Reaction of CH4 with CO2 and H2O over supported Ir catalyst

Erdöhelyi, András; Fodor, K.; Solymosi, F.

doi:10.1016/s0167-2991(97)80385-0

Cited by 34 publications

(16 citation statements)

References 15 publications

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“…[25] We measured similar turnover rates on Ir/Al 2 O 3 and Ir/ZrO 2 ( Figure 3), as also found for other metals with a wider range of supports. [2,16,17] Co-reactant activation on supports, even if it occurred, could not influence CH 4 turnover rates, because such steps are not kinetically relevant.…”

supporting

confidence: 84%

“…[2,16,17] Co-reactant activation on supports, even if it occurred, could not influence CH 4 turnover rates, because such steps are not kinetically relevant. Thus, previously reported support effects [25] cannot be compared with our data or with our mechanistic conclusions. The absence of support effects agrees with a previous study of reforming reactions catalyzed by Ir, [26] whose kinetic character is, however, equivocal, because of near-equilibrium conversions.…”

contrasting

confidence: 60%

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

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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supporting

confidence: 84%

contrasting

confidence: 60%

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

2004

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“…Bradford and Vannice have recently reviewed proposed mechanisms for both dry and steam reforming of methane over supported metal catalysts [5]. Significantly more complex partial pressure dependencies during dry reforming have been reported by Bradford and Vannice [41] on supported Pt catalysts and by Solymosi and co-workers [45] on supported Ir catalysts. Differences in observed partial pressure dependencies led to the proposal that adsorbed CH x combine with O* species to form CH x O fragments which eventually decompose to CO* and xH*.…”

Section: Resultsmentioning

confidence: 89%

Oxidation and reforming reactions of CH4 on a stepped Pt(557) single crystal

et al. 2007

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“…The last two reactions are, also, responsible for coke formation during reaction. It is well known that supported metals of groups 8, 9 and 10 are good catalysts for the dry reforming of methane (reaction (1)) [2][3][4][5][6][7][8][9][10]. Among those metals, Ni is specially interesting for industrial application due, mainly, to its lower cost and higher availability.…”

Section: Introductionmentioning

confidence: 99%

“…Among those metals, Ni is specially interesting for industrial application due, mainly, to its lower cost and higher availability. Thus, Ni based catalysts are under investigation in order to improve both their activity and, particularly, their selectivity with the objective of avoiding www.elsevier.com/locate/apcata Applied Catalysis A: General 301 (2006) [9][10][11][12][13][14][15] or, at least hindering, coke formation. As variables of such investigation, the following are attracting most of the attention: the nature of the support [11][12][13][14][15][16][17], the preparation method [13,[18][19][20][21] and the addition of promoters [12,19,[22][23][24][25][26][27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%