Effect of Catalyst Pellet-Diameter and Basicity on Transesterification of Soybean Oil into Biodiesel using K₂O/CaO-ZnO Catalyst over Hybrid Catalytic-Plasma Reactor

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

^* Corresponding author: luqman.buchori@che.undip.ac.id

Abstract

This research is aimed to study the effect of catalyst pellet-diameter and catalyst basicity on the transesterification process of soybean oil into biodiesel over a hybrid catalytic-plasma reactor. Various catalyst diameters (3, 5, and 7 mm) were tested in this reaction system. Catalyst basicity was also examined by comparing fresh and used catalyst as well as with and without K₂O promoter. All catalysts testing were performed in a hybrid plasma-catalytic reactor (dielectric barrier discharge – DBD type). From the results, the synergistic effects roles of the catalyst and the plasma in the transesterification process are important, in which the energetic electrons within plasma assist the reaction on the catalyst surface by an exciting bonded electron. The catalyst basicity was influenced by the composition of CaO on the catalyst as well as roles of the alkaline K₂O promoter. Catalyst basicity is important in producing biodiesel with high performance. Yield of fatty acid alkyl ester (FAAE) or biodiesel is slightly influenced by the catalyst diameter within the range of diameter studied.