NAP-XPS and in situ XRD study of the stability of Bi-modified MoVNbTeO catalysts for oxidative dehydrogenation of ethane

[Display omitted] •Bi-modified MoVNbTeO catalysts possess enhanced tolerance toward severe reaction conditions during ODE process.•Incorporated bismuth influences on Te mobility within 6-membered channels of M1 structure.•The improved stability and activity of MoVNbTeO catalysts relates to enhanced...

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Published in:	Applied catalysis. A, General Vol. 579; pp. 141 - 150
Main Authors:	Svintsitskiy, Dmitry A., Kardash, Tatyana Yu, Lazareva, Evgeniya V., Saraev, Andrey A., Derevyannikova, Elizaveta A., Vorokhta, Mykhailo, Šmíd, Břetislav, Bondareva, Valentina M.
Format:	Journal Article
Language:	English
Published:	Amsterdam Elsevier B.V 05-06-2019 Elsevier Science SA
Subjects:	Bismuth Catalysis Catalyst modification Catalysts Channels Deactivation Dehydrogenation Depletion Ethane EXAFS High temperature In situ M1 phase MoVNbTe NAP-XPS ODE Oxidative dehydrogenation of ethane Six-membered channel Slurry method Sublimation Tellurium Vapor phases X ray photoelectron spectroscopy Catalyst modification ODE MoVNbTe NAP-XPS In situ Six-membered channel Bismuth Oxidative dehydrogenation of ethane M1 phase EXAFS Tellurium Slurry method
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Summary:	[Display omitted] •Bi-modified MoVNbTeO catalysts possess enhanced tolerance toward severe reaction conditions during ODE process.•Incorporated bismuth influences on Te mobility within 6-membered channels of M1 structure.•The improved stability and activity of MoVNbTeO catalysts relates to enhanced Te surface concentration. This work presents the investigation of Bi-modified MoVNbTeO catalysts for oxidative dehydrogenation of ethane (ODE) using the combination of NAP-XPS, in situ XRD and XANES/EXAFS techniques. It was found that introduction of Bi improves the tolerance of catalysts toward severe reaction conditions (high temperature and/or enhanced ethane/oxygen ratio) resulting in a significant decrease in the degree of deactivation. In accordance with NAP-XPS data, the surface/subsurface Te concentration was maintained for Bi-containing MoVNbTeO catalysts even after treatment with a reducing reaction mixture (C2H6/O2 >3) at temperatures up to 460 °C. In the case of the unmodified catalyst, such treatment resulted in the surface/subsurface depletion of Te due to the reduction into the Te° state followed by its sublimation into the gas phase. The incorporation of Bi within extended six-membered channels of the M1 structure was suggested based on XANES/EXAFS data. Such incorporation probably influences the mobility of Te within channels, resulting in the limitation of Te diffusion from the particle bulk to the surface. The improved tolerance of catalytically active M1 phase toward severe reaction conditions was confirmed by in situ XRD data during heating in a mixture of 8 wt % C2H6/He.
ISSN:	0926-860X 1873-3875
DOI:	10.1016/j.apcata.2019.04.027