1407. HERRINGTON, E. F. G., AND RIDEAL, E. K. Poisoning of Metallic Catalysts. Trans. Faraday Soc., vol. 40, 1944, pp. 505-516; Chem. Abs., vol. 39, 1945, p. 2248.

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Literature Abstracts

Phenomena of poisoning are examined to determine whether they are compatible with the hypothesis that uniform crystal facets rather than active patches are the sites of catalytic activity. These considerations are restricted to the active hydrogenating catalysts, for example, Ni, Co, Pt, Pd, in the face-centered cubic form, where the reaction velocity in simple hydrogenation is usually of zero order in respect to the material undergoing hydrogenation. It is assumed that the rate is proportional to the surface concentration of the given reactant. If after poisoning with a substance that occupies 1 active center, a fraction θ of the active spots is bare and an isolated group of n centers is required for reaction, then the number of unpoisoned groups is proportional to θⁿ. With this mechanism, the plot of activity against poison concentration is linear throughout the entire poison range only when N=1. Much of the observed behavior during the poisoning of heterogeneous catalysts can be duplicated by the poisoning of a uniform set of sites. It is stated that an explanation of catalytic behavior requiring active spots appears in many cases to be unnecessary.