Preparation of highly dispersed SnO/TiO2 catalysts and their performances in catalyzing polyol ester

Abstract

A series of stannous oxide supported on rutile titanium dioxide (SnO/TiO₂) were prepared by a conventional incipient wetness impregnation method, and their performance as catalysts for fatty acid esterification reactions was investigated. The effects of Sn precursors (SnCl₂·2H₂O or SnC₂O₄), loading amounts (5–15%), and treating ambiences (air and N₂) were explored. The optimized 10% SnO/TiO₂–Cl with SnCl₂·2H₂O as the Sn precursor and thermal treatment in N₂ showed the best esterification performance. Specifically, 10% SnO/TiO₂–Cl catalyzed the esterification process of trimethylolpropane and n-octanoic acid with a conversion of 99.6% over 5 h at 160 °C, and 10% SnO/TiO₂–Cl was efficient for six catalytic cycles. Based on the results of X-ray diffraction (XRD), Raman spectra, high-resolution transmission electron microscopy (HRTEM), infrared spectra of pyridine adsorption (Py-IR), and ammonia temperature programmed desorption (NH₃-TPD), the improved catalytic performance is supposed to be attributable to the high dispersion of the Sn species on 10% SnO/TiO₂–Cl as the moderate Lewis acid sites.