Methane photoactivation on copper molybdate. An experimental and theoretical study

Journal Article · Thu Dec 17 04:00:00 EST 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100310a019· OSTI ID:5354250

Ward, M D; Brazdil, J F; Mehandru, S P; Anderson, A B

It is shown experimentally that the activity of UV-irradiated MoO/sub 3/ for the partial oxidation of methane in the presence of O/sub 2/ at 100/sup 0/C, leading to methanol formation, is markedly enhanced when Cu/sup II/ is added to the catalyst. The rate of methanol formation is maximum when the concentrations of copper and molybdenum are equal. Visible light activates CuMoO/sub 4/ but not MoO/sub 3/. The authors have made a molecular orbital study of the photoactivity of CuMoO/sub 4/ toward hydrogen abstraction from methane at O/sup -/ centers. The activity of CuMoO/sub 4/ in the visible region is assigned to O 2p ..-->.. Cu 3d excitations; the Cu 3d band levels lie below the Mo 4d band and the orbitals have a large O 2p component. Mechanisms are proposed for increasing the lifetimes of the electron-hole pairs and thereby account for the synergistic effect in CuMoO/sub 4/ which shows enhanced photoactivity compared with either CuO, which is photoinactive, or MoO/sub 3/. Empty band-gap orbitals serve to stabilize homolytic H and xCH/sub 3/ adsorption on O/sup 2 -/ sites relative to MoO/sub 3/, and filled band-gap orbitals stabilize homolytic adsorption on Mo/sup VI/ sites. Heterolytic adsorption on Mo/sup VI/ and O/sup 2 -/ sites is stable but not on Cu/sup II/ and O/sup 2 -/ sites. Homolytic adsorption is unstable on Cu/sup II/ sites

• Research Organization: Standard Oil Research and Development, Cleveland, OH (USA)
• OSTI ID: 5354250
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:26; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALCOHOLS
ALKANES
CATALYSIS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
DATA
ELECTRONIC STRUCTURE
EXPERIMENTAL DATA
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
METHANE
METHANOL
MOLECULAR ORBITAL METHOD
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
REFRACTORY METAL COMPOUNDS
SORPTIVE PROPERTIES
SURFACE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YIELDS