Supported solid and heteropoly acid catalysts for production of biodiesel

Biodiesel has developed attraction of most researchers recently because of its renewable resources and environmental benefits. Transesterification process in the presence of catalysts is the most common way, which is used for biodiesel production. Heterogeneous acid catalysts are considered more reliable than any other catalysts to carry out most vital reactions related to green chemistry (biodiesel production), because the production of biodiesel from solid acid catalysts is considered economically favorable. Nowadays, biodiesel is preparing from low quality feedstock by using solid acids catalysts in many research laboratory throughout the world. This article discusses how much catalyst shapes affect the efficiency of catalyst during catalysis. Different types of supports (zinc oxide, alumina, zirconia, and silica) are used to increase the efficiency of catalysts. Supported Lewis acid, Brønsted acid, and heteropoly acid catalysts show good efficiency for the catalytic transesterification of oil with alcohol. Heteropoly acid catalysts are tremendous and environment friendly acid catalyst and have ability to tolerate contaminations of oil resources such as water contents and free fatty acids (FFAs) contents. Keggin-type heteropoly acids are easily available and having stable structure while Wells–Dawson-type heteropoly acids are included in super acid class, due to these reasons heteropoly acids are considered as best acidic catalysts for biodiesel production by catalytic transesterification process. Therefore, this review also focused on the deactivation, regeneration and advantages of supported solid acid catalysts used for the catalytic production of biodiesel through transesterification.