Transesterification of vegetable oil to biodisel using CaO-ZnO catalyst

Abstract

CaO-ZnO catalysts (with various Ca:Zn atomic ratios of 1:5, 1:3, 1:1, and 3:1) was prepared by incipient-wetness impregnation (IWI) or co-precipitation (CP) method. The samples were evaluated to find the best CaO-ZnO catalyst for use in the transesterification of palm oil with methanol for biodiesel production under condition of 15:1 methanol to oil molar ratio, 6 wt% catalyst, reaction temperature at 60ºC, and reaction time of 8 h. The fresh and spent catalysts were characterized by several techniques, including BET method, CO₂-TPD, TPR, SEM, XRF, FTIR, XRD and Hemmett Indicator. The effects of precursor concentration, type of precipitant, Ca:Zn atomic ratio and calcination temperature on the catalytic performance were studied. The highest FAME yield (83.82 and 81.73 % for IWI and CP catalysts, respectively) was obtained at the Ca:Zn atomic ratio of 1:3, and calcination temperature of 900ºC for IWl catalysts and 800 ºC for CP catalysts, respectively. The results from characterization indicated that the activity of catalyst depended on their basic properties, particle size and surface area. However, surface area of CaO-ZnO catalyst slightly affected to the biodiesel yield.