Influence of Brønsted acid sites on the product distribution in the hydrodeoxygenation of methyl laurate over supported Ru catalysts

Abstract

The production of biofuels (hydrocarbons) from renewable biomass resources has attracted much attention in the fields of green energy and sustainable chemistry. Herein, catalytic hydrodeoxygenation of methyl laurate (n-C₁₁H₂₃COOCH₃) to produce hydrocarbons n-C₁₂H₂₆ and n-C₁₁H₂₄ has been investigated over Ru dispersed on acidic supports H-ZSM-5, Al₂O₃ and SiO₂, and the reaction rate and the product distribution were discussed and correlated with surface Brønsted and Lewis acid sites and active Ru species in detail. The reaction rate at the initial stage increased with the amount of the total acid sites, and the ratio of n-C₁₂H₂₆/n-C₁₁H₂₄ and the selectivity to n-C₁₂H₂₆ were positively correlated with the amount of Brønsted acid sites. The Ru active species presented to be more electron-deficient on the catalysts with a larger amount of Brønsted acid sites on which an η¹-(O) adsorption configuration of 1-C₁₁H₂₃CHO was confirmed, which favoured the formation of n-C₁₂H₂₆, thus varying the product distribution. Besides, Brønsted acid sites could provide protons to promote the hydrogenolysis of n-C₁₁H₂₃COOCH₃ and the following dehydration to produce n-C₁₂H₂₆.