Evidence for the migration of ZnOx in a Cu/ZnO methanol synthesis catalyst |
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Authors: | Y Kanai T Watanabe T Fujitani M Saito J Nakamura T Uchijima |
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Affiliation: | (1) Research Institute of Innovative Technology for the Earth, Tsukuba, 305 Ibaraki, Japan;(2) National Institute for Resources and Environment, Tsukuba, 305 Ibaraki, Japan;(3) Institute of Materials Science, University of Tsukuba, Tsukuba, 305 Ibaraki, Japan |
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Abstract: | The behavior and role of ZnO in Cu/ZnO catalysts for the hydrogenations of CO and CO2 were studied using XRD, TEM coupled with EDX, TPD and FT-IR. As the reduction temperature increased, the specific activity for the hydrogenation of CO2 increased, whereas the activity for the hydrogenation of CO decreased. The EDX and XRD results definitely showed that ZnO
x
(x = 0–1) moieties migrate onto the Cu surface and dissolve into the Cu particle forming a Cu-Zn alloy when the Cu/ZnO catalysts were reduced at high temperatures above 600 K. The content of Zn dissolved in the Cu particles increased with reduction temperature and reached 18% at a reduction temperature of 723 K. The CO-TPD and FT-IR results suggested the presence of Cu+ sites formed in the vicinity of ZnO
x
on the Cu surface, where the Cu+ species were regarded as an active catalytic component for methanol synthesis. |
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Keywords: | methanol synthesis Cu/ZnO catalyst Cu-Zn alloy effect of reduction temperature |
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