High Efficiency Conversion of Lignocellulosics to Sugars for Liquid Fuel Production by the ACOS Process

Abstract

Decline of world oil reserves and pollution problems from burning of fossil fuels and lead require that methods for safe alternate liquid fuels be developed. Ethanol is one of the most important alternate liquid fuels since it can be produced readily by fermentation of sugars. Wood and vegetable growth are excellent sources of sugars to support an ethanol fuel economy of significant proportions. Acid Catalysed Organosolv Saccharification (ACOS) is a new means for total biomass dissolution and recover of component sugars and lignin from wood. The process uses an acidified aqueous acetone solution for the high-temperature hydrolysis of biomass. Acetone provides an excellent reaction medium for dissolution of both sugars and lignins and through a transient derivatization of the sugars protects them from further reaction (dehydration) to furfurals and humic substances. Therefore, sugar and lignin recoveries are quantitative. The ACOS process is 700 times faster than the conventional weak acid hydrolysis processes and wood can be dissolved in 30 sec by this process. The lignin is recovered as a low molecular weight powder by-product. This process is applicable to both coniferous and deciduous woods and agricultural residues such as corn stover, straw and bagasse. In case of such residues the ethanol yield can be doubled (straw and corn stover) or tripled (bagasse) compared to what has been obtained from the grain and sugarcane juice so far. Hitherto these residues were merely discarded or burned.