Recyclable Catalyst of ZnO/SiO2 Prepared from Salacca Leaves Ash for Sustainable Biodiesel Conversion

Abstract

This paper reports on the first case of the recyclable catalysts of ZnO/SiO2 prepared from salacca leaf ash as a source of silica for biodiesel production. The catalysts were prepared using a hydrothermal synthesis method, and the catalyst was utilized for biodiesel conversion from rice bran oil. Physicochemical properties of the catalysts were studied by multiple instrumental analyses consisting of XRD, SEM, TEM, and surface acidity measurements on pyridine adsorption followed by FTIR analysis. The study focuses on the effect of Zn content on the physicochemical character. As such, a varied Zn content of 20, 25, and 30 % wt. was applied. In order to evaluate the influencing parameters for the catalytic process, a response surface methodology based on the Box-Behnken design was applied in optimization. The selected parameters of catalysis included the Zn content, catalyst dose, methanol and oil ratio, and the time of reaction. It was concluded that all tested parameters—with the exception of Zn content—significantly influence the yield of the reaction. The catalyst demonstrated a reusable feature, as there was an insignificant yield value of catalytic activity until the fifth cycle during the simple procedure of recycling. This suggests that the material was potentially developed for biodiesel conversion.