Influence of Cu-speciation in mordenite on direct methane to methanol conversion: Multi-Technique characterization and comparison with NH3 selective catalytic reduction of NOx

Pappas, Dimitrios; Kvande, Karoline; Kalyva, Maria; Dyballa, Michael; Lomachenko, Kirill A.; Arstad, Bjørnar; Borfecchia, Elisa; Bordiga, Silvia; Olsbye, Unni; Beato, Pablo; Svelle, Stian

doi:10.1016/j.cattod.2020.06.050

Cited by 17 publications

(21 citation statements)

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“…These are shifted to about 8983 eV after Cu 2+ → Cu + reduction. This 2.5–3.2 eV shift after Cu 2+ one-electron reduction has been reported by various workers. ,− One would thus expect that the calculated near-edge X-ray absorption spectra of our [Cu 2 O] 2+ cluster models would also show some shift. This would be a way to confirm the involvement of the Cu 2+ /Cu + redox couple in methane activation by [Cu 2 O] 2+ and [Cu 3 O 3 ] 2+ (Figures and ).…”

Section: Resultssupporting

confidence: 87%

Methane C–H Activation by [Cu₂O]²⁺ and [Cu₃O₃]²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

et al. 2021

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There is an ongoing debate regarding the role of [Cu3O3]2+ in methane-to-methanol conversion by copper-exchanged zeolites. Here, we perform electronic structure analysis and localized orbital bonding analysis to probe the redox chemistry of its Cu and μ-oxo sites. Also, the X-ray absorption near-edge structure, XANES, of methane activation in [Cu3O3]2+ is compared to that of the more ubiquitous [Cu2O]2+. Methane C–H activation is associated with only the Cu2+/Cu+ redox couple in [Cu2O]2+. For [Cu3O3]2+, there is no basis for the Cu3+/Cu2+ couple’s participation at the density functional theory ground state. In [Cu3O3]2+, there are many possible intrazeolite intermediates for methane activation. In the nine possibilities that we examined, methane activation is driven by a combination of the Cu2+/Cu+ and oxyl/O2– redox couples. Based on this, the Cu 1s-edge XANES spectra of [Cu2O]2+ and [Cu3O3]2+ should both have energy signatures of Cu2+ → Cu+ reduction during methane activation. This is indeed what we obtained from the calculated XANES spectra. [Cu2O]2+ and [Cu3O3]2+ intermediates with one Cu+ site are shifted by 0.9–1.7 eV, while those with two Cu+ sites are shifted by 3.0–4.2 eV. These are near a range of 2.5–3.2 eV observed experimentally after contacting methane with activated copper-exchanged zeolites. Thus, activation of methane by [Cu3O3]2+ will lead to formation of Cu+ sites. Importantly, for future quantitative XANES studies, involvement of O– + e– → O2– in [Cu3O3]2+ implies a disconnect between the overall reactivity and the number of electrons used in the Cu2+/Cu+ redox couple.

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Section: Resultssupporting

confidence: 87%

Methane C–H Activation by [Cu₂O]²⁺ and [Cu₃O₃]²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

et al. 2021

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“…In this sense, Grundner et al suggest that in the case of the Cu-MOR system the 0.35 mol CH3OH /mol Cu yield is a clear proof of the presence of a trinuclear copper active site (Grundner et al, 2015;Grundner et al, 2016). In addition, Pappas et al (2021) reported a value close to 0.5 mol CH3OH /mol Cu (Figure 2), suggesting that the nature of the active site is binuclear. Thus, it is evident that further and more detailed investigation is required to clarify the phenomenology in depth.…”

Section: Conversion Of Methane To Methanolmentioning

confidence: 96%

“…The methanol productivity normalized to Cu content is one of the typical values reported in the literature for both Cu-ZSM-5 and Cu-MOR systems, whose dimensions correspond to those of mole of methanol per mole of copper (mol CH3OH /mol Cu ). Some of the highest reported values are 0.20 ( Narsimhan et al, 2016 ) and 0.47 ( Pappas et al, 2021 ) mol CH3OH /mol Cu for the Cu-ZSM-5 and Cu-MOR systems. This would suggest that if we follow the idea that only one copper atom is needed to produce one molecule of CH 3 OH, only one part or one tiny fraction of the copper atoms participate in the partial oxidation of methane.…”

