The activities of sulfated iron-tin mixed oxide catalysts for esterification of free fatty acids in crude palm oil were investigated. The iron-tin mixed oxides were prepared from co-precipitation method when the iron content was fixed at 10 mol%. Types of iron precursor, sulfate concentration and calcination temperature were varied. The optimum study in the esterification reaction variables (stirring speed, reaction time, catalyst loading, methanol/oil molar ratio and reaction temperature) was also conducted with the best sulfated iron-tin mixed oxide catalyst. The findings show that iron sulfate is the best precursor. The activities of sulfated iron-tin mixed oxide catalysts increase with sulfate concentration. The optimum calcination temperature to prepare sulfated iron-tin mixed oxides is 450°C. The addition of iron oxide into sulfated tin oxide improves the stability of the catalyst during the reusability process. Therefore, sulfated iron-tin mixed oxide is a better candidate than sulfated tin oxide for esterification of free fatty acids. For the esterification study, the optimum reaction conditions are: the stirring speed of 250 rpm, the catalyst loading of 4.5 wt% of the oil, the methanol/oil molar ratio of 14.2, the reaction temperature of 80°C and the reaction time of 3 h.
The International Journal of Chemical Reactor Engineering covers the broad fields of theoretical and applied reactor engineering. The
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