SELECTIVE OXIDATION OF NORMAL-BUTANE TO MALEIC-ANHYDRIDE - A COMPARATIVE-STUDY BETWEEN PROMOTED AND UNPROMOTED VPO CATALYSTS

A comparative study has been conducted between a promoted VPO catalyst (promoted with molybdenum and cerium added simultaneously) and an unpromoted VPO catalyst with respect to their characteristics and catalytic performance. It was observed that the promoted VPO catalyst produced higher yields of maleic anhydride (MA) as compared to the unpromoted one but at comparatively more severe conditions of operations (i.e., higher reaction temperature, higher contact time and higher inlet n-butane concentration). Characterization studies revealed that molybdenum prevents further reduction of V(IV) to V(III), whose transformation was probably responsible for the production of oxides of carbon. As a result, promoted catalyst showed higher selectivity toward MA as compared to the unpromoted one.