Effect of metal type on cis-trans selectivity and stability of the catalyst for partial hydrogenation of FAMEs

Abstract

Biodiesel or fatty acid methyl ester (FAME) can be produced by transesterification from vegetable oils or animal fats with methanol. The main problems of biodiesel quality are oxidative stability and cold flow properties, which can be improved by partial hydrogenation. This research focused on the effect of metal type on the partial hydrogenation reaction of polyunsaturated FAMES under reaction conditions of 0.4 MPa hydrogen pressure and 80-120℃ temperature. The effect of a Mg modifier on cis-trans selectivity over a partial hydrogenation reaction of polyunsaturated FAMES using soybean oil as a feedstock was also studied. Three of metal (Pd, Pt, and Ni) supported on SiO2 were prepared by incipient wetness impregnation. The catalysts and products were characterized by using AAS, SAA, XRD, GC, FTIR, Rancimat Tester, and CO pulse chemisorption. Among the catalysts studied, the Pd catalyst presented the highest catalytic activity since it could convert both Cl8:3 and Cl8:2 rapidly after 4 h of reaction time. Moreover, it substantially increased the amount of cis-C18:1. On the other hand, Ni catalyst showed the lowest catalytic activity. In addition, it was found that all magnesium-modified catalysts decreased trans-Cl8:1 formation in the partial hydrogenation of soybean oil biodiesel.