Methane activation on Ni(111): Effects of poisons and step defects

Abild‐Pedersen, Frank; Lytken, Ole; Engbæk, Jakob; Nielsen, Gunver; Chorkendorff, Ib; Nørskov, Jens K.

doi:10.1016/j.susc.2005.05.057

Cited by 231 publications

(198 citation statements)

References 39 publications

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“…6,40 Our results suggest that modifying the nickel step-sites could provide a way to control graphene formation. Additives, such as atomic sulfur, carbon, Ag and Au, all show a preference for adsorption at the steps on Ni͑111͒, 16,25,27,41 and it has been demonstrated that such additives will decrease the reactivity of methane reforming and at the same time block formation of graphitic structures at the steps.…”

Section: Discussionmentioning

confidence: 99%

“…16,25,26 For methane, the activation of the first C-H bond is rate-limiting for the decomposition and it is associated with an activation energy barrier, obtained from DFT, of less than 1 eV at the undercoordinated step sites on Ni. 16,27 The decomposition barrier is less than the barriers we identify for graphene growth, and methane decomposition will, therefore, not be considered further in the following.…”

Section: A Energetics Of Carbon Adsorptionmentioning

confidence: 99%

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Mechanisms for catalytic carbon nanofiber growth studied byab initiodensity functional theory calculations

et al. 2006

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Mechanisms and energetics of graphene growth catalyzed by nickel nanoclusters were studied using ab initio density functional theory calculations. It is demonstrated that nickel step-edge sites act as the preferential growth centers for graphene layers on the nickel surface. Carbon is transported from the deposition site at the free nickel surface to the perimeter of the growing graphene layer via surface or subsurface diffusion. Three different processes are identified to govern the growth of graphene layers, depending on the termination of the graphene perimeter at the nickel surface, and it is argued how these processes may lead to different nanofiber structures. The proposed growth model is found to be in good agreement with previous findings.

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Section: Discussionmentioning

confidence: 99%

Section: A Energetics Of Carbon Adsorptionmentioning

confidence: 99%

Mechanisms for catalytic carbon nanofiber growth studied byab initiodensity functional theory calculations

et al. 2006

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“…For NiAl(110) it is noticable that CO is most stable on the Ni-rich surface. The reason for this is, that Ni in the topmost layer is stretched relative to a bulk Ni lattice constant resulting in a stronger binding [52,53,54]. In all cases, Ni adsorbs in a three-fold hollow site, except for the NiAl(110) bulk terminated surface, on which it adsorbs atop.…”

Section: Adsorption Of Comentioning

confidence: 98%

First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

et al. 2011

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We investigate the structure and surface composition of the -Ni 3 Al(111) and -NiAl(110) alloy surfaces at conditions relevant for metal dusting corrosion related to catalytic steam reforming of natural gas. In regular service as protective coatings, nickel-aluminum alloys are protected by an oxide scale, but in case of oxide scale spallation, the alloy surface may be directly exposed to the reactive gas environment and vulnerable to metal dusting. By means of density functional theory and thermochemical calculations for both the Ni 3 Al and NiAl surfaces, the conditions under which C O and O H adsorption is to be expected and under which it is inhibited, are mapped out. Because C O and O H are regarded as precursors for nucleating graphite or oxide on the surfaces, phase diagrams for the surfaces provide a simple description of their stability. Specifically, this study shows how the C O and O H coverages depend on the steam to carbon ratio (S/C) in the gas and thereby provide a ranking of the carbon limits on the different surface phases.

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“…While the closed packed and defect free Ni(111) surface is rather resistant with respect to carbon formation [30], steps, e.g. at Ni(211), are nucleation sites for carbon growth causing catalyst deactivation [32]. The calculations of Wang et al [30] show that surface O and H atoms remove carbon deposits efficiently.…”

Section: Dry Reformingmentioning

confidence: 99%

Methane Activation by Heterogeneous Catalysis

2014

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Methane activation by heterogeneous catalysis will play a key role to secure the supply of energy, chemicals and fuels in the future. Methane is the main constituent of natural gas and biogas and it is also found in crystalline hydrates at the continental slopes of many oceans and in permafrost areas. In view of this vast reserves and resources, the use of methane as chemical feedstock has to be intensified. The present review presents recent results and developments in heterogeneous catalytic methane conversion to synthesis gas, hydrogen cyanide, ethylene, methanol, formaldehyde, methyl chloride, methyl bromide and aromatics. After presenting recent estimates of methane reserves and resources the physico-chemical challenges of methane activation are discussed. Subsequent to this recent results in methane conversion to synthesis gas by steam reforming, dry reforming, autothermal reforming and catalytic partial oxidation are presented. The high temperature methane conversion to hydrogen cyanide via the BMA-process and the Andrussow-process is considered as well. The second part of this review focuses on one-step conversion of methane into chemicals. This includes the oxidative coupling of methane to ethylene mediated by oxygen and sulfur, the direct oxidation of methane to formaldehyde and methanol, the halogenation and oxyhalogenation of methane to methyl chloride and methyl bromide and finally the non-oxidative methane aromatization to benzene and related aromates. Opportunities and limits of the various activation strategies are discussed.

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Methane activation on Ni(111): Effects of poisons and step defects

Cited by 231 publications

References 39 publications

Mechanisms for catalytic carbon nanofiber growth studied byab initiodensity functional theory calculations

Mechanisms for catalytic carbon nanofiber growth studied byab initiodensity functional theory calculations

First-principles investigations of Ni3Al(111) and NiAl(110) surfaces at metal dusting conditions

Methane Activation by Heterogeneous Catalysis

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