| Abstract
| - Significant differences are observed in the hydrogen sorption behavior of as-received, HF-treated, andoxidized PdZr alloys. Removal by HF treatment of the surface ZrO2 layer, which blocks sorption of hydrogen,and a part of the bulk Zr generates a porous surface layer of increased surface area. The resulting specimensorbs hydrogen even at low H2 partial pressure. A thick oxide layer composed of a mixture of PdO andZrO2 is formed by aerobic oxidation (553 K, 3 h). A diffusion controlled slow H2 sorption by Pd in the surfacelayer followed by a rapid and large H2 sorption by the bulk alloy is observed. This results in the fracturingof the surface oxide layer and the formation of the hydrides of the constituent elements. The pretreatedalloy samples studied exhibit high catalytic activities and selectivities in the hydrogenation of compoundswith multiple unsaturation (cycloocta-1,3-diene, phenylacetylene, 1-pentyne).
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