Influence of the reaction atmosphere on the characteristics and performance of VPO catalysts

Butane-rich and oxygen-rich mixtures have been fed to a fixed bed reactor l oaded with VPO catalyst used in the production of maleic anhydride. The exp eriments were designed in such a way that the evolution of the state of the catalyst surface and of the catalytic performance along the bed could be f ollowed and related to each other. The results obtained indicate that a mar ked pattern of catalyst reduction exists in the reactor used under butane-r ich conditions, leading to the appearance of V3+ phases. This causes a stro ng decrease in the selectivity to maleic anhydride. (C) 2000 Academic Press .