Activation of Methane by Gaseous Metal Ions

Schröder, Detlef

doi:10.1002/anie.200906518

Cited by 34 publications

(9 citation statements)

References 44 publications

(16 reference statements)

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“…[1][2][3] Gas phase ion reactivity combined with quantum chemical calculations provides the ability to study the mechanistic underpinnings of catalyzing this activation free from the complications inherent to bulk or solution phases. [4][5][6][7][8] The observation of methane activation by MgO + is of particular note, 9 as prior studies had focused on transition metals, such as the well performing but expensive palladium-based catalysts. 10 Detailed understanding of methane activation by main group metal oxide species such as MgO + presents the potential to develop cost effective catalysts for large scale utilization of this important chemical feedstock.…”

Section: Introductionmentioning

confidence: 99%

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Sweeny

Pan

Kassem

et al. 2020

Phys. Chem. Chem. Phys.

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The kinetics of MgO + + CH 4 was studied experimentally using the variable ion source, temperature adjustable selected ion flow tube (VISTA-SIFT) apparatus from 300 − 600 K and computationally by running and analyzing reactive atomistic simulations. Rate coefficients and product branching fractions were determined as a function of temperature. The reaction proceeded with a rate of k = 5.9 ± 1.5 × 10 −10 (T /300 K) −0.5±0.2 cm 3 s −1 . MgOH + was the dominant product at all temperatures, but Mg + , the co-product of oxygen-atom transfer to form methanol, was observed with a product branching fraction of 0.08 ± 0.03(T /300 K) −0.8±0.7 . Reactive molecular dynamics simulations using a reactive force field, as well as a neural network trained on thousands of structures yield rate coefficients about one order of magnitude lower.This underestimation of the rates is traced back to the multireference character of the transition state [MgOCH 4 ] + . Statistical modeling of the temperature-dependent kinetics provides further insight into the reactive potential surface. The rate limiting step was found to be consistent with a four-centered activation of the C-H bond, consistent with previous calculations. The product branching was modeled as a competition between dissociation of an insertion intermediate directly after the ratelimiting transition state, and traversing a transition state corresponding to a methyl migration leading to a Mg-CH 3 OH + complex, though only if this transition state is stabilized significantly relative to the dissociated MgOH + + CH 3 product channel.An alternative non-statistical mechanism is discussed, whereby a post-transition state bifurcation in the potential surface could allow the reaction to proceed directly from the four-centered TS to the Mg-CH 3 OH + complex thereby allowing a more robust competition between the product channels. a) rvborgmailbox@us.af.mil b) m.meuwly@unibas.ch

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Section: Introductionmentioning

confidence: 99%

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Sweeny

Pan

Kassem

et al. 2020

Phys. Chem. Chem. Phys.

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“…In contemporary chemistry, although tremendous efforts have been devoted to elucidate the complex nature of active sites and mechanistic aspects to develop highly active catalysts, many chemical reactions remain to be mastered. For instance, the transformation of nonactivated hydrocarbons into value-added products under ambient conditions is still a challenging task by now, − in which C–H bond activation is the crucial step. ,− In addition to the vast amount of literature on condensed-phase studies of transition metal oxide catalysts, reports on transition metal nitrides (TMNs) show that they are another interesting class of heterogeneous catalysts. − Notably, molybdenum nitride , and other nitrides have been demonstrated to have superior catalytic properties in a number of chemical reactions, including dehydrogenation, ammonia decomposition, and so on. This kind of catalyst is also known as one of the promising replacements of costly noble metals (NMs), because their activities resemble those of NMs.…”

Section: Introductionmentioning

confidence: 99%

Origin of the Different Reactivity of the Triatomic Anions HMoN^– and ZrNH^– toward Alkane: Compositions of the Active Orbitals

Hou

et al. 2016

J. Phys. Chem. A

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The reactivity of the triatomic anions HMoN and ZrNH toward alkanes was investigated by means of mass spectrometry in conjunction with density functional theory calculations. HMoN can activate C-H bond of ethane with the liberation of ethene and hydrogen molecules, and the generation of hydrogen molecules is the major reaction channel; however, no C-H bond activation of ethane was observed over ZrNH ion, and the density functional theory calculations suggest this pathway is hampered by intrinsic energy barrier. In sharp contrast, another triatomic anion HNbN can bring about methane activation under thermal conditions, as reported previously. A strong dependence of the chemical reactivity of alkane activation on compositions of active orbitals in the above-mentioned systems is discussed. This combined experimental/computational study may provide new insights into the importance of compositions of active orbitals and their essential role in the reactions of related systems with alkanes.

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“…Gas-phase studies of well-defined atomic clusters under isolated, controlled, and reproducible conditions provide one useful method to uncover the mechanistic details of elementary reactions in related single-atom catalysis. − The reactivity of various bare single noble-metal species such as Rh +/o/ , − Pt ± , − and so on, ,− and ligated single noble-metal ions ,− toward methane has been widely studied. To have a better understanding of the molecular level mechanisms and the role of single noble-metal atoms in methane conversion over realistic catalysts, it is quite necessary to study the reactions between methane and the composite systems with both the single noble-metal atoms and the oxide clusters support.…”

Section: Introductionmentioning

confidence: 99%

Selective Conversion of Methane by Rh₁-Doped Aluminum Oxide Cluster Anions RhAl₂O₄^–: A Comparison with the Reactivity of PtAl₂O₄^–

Zhao

2018

J. Phys. Chem. A

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Studying the elementary reactions of single-noble-metal-atom-doped species can give theoretical guidance for the design of related single-atom catalysis. Using a combination of mass spectrometry and density functional theory calculations, the reaction of RhAlO with the most stable alkane molecule CH under thermal conditions has been studied. The methane tends to be converted into syngas (free H and adsorbed CO) with activation of four C-H bonds. In sharp contrast, formaldehyde was generated in the previously reported reaction of PtAlO with CH. Density functional theory calculations show that the difference in reactivity between RhAlO and PtAlO is found to be due to a higher energy barrier of the third C-H bond activation for the Pt analogue. This work provides the first comparative study on the reactivity of single noble-metal atoms (Rh, Pt) on the same cluster support (AlO) and can be helpful for rational design of single-atom catalysts for selective methane conversion.

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Activation of Methane by Gaseous Metal Ions

Cited by 34 publications

References 44 publications

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Origin of the Different Reactivity of the Triatomic Anions HMoN^– and ZrNH^– toward Alkane: Compositions of the Active Orbitals

Selective Conversion of Methane by Rh₁-Doped Aluminum Oxide Cluster Anions RhAl₂O₄^–: A Comparison with the Reactivity of PtAl₂O₄^–

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Activation of Methane by Gaseous Metal Ions

Cited by 34 publications

References 44 publications

Thermal activation of methane by MgO+: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Thermal activation of methane by MgO+: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Origin of the Different Reactivity of the Triatomic Anions HMoN– and ZrNH– toward Alkane: Compositions of the Active Orbitals

Selective Conversion of Methane by Rh1-Doped Aluminum Oxide Cluster Anions RhAl2O4–: A Comparison with the Reactivity of PtAl2O4–

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Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Thermal activation of methane by MgO⁺: temperature dependent kinetics, reactive molecular dynamics simulations and statistical modeling

Origin of the Different Reactivity of the Triatomic Anions HMoN^– and ZrNH^– toward Alkane: Compositions of the Active Orbitals

Selective Conversion of Methane by Rh₁-Doped Aluminum Oxide Cluster Anions RhAl₂O₄^–: A Comparison with the Reactivity of PtAl₂O₄^–