Direct synthesis of benzyl acetate and optimisation of reaction conditions for the gas phase acetoxylation of toluene

TiO2 supported Pd-Sb catalysts were prepared by impregnation method and tested for the selective vapour phase acetoxylation of toluene to benzyl acetate (BA). Investigations were carried out to optimise reaction variables such as effects of reaction temperature, acetic acid/toluene mole ratio, O2/toluene mole ratio, contact time, etc. to obtain better performance of the catalysts. Additionally, the influence of Sb/Pd ratio on catalytic performance was also checked under optimised reaction conditions. The activity of the catalysts was found to increase continuously with increasing Sb/Pd ratio up to 0.7 and then decreased with further increase in Sb/Pd ratio to 1.75. The catalyst with Sb/Pd ratio of 0.7 exhibited the best performance among all other catalysts of this series giving a conversion of toluene as high as ca. 68% with BA selectivity of 85%. All these catalysts were observed to deactivate with time on stream due to considerable amount of coke deposition. However, these catalysts can be regenerated in air and reused for more number of cycles with consistent performance.