Catalytic reduction of carbon monoxide over potassium modified iron surfaces

We study the filling of single‐walled carbon nanotubes (SW‐ CNTs) with ferrocene molecules. Using e‐DIPS SWCNTs with a mean diameter of 1.7 nm, we obtain a filling factor as high as 90%. At elevated temperatures in high vacuum the filled SWCNTs are transformed to double‐walled carbon nanotubes (DWCNTs). Temperature dependence of inner tube growth is investigated by Raman spectroscopy. The electronic properties of the obtained nanostructures are studied by X‐ray photoelectron spectroscopy and near edge X‐ray absorption fine structure spectroscopy. It is found that the growth temperature is higher for larger diameter inner tubes. It is demonstrated that ferrocene filling leads to electron doping of SWCNTs.

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“…In addition, the Fe 2p edges are shifted by 0.5 eV to lower binding energies. According to the literature, the Fe 2

p_{3 / 2}

peak of the bulk iron carbides appears at binding energies of 707.2 eV for

{Fe}_{3}

C () and 707.3 eV for Fe 5 C 2 (). Hence, the energy shift can be attributed to the formation of iron carbides inside the nanotubes.…”

Section: Resultsmentioning

confidence: 96%

Inner tube growth properties and electronic structure of ferrocene-filled large diameter single-walled carbon nanotubes

Kharlamova

Sauer

Saito

et al. 2013

Phys. Status Solidi B

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“…Our recent work also showed that individual K + of a single‐site catalyst with hybridized d–sp orbitals had a high electronic DOS and possessed excellent ability to activate both molecular oxygen and lattice oxygen, and thus, the catalyst showed high catalytic activity for HCHO oxidation . It should be mentioned that previous studies found that potassium exhibited promotion effects in the Fisher–Tropsch reaction and ammonia synthesis, and the promoting function of potassium mainly originated from the electron‐donating effects of potassium. Likewise, electron‐abundant alkali metals can facilitate the dissociation of O 2 by charge transfer from potassium to the antibonding orbitals of O 2 ; thus showing significant activity in oxidation reactions …”

Section: Introductionmentioning

confidence: 76%

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Gao

Chen

Wan

et al. 2017

Chemistry A European J

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Alkali-metal ions often act as promoters rather than active components due to their stable outermost electronic configurations and their inert properties in heterogeneous catalysis. Herein, inert alkali-metal ions, such as K and Rb , are activated by electron transfer from a Hollandite-type manganese oxide (HMO) support for HCHO oxidation. Results from synchrotron X-ray diffraction, absorption, and photoelectron spectroscopies demonstrate that the electronic density of states of single alkali-metal adatoms is much higher than that of K or Rb , because electrons transfer from manganese to the alkali-metal adatoms through bridging lattice oxygen atoms. Electron transfer originates from the interactions of alkali metal d-sp frontier orbitals with lattice oxygen sp orbitals occupied by lone-pair electrons. Reaction kinetics data of HCHO oxidation reveal that the high electronic density of states of single alkali-metal adatoms is favorable for the activation of molecular oxygen. Mn L -edge and O K-edge soft-X-ray absorption spectra demonstrate that lattice oxygen partially gains electrons from the Mn e orbitals, which leads to the upshift in energy of lattice oxygen orbitals. Therefore, the facile activation of molecular oxygen by the electron-abundant alkali-metal adatoms and active lattice oxygen are responsible for the high catalytic activity in complete oxidation of HCHO. This work could assist the design of efficient and cheap catalysts by tuning the electronic states of active components.

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“…The catalytic reduction of CO over Fe and K-promoted Fe single-crystal surfaces was studied (Dwyer and Hardenbergh, 1984). Iron surfaces in the absence of surface alkali exhibited a high hydrogenation activity resulting in a product distribution consisting of small (C1-C6) alkanes.…”

Section: Alkali Promotionmentioning

confidence: 99%

Direct catalytic conversion of synthesis gas to lower olefins

Janardanarao¹

1990

Ind. Eng. Chem. Res.

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Catalytic reduction of carbon monoxide over potassium modified iron surfaces

Cited by 6 publications

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Inner tube growth properties and electronic structure of ferrocene-filled large diameter single-walled carbon nanotubes

Inner tube growth properties and electronic structure of ferrocene-filled large diameter single-walled carbon nanotubes

Activating Inert Alkali‐Metal Ions by Electron Transfer from Manganese Oxide for Formaldehyde Abatement

Direct catalytic conversion of synthesis gas to lower olefins

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