Partial hydrogenation of polyunsaturated fatty acid methyl ester for biodiesel upgrading using palladium supported on silica

Abstract

Biodiesel or fatty acid methyl ester (FAME) can be produced by transesterification of vegetable oils with methanol in the presence of a catalyst. However, some biodiesel properties such as oxidative stability and cold flow properties depend on the degree of unsaturation in FAME chains. If vegetable oils contain higher amounts of unsaturated fatty acid, they have lower oxidative stability but good cold flow properties. Therefore, the quality of biodiesel can be improved by partial hydrogenation. This research focused on the catalytic performance of partial hydrogenation of polyunsaturated FAMEs from palm oil using palladium supported on silica (Pd/SiO2), prepared by the incipient wetness impregnation method, as a catalyst. The effects of pore size of the support and Pd loading on catalytic activity were also studied. The partial hydrogenation reaction was performed in a batch reactor. The Pd/SiO2 were characterized by Gas Chromatograph, X-ray Diffractometer, Scanning Electron Microscope with Energy Dispersive Spectrometer, Temperature Programmed Desorption / Reduction / Oxidation analyzer and Atomic Absorption Spectrometer. The catalysts with large pore size (Q50) had higher activity and produced more trans-isomers.