The Impact of Reaction Pressure on the Catalytic Performance of the Pd-Sb/TiO2 Catalyst in the Acetoxylation of Toluene into Benzyl Acetate

The acetoxylation of toluene in the presence of acetic acid and oxygen was performed over a Pd-Sb/TiO2 catalyst at 210 degrees C and at various reaction pressures (1-10 bar). A remarkable improvement in the catalytic performance and a significant shortening of the induction period were found with an increase in pressure. At a pressure of 6 bar, the highest toluene conversion of 75% and 100% selectivity for benzyl acetate were observed. This result could be due to both the restructuring of the catalyst surface and to the formation of active Pd-Sb particles of desired size, composition, and shape during the course of the induction period. Samples of the most-active and spent catalysts were studied by ex situ and in situ XRD, XPS, and TEM.