Electron microscopic investigation of changes in the surface of solid catalysts during operation

Summary

• 1. The data given in this paper show that the changes in solid metallic catalysts during operation are of much wider occurrence than has generally been considered up to now. The metallic catalysts (Pt, Pd, Cu, Fe, alloys of platinum and rhodium) undergo characteristic and fairly complex changes in surface structure from the very beginning of operation, and these changes continue even during long periods of operation.

• 2. When catalytic reactions are carried out on tempered, polished, solid metallic catalysts, the electronmicroscope method enables qualitative differences in the disintegration of the individual crystal boundaries which go to make up the polycrystalline surface to be observed (“zonality” of disintegration).

• 3. A parallel study of the disintegration and catalytic activity of the individual boundaries of a copper monocrystal in the oxidation of hydrogen showed that there is no well-defined functional relationship between the degree of disintegration in this reaction and the catalytic activity. Thus, it is impossible to draw conclusions about the catalytic activity of these surfaces from the differences in the disintegration of the boundaries in the reaction.