Alumina supported calcium/lanthanide oxides catalysts for biodiesel production from refined cooking oil

Abstract

In recent years, fossil fuels have played a key role in the researcher’s quest for energy sustainable system. The exploration of fossil fuels replacement has become a focus of intense interest, making it possible to resolve numerous current social problems such as the increasing prices of crude petroleum and environmental stress condition like global warming and air pollution due to the burning of fossil fuels. The application of this biodiesel is growing. However, the optimization of each reaction parameters to attain a high yield has not yet been explored in detail. This study has focused on the use of the heterogeneous base catalyst for biodiesel production. Biodiesel was prepared from the refined cooking oil by transesterification using methanol in the presence of calcium oxides-based supported on alumina by wetness impregnation method. Calcium oxides-based supported on alumina were used as catalysts for the transesterification reaction of refined cooking oil due to their highly basic characteristic. A comparison of the lanthanum oxides, cerium oxides and praseodymium oxides as a dopant was synthesized. The catalytic performance of the prepared catalysts was examined by gas chromatography-flame ionization detector (GC-FID). The three most potential catalyst was selected for the optimization of the transesterification and characterization study. Ce/Ca/Al2O3 catalyst calcined at 900ºC with 3 times of alumina coating and 10:90 wt.% dopant ratio to based, showed the highest biodiesel yield of 94.25% at mild reaction conditions (65°C, 1:18 oil:methanol mole ratio, 10 wt.% catalyst loading within 3 hours). The physicochemical properties of the potential catalysts were studied using nitrogen analysis (NA) and CO2-temperature programmed desorption (CO2-TPD) has 130.79 m2/g surface areas and 1.6132 mmol/g basicity. X-ray diffraction (XRD) and field electron emission microscopy (FESEM) analysis showed Ce/Ca/Al2O3 catalyst had a polycrystalline structure with small particle sizes. X-ray fluorescence (XRF), Energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) confirmed the existence of Ce, La, Pr, Ca, Al and O species in each potential catalyst. At the end of this study, it was proven that Ce/Ca(10:90)/Al2O3 catalyst can catalyze the transesterification reaction of refined cooking oil gave highest biodiesel yield (94.25%).