Two Step Process for Biodiesel Production Using Non-Edible Oils

Abstract

Biofuels are one of the most promising alternatives to conventional petroleum based fuels. Biodiesel has become more attractive recently because of its environmental benefits and because of its availability from renewable sources. Non-edible oils have been explored to make biodiesel (long chain fatty alkyl ester), in order to substitute the uncertain supplies of conventional diesel fuel. In the present study, non-edible oils – linseed oil, mahua oil and neem oil – have been transesterified to produce their methyl esters (biodiesel). These oils have been studied using alkali and acid catalyst depending on free fatty acids (FFA) content of the oil. Linseed oil is transesterified with methanol in presence of sodium hydroxide as catalyst whereas neem and mahua oil are transesterified using a two-stage procedure, namely, methylation of FFA portion of the oils using an acid catalyst in the first stage and later completing the methanolysis of the remaining triglycerides in the second stage using an alkali catalyst. The maximum yield of methyl ester for linseed oil is 96.56% and for mahua and neem oil, 86.21% and 83.04% respectively. The best methanol to oil ratio required has been found to be 8:1, 30:1 and 30:1 and optimum temperature conditions as 70°C, 75°C and 70°C for linseed oil, mahua oil and neem oil, respectively. The fatty acid methyl esters produced by these oils have been analysed to ensure their suitability as diesel fuel.