Characterization of K2O/CaO-ZnO Catalyst for Transesterification of Soybean Oil to Biodiesel

In this study, heterogeneous solid base catalysts (K2O/CaO-ZnO) were developed and characterized for transesterification of soybean oil to biodiesel. In the catalyst, CaO-ZnO prepared by coprecipitation was promoted by K2O by impregnation method. The catalysts were characterized by using X-Ray Diffraction (XRD) and Brunauer Emmett Teller (BET) surface area. The catalysts were compared to ZnO and CaO-ZnO catalysts to study their activities in the transesterification process under suitable conditions (reaction temperature of 60 oC, catalyst loading of 6 wt.%, methanol to oil molar ratio of 15:1, and reaction time of 4 h). From the catalyst testing results, the 2 wt.% K2O/CaO-ZnO showed the highest catalytic activity with Fatty Acid Methyl Ester (FAME) yield of 81.08%. The incorporation of K2O on the CaO-ZnO catalyst enhanced the catalytic transesterification activity due to increasing its basicity and surface area.