Theoretical Description of Molybdena Based Catalysts; DFT Cluster Model Study.

Renata Tokarz-Sobieraj 

Polish Academy of Sciences, Institute of Catalysis and Surface Chemistry, Niezapominajek 8, Kraków 30-239, Poland

Abstract

Molybdenum oxide-based catalysts are active and selective in many catalytic reactions. The catalytic properties of such catalysts strongly depend on acid-base properties of catalysts surfaces, which determine the strength of surface-substrate interactions and facilitate the desorption of products from the surface. MoOX systems are particularly good examples for studying the role of different electronic and geometric factors on catalytic properties of the system due to the richness of surface active sites. This richness results from the possibility of different coordination number and oxidation states of Mo and O ions as well as geometrical and chemical environment of surface sites.

For theoretical description ab initio density functional theory (StoBe code) is applied. First, the nucleophilic properties of differently coordinated surface O atoms, which are present at pure (010)MoO3 surface are discussed. In the next step the results of the creation of local mono- and di-vacancy of O type are studied. In addition, process of surface re-oxidation that leads to the formation of very active surface oxygen species is also investigated. Further, metal reduction states (MoO3, MoO2) are studied in order to examine their influence on electronic parameters of oxygen sites. The influence of the additional atoms (Mn, Co) on chemical properties of active sites is examined by the comparison of the electronic structure of cobalt and manganese molybdates (CoMoO4, MnMoO4) with the pure Mo-O (MoO3) system.

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Presentation: Keynote lecture at E-MRS Fall Meeting 2006, Symposium B, by Renata Tokarz-Sobieraj
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-11 09:15
Revised:   2009-06-07 00:44
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