Mg-Al Hydrotalcite/γ-Al<sub>2</sub>O<sub>3</sub> as Fixed-Bed Catalyst in Biodiesel Production

Abstract

Batch-type base catalysis is currently the main process used for biodiesel production. Methods to reduce costs, improve capacity and decrease the emission of pollutants in the production of biodiesel are of great significance. This paper studied the reaction conditions for fatty acid methyl ester (FAME, referred to as biodiesel) production through the transesterification of soybean oil with methanol in the presence of Mg-Al hydrotalcite/γ-Al2O3 as a fixed-bed catalyst. The influences of the methanol-oil ratio, space velocity, reaction temperature and pressure on product conversion were investigated. The results indicated that the optimum reaction conditions were as follows: methanol/oil ratio of 21:1, space velocity of 0.5 h-1, reaction temperature of 340°C, and reaction pressure of 2 MPa. Under these conditions, the one stage conversion rate was 80% and the lifetime of the catalyst was 220 h. The catalyst can process raw materials with high total acid numbers using two stages project.