ON THE MECHANISM OF N-BUTANE OXIDATION TO MALEIC-ANHYDRIDE ON VPO CATALYSTS .1. A KINETICS STUDY ON A VPO CATALYST AS COMPARED TO VPO REFERENCE PHASES

In order to obtain more information on the mechanism of butane oxidation, the oxidation of n-butane, butadiene, furan, and maleic anhydride (MA) is studied on different VPO structures: αII, β, γ and δ VOPO4, on the one hand, and (VO)2P2O7 and the activated VPO catalyst, on the other hand. A general scheme is proposed for the oxidation of butane on these different structures. A direct route to maleic anhydride which implies alkoxide intermediates without desorption in the gas phase of butene, butadiene, and furan is proposed as an alternative to the olefinic route. The activated VPO catalyst is more selective to MA than is (VO)2P2O7, while αII VOPO4 dehydrogenates to butadiene. β VOPO4 gives mainly COx, while γ and δ VOPO4 are fairly selective to MA. © 1994 Academic Press, Inc.