ADSORPTION OF SMALL MOLECULES ON THE Cu (111) SURFACE

 

 

J. R. B. Gomes and J. A. N. F. Gomes

 

CEQUP / FCUP, Departamento de Química
Rua do Campo Alegre, 687 - 4150 Porto (Portugal)

The copper surface was found to be quite interesting for the study of catalytic reactions.^1-5 A catalyst based on Cu/ZnO is used in industry to obtain methanol from syn-gas. On the course of this kind of reactions involving methanol, a number of intermediates and products have been observed experimentally. Among them, methoxy radical is the most extensively studied intermediate which is found in the oxidation of methanol. Further knowledge about the adsorption parameters for the intermediates in the oxidation of formaldehyde to CO and H₂ is needed. H₂CO₂ and HCO₂ were experimentally found and must have a key role in this reaction.
Vibrational frequencies, adsorption energies and adsorption geometries obtained from DFT calculations using the B3LYP hybrid method for H₂CO, H₂CO₂ and HCO₂ adsorbed on the Cu (111) surface will be presented in this poster. The results show that the radicalar species are chemisorbed on the surface by the oxygen atoms at distances of ca. 1.9 - 2.0 A and that formaldehyde is weakly adsorbed.

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- W. S. Sim, P. Gardner and D. A. King, J. Phys. Chem., 100 (1996) 12509.
4- J. R. B. Gomes and J. A. N. F. Gomes, Teochem, in print.
5- J. R. B. Gomes and J. A. N. F. Gomes, submitted.

Acknowledgements

Financial support from the Fundação para a Ciência e Tecnologia (Lisbon) and project PRAXIS/3/3.1/MMA/1780/95 is aknowledged. JRBG thanks PRAXIS for a doctoral scolarship (BD/5522/95).