Mixed Oxides as Heterogeneous Catalysts for Transesterification Reaction

Abstract

Mixed oxides of La, Mg and Ca in three different combinations La/Mg, La/Ca and La/Mg/Ca with different weight proportions of elements were evaluated as catalysts for the transesterification of used cotton seed oil with methanol. These catalysts were characterized with Powder XRD, TEM, and Hammett indicator test. Among three combinations, La/Mg mixed oxides in all the studied proportion (La: Mg in 1:1, 1:2 and 1:3 wt/wt) were found to complete the transesterification of used cotton seed oil. La/Mg in 1:3 ratio was found to be efficient catalyst for the completion of the reaction in lesser time period. Hence, La/Mg in 1:3 ratios was studied for optimizing other parameters. An amount of 5 wt% of La/Mg catalyst (1:3) and oil: methanol molar ratio of 1:136 at reflux temperature were the optimum reaction parameters. All the studied proportions (1:2:1, 1:3:1, 1:4:1, 1:5:1 wt/wt) of La/Mg/Ca catalysts also catalyze the transesterification completely, but lesser reaction time was observed with 1: 4: 1 molar ratio. La/Ca mixed oxides (1:1, 1:2, 1:3, and 1:4 wt/wt) were found to be the less active catalysts in comparison to the La/Mg, La/Mg/Ca catalysts.