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Title: Surface heterogeneity of zirconia-supported V{sub 2}O{sub 5} catalysts. The link between structure and catalytic properties in oxidative dehydrogenation of propane

Abstract

Undoped and alkali-doped zirconia-supported vanadia catalysts for the oxidative dehydrogenation of propane were prepared by impregnation and characterized by various techniques. The chemical state of surface and bulk vanadium was investigated as a function of the calcination temperature, V{sub 2}O{sub 5} loading, and the nature and content of alkali-metal additives. It is found that on the surface vanadium is present in the form of isolated vanadyl species or oligomeric vanadates, or as nanocrystalline V{sub 2}O{sub 5} and that V{sup 5+} and V{sup 4+} ions coexist in octahedral and tetrahedral coordination, while within the bulk of zirconia matrix, V{sup 4+} ions are stabilized in a V{sub x}Zr{sub 1{minus}x}O{sub 2} solid solution. Presence of the alkali-metal additives and water changes the dispersion of surface vanadium species favoring, in both cases, formation of mononuclear vanadyl surface complexes. Surface heterogeneity plays a vital role for the catalytic performance of V{sub 2}O{sub 5}/ZrO{sub 2} catalysts in oxidative dehydrogenation of propane. Catalytic properties are related to the nature of VO{sub x} surface species and correlates well with their reducibility. The maximum of catalytic activity was observed for catalysts with vanadia content between 3 and 5 mol %, for which octahedral polyvanadate surface species are dominant. Itmore » is proposed that the catalytic activity is affected by the nucleophilicity of bridging oxygen in V-O-V entities, modified by the adjacent alkali cations.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Jagiellonia Univ., Cracow (PL)
OSTI Identifier:
20000515
Report Number(s):
CONF-9808111-
Journal ID: ISSN 0743-7463; LANGD5
Resource Type:
Journal Article
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 15; Journal Issue: 18; Conference: Third international symposium on effects of surface heterogeneity in adsorption and catalysis on solids, Torun (PL), 08/09/1998--08/16/1998; Other Information: PBD: 31 Aug 1999; Journal ID: ISSN 0743-7463
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 10 SYNTHETIC FUELS; VANADIUM OXIDES; ZIRCONIUM OXIDES; CATALYTIC EFFECTS; PROPANE; DEHYDROGENATION; PHASE STUDIES

Citation Formats

Adamski, A., Sojka, Z., Dyrek, K., Che, M., Wendt, G., and Albrecht, S. Surface heterogeneity of zirconia-supported V{sub 2}O{sub 5} catalysts. The link between structure and catalytic properties in oxidative dehydrogenation of propane. United States: N. p., 1999. Web. doi:10.1021/la981431m.
Adamski, A., Sojka, Z., Dyrek, K., Che, M., Wendt, G., & Albrecht, S. Surface heterogeneity of zirconia-supported V{sub 2}O{sub 5} catalysts. The link between structure and catalytic properties in oxidative dehydrogenation of propane. United States. doi:10.1021/la981431m.
Adamski, A., Sojka, Z., Dyrek, K., Che, M., Wendt, G., and Albrecht, S. Tue . "Surface heterogeneity of zirconia-supported V{sub 2}O{sub 5} catalysts. The link between structure and catalytic properties in oxidative dehydrogenation of propane". United States. doi:10.1021/la981431m.
@article{osti_20000515,
title = {Surface heterogeneity of zirconia-supported V{sub 2}O{sub 5} catalysts. The link between structure and catalytic properties in oxidative dehydrogenation of propane},
author = {Adamski, A. and Sojka, Z. and Dyrek, K. and Che, M. and Wendt, G. and Albrecht, S.},
abstractNote = {Undoped and alkali-doped zirconia-supported vanadia catalysts for the oxidative dehydrogenation of propane were prepared by impregnation and characterized by various techniques. The chemical state of surface and bulk vanadium was investigated as a function of the calcination temperature, V{sub 2}O{sub 5} loading, and the nature and content of alkali-metal additives. It is found that on the surface vanadium is present in the form of isolated vanadyl species or oligomeric vanadates, or as nanocrystalline V{sub 2}O{sub 5} and that V{sup 5+} and V{sup 4+} ions coexist in octahedral and tetrahedral coordination, while within the bulk of zirconia matrix, V{sup 4+} ions are stabilized in a V{sub x}Zr{sub 1{minus}x}O{sub 2} solid solution. Presence of the alkali-metal additives and water changes the dispersion of surface vanadium species favoring, in both cases, formation of mononuclear vanadyl surface complexes. Surface heterogeneity plays a vital role for the catalytic performance of V{sub 2}O{sub 5}/ZrO{sub 2} catalysts in oxidative dehydrogenation of propane. Catalytic properties are related to the nature of VO{sub x} surface species and correlates well with their reducibility. The maximum of catalytic activity was observed for catalysts with vanadia content between 3 and 5 mol %, for which octahedral polyvanadate surface species are dominant. It is proposed that the catalytic activity is affected by the nucleophilicity of bridging oxygen in V-O-V entities, modified by the adjacent alkali cations.},
doi = {10.1021/la981431m},
journal = {Langmuir},
issn = {0743-7463},
number = 18,
volume = 15,
place = {United States},
year = {1999},
month = {8}
}