Biodiesel production via ethanolysis of jatropha oil using molybdenum impregnated calcium oxide as solid catalyst

Abstract

Molybdenum impregnated calcium oxide (Mo/CaO) was prepared via a wet impregnation method by varying Mo loading (1–5 wt%) and calcination temperature (300–800 °C). Powder X-ray diffraction study of the Mo/CaO catalyst supported the homogeneous doping of Mo in CaO as no peak corresponding to molybdenum oxide was obtained. The prepared catalyst was successfully employed for the ethanolysis of high free fatty acid (up to 18 wt%) containing vegetable oils with ethanol to give >99% fatty acid ethyl ester (FAEE) yield under the optimal reaction conditions of ethanol to oil molar ratio of 12 : 1, catalyst concentration of 5 wt% (catalyst/oil) and reaction temperature of 65 °C. The catalyst was recovered and reused five times without significant loss in its activity. The Koros–Nowak criterion test demonstrated that catalytic activity was independent from the mass transport phenomenon. Under optimized reaction conditions the activation energy (E_a) for Mo/CaO catalyzed ethanolysis was found to be 66.02 kJ mol⁻¹. Thermodynamic activation parameters of the reactions were evaluated based on activation complex theory (ACT) and obtained values of ΔG^‡ = 43.62 kJ mol⁻¹, ΔH^‡ = 64.10 kJ mol⁻¹ and ΔS^‡ = −60.58 J mol⁻¹ K⁻¹ supported an unspontaneous, endothermic and associative mechanism of reaction.