XPS study of the size effect in ethene epoxidation on supported silver catalysts

Abstract

Supported silver catalysts (Ag/α-Al₂O₃) with different particle sizes (100–1000 Å) have been prepared and studied by XPS. It has been shown that the increase in the ethene epoxidation rate with silver particle size (size effect) is accompanied by a decrease in the Ag 3d_5/2 binding energy value. The variation in E_b(Ag 3d_5/2) cannot be explained in terms of a change in the metallic character of the silver (initial state effect), but seems to be determined by the differential charging of the supported silver. The latter effect originates from the easier screening of surface charge induced by photoemission on the silver particles owing to their internal conductivity, rather than that on the dielectric support. The correlation between the internal conductivity of supported silver particles and their catalytic activity is discussed in the context of possible mechanisms for ethene epoxidation.

References

1. G. C. Bond, Surf. Sci., 1985, 156, 966.
2. M. Che and C. O. Bennett, Adv. Catal., 1989, 36, 55.
3. P. Briot, A. Auroux, D. Jones and M. Primet, J. Catal., 1990, 59, 141.
4. B. Tardy, C. Noupa, C. Leclercq, J. C. Bertolini, A. Hoareau, M. Treilleux, J. P. Faure and G. Nihoul, J. Catal., 1991, 129, 1.
5. R. C. Baetzold, M. G. Mason and J. F. Hamilton, J. Chem. Phys., 1980, 72, 366.
6. G. K. Wertheim, S. B. DiCenzo and D. N. E. Buchanan, J. Phys. Chem., 1986, 33, 5384.
7. C. N. R. Rao, H. K. N. Aiyer, T. Arunarkavalli and G. U. Kulkarni, Catal. Lett., 1994, 23, 37.
8. X. P. Xu and D. W. Goodman, Catal. Lett., 1994, 24, 31.
9. D. W. Goodman, Surf. Sci., 1994, 300, 837.
10. L. V. Nosova, M. V. Stenin, Yu. N. Nogin and Yu. A. Ryndin, Appl. Surf. Sci., 1992, 55, 43.
11. J. K. Lee, X. E. Verykios and R. Pitchai, Appl. Catal., 1989, 50, 171.
12. S. Cheng and A. Clearfield, J. Catal., 1985, 94, 455.
13. S. R. Seyedmonir, J. K. Plischke, M. A. Vannice and H. W. Young, J. Catal., 1990, 123, 534.
14. S. N. Goncharova, E. A. Paukshtis and B. S. Bal'zhinimaev, Appl. Catal., 1995, 126, 67.
15. S. V. Tsybulya, G. N. Kryukova, S. N. Goncharova, A. N. Shmakov and B. S. Balzhinimaev, J. Catal., 1995, 154, 194.
16. C. D. Wagner, W. M. Riggs, L. E. Davis, J. F. Moulder and G. E. Muilenberg, Handbook of X-ray Photoelectron Spectroscopy, Perkin-Elmer, Eden Prarie, MN, 1979.
17. G. Johansson, J. Hedman, A. Berndtsson, M. Klasson and R. Nilsson, J. Electron Spectrosc. Relat. Phenom., 1973, 2, 295.
18. D. A. Bulushev, E. A. Paukshtis, Yu. N. Nogin and B. S. Bal'zhinimaev, Appl. Catal., 1995, 123, 301.
19. T. Juska, Z. Bastl, T. Derer and G. Kiss, Poverkhnost (in Russian), 1987, 10, 96.
20. G. Schön, Acta Chem. Scand., 1973, 27, 2623.
21. J. S. Hammond, S. W. Gaarenstroom and N. Winograd, Anal. Chem., 1975, 47, 2193.
22. T. L. Barr, Crit. Rev. Anal. Chem., 1991, 22, 229.
23. T. L. Barr, J. Vac. Sci. Technol. A, 1989, 7, 1677.
24. C. D. Wagner, Anal. Chem., 1975, 47, 1201.
25. C. D. Wagner, C. D. Gale and R. H. Raymond, Anal. Chem., 1979, 51, 466.
26. V. I. Bukhtiyarov, I. P. Prosvirin and R. I. Kvon, J. Electron Spectrosc. Relat. Phenom., 1996, 77, 7.
27. R. C. Baetzold, Surf. Sci., 1981, 106, 243.
28. V. Vijayakrishnan, A. Chainani, D. D. Sarma and C. N. R. Rao, J. Phys. Chem., 1992, 96, 8679.
29. Yu. A. Ryndin, L. V. Nosova, A. I. Boronin and A. L. Chuvilin, Appl. Catal., 1988, 42, 131.
30. A. F. Carley, M. K. Rajumon and M. W. Roberts, J. Solid State Chem., 1993, 106, 156.
31. J. Li, Z. Zhang, L. Cai, J. Xu, C. Tang, Q. Zhong, Ya. Xiong and K. Huang, Proc. 9th Int. Congr. Catal., Calgary, 1988, vol. 4, p. 1680.
32. V. M. Mastikhin, I. L. Mudrakovsky, S. N. Goncharova, B. S. Balzhinimaev, S. P. Noskova and V. I. Zaikovsky, React. Kinet. Catal. Lett., 1992, 48, 425.
33. J. K. Plischke, A. J. Benesi and M. A. Vannice, J. Phys. Chem., 1992, 96, 3799.
34. V. M. Mastikhin, S. N. Goncharova, V. M. Tapilin, V. V. Terskikh and B. S. Balzhinimaev, J. Mol. Catal., 1995, 9, 175.
35. H. E. Rhodes, P.-K. Wang, H. T. Stokes and C. Slichter, Phys. Rev. B, 1982, 26, 3559.
36. C. Backx, J. Moolhuysen, P. Geenen and R. A. van Santen, J. Catal., 1981, 72, 364.
37. J. K. Plischke and M. A. Vannice, Appl. Catal., 1988, 42, 255.
38. C. T. Campbell, J. Catal., 1985, 94, 436.
39. V. I. Bukhtiyarov, A. I. Boronin and V. I. Savchenko, Surf. Sci., 1990, 232, L205.
40. V. I. Bukhtiyarov, A. I. Boronin, I. P. Prosvirin and V. I. Savchenko, J. Catal., 1994, 150, 268.
41. V. I. Bukhtiyarov, I. P. Prosvirin and R. I. Kvon, Surf. Sci., 1994, 320, L47.