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Mechanistic aspects of the selective methanation of CO over Ru/TiO2 catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
55451 47053 2012 10 PDF Available
Title
Mechanistic aspects of the selective methanation of CO over Ru/TiO2 catalyst
Abstract

The mechanism of selective methanation of CO/CO2 over 5%Ru/TiO2 catalyst is investigated employing in situ FTIR spectroscopy (DRIFTS) and transient mass spectrometry techniques. It is shown that interaction of the prereduced catalyst with the reaction mixtures results in the development of various Ru-bonded carbonyl species on reduced and partially oxidized sites as well as on sites located at the metal-support interface. The nature and population of these species depend strongly on feed composition and reaction temperature. Results of the present study confirm our previous suggestion that the mechanism of CO methanation includes both dissociative and associative reaction pathways. The former, which dominates at lower reaction temperatures, involves hydrogenation of surface carbon produced by dissociative adsorption of CO, whereas the latter involves hydrogenation of CO species adsorbed at the metal-support interface. At low temperatures, typically <250 °C, dissociation of CO results in accumulation of adsorbed oxygen species which cannot be removed from the catalyst surface, rendering it inactive. Catalytic activity is restored at higher temperatures, where partially oxidized sites are reduced efficiently by adsorbed hydrogen atoms. The associative reaction pathway is the only one which is operable under conditions of CO2 methanation and proceeds via intermediate formation of carbonyl species at the metal-support interface, produced by the RWGS reaction. Selective methanation of CO in CO/CO2 mixtures occurs efficiently under conditions where the dissociative reaction pathway is operable and the associative reaction pathway is completely suppressed.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (98 K)Download as PowerPoint slideHighlights► Ruthenium is a highly selective catalyst for CO methanation in presence of CO2. ► CO methanation occurs via two roots, a dissociative one and an associative one. ► The associative pathway is the only one operable under conditions of CO2 methanation.

Keywords
Ruthenium; TiO2; Selective methanation; Carbon monoxide; Carbon dioxide; Hydrogen; FTIR; Transient-MS
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Mechanistic aspects of the selective methanation of CO over Ru/TiO2 catalyst
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 181, Issue 1, 12 February 2012, Pages 138–147
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
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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Any Questions? feel free to contact us