A comparative study of supported TiO2 catalysts and activity in ester exchange between dimethyl oxalate and phenol

Abstract

Various supported TiO2 catalysts, TiO2/SiO2, TiO2/Al2O3 and TiO2/MgO, were prepared by impregnation method and their activities in the transesterification of dimethyl oxalate (DMO) with phenol were tested. To further investigate the relationship between the catalyst performances and carrier properties, a series of characterization methods, such as BET specific surface area measurement, temperature-programmed desorption (NH3-TPD, CO2-TPD), and FT-IR analysis of adsorbed pyridine were utilized. The results indicated that the carrier had an important effect on the selectivities to products. The activities of supported TiO2 catalysts were improved significantly when TiO2 was supported on high surface area carriers. The weak acid sites were responsible for the formation of methyl phenyl oxalate (MPO) and diphenyl oxalate (DPO), while the intermediate acid sites and base sites were favorable for the formation of byproduct, anisole (AN).