caa a22 4500 475844599 CHVBK 20180406123910.0 cr unu---uuuuu 170329e20000501xx s 000 0 eng 10.1023/A:1019180504770 doi (NATIONALLICENCE)springer-10.1023/A:1019180504770 The structure of vanadium oxide species on γ-alumina; an in situ X-ray absorption study during catalytic oxidation [Elektronische Daten] [M. Ruitenbeek, A.J. van Dillen, F.M.F. de Groot, I.E. Wachs, J.W. Geus, D.C. Koningsberger] The mechanism of catalytic oxidation reactions was studied using in situ X-ray absorption spectroscopy (XAFS) over a 17.5 wt% V2O5/Al2O3 catalyst, i.e., at reaction temperatures and in the presence of reactants. It was found that X-ray absorption near-edge structure (XANES) is a powerful tool to study changes in the local environment and the oxidation state of the vanadium centres during catalytic oxidation. At 623 K, the catalyst follows the associative mechanism in CO oxidation. XAFS revealed that the Mars-van Krevelen mechanism is operative at 723 K for CO oxidation. The extended X-ray absorption fine structure (EXAFS) results showed that the structure of the supported V2O5 phase consists of monomeric tetrahedral (Al-O)3-V=O units after dehydration in air at 623 K. However, the residuals of the EXAFS analysis indicate that an extra contribution has to be accounted for. This contribution probably consists of polymeric vanadate species. The structure remains unchanged during steady-state CO oxidation at 623 and 723 K. Furthermore, when oxygen was removed from the feed at 623 K, no changes in the spectra occurred. However, when oxygen is removed from the feed at 723 K, reduction of the vanadium species was observed, i.e., the vanadyl oxygen atom is removed. The V3+ ion subsequently migrates into the γ-Al2O3 lattice, where it is positioned at an Al3+ octahedral position. This migration process appears to be reversible; so the (Al-O)3-V=O units are thus restored by re-oxidation. Kluwer Academic Publishers, 2000 V2O5 nationallicence supported catalyst nationallicence γ-Al2O3 nationallicence monolayer nationallicence CO oxidation nationallicence X-ray absorption spectroscopy nationallicence XANES nationallicence EXAFS nationallicence principal component analysis nationallicence temperature-programmed reduction nationallicence Ruitenbeek M. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut van Dillen A.J. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut de Groot F.M.F. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut Wachs I.E. Zettlemoyer Center for Surface Studies, Department of Chemical Engineering, Lehigh University, 7 Asa Drive, Bethlehem, 18015, PA, USA aut Geus J.W. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut Koningsberger D.C. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut Topics in Catalysis Kluwer Academic Publishers 10/3-4(2000-05-01), 241-254 1022-5528 10:3-4<241 2000 10 11244 https://doi.org/10.1023/A:1019180504770 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1019180504770 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ruitenbeek M. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- van Dillen A.J. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- de Groot F.M.F. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Wachs I.E. Zettlemoyer Center for Surface Studies, Department of Chemical Engineering, Lehigh University, 7 Asa Drive, Bethlehem, 18015, PA, USA aut NATIONALLICENCE 700 1- Geus J.W. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 700 1- Koningsberger D.C. Debye Institute, Department of Inorganic Chemistry and Catalysis, Utrecht University, PO Box 80083, 3508 TB, Utrecht, The Netherlands aut NATIONALLICENCE 773 0- Topics in Catalysis Kluwer Academic Publishers 10/3-4(2000-05-01), 241-254 1022-5528 10:3-4<241 2000 10 11244 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer