EFFECT OF TEMPERATURE ON THE TRANSESTERIFICATION REACTION USING ANION EXCHANGE RESIN AS HETEROGENEOUS CATALYST

Biodiesel is conventionally obtained from transesterification reaction of a triacylglycerol and a short chain alcohol in the presence of homogeneous or heterogeneous catalysts. Heterogeneous catalysts have the advantage that they can be easily separated for reuse, thereby reducing the biodiesel purification steps. This study aimed to evaluate the effect of temperature on the transesterification reaction using Purolite A503S anion exchange resin as heterogeneous catalyst for biodiesel production. The reactants used were anhydrous ethanol and palm olein, as a source of triacylglycerols. Initially, the palm olein was physically and chemically characterized in free fatty acid (FFA) content, fatty acid composition, density and viscosity. The physical properties were performed in Anton Paar viscometer and densimeter at temperatures from 20 to 70 °C. Reactions were performed in a jacketed reactor coupled to a thermostatic bath using an olein: ethanol molar ratio of 1:13, 15% resin to olein mass, stirring at 400 rpm and temperature range from 33.1 to 60 °C (maximum temperature specified by the resin manufacturer) for 10 hours. To determine the biodiesel conversion, the reaction products were characterized in triacylglycerols, diacylglycerols, monoacylglycerols, ethyl esters and ethanol using HPSEC chromatographic method, and glycerol by reaction stoichiometry. The FFA content of palm olein was 0.04% and its fatty acid composition showed 37 % in palmitic acid, 47.2% in oleic acid and 9.7% in linoleic acid. The density and viscosity data ranged from 912 to 896 kg.m-3 and from 90 to 20.10-3Pa.s at temperature range of 20-70 °C, respectively. The results on biodiesel conversion showed an increase from 90% at 33.1 °C to 97% at 60 °C, which may be explained by the reduction in the external resistance to mass transfer due to the decrease in viscosity. In the studied conditions, high biodiesel conversions were possible using Purolite A503S.