Eco-friendly lubricant by partial hydrogenation of palm oil over Pd/γ-Al2O3 catalyst

Abstract

In the presence of environmental crisis, the utilization of palm oil for eco-friendly lubricant is interesting. However, the palm oil has poor oxidation resistance due to the presence of unsaturated fatty acids (oleic acid; C18:1, linoleic acid; C18:2 and linolenic acid; C18:3). The aim of this study is to improve oxidation stability of palm oil by decreasing the amount of multiple unsaturated fatty acids via partial hydrogenation over heterogeneous catalysts, and to study physicochemical properties of the hydrogenated palm oil. The partial hydrogenation of palm olein is carried out in Parr reactor, using Pd/γ-Al2O3 as catalyst. Effects of reaction conditions (temperature, pressure, time, %loading of Pd on support and amount of catalyst) on oxidation stability of synthesized oil are studied. The results show that partial hydrogenation is able to transform the multiple unsaturated fatty acids into single unsaturated fatty acids. With severe reaction conditions, the stability of product is significantly increased. However, some wax formation is observed since all double bonds in fatty acids are saturated. Too high temperature promotes the carbon chain cutting of C18 molecule to lower carbon number molecule. Then, optimal reaction conditions that increase oil stability but do not cause crystallization of oil are needed to be investigated. With the optimal conditions, the oxidation stability of palm oil increased from 13.8 to 22.8h. The effect of these parameters on the transformation of fatty acid composition in oil is also discussed.