Continuous Catalytic Esterification and Hydrogenation of a Levoglucosan/Acetic Acid Mixture for Production of Ethyl Levulinate/Acetate and Valeric Biofuels

A mixture of levoglucosan (LG) and acetic acid (AA), representing water extracted fast pyrolysis oil, was continuously converted to ethyl levulinate (EL) and ethyl acetate (EA) using H-ZSM5 [120–230 °C, 600 psig, 80% ethanol (v/v)]. Fractional conversion of both reactants was 65% or greater at temperatures above 120 °C, and space time yields (STY) approached 140 and 15 g/L-cat/h for EA and EL, respectively, at 180 °C (LHSV = 4.9 h–1). Two potential pathways for EL formation from levoglucosan were apparent, one with glucose and ethyl α-d-glucopyranoside as intermediates and the other with furfural. Adding metal functionality (Ru/H-ZSM5) resulted in the production of valerate biofuels (esters of carboxylic acids C3 or greater; e.g., pentanoic and hexanoic acid ethyl esters) and EA from the mixture in the presence of hydrogen. Conversions for LG and AA using Ru/H-ZSM5 were similar to H-ZSM5, but ethyl levulinate space time yield declined (∼5 g/L-cat/h) as valerate biofuel STY increased (∼10 g/L-cat/h) at an ...