Roles of K₂O on the CaO-ZnO Catalyst and Its Influence on Catalyst Basicity for Biodiesel Production

Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Semarang - Indonesia

^* Corresponding author: istadi@live.undip.ac.id

Abstract

This research aimed to study the effect of K₂O impregnation on the basicity of the CaO-ZnO catalyst and its effect on biodiesel production. The effect of mole ratio of CaO to ZnO catalyst and %wt K₂O were also studied. The mole ratio of CaO to ZnO catalyst was varied at 1:1, 1:1.5, 1:2, 1:3, and 3:1, while the %wt K₂O was varied at 1, 3, and 5 %. The catalyst basicity was determined by titration method. The basicity of the catalyst increased after the CaO-ZnO catalyst was impregnated with K₂O in all mole ratios of CaO-ZnO catalyst. The addition of K₂O as a promoter also increase the basicity. The highest basicity was obtained at the CaO-ZnO mole ratio of 3:1 and 5%wt K₂O. The tranesterification process was carried out in a batch reactor at a methanol to oil mole ratio of 15:1, a reaction temperature of 60°C, a reaction time of 4 h, and a catalyst loading of 5%wt oil. The FAME yields obtained were 41.33%. These results proved that K₂O plays a role in enhancing the catalyst basicity. In addition, K₂O also serves as a binding agent to improve the mechanical properties of the catalyst.