Synthesis and Characterisation of Biodiesel

Abstract

The synthesis and characterisation of soybean oil alkyl esters (SOAE) has been carried out in the present study using alkaline catalysed transesterification reaction. Soybean oil was converted to biodiesel by transesterification reaction using batch process. The effects of various reaction parameters – type of alcohol (methanol, ethanol, n-propanol, iso-propanol, n-butanol and iso-butanol), type of catalyst (KOH, NaOH and CH3ONa), catalyst concentration (0.5, 1 and 1.5%), reaction temperature (30–40, 40–50, 50–60, 60–70 and 70–80°C) and reaction time – on biodiesel yield, were investigated. The quality of the biodiesel produced was evaluated by determining important properties, such as specific gravity, kinematic viscosity, flash point, fire point, pour point, and cloud point using ASTM (D 6751) methods. The characteristics of produced biodiesel were found to be within the prescribed ASTM (D 6751) specifications, thus, indicating that SOAE are acceptable as a substitute for petroleum diesel. The yield and quality of biodiesel obtained from soybean oil transesterification with methanol using 0.5% KOH as catalyst was found to be the best. It was also found that methanol and KOH were the best alcohol and the best catalyst, respectively, for transesterification of soybean oil at 65°C with 10:3 volume ratio of oil to alcohol.