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Ce-Pr mixed oxides as active supports for Water-gas Shift reaction: Experimental and density functional theory characterization

Paper ID Volume ID Publish Year Pages File Format Full-Text
39559 45827 2014 10 PDF Available
Title
Ce-Pr mixed oxides as active supports for Water-gas Shift reaction: Experimental and density functional theory characterization
Abstract

•Upon Pr addition, surface Ce cations are preferentially replaced by Pr ones.•Pr doping promoted the formation of oxygen vacancies.•Anionic defects formation resulted in preferential reduction of Pr cations.•Addition of Pr increased the oxygen storage capacity.•Water-gas Shift intrinsic reaction rate increased as Pr content increased.

Experimental measurements by several techniques and density functional theory (DFT) calculations are combined to characterize Ce-Pr mixed oxides and deeply understand the influence of Pr dopant in their geometric and electronic structure, reducibility and catalytic behavior concerning the Water-gas Shift reaction (WGSR). Samples with nominal Pr dopant content of 0, 5, 15 and 50 at% (atomic percentage) are synthesized via urea decomposition method and subsequent calcination in air at 450 °C. X-ray diffraction characterization shows an increase of ceria lattice parameter for Pr loadings lower than 15 at%, which is consistent with a solid solution formation. X-ray photoelectron spectra indicate a surface enrichment in Pr cations and a diminution of Ce3+ surface concentration as Pr content increases. DFT calculations confirm the preferential reduction of Pr cations due to a single oxygen vacancy formation in Ce-Pr mixed oxides, and also a significant decrease in the energy needed for this O removal compare to that in pure CeO2. Both experimental measurements and DFT calculations evidence that the addition of Pr dopant to ceria promotes oxygen vacancies formation, redox properties and oxygen storage capacity (OSC). Even more, the same promoting effect of Pr in the WGSR intrinsic catalytic activity of Ce-Pr mixed oxides is observed.

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Keywords
Ce-Pr mixed oxides; DFT calculations; Oxygen storage capacity; Water-gas Shift reaction
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Ce-Pr mixed oxides as active supports for Water-gas Shift reaction: Experimental and density functional theory characterization
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 485, 5 September 2014, Pages 123–132
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
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Price after discount Only $4.95
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Full-text PDF Download
Online Support
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