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

A series of stannous oxide supported on rutile titanium dioxide (SnO/TiO) 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 (SnCl·2HO or SnCO), loading amounts (5-15%), and treating ambiences (air and N) were explored. The optimized 10% SnO/TiO-Cl with SnCl·2HO as the Sn precursor and thermal treatment in N showed the best esterification performance. Specifically, 10% SnO/TiO-Cl catalyzed the esterification process of trimethylolpropane and -octanoic acid with a conversion of 99.6% over 5 h at 160 °C, and 10% SnO/TiO-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 (NH-TPD), the improved catalytic performance is supposed to be attributable to the high dispersion of the Sn species on 10% SnO/TiO-Cl as the moderate Lewis acid sites.