CORRELATION OF CATALYTIC BEHAVIOR WITH ELECTRONIC-STRUCTURE, LATTICE STRUCTURE AND SURFACE-COMPOSITION IN POWDERED ALLOYS FROM THE PSEUDOBINARY SYSTEMS CERH3-XPDX AND ZRRH3-XPDX

Using the simple liquid phase hydrogenation of 1-octyne as the test reaction, the catalytic properties of powdered alloys from the two pseudobinary systems, CeRh3-xPdx and ZrRh3-xPdx (0≤x≤3), have been correlated with their electronic and crystal structures. Lattice parameter and magnetic susceptibility measurements on the two sets of powdered alloys indicated significant differences at x > 2.4 which could be interpreted in terms of differences in the rate of filling of the d-type conduction band with increasing palladium concentration in the two systems. This difference in behaviour of the two systems can be used to explain the significant differences in the rates of the hydrogenation reaction for the two sets of alloys at compositions in excess of x = 2.4. There is also some suggestion of a geometrical factor influencing the behaviour of the zirconium alloys around the x ≅ 2.4 composition. Auger electron spectroscopy observations indicated pronounced deviations from the bulk composition at the surface of the powders and these are particularly marked in the case of the cerium alloys. The high CeO2 content in these alloys could explain the very different selectivity behaviour of the rhodium-rich alloys in the cerium system when compared with the corresponding zirconium alloys. © 1979.