Biodiesel by acid-catalyzed transesterification with butanol

Abstract

Jatropha oil and Rapeseed oil was transesterified with n-butanol by the use of H2SO4. Before conducting the experiments a review of the effect of alcohol type was preformed. Alcohols from methanol to butanol, branched and straight, were reviewed for the effect on the acid catalyzed transesterification reaction. From the review it was found that propanol and butanol were the best for the acidic transesterification reaction.

Variables such as time, temperature, alcohol amount and catalyst concentration were investigated in the experiments. The variables were compared to the responses yield, viscosity and acid number by employing response surface methodology. All experiments were analyzed with H-NMR and a NMR atlas was constructed. The time needed for a complete acid esterification with transesterification was found equal to the time needed for acid esterification with alkali transesterification. For the acidic transesterification it was found that temperature plays a vital role and needs to be as high as possible, preferably the boiling point of butanol. Catalyst concentration was compromised between acid number and viscosity to 2 % v/v. The amount of alcohol was proven to reach an optimum for rapeseed oil at 7.0 equivalents, whereas 7.5 equivalents were found for jatropha oil.