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Kvande K, Garetto B, Deplano G, Signorile M, Solemsli BG, Prodinger S, Olsbye U, Beato P, Bordiga S, Svelle S, Borfecchia E. Understanding C-H activation in light alkanes over Cu-MOR zeolites by coupling advanced spectroscopy and temperature-programmed reduction experiments. Chem Sci 2023; 14:9704-9723. [PMID: 37736625 PMCID: PMC10510758 DOI: 10.1039/d3sc01677c] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/19/2023] [Indexed: 09/23/2023] Open
Abstract
The direct activation of methane to methanol (MTM) proceeds through a chemical-looping process over Cu-oxo sites in zeolites. Herein, we extend the overall understanding of oxidation reactions over metal-oxo sites and C-H activation reactions by pinpointing the evolution of Cu species during reduction. To do so, a set of temperature-programmed reduction experiments were performed with CH4, C2H6, and CO. With a temperature ramp, the Cu reduction could be accelerated to detect changes in Cu speciation that are normally not detected due to the slow CH4 adsorption/interaction during MTM (∼200 °C). To follow the Cu-speciation with the three reductants, X-ray absorption spectroscopy (XAS), UV-vis and FT-IR spectroscopy were applied. Multivariate curve resolution alternating least-square (MCR-ALS) analysis was used to resolve the time-dependent concentration profiles of pure Cu components in the X-ray absorption near edge structure (XANES) spectra. Within the large datasets, as many as six different CuII and CuI components were found. Close correlations were found between the XANES-derived CuII to CuI reduction, CH4 consumption, and CO2 production. A reducibility-activity relationship was also observed for the Cu-MOR zeolites. Extended X-ray absorption fine structure (EXAFS) spectra for the pure Cu components were furthermore obtained with MCR-ALS analysis. With wavelet transform (WT) analysis of the EXAFS spectra, we were able to resolve the atomic speciation at different radial distances from Cu (up to about 4 Å). These results indicate that all the CuII components consist of multimeric CuII-oxo sites, albeit with different Cu-Cu distances.
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Affiliation(s)
- Karoline Kvande
- Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo 1033 Blindern 0315 Oslo Norway
| | - Beatrice Garetto
- Department of Chemistry, NIS Center and INSTM Reference Center, University of Turin, 10125 Turin Via P. Giuria 7 Italy
| | - Gabriele Deplano
- Department of Chemistry, NIS Center and INSTM Reference Center, University of Turin, 10125 Turin Via P. Giuria 7 Italy
| | - Matteo Signorile
- Department of Chemistry, NIS Center and INSTM Reference Center, University of Turin, 10125 Turin Via P. Giuria 7 Italy
| | - Bjørn Gading Solemsli
- Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo 1033 Blindern 0315 Oslo Norway
| | - Sebastian Prodinger
- Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo 1033 Blindern 0315 Oslo Norway
| | - Unni Olsbye
- Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo 1033 Blindern 0315 Oslo Norway
| | - Pablo Beato
- Topsoe A/S, Haldor Topsøes Allé 1 DK-2800 Kgs. Lyngby Denmark
| | - Silvia Bordiga
- Department of Chemistry, NIS Center and INSTM Reference Center, University of Turin, 10125 Turin Via P. Giuria 7 Italy
| | - Stian Svelle
- Centre for Materials Science and Nanotechnology (SMN), Department of Chemistry, University of Oslo 1033 Blindern 0315 Oslo Norway
| | - Elisa Borfecchia
- Department of Chemistry, NIS Center and INSTM Reference Center, University of Turin, 10125 Turin Via P. Giuria 7 Italy
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Copper-zeolites Prepared by Solid-state Ion Exchange - Characterization and Evaluation for the Direct Conversion of Methane to Methanol. Top Catal 2022. [DOI: 10.1007/s11244-022-01763-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
AbstractDirect conversion of methane to methanol (MTM) over Cu-zeolites is a so-called “dream reaction” for the chemical industry. There is still a lot that can be done in order to optimize the reaction by e.g. achieving a deeper understanding of the reaction mechanism and the nature of the Cu-sites. In this study, we investigated a solid-state ion exchange method to incorporate CuI ions into zeolites (MOR, BEA, ZSM-5 and FAU), as a more scalable technique. The solid-state ion exchange led to a Cu/Al ration of about 0.8, however with a heterogeneous distribution of Cu. Regardless, Fourier transform-infrared spectroscopy still revealed that most Brønsted acid sites were exchanged in all four samples. Further, CH4-temperature programmed reaction experiments showed that some Cu-sites formed were reactive towards CH4, with CuI-MOR and CuI-FAU having the largest CH4 consumption. Ultimately, the CuI-zeolites were tested in the MTM reaction and proved capable of producing methanol, even without the presence of Brønsted sites. A MOR with lower Cu/Al ratio (0.30) was also tested for comparison, and as this sample obtained a much higher productivity than the CuI-MOR with high Cu-loading (0.10 vs. 0.03 molMeOH/molCu), it was demonstrated that some fine-tuning is necessary to obtain the active Cu sites for methane activation.
