Transesterification of vegetable oil to biodiesel using a heteropolyacid solid catalyst

A clean, facile, and ecologically friendly method for the production of biodiesel has been developed. A solid acid, namely the heteropolyacid (HPA) Cs2.5H0.5PW12O40, has been used as a heterogeneous catalyst for the production of biodiesel from Eruca sativa Gars. oils (ESG oil) with methanol at a certain temperature. A study for optimizing the reaction conditions such as the reaction time, temperature, the oil to methanol ratio, the amount of catalyst, and the usage times of the catalyst, has been performed. The Cs2.5H0.5PW12O40 heterogeneous acid catalyst shows almost the same activity under the optimized reaction conditions as compared to a conventional homogeneous catalyst such as sodium hydroxide or sulfuric acid, and can easily be separated from the products and can be used for several more runs. The most important features of this catalyst are that the catalytic activity is not effected by the content of free fatty acids and content of water in the vegetable oil and that the esterification can occur at a lower temperature (room temperature) and be finished within a shorter time. ne results illustrate that the Cs2.5H0.5PW12O40 is an excellent, water-tolerant and environmentally benign solid acid catalyst for the production of biodiesel. The fuel properties of ESG biodiesel were found to be in agreement with the ASTM standard.