Preparação, caracterização e aplicação de polissulfona sulfonada como catalisador heterogêneo na reação de esterificação do ácido oleico com metanol

Abstract

The chemical modification of hydrofobic polymer matrices is an alternative way to change properties such as adhesion, wettability, biocompatibility, catalytic capacity among others. The heterogeneous acid catalysts were used in this work due to their advantages such as reuse, reduction of equipment corrosion and can be easily removed from the reaction mixture. Thus, methyl biodiesel was synthesized via the esterification of oleic acid using the polysulfone sulfonated (PSOS) polymer matrix as heterogeneous catalysts. PSOS was obtained from the sulfonation of Polysulfone employing concentrated sulfuric acid H2SO4 (98%). Different ratios of reagents and temperatures (° C) were employed. The chemical modification was confirmed by the functional groups analyzes through infrared spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TGA) and acid-base titration of the acid groups. In the reaction of oleic acid with methanol the catalysts PSO, PSOS1, PSOS2, PSOS3, PSOS4, PSOS5 and PSOS6 were evaluated. The reaction was carried out at a temperature of 100 ° C, with a molar ratio of oleic acid: methanol 1:10, with 5% (w / w) catalyst to oleic acid mass in times of 0.5 to 6.0 hours. The conversion was obtained by the height of the ester and carboxylic acid carbonyl bands in the infrared spectra and by the methyl ester peak area observed in the chromatograms obtained on a gas chromatography equipment. The best performance was observed for catalyst PSOS4 and PSOS6 with approximately 97.3% and 75.0% conversion. These results show that the modified polymers in this work show potential for use in fatty acid esterification reactions that can be employed in biodiesel production.