The influence of activation conditions on V-Mo based catalysts for benzene oxidation to maleic anhydride

The influence of the activation conditions on the catalytic performance and microstructure of supported V-Mo oxides used for benzene oxidation to maleic anhydride has been investigated. To activate the catalysts, two sets of activation conditions were tested. In condition I, the catalysts were activated in an atmosphere of air and benzene, which was similar to the industrial practice. In condition II, the catalysts were pre-activated in an atmosphere consisting of the gas products produced by the decomposition of the freshly prepared catalysts during activation process. The activity and selectivity of the catalysts were evaluated on a bench scale reactor as well as on a pilot reactor. The catalysts activated by condition II at the appropriate temperature showed a better performance: the selectivity and yield of MA were nearly 80 and 100 wt%, respectively. They are 5 % higher than those of the catalyst activated by condition I. The catalysts were characterized in terms of several techniques including isotherm adsorption, TG-DTG, XRD, SEM, EDX and XPS. The characterization results indicated that the microstructures of the catalysts were significantly influenced by the activation conditions. Based on the above information, the better performance exhibited by the catalyst activated by condition II are analyzed.