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Preferential oxidation of CO in excess H2 over CuO/CeO2 catalysts: Performance as a function of the copper coverage and exposed face present in the CeO2 support

Paper ID Volume ID Publish Year Pages File Format Full-Text
54117 46997 2014 10 PDF Available
Title
Preferential oxidation of CO in excess H2 over CuO/CeO2 catalysts: Performance as a function of the copper coverage and exposed face present in the CeO2 support
Abstract

•CuO/CeO2 is more selective in CO-PROX if CeO2 support has cube-shaped nanoparticles.•Nanocube-based CuO/CeO2 retains Cu+ carbonyls to higher T under CO-PROX reaction.•Effect is due to stabilization of Cu against reduction to Cu0.•XRD and EPR indicate different CuO growth mode on CeO2 nanocubes.•DFT evidences stronger interaction of CuO on (0 0 1) than on (1 1 1) CeO2 surface.

CuO/CeO2 catalysts where the support has different nanoparticle shapes exposing different lattice planes are examined for the preferential oxidation of CO in the presence of excess H2 (CO-PROX reaction) in operando DRIFTS conditions. Even for catalysts with same surface concentration of Cu the selectivity for CO2 formation is found close to 100% up to higher temperatures when the support is in form of nanocubes (exposing the less stable (0 0 1) lattice planes). DRIFTS data allow relating this to a higher stability of the Cu species forming the Cu+ carbonyls associated to the high activity and selectivity, so that they are fully reduced at higher temperature in agreement with TPR data. DFT calculations show that CuO nanoparticles interact more strongly (distorting more their structure) with the CeO2 (0 0 1) surface than with the (1 1 1) surface, while XRD indicates that the formation of well developed CuO nanocrystals is more difficult on nanocube shaped CeO2 than on other CeO2 morphologies. Also EPR spectra show that the CuO entities nucleate on the ceria nanocubes differently. The higher stabilization of the oxidized state indicated by DFT, together with the mentioned structural distortion, may be then the reason for the improved selectivity.

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Keywords
Nanostructured CuO/CeO2 catalysts; CO-PROX; Operando-DRIFTS; EPR; TPR; DFT
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Preferential oxidation of CO in excess H2 over CuO/CeO2 catalysts: Performance as a function of the copper coverage and exposed face present in the CeO2 support
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 229, 15 June 2014, Pages 104–113
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
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Price was $35.95
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Price after discount Only $4.95
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