Residue-based activated carbon from passion fruit seed as support to H3PW12O40 for the esterification of oleic acid
Heterogeneous acid catalysts using heteropolyacid supported on porous solids have been studied for the production of biofuel. Activated carbon is widely used as catalytic supports because of its high surface area, which allows high dispersion of the active phase. The aim of this work was to study the methyl esterification of oleic acid as a model compound for acidic lipids for the production of biodiesel using 12-tungstophosphoric acid (HPW) supported on activated carbon derived from passion fruit biomass (ACP), prepared by chemical activation using ZnCl2. The composites (HPW/ACP) were prepared containing 10-30 wt% of HPW by following two procedures: aqueous impregnation method and incipient moisture. The materials were characterized by Thermogravimetric analysis (TG/DTG), Fourier transform infrarred spectroscopy (FTIR), X-ray diffraction (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), solid state NMR 13C and 31P and X-Ray photoelectron spectroscopy (XPS). Catalytic results indicated that the conversion of oleic acid with methanol as well as the stability of the catalyst improved in the aqueous impregnation prepared samples due to the greater surface coating of the material observed in the surface area. The preparation method, thus, was determinant for the activity and stability of the catalysts.