The adsorption of CO on Ir(111) investigated with FT-IRAS

Lauterbach, Jochen A.; Boyle, R W; Schick, Matthias; Mitchell, William J.; Meng, B.; Weinberg, W. H.

doi:10.1016/0039-6028(95)01114-5

“…Several authors [5][6][7] found, that CO desorbs between 400 K and 600 K, and that the CO saturation coverage at room temperature equals 7/12 ML. This value was used to normalize the C 1s signal.…”

Section: Introductionmentioning

confidence: 98%

Benzene adsorption and oxidation on Ir(111)

Weststrate

¹

,

Bakker

²

,

Gluhoi

³

et al. 2007

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“…H 2 and CO desorb from Ir (111) at 380 K (0.5-L exposure) and 510 K (1-L exposure), respectively. [12,13] CO adsorption enthalpies (150 kJ mol À1 ) would lead to CO coverages below 0.1 % at 873 K, even at equilibrium CH 4 conversions (for equimolar CH 4 -CO 2 reactants, 100 kPa); thus, no inhibition by chemisorbed CO is expected or, indeed, detected.…”

mentioning

confidence: 93%

“…The fast and quasi-equilibrated nature of co-reactant activation was dem- Communications onstrated by the identical 13 C content in the CO and CO 2 leaving a catalyst bed used to react CO 2 /CH 4 / 13 CO (1:1:0.4) mixtures. [14] The uncovered nature of Ir surfaces and the persistence and catalytic relevance of Ir dispersions measured before reaction were confirmed by measuring rates of CO oxidation, a structure-insensitive reaction, [15] before and after re-forming reactions.…”

mentioning

confidence: 99%

Structural and Mechanistic Requirements for Methane Activation and Chemical Conversion on Supported Iridium Clusters

Jin

¹

,

Iglesia

²

2004

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Chemical conversion of CH 4 into larger molecules is practiced by initially forming H 2 -CO mixtures over metal catalysts. These reactions use CO 2 or H 2 O as co-reactants in processes which also produce H 2 , that is then used in refining and petrochemical processes and in fuel cells. The strong bonds in CH 4 (439 kJ mol) and the endothermic nature of reforming reactions call for high temperatures and stable catalysts.[2-4] Supported Ir clusters catalyze CO 2 -CH 4 reactions without detectable carbon formation, [5][6][7] with turnover rates higher than those found with other Group VIII metals, except Pt. [2] Experimental and theoretical studies on model surfaces [8,9] have suggested that CÀH bond activation is sensitive to surface structure and requires coordinatively unsaturated sites. [10,11] The effects of cluster size and of concomitant changes in surface coordination on re-forming turnover rates remain unexplored for Ir catalysts. Contradictory conclusions about the kinetic relevance of CÀH activation steps within catalytic sequences remain, and catalytic supports have often been claimed to be required for the activation of CO 2 or H 2 O co-reactants. [6,7]

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“…The fast and quasi-equilibrated nature of co-reactant activation was dem- Zuschriften onstrated by the identical 13 C content in the CO and CO 2 leaving a catalyst bed used to react CO 2 /CH 4 / 13 CO (1:1:0.4) mixtures. [14] The uncovered nature of Ir surfaces and the persistence and catalytic relevance of Ir dispersions measured before reaction were confirmed by measuring rates of CO oxidation, a structure-insensitive reaction, [15] before and after re-forming reactions.…”

mentioning

confidence: 99%

Structural and Mechanistic Requirements for Methane Activation and Chemical Conversion on Supported Iridium Clusters

Jin¹,

Iglesia²

2004

View full text Add to dashboard Cite

Chemical conversion of CH 4 into larger molecules is practiced by initially forming H 2 -CO mixtures over metal catalysts. These reactions use CO 2 or H 2 O as co-reactants in processes which also produce H 2 , that is then used in refining and petrochemical processes and in fuel cells. The strong bonds in CH 4 (439 kJ mol) and the endothermic nature of reforming reactions call for high temperatures and stable catalysts.[2-4] Supported Ir clusters catalyze CO 2 -CH 4 reactions without detectable carbon formation, [5][6][7] with turnover rates higher than those found with other Group VIII metals, except Pt. [2] Experimental and theoretical studies on model surfaces [8,9] have suggested that CÀH bond activation is sensitive to surface structure and requires coordinatively unsaturated sites. [10,11] The effects of cluster size and of concomitant changes in surface coordination on re-forming turnover rates remain unexplored for Ir catalysts. Contradictory conclusions about the kinetic relevance of CÀH activation steps within catalytic sequences remain, and catalytic supports have often been claimed to be required for the activation of CO 2 or H 2 O co-reactants. [6,7]

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The adsorption of CO on Ir(111) investigated with FT-IRAS

Cited by 87 publications

References 41 publications

Benzene adsorption and oxidation on Ir(111)

Benzene adsorption and oxidation on Ir(111)

Structural and Mechanistic Requirements for Methane Activation and Chemical Conversion on Supported Iridium Clusters

Structural and Mechanistic Requirements for Methane Activation and Chemical Conversion on Supported Iridium Clusters

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