Methane-to-methanol conversion by first-row transition-metal oxide ions: ScO+, TiO+, VO+, CrO+, MnO+, FeO+, CoO+, NiO+, and CuO+

研究成果: ジャーナルへの寄稿記事

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The reaction pathway and energetics for methane-to-methanol conversion by first-row transition-metal oxide ions (MO+s) are discussed from density functional theory (DFT) B3LYP calculations, where M is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The methane-to-methanol conversion by these MO+ complexes is proposed to proceed in a two-step manner via two transition states: MO+ + CH4 → OM+(CH4) → [TS] → OH-M+-CH3 → [TS] → M+(CH3OH) → M+ + CH3OH. Both high-spin and low-spin potential energy surfaces are characterized in detail. A crossing between the high-spin and the low-spin potential energy surfaces occurs once near the exit channel for ScO+, TiO+, VO+, CrO+, and MnO+, but it occurs twice in the entrance and exit channels for FeO+, CoO+, and NiO+. Our calculations strongly suggest that spin inversion can occur near a crossing region of potential energy surfaces and that it can play a significant role in decreasing the barrier heights of these transition states. The reaction pathway from methane to methanol is uphill in energy on the early MO+ complexes (ScO+, TiO+, and VO+); thus, these complexes are not good mediators for the formation of methanol. On the other hand, the late MO+ complexes (FeO+, NiO+, and CuO+) are expected from the general energy profiles of the reaction pathways to efficiently convert methane to methanol. Measured reaction efficiencies and methanol branching ratios for MnO+, FeO+, CoO+, and NiO+ are rationalized from the energetics of the high-spin and the low-spin potential energy surfaces. The energy diagram for the methane-to-methanol conversion by CuO+ is downhill toward the product direction, and thus CuO+ is likely to be an excellent mediator for methane hydroxylation.

元の言語英語
ページ(範囲)12317-12326
ページ数10
ジャーナルJournal of the American Chemical Society
122
発行部数49
DOI
出版物ステータス出版済み - 12 13 2000
外部発表Yes

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Methane
Oxides
Transition metals
Methanol
Metals
Potential energy surfaces
Ions
Hydroxylation
Density functional theory

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

これを引用

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title = "Methane-to-methanol conversion by first-row transition-metal oxide ions: ScO+, TiO+, VO+, CrO+, MnO+, FeO+, CoO+, NiO+, and CuO+",
abstract = "The reaction pathway and energetics for methane-to-methanol conversion by first-row transition-metal oxide ions (MO+s) are discussed from density functional theory (DFT) B3LYP calculations, where M is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The methane-to-methanol conversion by these MO+ complexes is proposed to proceed in a two-step manner via two transition states: MO+ + CH4 → OM+(CH4) → [TS] → OH-M+-CH3 → [TS] → M+(CH3OH) → M+ + CH3OH. Both high-spin and low-spin potential energy surfaces are characterized in detail. A crossing between the high-spin and the low-spin potential energy surfaces occurs once near the exit channel for ScO+, TiO+, VO+, CrO+, and MnO+, but it occurs twice in the entrance and exit channels for FeO+, CoO+, and NiO+. Our calculations strongly suggest that spin inversion can occur near a crossing region of potential energy surfaces and that it can play a significant role in decreasing the barrier heights of these transition states. The reaction pathway from methane to methanol is uphill in energy on the early MO+ complexes (ScO+, TiO+, and VO+); thus, these complexes are not good mediators for the formation of methanol. On the other hand, the late MO+ complexes (FeO+, NiO+, and CuO+) are expected from the general energy profiles of the reaction pathways to efficiently convert methane to methanol. Measured reaction efficiencies and methanol branching ratios for MnO+, FeO+, CoO+, and NiO+ are rationalized from the energetics of the high-spin and the low-spin potential energy surfaces. The energy diagram for the methane-to-methanol conversion by CuO+ is downhill toward the product direction, and thus CuO+ is likely to be an excellent mediator for methane hydroxylation.",
author = "Y. Shiota and K. Yoshizawa",
year = "2000",
month = "12",
day = "13",
doi = "10.1021/ja0017965",
language = "English",
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T1 - Methane-to-methanol conversion by first-row transition-metal oxide ions

T2 - ScO+, TiO+, VO+, CrO+, MnO+, FeO+, CoO+, NiO+, and CuO+

AU - Shiota, Y.

AU - Yoshizawa, K.

PY - 2000/12/13

Y1 - 2000/12/13

N2 - The reaction pathway and energetics for methane-to-methanol conversion by first-row transition-metal oxide ions (MO+s) are discussed from density functional theory (DFT) B3LYP calculations, where M is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The methane-to-methanol conversion by these MO+ complexes is proposed to proceed in a two-step manner via two transition states: MO+ + CH4 → OM+(CH4) → [TS] → OH-M+-CH3 → [TS] → M+(CH3OH) → M+ + CH3OH. Both high-spin and low-spin potential energy surfaces are characterized in detail. A crossing between the high-spin and the low-spin potential energy surfaces occurs once near the exit channel for ScO+, TiO+, VO+, CrO+, and MnO+, but it occurs twice in the entrance and exit channels for FeO+, CoO+, and NiO+. Our calculations strongly suggest that spin inversion can occur near a crossing region of potential energy surfaces and that it can play a significant role in decreasing the barrier heights of these transition states. The reaction pathway from methane to methanol is uphill in energy on the early MO+ complexes (ScO+, TiO+, and VO+); thus, these complexes are not good mediators for the formation of methanol. On the other hand, the late MO+ complexes (FeO+, NiO+, and CuO+) are expected from the general energy profiles of the reaction pathways to efficiently convert methane to methanol. Measured reaction efficiencies and methanol branching ratios for MnO+, FeO+, CoO+, and NiO+ are rationalized from the energetics of the high-spin and the low-spin potential energy surfaces. The energy diagram for the methane-to-methanol conversion by CuO+ is downhill toward the product direction, and thus CuO+ is likely to be an excellent mediator for methane hydroxylation.

AB - The reaction pathway and energetics for methane-to-methanol conversion by first-row transition-metal oxide ions (MO+s) are discussed from density functional theory (DFT) B3LYP calculations, where M is Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu. The methane-to-methanol conversion by these MO+ complexes is proposed to proceed in a two-step manner via two transition states: MO+ + CH4 → OM+(CH4) → [TS] → OH-M+-CH3 → [TS] → M+(CH3OH) → M+ + CH3OH. Both high-spin and low-spin potential energy surfaces are characterized in detail. A crossing between the high-spin and the low-spin potential energy surfaces occurs once near the exit channel for ScO+, TiO+, VO+, CrO+, and MnO+, but it occurs twice in the entrance and exit channels for FeO+, CoO+, and NiO+. Our calculations strongly suggest that spin inversion can occur near a crossing region of potential energy surfaces and that it can play a significant role in decreasing the barrier heights of these transition states. The reaction pathway from methane to methanol is uphill in energy on the early MO+ complexes (ScO+, TiO+, and VO+); thus, these complexes are not good mediators for the formation of methanol. On the other hand, the late MO+ complexes (FeO+, NiO+, and CuO+) are expected from the general energy profiles of the reaction pathways to efficiently convert methane to methanol. Measured reaction efficiencies and methanol branching ratios for MnO+, FeO+, CoO+, and NiO+ are rationalized from the energetics of the high-spin and the low-spin potential energy surfaces. The energy diagram for the methane-to-methanol conversion by CuO+ is downhill toward the product direction, and thus CuO+ is likely to be an excellent mediator for methane hydroxylation.

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