Screening performance of methane activation over atomically dispersed metal catalysts on defective boron nitride monolayers: A density functional theory study

Cao, Xiaoming; Zhou, Haijin; Zhao, Liyang; Chen, Xuning; Hu, P.

doi:10.1016/j.cclet.2020.09.015

Cited by 15 publications

(8 citation statements)

References 40 publications

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“…The O–O bond length of the chemisorbed O 2 is 1.424 Å, indicating that the O 2 presents as peroxide O 2 2− on Z[CrO 2 ] + . 29–32 The spin charge density analysis further confirms that the peroxide O 2 2− and Cr 3+ would exist at Z[CrO 2 ] + (Fig. S15b, ESI†) since [CrO 2 ] needs to compensate a charge to the skeleton of the zeolite.…”

Section: Resultsmentioning

confidence: 78%

ZSM-5-confined Cr₁–O₄ active sites boost methane direct oxidation to C1 oxygenates under mild conditions

Zeng

Cheng

et al. 2023

EES. Catal.

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Section: Resultsmentioning

confidence: 78%

ZSM-5-confined Cr₁–O₄ active sites boost methane direct oxidation to C1 oxygenates under mild conditions

Zeng

Cheng

et al. 2023

EES. Catal.

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“…The spin charge analysis (Figure S4a) shows that O2 could obtain one electron from Z[Cu] + to form •O2 -*. The O-O bond of O2 is thereby strengthened to 1.316 Å, implying the formation of superoxide as well 77 .…”

Section: Resultsmentioning

confidence: 99%

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

Cheng

Chen

et al. 2022

Preprint

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The oxidant is a crucial factor affecting the performance of direct oxidation of methane to methanol (DMTM). It is still extremely challenging to realize one-pot DMTM using dioxygen. So far, hydrogen peroxide is still the most frequently reported green oxidant for DMTM with high selectivity of methanol. Aiming to achieve insights into the influence of oxidants on the DMTM performance and to improve catalysts, we computationally investigated the reaction mechanisms of DMTM using hydrogen peroxide at mono-copper sites in three kinds of Cu-exchanged zeolites with different sizes of the micropores. We identified the common advantage and limitations of hydrogen peroxide as the oxidant. In contrast to molecular oxygen, the O-O bond of hydrogen peroxide could be easily broken to produce reactive surface oxygen species, enabling the facile C-H bond activation of methane at a lower temperature. However, the radical-like mechanism for the C-H bond activation in DMTM using hydrogen peroxide makes the C-H bond breaking of methanol ineluctably superior to methane. This leads to the inevitable trade-off between selectivity and activity for DMTM. Moreover, the lower O-H bonding energy of hydrogen peroxide would also result in the significant self-decomposition of hydrogen peroxide. Despite the existence of these bottlenecks, the kinetic analysis manifests that it is still promising to improve catalysts to boost the performance of DMTM using hydrogen peroxide.

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“…On the one hand, the covalent H 3 C-H (four covalent bonds) resonance structure comprises about 74% of the ground state description of CH 4 , resulting in a high C–H bond strength (434 kJ/mol). − As a result, the activation and dissociation of the C–H bonds seriously hinder the efficient conversion of CH 4 . On the other hand, the highest occupied molecular orbital (HOMO) in the CH 4 molecule is low-lying and its lowest unoccupied molecular orbital (LUMO) is high-lying, which results in the fact that the electron transfer could almost not take place between catalysts and adsorbed CH 4 molecules. ,,, Hence, it is extremely difficult to realize the effective activation of CH 4 only by modulating the local electron density of active sites in catalysts.…”

Section: Introductionmentioning

confidence: 99%

“…10 On the other hand, the highest occupied molecular orbital (HOMO) in the CH 4 molecule is low-lying and its lowest unoccupied molecular orbital (LUMO) is high-lying, which results in the fact that the electron transfer could almost not take place between catalysts and adsorbed CH 4 molecules. 1,8,11,12 Hence, it is extremely difficult to realize the effective activation of CH 4 only by modulating the local electron density of active sites in catalysts.…”

Section: Introductionmentioning

confidence: 99%

Regulating the Spin State of Single Noble Metal Atoms by Hydroxyl for Selective Dehydrogenation of CH₄ Direct Conversion to CH₃OH

Cao

Yang

Wang

et al. 2022

ACS Appl. Mater. Interfaces

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The key scientific challenge for methane (CH 4 ) direct conversion to methanol (CH 3 OH) is considered to be the prevention of overoxidation of target products, which is restrained by the difficulty in the well-controlled process of selective dehydrogenation. Herein, we take single noble metal atomanchored hexagonal boron nitride nanosheets with B vacancies (M SA /B 1−x N) as the model materials and first propose that the dehydrogenation in the direct conversion of CH 4 to CH 3 OH is highly dependent on the spin state of the noble metal. The results reveal that the noble metal with a higher spin magnetic moment is beneficial to the formation of the spin channels for electron transfer, which boosts the dissociation of C−H bonds. The promoted process of dehydrogenation will lead not only to the effective activation of CH 4 but also to the easy overoxidation of CH 3 OH. More importantly, it is found that the spin state of noble metals can be regulated by the introduction of hydroxyl (OH), which realizes the selective dehydrogenation in the process of CH 4 direct conversion to CH 3 OH. Among them, Ag SA /B 1−x N exhibits the best performance owing to the dynamic regulation spin state of a single Ag atom by OH. On the one hand, the introduction of OH significantly reduces the energy barrier of C−H bond dissociation by the increase in the spin magnetic moment. On the other hand, the high spin magnetic moment of a single Ag atom during the process of subsequent dehydrogenation can be modulated to nearly zero. As a result, the spin channel for electron transfer between the adsorbed CH 3 OH and reactive sites is broken, which hinders its overoxidation. This work opens a new path to designing catalysts for selective dehydrogenation by tuning the spin state of local electronic structures.

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Screening performance of methane activation over atomically dispersed metal catalysts on defective boron nitride monolayers: A density functional theory study

Cited by 15 publications

References 40 publications

ZSM-5-confined Cr₁–O₄ active sites boost methane direct oxidation to C1 oxygenates under mild conditions

ZSM-5-confined Cr₁–O₄ active sites boost methane direct oxidation to C1 oxygenates under mild conditions

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

Regulating the Spin State of Single Noble Metal Atoms by Hydroxyl for Selective Dehydrogenation of CH₄ Direct Conversion to CH₃OH

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Screening performance of methane activation over atomically dispersed metal catalysts on defective boron nitride monolayers: A density functional theory study

Cited by 15 publications

References 40 publications

ZSM-5-confined Cr1–O4 active sites boost methane direct oxidation to C1 oxygenates under mild conditions

ZSM-5-confined Cr1–O4 active sites boost methane direct oxidation to C1 oxygenates under mild conditions

Advantages and Limitations of Hydrogen Peroxide for Direct Oxidation of Methane to Methanol at Mono-Copper Active Sites in Cu-Exchanged Zeolites

Regulating the Spin State of Single Noble Metal Atoms by Hydroxyl for Selective Dehydrogenation of CH4 Direct Conversion to CH3OH

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ZSM-5-confined Cr₁–O₄ active sites boost methane direct oxidation to C1 oxygenates under mild conditions

ZSM-5-confined Cr₁–O₄ active sites boost methane direct oxidation to C1 oxygenates under mild conditions

Regulating the Spin State of Single Noble Metal Atoms by Hydroxyl for Selective Dehydrogenation of CH₄ Direct Conversion to CH₃OH