Heterogeneization of Biodiesel Production by Simultaneous Esterification and Transesterification of Oleins

The production of biodiesel via simultaneous esterification and transesterification reactions of residual fats such as palm oleins, with variable TG and FFA composition, using methanol and methane sulfonic acid (MSA) or an acid carbon-based structured catalyst (SO3H-C) as homogeneous and heterogeneous catalysts respectively, has been investigated. The influence of various parameters, such as methanol to oil molar ratio, operating temperature, amount of catalyst, or nature and composition of the raw materials on the fatty acid methyl esters (FAME) yield was studied. It was determined that increasing the methanol to oil molar ratio resulted in an increase in the conversion of TG and FFA and a higher FAME yield; besides, reaction temperature has a strong effect. The best conditions tested to obtain the highest FAME yield (99.2%) was a methanol to oil molar ratio of 12:1, 120 °C (12 bar), a reaction time of at least 1 h, and 3% MSA as a homogeneous catalyst. The work demonstrated that an acidic solid catalyst, SO3H-C, homemade prepared, could be used as a heterogeneous catalyst in the simultaneous process under the optimized reaction conditions, achieving a complete esterification conversion with some limitations with respect to the transesterification reaction and a FAME yield close to 90.5%.