Hydrodeoxygenation of biomass-derived fatty acids and esters to biofuels on RuRe/ZSM-5 catalysts: Synergistic effects of ReOx and Brønsted acid sites

Abstract

The hydrodeoxygenation of fatty acids and esters is a critical pathway to produce biofuels. We report an efficient RuRe/ZSM-5(18) catalyst for hydrodeoxygenation of methyl laurate, the selectivity of n-C12H26 reached up to 95.2 % at complete conversion under the reaction conditions of 200 °C, 3 MPa H2, 3 h. The contribution of ReOx and acid sites was discussed from the perspective of dynamics and thermodynamics. ReOx was available for the adsorption of substrate and intermediates, the acidity from ReOx species and ZSM-5 are conducive to the cleavage of CO bond. The synergistic effects of ReOx and Brønsted acid sites induced Ru0 species to be electron-deficient, which preferred to adsorb aldehyde group in a linear adsorption configuration and facilitated for the hydrogenation of the aldehyde intermediate to alcohol, followed by dehydration to produce hydrocarbons. Thus, RuRe/ZSM-5(18) catalyst presented superior activity and chemoselectivity in the hydrodeoxygenation of methyl laurate as well as a series of fatty acids and esters without loss in carbon numbers in reactant.