Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO3/TiO2 catalysts monitored by in situ Raman spectroscopy

George Tsilomelekis; Antonios Tribalis; Angelos G. Kalampounias; Soghomon Boghosian; George D. Panagiotou; Kyriakos Bourikas; Christos Kordulis; Alexis Lycourghiotis

doi:10.1016/S0167-2991(10)75120-X

Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO₃/TiO₂ catalysts monitored by in situ Raman spectroscopy

George Tsilomelekis, Antonios Tribalis, Angelos G. Kalampounias, Soghomon Boghosian, George D. Panagiotou, Kyriakos Bourikas, Christos Kordulis, Alexis Lycourghiotis

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

6 Scopus citations

Abstract

The evolution of the molecular structure of molybdena/titania catalysts prepared by the equilibrium-deposition-filtration (EDF) method is monitored by in situ Raman spectroscopy in the temperature range 25-430°C. The study is based on a recently proposed picture for the interfacial speciation of Mo(VI) oxo-species deposited at the "titania/electrolytic solution" interface of "wet" catalyst pastes and on the temperature-dependent features of in situ Raman "snap-shots" obtained with increasing temperature. The configurations of the deposited Mo(VI) oxo-species on "wet" (i.e. prior to drying) samples conform to the theoretically previewed speciation for the respective pH's and concentrations of the precursor electrolyte and impregnating solutions; for initial Mo(VI) concentrations up to 2.5×10^-2 M the predominant deposited species evolve from monomeric MoO₄^2- ions retained above a bridging surface hydroxyl through a hydrogen bond [Ti₂OH...O-MoO₃] (for solution pH=9) to a mixture with inner sphere mononuclear mono-substituted (with the terminal surface oxygen of titania) complex [Ti-OMoO₃] (for solution pH=6) and to a simultaneous occurrence of the former monomeric species with Mo₇O₂₄^6- and HMo₇O ₂₄^5- (for solution pH=4). A gradual transformation of the complex configurations is monitored with rising temperature by in situ Raman snap-shots and the spectra of the final calcined samples exhibit the features of dispersed mono-oxo (Ti-O)₃Mo=O species. A low presence of associated species (possessing Mo-O-Mo linkages) is evident for the higher loaded samples.

Original language	English (US)
Title of host publication	Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium
Publisher	Elsevier Inc.
Pages	613-616
Number of pages	4
ISBN (Print)	9780444536013
DOIs	https://doi.org/10.1016/S0167-2991(10)75120-X
State	Published - 2010
Externally published	Yes

Publication series

Name	Studies in Surface Science and Catalysis
Volume	175
ISSN (Print)	0167-2991

All Science Journal Classification (ASJC) codes

Catalysis
Condensed Matter Physics
Physical and Theoretical Chemistry
Surfaces, Coatings and Films
Materials Chemistry

Keywords

In situ Raman
Molybdena catalysts
Oxomolybdenum species
Temperature evolution
Titania

Access to Document

10.1016/S0167-2991(10)75120-X

Cite this

Tsilomelekis, G., Tribalis, A., Kalampounias, A. G., Boghosian, S., Panagiotou, G. D., Bourikas, K., Kordulis, C., & Lycourghiotis, A. (2010). Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO₃/TiO₂ catalysts monitored by in situ Raman spectroscopy. In Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium (pp. 613-616). (Studies in Surface Science and Catalysis; Vol. 175). Elsevier Inc.. https://doi.org/10.1016/S0167-2991(10)75120-X

Tsilomelekis, George ; Tribalis, Antonios ; Kalampounias, Angelos G. et al. / Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO₃/TiO₂ catalysts monitored by in situ Raman spectroscopy. Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium. Elsevier Inc., 2010. pp. 613-616 (Studies in Surface Science and Catalysis).

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title = "Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO3/TiO2 catalysts monitored by in situ Raman spectroscopy",

abstract = "The evolution of the molecular structure of molybdena/titania catalysts prepared by the equilibrium-deposition-filtration (EDF) method is monitored by in situ Raman spectroscopy in the temperature range 25-430°C. The study is based on a recently proposed picture for the interfacial speciation of Mo(VI) oxo-species deposited at the {"}titania/electrolytic solution{"} interface of {"}wet{"} catalyst pastes and on the temperature-dependent features of in situ Raman {"}snap-shots{"} obtained with increasing temperature. The configurations of the deposited Mo(VI) oxo-species on {"}wet{"} (i.e. prior to drying) samples conform to the theoretically previewed speciation for the respective pH's and concentrations of the precursor electrolyte and impregnating solutions; for initial Mo(VI) concentrations up to 2.5×10-2 M the predominant deposited species evolve from monomeric MoO42- ions retained above a bridging surface hydroxyl through a hydrogen bond [Ti2OH...O-MoO3] (for solution pH=9) to a mixture with inner sphere mononuclear mono-substituted (with the terminal surface oxygen of titania) complex [Ti-OMoO3] (for solution pH=6) and to a simultaneous occurrence of the former monomeric species with Mo7O246- and HMo7O 245- (for solution pH=4). A gradual transformation of the complex configurations is monitored with rising temperature by in situ Raman snap-shots and the spectra of the final calcined samples exhibit the features of dispersed mono-oxo (Ti-O)3Mo=O species. A low presence of associated species (possessing Mo-O-Mo linkages) is evident for the higher loaded samples.",

keywords = "In situ Raman, Molybdena catalysts, Oxomolybdenum species, Temperature evolution, Titania",

author = "George Tsilomelekis and Antonios Tribalis and Kalampounias, {Angelos G.} and Soghomon Boghosian and Panagiotou, {George D.} and Kyriakos Bourikas and Christos Kordulis and Alexis Lycourghiotis",

