The aim of this research was to determine the optimum parameters for synthesis and characterization of mixed rare earth hydroxide (for use as a catalyst) through co-precipitation, with sodium hydroxide as precipitation agent at pH 12. The effects of precipitation temperature (30 ,60 or 100 oC) and stirring speed (400 or 600 rpm) on the chemical composition, crystal structure and surface characteristics of the catalyst were investigated. The chemical composition of the catalyst was analyzed using X-ray fluorescence (XRF), and it was composed of CeO2, Nd2O3, La2O3, and Y2O3. X-ray diffraction (XRD) studies indicated that all samples had cubic structure of CeO2. The optimal temperature and stirring speed for precipitation of mixed rare earth catalyst were 60 oC and 400 rpm, respectively, giving large specific surface after calcination at 300 oC. The high 190 m2 g-1 BET surface area and 1220 µmol g-1 total basic sites were achieved, indicating small crystallite sizes and large amount of active sites in the catalyst. From the above results, the optimized catalyst is considered a promising solid catalyst for biodiesel production.
