Bimetallic Catalyst Particle Nanostructure. Evolution from Molecular Cluster Precursors
| Autor: | Michael S. Nashner, Ralph G. Nuzzo, David L. Adler, Philip D. Lane, David M. Somerville, and John R. Shapley |
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| Rok vydání: | 1996 |
| Předmět: |
chemistry.chemical_classification
Extended X-ray absorption fine structure Inorganic chemistry General Chemistry Biochemistry Catalysis Metal Crystallography Colloid and Surface Chemistry chemistry Hydrogenolysis visual_art visual_art.visual_art_medium Cluster (physics) Molecule Counterion Bimetallic strip |
| Zdroj: | Journal of the American Chemical Society. 118:12964-12974 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | A set of supported bimetallic catalysts, designated [Re7Ir−N], [Re7Ir−P], [Re5IrRe2−N], and [Re5IrRe2−P], has been prepared from two structural isomers (1 and 2) of the cluster compound [Z]2[Re7IrC(CO)23] (Z+ = NEt4+, N(PPh3)2+) by deposition onto high surface area alumina (≤1% Re) and activation in H2 at 773 K. The specific activities of the catalysts for ethane hydrogenolysis at 500 K vary significantly (3−63 mmol of CH4/mol of Re7Ir per s) and depend on both the metal framework structure and the counterion present in the precursor. Interpretation of EXAFS data (from both Re and Ir L3-edges) has enabled the development of specific models for the catalyst particle nanostructures that correlate with the catalytic activities. The more active catalysts ([Re7Ir−N] and [Re5IrRe2−N]) are modeled by a hemisphere of close-packed (hcp) metal atoms (average diameter 1 nm) with Ir at the core. On the other hand, the less active catalysts ([Re7Ir−P] and [Re5IrRe2−P]) are better described as two-dimensional layer str... |
| Databáze: | OpenAIRE |
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