γ-Al₂O₃-Supported Re−Pt Cluster Catalyst Prepared from [Re₂Pt(CO)₁₂]:  Characterization by Extended X-ray Absorption Fine Structure Spectroscopy and Catalysis of Methylcyclohexane Dehydrogenation

A model catalyst prepared from [Re 2 Pt(CO) 12 ] supported on γ-Al 2 O 3 was characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy, and its stability in operation in a flow reactor was tested for the dehydrogenation of methylcyclohexane at 1 atm and 400 °C. EXAFS data characterizing the unused catalyst measured at both the Re L III and Pt L III edges at liquid nitrogen temperature with the sample in the presence of H 2 distinguish the Re−Pt from the Pt−Pt and Re−Re interactions. The EXAFS results form the basis of a simplified model of the supported bimetallic structures, consisting of Re 4 Pt 2 entities, with oxophilic Re in a low positive oxidation state interacting strongly with the oxygen atoms of the γ-Al 2 O 3 support and stabilizing the dispersion of the Pt atoms. The catalyst made from [Re 2 Pt(CO) 12 ] was found to be more resistant to deactivation during catalytic dehydrogenation of methylcyclohexane than catalysts prepared conventionally from Re and Pt salt precursors. The catalyst prepared from [Re 2 Pt(CO) 12 ] was more highly dispersed than the others, and its resistance to deactivation is attributed to the role of Re in stabilizing the dispersion of the Pt.