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Influence of Components Deposition Order on Silver Species Formation in Bimetallic Ag-Fe System Supported on Mordenite. Catalysts 2022. [DOI: 10.3390/catal12111453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In the present work, various experimental and theoretical methods were combined to study in detail the modifying effect of differences in the order of deposition of components on the state of silver in bimetallic iron–silver samples based on mordenite. In each of the silver-containing samples, the formation of large (≥2 nm in diameter) varieties of silver was observed, which differed from the varieties in the other samples, and in varying degrees. The formation of large Ag NPs on the outer surface of mordenite is explained by the redox interaction of Ag+-Fe2+ and the selectivity of ion exchange. The local surrounding of Ag in the studied samples is different: for AgMOR—monatomic species dominate, FeAgMOR—silver dimers and AgFeMOR—metal particles. In all investigated samples, the partially charged intra-channel Agnδ+ clusters (~0.7 nm in size) were formed due to partial Ag+ reduction and subsequent Ag0 agglomeration into the mordenite channel. Most of the silver in the bulk of the zeolite is represented in the cationic state attached to the mordenite framework by differently coordinated electrostatic forces, which can be Ag-O, Ag-Si or Ag-Al, with variations in interatomic distances and do not depend on the order of metal deposition. In addition, the arrangement of the cations in the side pockets means that the transport channels of mordenite are free, which is favorable for the application of the materials under study in catalysis and adsorption.
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Gallego M, Corma A, Boronat M. Sub-nanometer Copper Clusters as Alternative Catalysts for the Selective Oxidation of Methane to Methanol with Molecular O 2. J Phys Chem A 2022; 126:4941-4951. [PMID: 35861145 PMCID: PMC10388348 DOI: 10.1021/acs.jpca.2c02895] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The partial oxidation of methane to methanol with molecular O2 at mild reaction conditions is a challenging process, which is efficiently catalyzed in nature by enzymes. As an alternative to the extensively studied Cu-exchanged zeolites, small copper clusters composed by just a few atoms appear as potential specific catalysts for this transformation. Following previous work in our group that established that the reactivity of oxygen atoms adsorbed on copper clusters is closely linked to cluster size and morphology, we explore by means of DFT calculations the ability of bidimensional (2D) and three-dimensional (3D) Cu5 and Cu7 clusters to oxidize partially methane to methanol. A highly selective Eley-Rideal pathway involving homolytic C-H bond dissociation and a non-adsorbed radical-like methyl intermediate is favored when bicoordinated oxygen atoms, preferentially stabilized at the edges of 2D clusters, are available. Cluster morphology arises as a key parameter determining the nature and reactivity of adsorbed oxygen atoms, opening the possibility to design efficient catalysts for partial methane oxidation based on copper clusters.
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Affiliation(s)
- Mario Gallego
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València - Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Avelino Corma
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València - Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, 46022 Valencia, Spain
| | - Mercedes Boronat
- Instituto de Tecnología Química (UPV-CSIC), Universitat Politècnica de València - Consejo Superior de Investigaciones Científicas, Avda. de los Naranjos s/n, 46022 Valencia, Spain
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Sánchez-López P, Kotolevich Y, Yocupicio-Gaxiola RI, Antúnez-García J, Chowdari RK, Petranovskii V, Fuentes-Moyado S. Recent Advances in Catalysis Based on Transition Metals Supported on Zeolites. Front Chem 2021; 9:716745. [PMID: 34434919 PMCID: PMC8380812 DOI: 10.3389/fchem.2021.716745] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
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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Affiliation(s)
- Perla Sánchez-López
- Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
| | - Yulia Kotolevich
- Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
| | | | - Joel Antúnez-García
- Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
| | - Ramesh Kumar Chowdari
- Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
| | - Vitalii Petranovskii
- Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
| | - Sergio Fuentes-Moyado
- Departamento de Nanocatálisis, Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Ensenada, Mexico
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Suleiman O, Panthi D, Adeyiga O, Odoh SO. Methane C-H Activation by [Cu 2O] 2+ and [Cu 3O 3] 2+ in Copper-Exchanged Zeolites: Computational Analysis of Redox Chemistry and X-ray Absorption Spectroscopy. Inorg Chem 2021; 60:6218-6227. [PMID: 33876934 DOI: 10.1021/acs.inorgchem.0c03693] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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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Affiliation(s)
- Olabisi Suleiman
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, Nevada 89557-0216, United States
| | - Dipak Panthi
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, Nevada 89557-0216, United States
| | - Olajumoke Adeyiga
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, Nevada 89557-0216, United States
| | - Samuel O Odoh
- Department of Chemistry, University of Nevada Reno, 1664 N. Virginia Street, Reno, Nevada 89557-0216, United States
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Kiani D, Sourav S, Tang Y, Baltrusaitis J, Wachs IE. Methane activation by ZSM-5-supported transition metal centers. Chem Soc Rev 2021; 50:1251-1268. [PMID: 33284308 DOI: 10.1039/d0cs01016b] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review focuses on recent fundamental insights about methane dehydroaromatization (MDA) to benzene over ZSM-5-supported transition metal oxide-based catalysts (MOx/ZSM-5, where M = V, Cr, Mo, W, Re, Fe). Benzene is an important organic intermediate, used for the synthesis of chemicals like ethylbenzene, cumene, cyclohexane, nitrobenzene and alkylbenzene. Current production of benzene is primarily from crude oil processing, but due to the abundant availability of natural gas, there is much recent interest in developing direct processes to convert CH4 to liquid chemicals. Among the various gas-to-liquid methods, the thermodynamically-limited Methane DehydroAromatization (MDA) to benzene under non-oxidative conditions appears very promising as it circumvents deep oxidation of CH4 to CO2 and does not require the use of a co-reactant. The findings from the MDA catalysis literature is critically analyzed with emphasis on in situ and operando spectroscopic characterization to understand the molecular level details regarding the catalytic sites before and during the MDA reaction. Specifically, this review discusses the anchoring sites of the supported MOx species on the ZSM-5 support, molecular structures of the initial dispersed surface MOx sites, nature of the active sites during MDA, reaction mechanisms, rate-determining step, kinetics and catalyst activity of the MDA reaction. Finally, suggestions are given regarding future experimental investigations to fill the information gaps currently found in the literature.
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Affiliation(s)
- Daniyal Kiani
- Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA.
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