Lithium-doped ceria supported SBA−15 as mesoporous solid reusable and heterogeneous catalyst for biodiesel production via simultaneous esterification and transesterification of waste cottonseed oil

Abstract

Abstract Lithium doped ceria loaded SBA-15 has been synthesised under normal atmospheric condition (without using hydrothermal treatment) and following wet impregnation route. The catalyst has been characterised by using different techniques viz., BET method for surface area measurements, FE-SEM for surface morphology study, XPS for the determination of catalyst composition and element oxidation state. The catalyst was found to possess both acidic and basic sites and hence, successfully employed for the simultaneous esterification and transesterification of waste cottonseed oil. Under optimized reaction conditions of catalyst concentration 10 wt%, methanol to oil molar ratio of 40:1 at 65 °C, the catalyst was able to give >98% fatty acid methyl ester yield within 4 h of reaction time. The catalyst was recovered and reused during 5 successive runs without any significant loss of activity. The activation energy (Ea) for the reaction was found to be 57.7 kJ mol−1, while ΔH‡, ΔG‡ and ΔS‡ were found to be 59.4 kJ mol−1, +95.9 kJ mol−1and - 0.108 kJ mol−1, respectively. On the basis of thermodynamic parameters, the reaction is expected to be endothermic, non spontaneous and following an associative pathway.