Production, characterization and use of sulfonated polystyrene and polysulfone membranes as catalysts in the esterification reaction of oleic acid

Abstract

Biodiesel is a renewable and non-toxic biofuel that can be produced by the esterification reaction. In this reaction, acid catalysts are used and, due to the numerous advantages, heterogeneous catalysts are gaining space. Polysulfone (PSF) and sulfonated polystyrene (PSS) membranes were prepared to catalyze the esterification reaction of oleic acid with methanol, producing biodiesel. Several morphological types of membranes were obtained: dense, porous and electrospun. The reaction conditions were: temperature of 100 °C, molar ratio of 10:1 (methanol:oleic acid), 5% catalyst and time of 2 hours. By means of the BET and BJH methods it was possible to obtain the surface area of the membranes, volume and pore size. The consumption of oleic acid and the formation of the ester were confirmed by the analyzes of CGMS and the FTIR bands, respectively. For the membranes that presented the PSS, 2 hours of reaction were enough for almost total consumption of oleic acid, except for the dense membrane.