Section: Catalytic Processes With Transition Metals On Zeolitesmentioning

confidence: 98%

“…Other zeolite structures such as ERI, CHA, MFI exchanged with copper have also been evaluated in the MTM reaction ( Beznis et al, 2010 ; Paolucci et al, 2016 ; Martini et al, 2020 ; Zhu et al, 2020b ); however, the Cu-MOR system remains one of the most promising. Notwithstanding, the most suitable site for partial oxidation in the MTM reaction continues to be a matter of discussion ( Groothaert et al, 2005 ; Mentzen and Bergeret, 2007 ; Woertink et al, 2009 ; Smeets et al, 2010 ; Grundner et al, 2015 , 2016 ; Narsimhan et al, 2016 ; Pappas et al, 2021 ).…”

Section: Catalytic Processes With Transition Metals On Zeolitesmentioning

confidence: 99%

Section: Catalytic Processes With Transition Metals On Zeolitesmentioning

confidence: 99%

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Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

et al. 2021

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This article reviews the current state and development of thermal catalytic processes using transition metals (TM) supported on zeolites (TM/Z), as well as the contribution of theoretical studies to understand the details of the catalytic processes. Structural features inherent to zeolites, and their corresponding properties such as ion exchange capacity, stable and very regular microporosity, the ability to create additional mesoporosity, as well as the potential chemical modification of their properties by isomorphic substitution of tetrahedral atoms in the crystal framework, make them unique catalyst carriers. New methods that modify zeolites, including sequential ion exchange, multiple isomorphic substitution, and the creation of hierarchically porous structures both during synthesis and in subsequent stages of post-synthetic processing, continue to be discovered. TM/Z catalysts can be applied to new processes such as CO2 capture/conversion, methane activation/conversion, selective catalytic NOx reduction (SCR-deNOx), catalytic depolymerization, biomass conversion and H2 production/storage.

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Imine Oxidation Catalyzed by Zinc Hydroxyapatite: Kinetic Studies

et al. 2023

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The synthesis of N,N‐diphenylformamide from N‐benzylideneaniline and urea hydrogen peroxide is investigated using a zinc hydroxyapatite (ZnHAP) catalyst. It was found that the catalyst resulted in the highest activity of 91 % conversion and 40 % selectivity at 130 °C in 2 h. A kinetic model was validated by Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) at different temperatures and the absence of mass transfer resistance was proved by the Weisz Prater criterion. Effect of different catalysts, catalyst loading, temperature, mole‐ratio, and speed of stirring was studied. The as‐synthesized catalyst is characterized by FTIR, BET nitrogen adsorption‐desorption, TEM, EDX, TPD‐NH3, XPS, ICP‐MS and XRD. ZnHAP catalyst was found to be stable up to three recycles with no loss in activity.

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Influence of Cu-speciation in mordenite on direct methane to methanol conversion: Multi-Technique characterization and comparison with NH3 selective catalytic reduction of NOx

Cited by 17 publications

References 50 publications

Methane C–H Activation by [Cu₂O]²⁺ and [Cu₃O₃]²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

Methane C–H Activation by [Cu₂O]²⁺ and [Cu₃O₃]²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

Imine Oxidation Catalyzed by Zinc Hydroxyapatite: Kinetic Studies

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Influence of Cu-speciation in mordenite on direct methane to methanol conversion: Multi-Technique characterization and comparison with NH3 selective catalytic reduction of NOx

Cited by 17 publications

References 50 publications

Methane C–H Activation by [Cu2O]2+ and [Cu3O3]2+ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

Methane C–H Activation by [Cu2O]2+ and [Cu3O3]2+ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites

Imine Oxidation Catalyzed by Zinc Hydroxyapatite: Kinetic Studies

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Product

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Methane C–H Activation by [Cu₂O]²⁺ and [Cu₃O₃]²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy

Methane C–H Activation by [Cu₂O]²⁺ and [Cu₃O₃]²⁺ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy