Recent Progress on Heteropolyacids for Green Fuels Synthesis

Decreasing fossil fuel reserves and growing concerns are driving the utilization of renewable feedstocks as green fuel sources. Heteropolyacids (HPAs) are one of the most promising catalytic materials in green biodiesel production. Their unique chemical and physical properties are outstanding and could allow the preparation of composite materials. In this review, esterification /transesterification for biodiesel synthesis using various types of HPAs base catalysts including pristine HPAs, substituted HPAs, supported HPAs and encapsulated HPAs has been described. In addition, esterification/transesterification reaction conditions such as reaction time and temperature, alcohol content and catalyst dosage affect the catalytic activity of the HPAs base catalysts, which are also discussed in detail. Finally, the present drawbacks and future challenges on HPAs based catalytic systems for the production of biodiesel are also addressed in the concluding remarks.