MgO/γ-Alumina and CaO/γ-Alumina Catalysts for the Transesterification of Castor Oil (Ricinus Communis) into Biodiesel

MgO/γ-alumina and CaO/γ-alumina heterogeneous base catalysts have been prepared by wet impregnation, using ۱۰ wt.% of metal oxide precursors, and used in the transesterification reaction of castor oil (Riccinus communis) into biodiesel. Catalyst characterization includes X-Ray Diffraction (XRD), Fourie Transform InfraRed (FT-IR) spectroscopy, X-Ray Fluorescence (XRF), Surface Area Analyzer (SAA), average pore radius (BJH), and basicity. The catalyst performance was observed from the activity and selectivity of the catalyst in converting castor oil into methyl ester with the batch system at ۶۰°C for ۲ hours. The castor oil biodiesel was analyzed using GC-MS to determine the selectivity of the catalyst towards methyl ricinoleate. The results showed that the addition of MgO and CaO to γ-alumina increased the basicity and average pore radius but decreased the specific surface area of γ-alumina. The FAME yields of γ-alumina, MgO/γ-alumina, CaO/γ-alumina, MgO, CaO, and KOH catalysts with ۳ wt.% ratio were ۸۱.۱۵%, ۸۲.۱۷%, ۸۲.۴۵%, ۸۲.۰۲%, ۸۲.۱۶%, and ۸۴.۵۷%. The selectivity to methyl ricinoleate was the highest for CaO/γ-alumina catalyst which was ۸۷.۵۷% area GC. The yield of FAME at various weight ratios of CaO/γ-alumina (۱, ۲, ۳, ۴, and ۵ wt.%) were ۸۱.۸۱%, ۸۲.۱۳%, ۸۲.۴۵%, ۸۳.۵۷%, and ۸۳.۹۶% and the selectivity to methyl ricinoleate was the largest at ۴ wt.% CaO/γ-alumina catalyst which was ۹۰.۲۰% GC area. Castor oil biodiesel was analyzed using the American Standard of Testing Materials (ASTM) method for biodiesel eligibility. ASTM test results for castor oil biodiesel showed a kinematic viscosity (۴۰°C) of ۱۵.۷۶ mm۲/s which is above the biodiesel standard because the kinematic viscosity of castor oil was also high. The flash point of ۲۲۲.۵°C, pour point <۲۷°C, and cloud point of ۱۵°C have fulfilled the requirements of the biodiesel standard.

کلیدواژه ها:

Heterogeneous catalyst ، MgO/γ-alumina ، CaO/γ-alumina ، castor oil (Ricinus communis) ، transesterification ، biodiesel