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Preferential CO oxidation in excess of hydrogen over Au/HMS catalysts modified by Ce, Fe and Ti oxides

Paper ID Volume ID Publish Year Pages File Format Full-Text
47027 46456 2010 13 PDF Available
Title
Preferential CO oxidation in excess of hydrogen over Au/HMS catalysts modified by Ce, Fe and Ti oxides
Abstract

The effect of the modification of HMS (hexagonal mesoporous silica) support with Fe3+, Ce4+ or Ti4+ ions on the physico-chemical and catalytic properties of mesoporous Au/HMS catalyst was evaluated in the preferential oxidation (PROX) of CO, in hydrogen-rich stream (50 vol.% H2) and in the total CO oxidation (TOX) reaction. The bare supports were prepared via neutral S0I0 templating route, employing one pot synthesis, whereas the supported gold catalysts were prepared by the deposition–precipitation method. The reduced and spent Au catalysts have been studied by different techniques such as N2 physisorption, oxygen storage capacity (OSC), XRD, HRTEM, hydrogen chemisorption (by TPD-H2), DRS UV–vis, Mössbauer and XPS spectroscopic techniques. Among the catalysts studied, Au/HMS–Fe recorded the highest activity and stability for total CO oxidation. The XPS and DRS UV–vis data suggest that the active-sites configuration of this catalyst during this reaction could be small gold particles and ionic gold species stabilized by the support. The Au/HMS–Fe catalyst was also able to oxidize CO selectively in a hydrogen-rich gas mixture (PROX reaction) at a relevant temperature to hydrogen fuel cell applications (T50 = 83 °C). Additionally, the Au/HMS–Fe sample recorded the lowest hydrogen oxidation (undesired reaction) during the CO-PROX reaction in excess hydrogen. From the catalyst activity–structure correlation, the main factors influencing the superior catalytic behaviour of this sample in the CO-PROX reaction are (i) its largest Au species surface exposure, as determined by XPS for the spent catalysts; (ii) the largest population of small Au particles, as determined by HRTEM for the freshly reduced samples; (iii) the large oxygen and hydrogen storage capacities, and (iv) the lowest deactivation by the formation of surface coke species, as determined by coke burning followed by TGA technique.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Catalytic performance of mesoporous Au catalysts in the CO conversion. ▶ Effect of HMS modification support with Fe3+, Ce4+ or Ti4+ ions. ▶ High performance in both PROX and CO oxidation over Fe-containing sample. ▶ Effect of support on the stabilization of small gold particles and ionic gold species.

Keywords
CO oxidation; CO preferential oxidation; Mesoporous silica; HMS–Ce; HMS–Fe; HMS–Ti; Au catalysts
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Preferential CO oxidation in excess of hydrogen over Au/HMS catalysts modified by Ce, Fe and Ti oxides
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 100, Issues 3–4, 20 October 2010, Pages 450–462
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