Selective Oxidation of n‐Butane over Vanadium‐Phosphorus Oxide: Oxygen Activation and Dynamics. Issue 23 (9th November 2018)

• Record Type: Journal Article
• Authors: Schulz, Christian; Kraehnert, Ralph; Rosowski, Frank; Frank, Benjamin
• Is Part Of: ChemCatChem. Volume 10:Issue 23(2018)
• Page Start: 5523
• Page End: 5532
• Publication Date: 2018-11-09
• Subjects: VPP -- kinetics -- water -- reaction mechanism -- SSITKA; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201801177
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The complex microkinetics of the selective oxidation of n ‐butane to maleic anhydride (MAN) over vanadyl pyrophosphate‐based (VPP) catalysts has been widely investigated so far, however, they are still under debate. We present novel results of kinetic analyses and isotope labeling to shed light on the activation of gas‐phase oxygen and the dynamics of oxygen species on the catalyst surface and in the bulk. We suggest the existence of at least two catalytically relevant surface oxygen species responsible for selective and unselective activation of n ‐butane, which are formed by adsorption and consecutive dissociation of O2 at the active site. The formation of selective [O] from unselective [O2 ] is likely promoted by co‐fed H2 O, which increases the MAN selectivity. Regarding the VPP bulk serving as a reservoir for active [O] species it is concluded that the dynamic exchange is limited to the amorphous surface layer forming under reaction conditions, whereas the crystalline bulk is not involved into the reaction. Labelling studies are heavily influenced by vital 16 O/ 18 O scrambling of MAN isotopes with the reaction product H2 O. Abstract : Good O, bad O : The activation of oxygen during the selective oxidation of n ‐butane to maleic anhydride (MAN) over an industrial VPO catalyst was investigated with a focus on MAN selectivity and the influence of H2 O, which lowers the formation rate of carbon oxides.