Chemisorption of ethanol at Pt(111) and Pt(111)–O surfaces

Abstract

The chemisorption of ethanol at Pt(111) and Pt(111)–O surfaces has been studied using X-ray photoelectron (XP) and UV photoelectron (UP) spectroscopies. At atomically clean Pt(111) at 295 K only chemisorbed hydrocarbon species are present, identical spectra being observed with propene chemisorption. An oxygen-modified Pt(111) surface (ϑ₀=0.1) is also reactive but, in this case, both hydrocarbon and oxygenated species are present at 295 K. Chemisorption of acetaldehyde indicates that decarbonylation is facile, lending support for the step-wise mechanism proposed with ethanol. Studies at low temperature (200 K) also support a step-wise mechanism with an oxygenated species, possibly an ethoxide (C₂H₅O), being the intermediate. The presence of surface carbon at an otherwise clean Pt(111) surface leads to similar reactivity to C₂H₅OH as does Pt(111)–O.

References

1. A. Baiker and H.-U. Blaser, in Handbook of Heterogeneous Catalysis, ed. G. Ertl, H. Knozinger and J. Weitkamp, VCH, Weinheim, 1997, vol. 5, p. 2422.
2. K. E. Simons, P. A. Meheux, S. P. Griffiths, I. M. Sutherland, P. Johnston, P. B. Wells, A. F. Carley, M. K. Rajuman, M. W. Roberts and A. Ibbotson, Recl. Trav. Chim. Pays-Bas, 1994, 113, 465.
3. (a) A. F. Carley, M. K. Rajumon, M. W. Roberts and P. B. Wells, J. Chem. Soc., Faraday Trans., 1995, 91, 2167; (b) T. S. Amorelli, A. F. Carley, M. K. Rajumon, M. W. Roberts and P. B. Wells, Surf. Sci., 1994, 315, L990; (c) A. F. Carley, P. R. Chalker, J. C. Riviere and M. W. Roberts, J. Chem. Soc. Faraday Trans I, 1987, 83, 351.
4. S. P. Griffiths, PhD thesis, University of Hull, 1996.
5. P. B. Wells and A. G. Wikinson, Top. Catal., 1998, 5, 39.
6. J. A. Slipszenko, S. P. Griffiths, P. Johnston, K. E. Simons, W. A. H. Vermeer and P. B. Wells, J. Catal., 1998, 178, in press.
7. P. Gao, C.-H. Lin, C. Shannon, G. N. Salaita, J. H. White, S. A. Chaffins and A. T. Hubbard, Langmuir, 1991, 7, 1515.
8. J. F. E. Gootzen, W. Visscher and J. A. R. van Veen, Langmuir, 1996, 12, 5076.
9. J. A. A. van den Tillaart, B. F. M. Kuster and G. B. Marin, Appl. Catal. A, 1994, 120, 127.
10. J. W. Shin, W. J. Tornquist, C. Korzeniewski and C. S. Hoaglund, Surf. Sci., 1996, 364, 122.
11. B. A. Sexton, K. D. Rendulie and A. E. Hughes, Surf. Sci., 1982, 121, 181.
12. J. Wang and R. I. Masel, Surf. Sci., 1991, 243, 199.
13. J. Wang and R. I. Masel, J. Catal., 1990, 126, 519.
14. S. D. Jackson, M. B. T. Keegan, G. D. McLellan, P. A. Meheux, R. B. Moyes, G. Webb, P. B. Wells, R. Whyman and J. Willis, in Preparation and Characterisation of Catalysts, ed. G. Poncelet et al., Elsevier, Amsterdam, 1991, vol. V, p. 135.
15. G. Webb, Catal. Today, 1990, 7, 139.
16. G. F. Berndt, S. J. Thomson and G. Webb, J. Chem. Soc. Faraday Trans. 1, 1983, 79, 195.
17. G. A. Somorjai and F. Zaera, J. Phys. Chem., 1982, 86, 3070.
18. H. Ibach, M. A. Vannice and W. Erley, Surf. Sci., 1991, 254, 12.