A vanadium phosphorus oxide catalyst synthesized in rotating packed bed for high-efficiency selective oxidation of n-butane

Oxidation of n-butane to produce maleic anhydride (MA) by the vanadium phosphorus oxide (VPO) catalyst is important for the fine chemical industry. However, the improvement in MA yield exceeding 60% is still a big challenge. In this article, a VPO catalyst with increased MA yield originated from the tailored structure of VPO precursor prepared in a rotating packed bed (RPB) reactor with excellent micro-mixing efficiency. The activated VPO-RPB catalyst displayed the coexistence of X-1-VOPO4 and alpha(I)-VOPO4 phases and enhanced reducibility of V4+ state. Remarkably, the MA yield in n-butane oxidation catalyzed by VPO-RPB reached up to 66%, showing an increment by 14% compared with VPO-STR prepared in a stirring tank reactor (STR). The VPO-RPB showed the repeatable catalytic performance and achieved a promising scale-up production. This work provides the experimental evidence of a dual-phase (X-1-VOPO4 and alpha(I)-VOPO4) mechanism for n-butane oxidation, and reveals the structure-activity dependence of VPO catalyst.