Esterificação do ácido oleico utilizando catalisadores ácidos sulfatados e não sulfatados em materiais mesoporosos do tipo SBA-15

Abstract

Fatty acids such as oleic acid, have received particular attention as raw material, due to its abundance, availability and relatively high purity, being considered as potential materials for production of biodiesel. The esterification reaction of oleic acid using heterogeneous catalysts can be a promising alternative for biodiesel production. This study proposes to find a biodiesel through esterification of oleic acid with Zr-SBA-15, Nb-SBA-15, SO42–/Zr-SBA-15 and SO4 2–/Nb-SBA-15 catalysts, obtained by insertion of Zr and Nb in support SBA-15 and sulfation of the impregnated support. SBA-15 support was synthesized by hydrothermal method. Support SBA-15 was synthesized by hydrothermal method. The catalyst was initially synthesized by the wet impregnation method, followed by sulfation process. The catalysts were analyzed: X-ray diffraction (XRD), thermal analysis (TG/DTG), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption/desorption, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and acidity test to identify the structure, composition and verification the presence acid sites. The characterization results indicated that the SBA-15 support preserved the ordered hexagonal structure after the incorporation of Zr and Nb. It was observed the presence of nanoparticles these metal dispersed on the surface and within the microporous and mesoporous channels of Zr-SBA-15 and Nb-SBA-15 catalysts. After sulfation, increased amount of acid sites and the ordered structure was maintained. For Zr-SBA-15 and SO4 2–/Zr-SBA-15 catalyst was the formation of tetragonal and monoclinic structures of ZrO2, as for the other, Nb-SBA-15 and SO42–/Nb-SBA-15 catalyst were formed amorphous structures. The catalytic activity was evaluated by the esterification reaction of oleic acid via ethyl route, using all the synthesized catalysts. Biodiesel obtained with SO42–/Zr-SBA-15 presented physicochemical properties within the standards specified by the Resolution Nº 45/2014 ANP and obtained the best yield with 80.7%. It was found that sulfated catalysts, produced higher yields with respect to nonsulfated. The SBA-15 support showed no catalytic activity.