Catalytic Hydrodeoxygenation of Methyl Stearate and Microbial Lipids to Diesel-Range Alkanes over Pd/HPA-SiO2 Catalysts

Abstract

Catalytic hydrotreating of renewable oils is a promising way to get diesel alkanes, with the use of microbial lipids further facilitating scalable production of green diesel. The core issue of triglyceride hydrodeoxygenation (HDO) research is still to develop efficient catalysts under mild reaction conditions. Herein, we demonstrate that the heteropolyacid (HPA)-modified SiO2 supported Pd catalysts showed high activity for the HDO reaction of methyl stearate and soybean oil to diesel alkanes (C15∼C18, >90 wt % at 200 °C). Characterizations show that the Brønsted acid sites introduced by grafting heteropolyacid on SiO2 and metal sites of small Pd particles contribute to the high HDO activity of this bifunctional catalyst. Additionally, lipids produced by Rhodosporidium toruloides Y4 from glucose or corn stover were also transformed to about 75 wt % of diesel-range alkane products. This integration of microbial lipid production with chemical catalysis should facilitate the engineering of green diesel production from lignocellulosic biomass.