Eco-benign approach to produce biodiesel from neem oil using heterogeneous nano-catalysts and process optimization

Abstract

Catalytic transesterification of vegetable oil is a promising technique for biodiesel production versus a base catalyzed process due to higher contents of free fatty acids (FFA). In transesterification process, FFA converts into mono-esters and oil pretreatment enable furnish optimal methyl ester yield. In the present investigation, Fe, Ni and Cu doped ZnO nano-catalysts were prepared by co-precipitation method and employed for the conversion of neem oil (non-edible) as function of temperature, reaction time, oil to methanol ratio, stirring speed and catalyst dose. In case of Ni doped ZnO, oil to methanol ratio 1:5, stirring speed 150 rpm, time 80 min, 2% catalyst dose and 60 °C temperature yielded 80% biodiesel. Under similar conditions, Fe and Cu doped ZnO furnished 95% and 85% yield, respectively. Kinetics and thermodynamic model used to find out the conversion of oil in to biodiesel and the R2 values of Fe, Ni and Cu doped ZnO catalysts are 0.8233, 0.8935 and 0.9286 and process followed the pseudo first order kinetics. The physicochemical properties of biodiesel were investigated and compared with standards. The result revealed that the Fe, Ni and Cu doped ZnO catalysts are promising heterogeneous catalysts for transesterification of oil to biodiesel under mild reaction conditions.