Evaluation of K/SnO2 performance as a solid catalyst in the trans-esterification of a mixed plant oil

Abstract

In this investigation, a heterogeneous acid–base catalyst for biodiesel production was synthesized by the impregnation method. Tin oxide as an acidic material was obtained by hydrolysis of tin di-chloride and followed by impregnation with K2CO3 solution. The temperature of 65 °C, the methanol to oil molar ratio of 12:1, 3 wt% of catalyst in the reaction mixture, molar ratio of K:Sn = 2:1, the reaction time of 1.5 h were determined as the optimum conditions of trans-esterification reaction under studied conditions. The yield of reaction was calculated to be 97.5% under the optimum conditions. Reaching a high yield of 90% in a short time (30 min) of the trans-esterification reaction shows strong performance of the catalyst for biodiesel production. The advantages of using K/SnO2 catalyst were compared with the homogeneous catalyst KOH and heterogeneous catalyst K/γ-Al2O3 and it was found that K/SnO2 catalyst has enhanced leaching stability compared to KOH and K/γ-Al2O3 catalysts with less washing required for the methyl ester phase.