Catalytic methanation over single crystal nickel and ruthenium: Reaction kinetics on different crystal planes and the correlation of surface carbide concentration with reaction rate

Kelley, R. D.; Goodman, D. W.

doi:10.1016/0039-6028(82)90319-3

Cited by 110 publications

(54 citation statements)

References 10 publications

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“…The apparent activation energy for the global experiments of the methanation reaction found using the global signal to be 0.83 AE 0.02 eV is lower than the 1.2 eV found by Kelley and Goodman on Ru(110) and Ru(001). 5 This can be rationalized by their higher CO-to-hydrogen ratio, causing more CO to be present which can block reaction sites, and thus increase the apparent activation energy.…”

Section: Discussionmentioning

confidence: 99%

Is the methanation reaction over Ru single crystals structure dependent?

Vendelbo

Johansson

Nielsen

et al. 2011

Phys. Chem. Chem. Phys.

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The influence of monoatomic steps and defects on the methanation reaction over ruthenium has been investigated. The experiments are performed on a Ru(0 1 54) ruthenium single crystal, which contains one monoatomic step atom for each 27 terrace atoms. The methanation activity is measured at one bar of hydrogen and CO in a high pressure cell, which enables simultaneous measurements of the local reactivity of the well defined single crystal surface and the global reactivity of the entire crystal and its auxiliary support. By adding sulfur we observe that the measured activity from the well defined stepped front-side of the crystal is poisoned faster than the entire crystal containing more defects. We also observe that additional sputtering of the well-defined front-side increases the reactivity measured on the surface. Based on this, we conclude that the methanation reaction takes place on undercoordinated sites, such as steps and kinks, and that the methanation reaction is extremely structure dependent. Simulations of the flow, temperature, and product distributions in the high pressure cell are furthermore presented as supplementary information.

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Section: Discussionmentioning

confidence: 99%

Is the methanation reaction over Ru single crystals structure dependent?

Vendelbo

Johansson

Nielsen

et al. 2011

Phys. Chem. Chem. Phys.

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“…Another situation is encountered if the reactants or reactant intermediates form active sites on the surface that completely differ from the catalyst surface, which leads to an autocatalytic mechanism. For example, an active carbonaceous species, carbidic C, was observed to increase the methane formation from synthesis gas (CO+H 2 ) over single-crystal Ni(100) model catalysts [132,133]. Despite these problems, the "single-crystal approach" is the first step for gaining insight into the atomic-scale mechanism of heterogeneous catalytic reactions.…”

Section: Microkinetic Modeling Of Surface Reactionsmentioning

confidence: 99%

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Weiß

Ranke

2002

Progress in Surface Science

584

610

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Metal-oxide based catalysts are used for many important synthesis reactions in the chemical industry. A better understanding of the catalyst operation can be achieved by studying elemantary reaction steps on well-defined model catalyst systems. For the dehydrogenation of ethylbenzene to styrene in the presence of steam both unpromoted and potassium promoted iron-oxide catalysts are active. Here we review the work done over unpromoted single-crystalline FeO(111), Fe 3 O 4 (111) and α-Fe 2 O 3 (0001) films grown epitaxially on Pt(111) substrates. Their geometric and electronic surface structures were characterized by STM, LEED, electron microscopy and electron spectroscopic techniques. In an integrative approach, the interaction of water, ethylbenzene and styrene with these films was investigated mainly by thermal desorption and photoelectron emission spectroscopy. The adsorptiondesorption energetics and kinetics depend on the oxide surface terminations and are correlated to the electronic structures and acid-base properties of the corresponding oxide phases, which reveal insight into the nature of the active sites and into the catalytic function of semiconducting oxides in general. Catalytic studies, using a batch reactor arrangement at high gas pressures and post reaction surface analysis, showed that only α-Fe 2 O 3 (0001) containing surface defects is catalytically active, whereas Fe 3 O 4 (111) is always inactive. This can be related to the elementary adsorption and desorption properties observed in ultrahigh vacuum, which indicates that the surface chemical properties of the iron-oxide films do not change significantly across the "pressure-gap". A model is proposed according to which the active site involves a regular acidic surface sites and a defect site next to it. The results on metal-oxide surface chemistry also have implications for other fields, such as environmental science, biophysics and chemical sensors.-2 -"2kyEi9FYSQjBVrZxIPQ.FHIAC_WRa02_review.doc", Datum: 19.02.03

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“…CO hydrogenation is reported to be structure insensitive on Ni, Ru, 17 and Mo ͑Ref. 18͒ surfaces and similar claims has been made concerning Rh and Fe surfaces.…”

Section: G Structure Sensitivitymentioning

confidence: 50%

Monte Carlo study of CO hydrogenation on cobalt model catalysts

Hovi

Lahtinen

Liu

et al. 1995

The Journal of Chemical Physics

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Useful information on catalytic reactions can be achieved using Monte Carlo simulations combined with experimental data from model catalysts. We present a comprehensive analysis of the simulation studies of CO hydrogenation on a hexagonal surface using a discrete computer model for the irreversible reaction kinetics with no interactions between the surface species but their mutual reactions. The simulation results are compared to experimental data from a cobalt foil model catalyst at 101 kPa and 525 K. As a result, the following microscopic picture of the reaction on the catalyst surface is extracted: the rate-limiting reaction step is the termination of the carbon chains (α-hydrogenation), hydrogen atoms occupy different adsorption sites from other reactants, and the diffusion of hydrogen along the surface is fast. The model is also used to address the relevance of the ensemble effects for CO dissociation and the surface sensitivity of the CO hydrogenation reaction. Our simulation results imply that these aspects have little effect on the rates of hydrocarbon formation.

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Catalytic methanation over single crystal nickel and ruthenium: Reaction kinetics on different crystal planes and the correlation of surface carbide concentration with reaction rate

Cited by 110 publications

References 10 publications

Is the methanation reaction over Ru single crystals structure dependent?

Is the methanation reaction over Ru single crystals structure dependent?

Surface chemistry and catalysis on well-defined epitaxial iron-oxide layers

Monte Carlo study of CO hydrogenation on cobalt model catalysts

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