Evolution of the Cu/ZnO methanol synthesis catalyst during its reduction and re-oxidation |
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Authors: | Vladimir V Pelipenko Dmitry I Kochubey Alexander A Khassin and and Tamara M Yurieva |
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Institution: | (1) Boreskov Institute of Catalysis, Novosibirsk 630090, Russia;(2) Boreskov Institute of Catalysis, Novosibirsk 630090, Russia;(3) Boreskov Institute of Catalysis, Novosibirsk 630090, Russia;(4) Boreskov Institute of Catalysis, Novosibirsk 630090, Russia |
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Abstract: | Summary Cu K EXAFS studies of the structure of Cu-Zn oxide catalyst were performed for the as prepared samples, those after its activation
by hydrogen and after its subsequent re-oxidation. It was found that during the primary formation of the CuZnO solid solution,
the copper ions are dissolved in the extended stacking faults of the ZnO lattice as ultra-small oxide clusters. Activation
by hydrogen at 473 K leads to the reduction of most copper cations to Cu0with the formation of nanoparticles with the characteristic size of ca. 1.6 nm. The copper metal particles were re-oxidized to Cu2+at 523 K in<span lang=EN-US style='mso-ansi-language:EN-US'>ahelium flow containing 0.05 vol. % oxygen. The re-oxidized cations
do not form a CuO phase. Instead, they return to the extended stacking faults of ZnO. However, this time they form stripe-like
clusters of square-planar coordinated copper cations. |
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Keywords: | Copper EXAFS stacking fault methanol synthesis |
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