Metal oxide catalysts for biodiesel production

Abstract

Abstract The process of biodiesel production is generally carried out in the presence of a proper catalyst in order to accelerate the conversion rate of triglycerides or free fatty acids into methyl ester in a shorter reaction time. Catalyst can be classified into homogeneous and heterogeneous catalysts. The use of homogeneous catalysts causes many difficulties in the process of production, such as separating and washing. In case of using heterogeneous base catalysts, the interaction between the alkali catalysts and the FFA results in the soap formation. Thereby, transesterification in the presence of heterogeneous base catalysts requires refined raw materials with the low FFA content. Regarding these facts, heterogeneous acid catalysts get great attention due to the presence of high acid site strength and minimal leaching of the active site, and minimal undesirable side reaction. Besides, that, the faster reaction rate causes a high reduction of the cost of production. This chapter reviewed recent literatures on some important synthesis pathways to fabricate heterogeneous acid catalysts. Moreover, the catalytic activity and recyclability of the synthesized catalysts were reviewed.