The Activity of Surfaces

Abstract

IN recent years a good deal of attention has been given to the relation between the catalytic effect of a surface and its structure, and in this connexion it is perhaps of interest to point out that the general idea underlying many theories was published by me in 1911 (J. Chem. Soc., 475 ff., 1911) in a qualitative form. The hypothesis in relation to the specific problem studied, the dehydration of a salt crystal, was based on the view that the lattice structure of such a system was disturbed, and that the rearrangement of the surface (described as ‘amorphous’, in harmony with the prevailing views before the application of the X-rays to crystal analysis had been discovered) underwent a recrystallisation, a process which required time. It was further pointed out that “a treatment of somewhat simpler systems than the present, such as occur, for example, in the ‘ageing’ of deposited catalytic surfaces, would probably present points of interest”; and such has, in fact, proved to be so. This view of a catalytic surface is incompatible with a smooth ‘chess-board’ surface. The latter has now been recognised as inadequate. The application of the idea to heterogeneous reactions has been considered by Slonim (Z. Elektrochem., p. 439, 1930). The examination of all such surfaces by X-ray analysis would, clearly, throw much light on the general problem, as Slonim shows in a particular case. The method contemplated had, however, the use of reaction velocity in mind.