PREPARATION OF CALCIUM OXIDE SUPPORTED RICE HUSK SILICA AS CATALYST FOR BIODIESEL PRODUCTION

Abstract

This research aims to use calcium oxide supported on rice husk silica (CaO/SiO2) as a solid base catalyst. The catalyst was prepared by impregnation method and used in transesterification reaction of palm oil as feedstock with methanol to produce biodiesel. The factors influencing the preparation of catalyst were studied including calcination temperature and the weight percentage of CaO. The synthesized CaO/SiO2 catalyst was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FT-IR), N2 adsorption-desorption measurement techniques and the basicity of catalyst was determined by titration method. The results indicated that 30 wt.% of Ca(NO3)2 loaded on 5 wt.% of SiO2, calcined at 700ºC for 3 h, exhibited the most active catalyst. The transesterification of palm oil with methanol was studied for biodiesel synthesis. The effects of the mole ratio of methanol to oil, time of reaction, and mass of catalyst to oil were investigated to optimize the reaction condition. The results showed that by using 1:9 mole ratio of oil to methanol, 3 wt.% of catalyst based on oil weight at 65°C for 3 h of reaction time, 98.36% of methyl ester content was obtained. This catalyst could be reused up to 4 times with slightly loss in catalyst activity. As a result, the catalyst produced from calcium oxide supported on rice husk silica was proved to exhibit an excellent stability and a high activity for biodiesel production.