Selective oxidation of n-butane over MoV-containing oxidic bronze catalysts

MoV-containing oxidic bronze catalysts were synthesized, characterized, and tested in the selective oxidation of n-butane. For comparison, an activated V–P–O catalyst was also studied. The catalytic behavior of MoV-containing catalysts was found to be dependent on both the catalyst composition and the nature of crystalline phases. In this way, the M1 phase (i.e., Te2M20O57 and (SbO)2M20O56 in Te- and Sb-containing catalysts, respectively) is proposed as an active and selective crystalline phase for n-butane oxidation on these catalysts. The selectivity to maleic anhydride/acid obtained on MoV-catalysts follows the order: MoVTeNbO > MoVTeO = MoVSbNbO > MoVSbO > MoVNbO. Although less selective than a vanadium phosphorous catalyst, a higher productivity to MA is obtained over a MoVTeNbO mixed oxide catalyst as a consequence of its remarkably superior catalytic activity. Moreover, the amount of maleic anhydride obtained on oxidic bronze catalysts strongly depends on the composition of the feed. In addition, the nature of active sites, the reaction network for n-butane oxidation, and a comparison of their catalytic performance in the oxidation of C2–C4 alkanes are discussed.