Abstract
A conceptual picture is developed to explain the peculiar kinetic features of methane oxidation over supported Pd catalysts (observed by several investigators), notably the hysteresis in activity accompanying temperature cycles. Experiments were performed with supported Pdcatalysts to illustrate these features. The activity hysteresis is closely coupled with a hysteresis in oxygen content. The latter is in turn attributed to the properties of the PCT-diagram of the involved three-phase system; gas phase O2 and the two solid phases, Pd and PdOx. The two main ingredients in the mechanism are: (i) the so-called absorption and decomposition “plateau” pressures for the O2-Pd-PdO x system are different, i.e., show a hysteresis, (ii) these pressures are not independent ofx, but increase with increasing oxygen content. Both features are deviations from the “ideal” three-phase system and are frequently observed for H2-metalmetal hydride systems.
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References
R.J. Farrauto, M.C. Hobson, T. Kennelly and E.M. Waterman, APCAT 81 (1992) 227.
P. Briot and M. Primet, APCAT 68 (1990) 301.
J.G. McCarty, in:Int. Workshop on Catalytic Combustion, ed. H. Arai (Catalysis Society of Japan, Tokyo, 1994) p. 108.
F.H. Ribeiro, M. Chow and R. A. Dalla Betta, J. Catal. 146 (1994) 537.
E. Garbowski, C. Feumi-Jantou, N. Mouaddib and M. Primet. APCAT 109 (1994) 277.
K. Sekizawa, M. Machida, K. Eguchi and H. Arai, J. Catal. 142 (1993) 655.
R.F. Hicks, H. Qi, M.L. Young and R.G. Lee, J. Catal. 122 (1990) 280.
R. Hicks, H. Qi, M.L. Young and R.G. Lee, J. Catal. 122 (1990) 295.
C.F. Cullis and B.M. Willatt, J. Catal. 83 (1983) 267.
S. Lundgren, K.E. Keck and B. Kasemo, Rev. Sci. Instr. (1994), to be published.
J. Hall, S. Lundgren, K.E. Keck and B. Kasemo, Int. J. Ion Mass Spectrom. 108 (1991) 1.
B. Kasemo, K.E. Keck and T. Högberg, J. Catal. 66 (1980) 441.
B. Kasemo, Rev. Sci. Instr. 50 (1979) 1602.
P. Lööf, B. Kasemo and K.E. Keck, J. Catal. 118 (1989) 339.
P. Lööf, B. Stenbom, H. Nordén and B. Kasemo, J. Catal. 144 (1993) 60.
B. Bayer and H.G. Wiedemann, Thermochim. Acta 11 (1975) 79.
W.E. Bell, R.E. Inyard and M. Tagami, J. Phys. Chem. 70 (1966) 3735.
J. Murray, M.L. Post and J.B. Taylor, Mater. Res. Bull. 17 (1982) 887.
T.B. Flanagan and J.D. Clewley, J. Less-Common Metals 83 (1982) 127.
T.B. Flanagan, J.D. Clewley, T. Kuji and D.H. Everett, J. Chem. Soc. Faraday Trans. I 82 (1986) 2589.
W.M. Mueller, J.P. Blackledge and G.G. Lebowitz,Metal Hydrides (Academic Press, London, 1968).
G. Alefeld and J. Völkl,Hydrogen in Metals, Topics in Applied Physics, Vol. 29 (Springer, Berlin, 1978).
C.T. Campbell, D.C. Foyt and J.M. White, J. Phys. Chem. 81 (1976) 491.
J.J. Chen and E. Ruckenstein, J. Phys. Chem. 85 (1981) 1606.
H. Lieske and J. Völter, J. Phys. Chem. 89 (1985) 1841.
N.G. Schmahl and E. Minzl, Z. Phys. Chem. NF 47 (1965) 142.
M.W. Lee and R. Glosser, J. Appl. Phys. 57 (1985) 5236.
R. Feenstra, G.J. de Bruin-Hordijk, H.L.M. Bakker, R. Griessen and D.D. de Groot, J. Phys. F 13 (1983) L13.
R. Griessen, Phys. Rev. B 27 (1983) 7575.
R. Griessen and R. Feenstra, J. Phys. F 15 (1985) 1013
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Salomonsson, P., Johansson, S. & Kasemo, B. Methane oxidation over PdO x : on the mechanism for the hysteresis in activity and oxygen content. Catal Lett 33, 1–13 (1995). https://doi.org/10.1007/BF00817041
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DOI: https://doi.org/10.1007/BF00817041