year = "2010",

doi = "10.1016/S0167-2991(10)75120-X",

language = "English (US)",

isbn = "9780444536013",

series = "Studies in Surface Science and Catalysis",

publisher = "Elsevier Inc.",

pages = "613--616",

booktitle = "Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium",

address = "United States",

}

Tsilomelekis, G, Tribalis, A, Kalampounias, AG, Boghosian, S, Panagiotou, GD, Bourikas, K, Kordulis, C & Lycourghiotis, A 2010, Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO₃/TiO₂ catalysts monitored by in situ Raman spectroscopy. in Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium. Studies in Surface Science and Catalysis, vol. 175, Elsevier Inc., pp. 613-616. https://doi.org/10.1016/S0167-2991(10)75120-X

Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO₃/TiO₂ catalysts monitored by in situ Raman spectroscopy. / Tsilomelekis, George; Tribalis, Antonios; Kalampounias, Angelos G. et al.
Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium. Elsevier Inc., 2010. p. 613-616 (Studies in Surface Science and Catalysis; Vol. 175).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

TY - GEN

T1 - Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO3/TiO2 catalysts monitored by in situ Raman spectroscopy

AU - Tsilomelekis, George

AU - Tribalis, Antonios

AU - Kalampounias, Angelos G.

AU - Boghosian, Soghomon

AU - Panagiotou, George D.

AU - Bourikas, Kyriakos

AU - Kordulis, Christos

AU - Lycourghiotis, Alexis

PY - 2010

Y1 - 2010

N2 - The evolution of the molecular structure of molybdena/titania catalysts prepared by the equilibrium-deposition-filtration (EDF) method is monitored by in situ Raman spectroscopy in the temperature range 25-430°C. The study is based on a recently proposed picture for the interfacial speciation of Mo(VI) oxo-species deposited at the "titania/electrolytic solution" interface of "wet" catalyst pastes and on the temperature-dependent features of in situ Raman "snap-shots" obtained with increasing temperature. The configurations of the deposited Mo(VI) oxo-species on "wet" (i.e. prior to drying) samples conform to the theoretically previewed speciation for the respective pH's and concentrations of the precursor electrolyte and impregnating solutions; for initial Mo(VI) concentrations up to 2.5×10-2 M the predominant deposited species evolve from monomeric MoO42- ions retained above a bridging surface hydroxyl through a hydrogen bond [Ti2OH...O-MoO3] (for solution pH=9) to a mixture with inner sphere mononuclear mono-substituted (with the terminal surface oxygen of titania) complex [Ti-OMoO3] (for solution pH=6) and to a simultaneous occurrence of the former monomeric species with Mo7O246- and HMo7O 245- (for solution pH=4). A gradual transformation of the complex configurations is monitored with rising temperature by in situ Raman snap-shots and the spectra of the final calcined samples exhibit the features of dispersed mono-oxo (Ti-O)3Mo=O species. A low presence of associated species (possessing Mo-O-Mo linkages) is evident for the higher loaded samples.

AB - The evolution of the molecular structure of molybdena/titania catalysts prepared by the equilibrium-deposition-filtration (EDF) method is monitored by in situ Raman spectroscopy in the temperature range 25-430°C. The study is based on a recently proposed picture for the interfacial speciation of Mo(VI) oxo-species deposited at the "titania/electrolytic solution" interface of "wet" catalyst pastes and on the temperature-dependent features of in situ Raman "snap-shots" obtained with increasing temperature. The configurations of the deposited Mo(VI) oxo-species on "wet" (i.e. prior to drying) samples conform to the theoretically previewed speciation for the respective pH's and concentrations of the precursor electrolyte and impregnating solutions; for initial Mo(VI) concentrations up to 2.5×10-2 M the predominant deposited species evolve from monomeric MoO42- ions retained above a bridging surface hydroxyl through a hydrogen bond [Ti2OH...O-MoO3] (for solution pH=9) to a mixture with inner sphere mononuclear mono-substituted (with the terminal surface oxygen of titania) complex [Ti-OMoO3] (for solution pH=6) and to a simultaneous occurrence of the former monomeric species with Mo7O246- and HMo7O 245- (for solution pH=4). A gradual transformation of the complex configurations is monitored with rising temperature by in situ Raman snap-shots and the spectra of the final calcined samples exhibit the features of dispersed mono-oxo (Ti-O)3Mo=O species. A low presence of associated species (possessing Mo-O-Mo linkages) is evident for the higher loaded samples.

KW - In situ Raman

KW - Molybdena catalysts

KW - Oxomolybdenum species

KW - Temperature evolution

KW - Titania

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U2 - 10.1016/S0167-2991(10)75120-X

DO - 10.1016/S0167-2991(10)75120-X

M3 - Conference contribution

AN - SCOPUS:79551640367

SN - 9780444536013

T3 - Studies in Surface Science and Catalysis

SP - 613

EP - 616

BT - Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium

PB - Elsevier Inc.

ER -

Tsilomelekis G, Tribalis A, Kalampounias AG, Boghosian S, Panagiotou GD, Bourikas K et al. Temperature - Dependent evolution of molecular configurations of oxomolybdenum species on MoO₃/TiO₂ catalysts monitored by in situ Raman spectroscopy. In Scientific Bases for the Preparation of Heterogeneous Catalysts - Proceedings of the 10th International Symposium. Elsevier Inc. 2010. p. 613-616. (Studies in Surface Science and Catalysis). doi: 10.1016/S0167-2991(10)75120-X