Biodiesel Production using Heterogeneous catalyst under Ultrasound Synthesis

Abstract

Energy crisis is the key issue of present era. It is attached with the judicial use of energy, its conservation, availability and sustainability. Fossil fuels could not answer the above questions satisfactory. Alternative energy sources are the only options left with the world. Among all alternative energy sources, Biodiesel evolved as a promising renewable fuel of future. It is a valuable product from the renewable sources. Various methods are available to produce biodiesel. As a fuel it is cheap, creating less pollution compare to fossil fuel. It is also easy to produce. It does not require much change in the engine using fossil fuel. Transesterification is the widely accepted method for the production of biodiesel. Various approaches are available to produce biodiesel via transesterification using various catalysts, viz. conventional heating using alkali, acidic, heterogeneous and homogeneous catalysts, solid catalysts, enzymatic reactions, supercritical reaction, microwave synthesis and ultrasound synthesis. Various feed stocks for the production of biodiesel are also available in plenty of amount on earth viz. mainly edible and non-edible oils and algae. Review of various approaches under transesterification methods are carried out. Best results are summarized. For alkali catalyst, it is not giving good conversion with the high Free Fatty Acid (FFA) containing feed stocks as it leads to the formation of soap adhering main reaction. Acid catalyst can deal with high FFA containing oil, but at the cost of high oil to alcohol molar ratio. Solid catalysts, heterogeneous, need high temperature reaction temperature for getting activated. Enzymatic reactions are very unstable. Also, the cost of enzyme is a very crucial factor. Supercritical reactions are very fast and give high conversion in very few minutes. But they require very high pressure and high oil to alcohol molar ratio. It may be catalytic or non-catalytic. Choice of supercritical fluid and alcohol is a key for success. Microwave irradiation is a novel technique used for the production of biodiesel. It gives high conversion in a few minutes. Power consumption is also less compared to conventional heating. But it offers many problems in terms of commercialization. Ultrasound synthesis is giving good comparison against microwave irradiation. It is also using less energy and giving good conversion is few minutes. Ultrasound and microwave irradiation both can be carried out in batch as well as continuous mode. Ultrasound synthesis has potential to become commercial one. Both the techniques can deal with high FFA containing oils also. In this study, Jatropha was used as feedstock and heterogeneous catalysts like sodium silicate and calcium oxide were used for Biodiesel production. Parameters like oil to alcohol ratio, reaction time, catalyst quantity were varied and optimized. The experimental results showed that (a) Using sodium silicate, 1:3 molar ratios and 0.75 gm amount of catalyst, 55 0C temperature and 10 minutes of reaction time, 97.73% conversion was achieved. (b) Using calcium oxide, 1:12 molar ratio and 0.5 gm amount of catalyst, 55 0C temperature and 15 minutes of reaction time, 97.95% conversion was achieved. Moreover, sodium silicate has 5 times reusability and conversion difference was 92.75% to 84.54%. Experimental results were also compared with low FFA content oil.This will helps to identify the most appropriate method for production of bio-diesel technologically and economically.