Hydrodeoxygenation of 3-pentanone over bifunctional Pt-heteropoly acid catalyst in the gas phase: Enhancing effect of gold

Abstract

Hydrodeoxygenation (HDO) of 3-pentanone to yield n-pentane was carried out using bifunctional metal-acid catalysis at a gas-solid interface at 40–80 °C and 1 bar H2 pressure in a fixed-bed microreactor. The bifunctional catalysts studied comprised Pt as the metal component and Cs2.5H0.5PW12O40 (CsPW), an acidic Cs salt of Keggin-type heteropoly acid H3PW12O40, as the acid component. The bifunctional HDO pathway included hydrogenation of ketone to secondary alcohol on metal sites followed by dehydration of the alcohol to alkene on acid sites and finally alkene hydrogenation to alkane on metal sites. Addition of gold to the Pt/CsPW was found to increase both catalyst hydrogenation activity (turnover rate at Pt sites) and catalyst stability to deactivation, although the Au alone without Pt was almost totally inert. The enhancement of catalyst performance is suggested to be caused by PtAu alloying. Scanning transmission electron microscopy–energy dispersive X-ray spectroscopy (STEM-EDX) and X-ray diffraction (XRD) analysis of the PtAu/CsPW catalysts indicated the presence of bimetallic PtAu nanoparticles with a wide range of Pt/Au atomic ratios (0.5–7.7).