Sudanese Clays for Heterogenous Methanolysis of Castor Oil

Objective: To modify two Sudanese clays, called Jourdiqua and Jabbalmarra, with different loading of HCl, 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M and 1.00 M in order to increase their catalytic activities and then used in methanolysis of castor oil. Methods/Statistical analysis: Both raw and modified clay samples were used as catalysts under reaction conditions; 5wt% of catalyst to oil, molar ratio of methanol to oil of 27:1, 4 h reaction time and temperature of 67°C. The unmodified and modified clay samples were characterized by, thermogravimetric analysis-differential thermogravimetric (TGA-DTG), Brunauer-Emmett-Teller (BET), inductively coupled plasma-emission spectroscopy (ICP-ES), atomic absorption spectroscopy (AAS), X-ray powder diffraction (XRD), Fourier transform infra-red (FTIR) and field electron scanning emission microscopy (FESEM). Finding: Application/Improvement: BET analysis showed increase in specific surface area for both Jourdiqua and Jabbalmarra clays. Elemental analysis by ICP-ES showed decrease content in elements of Al, Mg, Na and K for both clays, due to the acid leaching. The biodiesel conversion was monitored using nuclear magnetic resonance (NMR) spectroscopy. An increase in conversion was observed for Jourdiqua clay from 51% to 90% when treated with 0.5 M HCl, the optimized concentration for the modification, while for Jabbalmarra 22.5% conversion was obtained with raw clay and after modification gave conversion of 82% in reaction conditions of temperature 65°C, reaction time of 4 h, molar ratio of methanol to oil of 18:1 and catalyst loading of 9%. It was observed that acid modification with 0.5 M HCl have improved tremendously the catalytic capability of the raw clays.