Fakultät II – Mathematik und Naturwissenschaften

Intermetallic compounds of palladium with gallium (PdGa and Pd3Ga7) are introduced as selective catalysts for the hydrogenation of acetylene. Both intermetallic compounds are selected as site-isolated palladium catalysts because of the increased average interatomic Pd-Pd distances and decreased Pd-Pd coordination numbers in their structures. Detailed investigations of PdGa and Pd3Ga7 by thermal analysis, in situ X-ray diffraction, and in situ X-ray absorption spectroscopy during thermal treatment under various inert or reactive gas atmospheres showed a high thermal stability. The long-range and short-range order structures of the materials remained intact up to temperatures of about 600 K with no phase transitions or decomposition detectable. In addition to high thermal stability, no incorporation of hydrogen in the intermetallic compounds under reducing conditions was detected. Both intermetallic compounds studied exhibit sufficient thermal stability, isolation of Pd centers under reaction conditions, and no incorporation of hydrogen in the bulk. Therefore, besides being interesting model systems, palladium gallium intermetallic compounds may also be promising candidates for application as highly selectiv