Insights into the C–H Bond Activation on NiO Surfaces: The Role of Nickel and Oxygen Vacancies and of Low Valent Dopants on the Reactivity and Energetics

Varghese, Jithin John; Mushrif, Samir H.

doi:10.1021/acs.jpcc.7b05226

Cited by 49 publications

(48 citation statements)

References 71 publications

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“…This phenomenon indicated that both the acidic sites and basic sites were responsible for the efficient methane oxidation, and it was important to boost the surface acidic sites and basic sites simultaneously. The reason could be that the abstraction of the H-atom from adsorbed methane occurred on the acid–base pair (M LC n + O LC 2– ) rather than on the single metal or lattice oxygen site of Ni 1– x Zr x O 2−δ catalysts. , Since the dissociation of methane was crucial for the further oxidation of methane, it could be inferred that the presence of abundant and well-balanced surface acidic–basic sites over Ni 0.89 Zr 0.11 O 2−δ promoted the adsorption and activation of methane, contributing to the higher activity.…”

Section: Resultsmentioning

confidence: 99%

Zr-Doped NiO Nanoparticles for Low-Temperature Methane Combustion

Wang

Lin

et al. 2021

ACS Appl. Nano Mater.

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The development of efficient and stable non-noble metalbased catalysts for low-temperature methane combustion is extremely important and still a profound challenge. Herein, high-performance Ni 1−x Zr x O 2−δ solid solution nanocatalysts were prepared through a homogeneous co-precipitation strategy, where the hydrolysis of CO 3 2− was controlled to facilitate the dispersion and interaction of Ni and Zr components. The structural and surface properties of nanocatalysts were facilely tuned by modulating the Zr doping content. An optimized incorporation of Zr into the NiO lattice endowed the Ni 0.89 Zr 0.11 O 2−δ nanocatalyst with a small crystallite size, large specific surface area, and simultaneously increased surface acidic−basic sites. Moreover, abundant active Ni 2+ and surface oxygen species were generated due to the promoted conversion of Ni 3+ to Ni 2+ , which played pivotal roles in the adsorption/ activation of methane and further oxidation of reaction intermediates to CO 2 . Consequently, Ni 0.89 Zr 0.11 O 2−δ exhibited an excellent low-temperature activity, high CO 2 selectivity, and superior catalytic stability under both dry and wet conditions.

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Section: Resultsmentioning

confidence: 99%

Zr-Doped NiO Nanoparticles for Low-Temperature Methane Combustion

Wang

Lin

et al. 2021

ACS Appl. Nano Mater.

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“…Transition metal complexes can serve as active sites for methane activation at rather mild temperatures, [1a,14] and promote different mechanisms of methane activation (homolytic, heterolytic and Fenton) [1a,15] . Over Lewis acidic metal oxides, methane can be activated through heterolytic splitting of the C−H bond, leading to the formation of methyl and hydroxyl species [14a,16] . The activation of methane is also affected by the presence of other species.…”

Section: Introductionmentioning

confidence: 99%

Selective Oxidation of Methane to Methanol over Ceria‐Zirconia Supported Mono and Bimetallic Transition Metal Oxide Catalysts

Lyu

Jocz

et al. 2021

ChemCatChem

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Several ceria‐zirconia supported mono and bi‐metallic transition metal oxide clusters containing Fe, Cu, and Ni are synthesized by dry impregnation. Through XRD, H2‐TPR, NH3‐TPD, pyridine adsorption followed by FTIR spectroscopy and XAS, the well‐dispersed nature of the transition metal oxide clusters is revealed, and the Lewis acidity of the catalysts is assessed. In‐situ FTIR spectroscopy is used to monitor the methane activation on catalyst surfaces. All catalysts activate methane at 250 °C forming methyl, alkyl, and methoxy species on the catalyst surface. By co‐feeding steam and oxygen together with methane, continuous direct oxidation of methane to methanol can be achieved, with the complete oxidation to CO2 as the other reaction path. Methoxy species are found to be a key intermediate for methanol production. Lowering the methane conversion improves the methanol selectivity. By extrapolation, it is estimated that methanol selectivity close to unity can be achieved below a threshold of methane conversion at about 0.002 %. The formation of CuO and NiO mixed metal oxides produces stronger Lewis acid sites and yields higher methanol selectivity.

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“…Note that the Osuf and Osub are denoted as O1 and O2 sites in the main text (Table 3. During the catalyst synthesis and reactions, surface vacancies can be generated and may alter the activity of the catalyst. [160][161][162][163][164] This has been tested, and it is found that the coordinatively unsaturated sites (Cucus and Osuf sites) are weakly bound to the surface (consistent with the study of Mamaiti et al 121 ) and two types of surface vacancies, namely Oxygen vacancy VO (Kröger-Vink Notation) (cf Fig. 3.8b) and Cu vacancy, VCu (Kröger-Vink Notation) (cf Fig.…”

Section: Clean Surface and Surface With Vacanciessupporting

confidence: 76%

“…In summary, this chapter demonstrates a synergistic application of XPS and The first activation of methane on TMOs [50][51] gives rise to methyl species in the system, which can further oxidize to partially oxygenated species like methanol, formaldehyde, formic acid before converting to fully oxygenated products like CO/CO2. Since the first activation of methane is usually the rate-limiting step, a large number of studies have studied the first activation of C-H bonds of methane, 37,44,[180][181] whereas subsequent activations of methane on TMOs are not widely investigated in the literature.…”

Section: Discussionmentioning

confidence: 92%

Investigating metal oxides for C1 chemistry : a computational and experimental study

Bhola¹

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Insights into the C–H Bond Activation on NiO Surfaces: The Role of Nickel and Oxygen Vacancies and of Low Valent Dopants on the Reactivity and Energetics

Cited by 49 publications

References 71 publications

Zr-Doped NiO Nanoparticles for Low-Temperature Methane Combustion

Zr-Doped NiO Nanoparticles for Low-Temperature Methane Combustion

Selective Oxidation of Methane to Methanol over Ceria‐Zirconia Supported Mono and Bimetallic Transition Metal Oxide Catalysts

Investigating metal oxides for C1 chemistry : a computational and experimental study

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