AC3B Technology for Direct Liquefaction of Lignocellulosic Biomass: New Concepts of Coupling and Decoupling of Catalytic/Chemical Reactions for Obtaining a Very High Overall Performance

The acid-catalyzed conversion of lignocellulosic biomass (AC3B) process has been developed for the direct liquefaction of lignocellulosic biomass. In the original version, the main products, ethyl esters, are produced in acidic medium containing ethanol, using a one-pot conversion system. Our research strategy for obtaining a high overall performance is based on two general concepts: (a) coupling of catalytic/chemical reactions that lead to desired products and (b) decoupling of reactions that produce unwanted products, by decreasing the effectiveness of these reactions. Concept (a) is realized by using oxidizers (hydrogen peroxide and Fenton's reagent) that promote a higher production of carboxylic acids as main intermediates, while concept (b) contributes to a significant decrease of undesired formation of polymeric products. As result of these reaction coupling and decoupling, the overall yield of liquid products has been multiplied by a factor of 2.5 (from 27 to over 70 wt%). Not only the yields of products from cellulose and hemicellulose components experience considerable increases, but also the lignin component starts undergoing a noticeable conversion. Essentially, the AC3B process, in the most recent version, consumes ethanol that is partly used to produce liquid fuels and chemicals from lignocellulosic biomass. The other amount of feed ethanol is converted-via diethyl ether and over ZSM-5-based catalysts-into aromatics-rich gasoline and liquefied petroleum gas-grade hydrocarbons. Sequence of actions that have significantly improved the total product yield (RP): AC = acidic medium, HP = addition of hydrogen peroxide, DL-st = use of a delignification step, FR = use of a Fenton-type reagent, PIn = use of a polymerization inhibitor.