Effect of different metal oxides on the catalytic activity of γ-Al2O3–MgO supported bifunctional heterogeneous catalyst in biodiesel production from WCO

Abstract

The catalytic activity of different γ-Al₂O₃–MgO supported bifunctional solid catalysts was successfully evaluated by carrying out simultaneous esterification–transesterification reactions in waste cooking oil. The physicochemical properties of the synthesized catalysts were studied using different characterization techniques to identify a catalyst of proper configuration for proper operation conditions to develop a sustainable and economical biodiesel production process. The results indicated that the Mo–Mn/γ-Al₂O₃-15 wt% MgO catalyst showed excellent performance in biodiesel production from selected waste cooking oil as compared with Mo–Zn/γ-Al₂O₃-15 wt% MgO or Mo–Sn/γ-Al₂O₃-15 wt% MgO catalysts and provided a biodiesel yield of 91.4% under optimal reaction conditions, i.e. methanol/oil molar ratio of 27 : 1, 5 wt% catalyst and a reaction temperature of 100 °C for 4 h. The good catalytic activity could be attributed to the existence of the optimal number of catalytically active sites on the surface of the catalyst. Moreover, the catalyst showed substantial reusability in biodiesel production from waste cooking oil.