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On the role of redox properties of CuO/CeO2 catalysts in the preferential oxidation of CO in H2-rich gases

Paper ID Volume ID Publish Year Pages File Format Full-Text
43563 45977 2008 12 PDF Available
Title
On the role of redox properties of CuO/CeO2 catalysts in the preferential oxidation of CO in H2-rich gases
Abstract

CuO/CeO2 catalysts with CuO content ranging from 0.5 wt.% to 8 wt.%, prepared by wet impregnation of commercial ceria, have been tested for the preferential oxidation of CO (CO-PROX) under H2-rich conditions at 70–210 °C. Catalytic activity increases up to 4 wt.% CuO content, with less concentrated catalysts showing higher intrinsic activity. Catalysts have been characterized by means of XRD, BET analysis and UV spectroscopy. Formation of segregated CuO clusters has been detected for Cu richest CuO/CeO2 sample. Redox properties have been deeply investigated using TP analysis (H2 TPR, CO TPR, TPO) of fresh or pre-treated samples. Participation of surface ceria, induced by the strong interaction with copper, to reduction/oxidation reactions in the temperature range explored (up to 430 °C) has been demonstrated. Different copper species and their reactivity towards H2 and CO have been individuated by comparing TPR of fully oxidized catalysts with those of partially oxidized catalysts. Active species have been identified as copper-ceria sites able to oxidize CO even at room temperature and to be re-oxidized by O2 at the same temperature. Transient experiments have been carried out at different temperature using a diluted mixture starting from oxidized or reduced catalysts and followed by a H2 TPR of the used samples. The results of these tests have showed that active centres for CO oxidation contain copper in the +2 oxidation state. At T > 100 °C some reduced copper sites are stabilized which promote H2 oxidation thus lowering the selectivity of the CO-PROX process.

Graphical abstractCuO/CeO2 catalysts have been tested for the preferential oxidation of CO. Redox properties have been deeply investigated using TP analysis, that together with transient kinetic tests showed that the participation of surface ceria, induced by the strong interaction with copper, is responsible for redox properties and catalytic performances. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
PROX; Copper; Ceria; CO oxidation; Hydrogen; Fuel cell; CuO/CeO2; Catalysis; CO removal; TPR; TPO
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On the role of redox properties of CuO/CeO2 catalysts in the preferential oxidation of CO in H2-rich gases
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 348, Issue 1, 30 September 2008, Pages 42–53
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us