ethanol.
Using wood residues as raw material, the yields in ethyl levulinate and other by-products—with the only exception of diethyl ether (DEE)—were similar for both procedures. The incorporation of some H-USY zeolite could significantly decrease the yield of DEE in the ethanolysis procedure.
Reported results obtained with some other biomass feedstocks (particularly, switch grass) showed a good relationship between the product levulinate yield and the cellulose content of the raw material.
The product extraction was carried out by a distillation technique that combines a temperature programmed heating with a vacuum level-programmed evacuation (technique of mild vacuum-assisted distillation, MVAD).
R. Le Van Mao, Q. Zhao, G. Dima and D. Petraccone (2010) New Process for the Acid-Catalyzed Conversion of Cellulosic Biomass (AC3B) into Alkyl Levulinates and Other Esters Using a Unique One-Pot System of Reaction and Product Extraction. Catalysis Letters. doi: 10.1007/s10562-010-0493-y