Enhanced transesterification of rapeseed oil to biodiesel catalyzed by KCl/CaO

Abstract

A series of supported solid base catalysts were prepared by impregnation of chloride salts over CaO. The catalytic activity of the prepared catalysts was tested for the transesterification reaction of biodiesel from rapeseed oil and methanol. The KCl/CaO catalyst containing 15% KCl exhibited the highest catalytic activity after calcination at 600 °C for 6 h. A reaction optimization study was carried out using KCl/CaO as catalyst leading to operation conditions for achieving a 98.3% yield of fatty acid methyl ester (FAME) at 2.5 h and 65 °C, a catalyst amount of 10%, and a mole ratio of methanol to rapeseed oil of 15:1. It was found that the highest FAME yield at 2.5 h was faster than that at 6 h for commercial CaO catalysts under the same reaction conditions. The characterization results showed that the pore size of CaO particles was greatly improved by the addition of KCl, which facilitated better access of the reactive molecules to the active sites of the catalyst.