Heterogeneous Catalysts Based on H3PW12O40 Heteropolyacid for Free Fatty Acids Esterification

1.1 Biodiesel chemical background The inevitable exhaustion of the fossil diesel reserves, besides the environmental impact generated by the green-house effect gas emission by these fuels has provoked the search by renewable feedstokes for energy production (Srivastava & Prasad, 2000; Sakay et al., 2009). Due to this crescent demand, the industry chemistry in all parts of world has search to develop environment friendly technologies for the production of alternative fuels (Di Serio et al., 2008; Marchetti et al., 2007). Biodiesel is a “green” alternative fuel that has arisen as an attractive option, mainly because it is less pollutant than its counterpart fossil and can be obtained from renewable sources (Maa & Hanna, 1999). Although it is undeniable that biodiesel is a more environmentally benign fuel, its actual production process cannot be classified as “green chemistry process” (Kulkarni et al., 2006). The major of the biodiesel manufacture processes are carry out under alkaline or acid homogeneous catalysis conditions, where is not possible the recycling catalyst, resulting in a greater generation of effluents and salts from neutralization steps of the products and wastes (Kawashima et al., 2008). Moreover, there are some important points related to raw materials commonly used, such as high costs, besides to crescent requirements of large land reserves for its cultivation.