Biodiesel production from waste cooking oil using a new heterogeneous catalyst SrO doped CaO nanoparticles

Biodiesel production from waste palm cooking oil (WPCO) was studied. Calcium oxide with a strontium ion additive (Sr-CaO) was employed as a catalyst in transesterification reaction of used palm oil with methanol. The Sr-CaO was synthesized by co-precipitation method between SrCl2 and Ca(NO3)2, then calcined at 900°C for 5 h. The catalyst was characterized by using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), Scanning electron microscope (SEM), and Fourier transform infrared spectrometer (FT-IR). The morphology and elements content of Sr and Ca in the catalyst were confirmed by SEM-EDX. The approximate catalyst diameter is 12.6±5.9 µm. The highest conversion was 99.33% (the reaction time 3 h, 5%w/w catalyst, methanol to oil molar ratio 9:1 and reaction temperature 80°C). The catalyst can be used up to the sixth cycles with a good yield. The synthesized biodiesel meet the requirement of standard biodiesel (EN 14103 and ASTM D445). These findings suggest that calcium oxide with a strontium ion additive (Sr-CaO) is an effective renewable biodiesel catalyst.