METHOXY OXIDATION TO FORMALDEHYDE ON METALLIC SURFACES
J. R. B. Gomes1, F. Illas2 and J. A. N. F. Gomes1
1 CEQUP / FCUP, Departamento de Química
Rua do Campo Alegre, 687 - 4150 Porto (Portugal)
2 Departament de Química Física, Universitat de Barcelona
C/ Martí i Franquìs,1 - 08028 Barcelona (Spain)
Methanol oxidation at metal surfaces has been studied intensively since Madix and co-workers1,2 published their results concerning temperature programmed desorption of methanol at copper surfaces in the late 70's. On all surfaces studied, methoxy radical, CH3O is the dominant surface intermediate and it is easily formed by O-H bond cleavage of methanol. Methoxy is preferentially adsorbed on Cu(111), Ag(111) and Au(111) surfaces3,4 at the fcc hollow sites with its oxygen atom pointing towards the surface and with its C-O axis normal to the surface.
Despite the existence of a substancial amount of work on this area, the mechanism of CH3O oxidation to formaldehyde is not totally clear in terms of the role of oxygen atoms present on the surface. On this poster, results from DFT quantum chemical calculations for CH3O adsorption and oxidation will be presented and discussed.
Thanks to C4, CESCA-CEPBA, for enabling access to the SP2 supercomputer through TMR contract #ERBFMGEGT950062. JRBG thanks PRAXIS for a doctoral scholarship (BD/5522/95).
1- R. J. Madix and I. E. Wachs, J. Catal. 53 (1978) 208
2- M. Bowker and R. J. Madix, Surf. Sci., 95 (1980) 190.
3- J. R. B. Gomes and J. A. N. F. Gomes, submitted.
4- J. R. B. Gomes and J. A. N. F. Gomes, submitted.
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