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Density functional theory study of sulfur tolerance of CO adsorption and dissociation on Rh–Ni binary metals

Paper ID Volume ID Publish Year Pages File Format Full-Text
41888 45903 2010 9 PDF Available
Title
Density functional theory study of sulfur tolerance of CO adsorption and dissociation on Rh–Ni binary metals
Abstract

The effect of Ni addition to improve the sulfur tolerance of a Rh catalyst for CO dissociation was studied using density functional theory (DFT) methods. Adsorption and dissociation were considered over the (1 1 1) surfaces of binary Rh1Ni2 and Rh2Ni1 metals with comparison to pure Rh and Ni surfaces. Sulfur adsorption on the Rh1Ni2(1 1 1) surface is 0.21 eV more endothermic than on the Rh(1 1 1) surface, suggesting that a Rh1Ni2 bimetallic catalyst has a higher sulfur tolerance than pure Rh catalysts due to a lower surface coverage of the sulfur poison. To compare catalytic activity in the presence of adsorbed sulfur, the CO dissociation rates over the binary and pure metals were calculated with 1/9 sulfur coverage. CO dissociation is fastest on the pure Rh surface under sulfur-free conditions, whereas among sulfur poisoned surfaces, the Rh1Ni2 surface shows the fastest CO dissociation rate. The CO dissociation barrier on Rh1Ni2 is destabilized less by a S coadsorbate than for the other metals. The addition of Ni atoms to a Rh catalyst improves the sulfur tolerance of the catalyst for CO dissociation by minimizing the repulsion between the adsorbed S atom and the CO dissociation transition state, as evidenced through a projected density of states analysis. The Rh1Ni2(2 2 1) stepped surface also shows a lower activation barrier and higher CO dissociation rate in the presence of sulfur than the Rh(2 2 1) stepped surface.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (75 K)Download as PowerPoint slideResearch highlights▶ Rh–Ni metals are more tolerant to S poisoning during reforming reactions. ▶ The adsorption of S is weakened on Rh–Ni surfaces in comparison to pure Rh surfaces. ▶ CO dissociation with S is faster on Rh–Ni surface than on pure metal surfaces.

Keywords
CO dissociation; Rh–Ni binary metals; Reforming; Methanation; Density functional theory; Sulfur poisoning
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Density functional theory study of sulfur tolerance of CO adsorption and dissociation on Rh–Ni binary metals
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 389, Issues 1–2, 1 December 2010, Pages 122–130
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