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Abstract:
A series of CuO/ZrO2 catalysts with different Cu loadings (4.1, 6.1 and 8.4 wt.%) were synthesized by a deposition-precipitation method and evaluated with the water-gas shift (WGS) reaction. In order to distinguish the different supported copper oxide species, (NH4)2CO 3-leaching process was conducted on the three CuO/ZrO2 catalysts. The parent and leached catalysts were characterized by ICP-OES, XPS, XRD, N2-physisorption, N2O titration, UV-Vis DRS, H 2-TPR and CO-TPR. The results reveal that three types of copper oxide species are present on the parent CuO/ZrO2 catalysts: (α) highly dispersed CuO that is weakly bound with ZrO2; (β) strongly bound Cu-[O]-Zr species, which can not be leached by (NH 4)2CO3 solution and is possibly associated with the surface oxygen vacancy of ZrO2; (γ) crystalline CuO. The XRD and TEM results of the freshly reduced catalysts disclose that the three types of CuO species are transformed into their corresponding metallic states after the H2-pretreatment. It is found that the reaction rate correlates well with the amount of Cu-[O]-Zr species, indicating the metallic Cu derived from this species should be the catalytically active copper species for the WGS reaction. Moreover, CO-TPR results disclose that the Cu-[O]-Zr species play a significant role in promoting the reactivity of the surface hydroxyl groups, as is thought to be responsible for the high WGS activity of the CuO/ZrO2 catalysts. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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International Journal of Hydrogen Energy
ISSN: 0360-3199
Year: 2014
Issue: 8
Volume: 39
Page: 3746-3754
3 . 3 1 3
JCR@2014
8 . 1 0 0
JCR@2023
ESI HC Threshold:184
JCR Journal Grade:1
CAS Journal Grade:2
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ESI Highly Cited Papers on the List: 0 Unfold All
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