Metal Sites in Zeolites: Synthesis, Characterization, and Catalysis

Chemical Reviews, Journal Year: 2022, Volume and Issue: 123(9), P. 6039 - 6106

Published: Sept. 1, 2022

Zeolites with ordered microporous systems, distinct framework topologies, good spatial nanoconfinement effects, and superior (hydro)thermal stability are an ideal scaffold for planting diverse active metal species, including single sites, clusters, nanoparticles in the framework-associated sites extra-framework positions, thus affording metal-in-zeolite catalysts outstanding activity, unique shape selectivity, enhanced recyclability processes of Brønsted acid-, Lewis metal-catalyzed reactions. Especially, thanks to advances zeolite synthesis characterization techniques recent years, zeolite-confined (denoted as metal@zeolite composites) have experienced rapid development heterogeneous catalysis, owing combination merits both intrinsic properties. In this review, we will present developments strategies incorporating tailoring zeolites advanced identification location, distribution, coordination environment species zeolites. Furthermore, catalytic applications demonstrated, emphasis on composites hydrogenation, dehydrogenation, oxidation Finally, point out current challenges future perspectives precise synthesis, atomic level identification, practical application catalyst system.

Language: Английский

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Synergy of Pd atoms and oxygen vacancies on In2O3 for methane conversion under visible light

Nature Communications, Journal Year: 2022, Volume and Issue: 13(1)

Published: May 25, 2022

Methane (CH4) oxidation to high value chemicals under mild conditions through photocatalysis is a sustainable and appealing pathway, nevertheless confronting the critical issues regarding both conversion selectivity. Herein, visible irradiation (420 nm), synergy of palladium (Pd) atom cocatalyst oxygen vacancies (OVs) on In2O3 nanorods enables superior photocatalytic CH4 activation by O2. The optimized catalyst reaches ca. 100 μmol h-1 C1 oxygenates, with selectivity primary products (CH3OH CH3OOH) up 82.5%. Mechanism investigation elucidates that such induced dedicated function Pd single atoms boosting hole electron transfer, respectively. O2 proven be only source for CH3OH production, while H2O acts as promoter efficient ·OH production facilitates product desorption indicated DFT modeling. This work thus provides new understandings simultaneous regulation activity cocatalysts vacancies.

Language: Английский

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Methane Oxidation to Methanol

Chemical Reviews, Journal Year: 2022, Volume and Issue: 123(9), P. 6359 - 6411

Published: Dec. 2, 2022

The direct transformation of methane to methanol remains a significant challenge for operation at larger scale. Central this is the low reactivity conditions that can facilitate product recovery. This review discusses issue through examination several promising routes and an evaluation performance targets are required develop process We explore methods currently used, emergence active heterogeneous catalysts their design reaction mechanisms provide critical perspective on future operation. Initial experiments discussed where identification gas phase radical chemistry limited further development by approach. Subsequently, new class catalytic materials based natural systems such as iron or copper containing zeolites were explored milder conditions. key issues these technologies conversion often overoxidation products. Despite this, interest high in wider appeal effective route products from C–H activation, particularly with need transition net carbon zero renewable sources exciting.

Language: Английский

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Au-ZSM-5 catalyses the selective oxidation of CH4 to CH3OH and CH3COOH using O2

Nature Catalysis, Journal Year: 2022, Volume and Issue: 5(1), P. 45 - 54

Published: Jan. 6, 2022

Language: Английский

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Single Atom Catalysts for Selective Methane Oxidation to Oxygenates

ACS Nano, Journal Year: 2022, Volume and Issue: 16(6), P. 8557 - 8618

Published: May 31, 2022

Direct conversion of methane (CH4) to C1–2 liquid oxygenates is a captivating approach lock carbons in transportable value-added chemicals, while reducing global warming. Existing approaches utilizing the transformation CH4 fuel via tandemized steam reforming and Fischer–Tropsch synthesis are energy capital intensive. Chemocatalytic partial oxidation remains challenging due negligible electron affinity, poor C–H bond polarizability, high activation barrier. Transition-metal stoichiometric catalysts harsh oxidants reaction conditions perform poorly with randomized product distribution. Paradoxically, which active enough break also promote overoxidation, resulting CO2 generation reduced carbon balance. Developing can bonds selectively make useful chemicals at mild vital commercialization. Single atom (SACs) specifically coordinated metal centers on support have displayed intrigued reactivity selectivity for oxidation. SACs significantly reduce induced electrostatic polarization facilitate accelerated rate low temperature. The distinct metal–support interaction stabilize intermediate prevent overoxidation products. present review accounts recent progress field selective oxygenates. chemical nature catalytic sites, effects interaction, stabilization species minimize thoroughly discussed forward-looking perspective improve performance.

Language: Английский

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First-Generation Organic Reaction Intermediates in Zeolite Chemistry and Catalysis

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(18), P. 14275 - 14345

Published: Aug. 10, 2022

Zeolite chemistry and catalysis are expected to play a decisive role in the next decade(s) build more decentralized renewable feedstock-dependent sustainable society owing increased scrutiny over carbon emissions. Therefore, lack of fundamental mechanistic understanding these processes is critical "technical bottleneck" that must be eliminated maximize economic value minimize waste. We have identified, considering this objective, related first-generation reaction intermediates (i.e., carbocations, radicals, carbenes, ketenes, carbanions) zeolite highly underdeveloped or undervalued compared other streams (e.g., homogeneous catalysis). This limitation can often attributed technological restrictions detect such "short-lived reactive" at interface (gas-solid/solid-liquid); however, recent rise sophisticated spectroscopic/analytical techniques (including under situ/operando conditions) modern data analysis methods collectively compete unravel impact organic intermediates. comprehensive review summarizes state-of-the-art evaluates their existing challenges future prospects, contribute significantly "circular economy" initiatives.

Language: Английский

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Atomic Insights into the Cu Species Supported on Zeolite for Direct Oxidation of Methane to Methanol via Low‐Damage HAADF‐STEM

Advanced Materials, Journal Year: 2023, Volume and Issue: 35(25)

Published: April 4, 2023

Precise determination of the structure-property relationship zeolite-based metal catalysts is critical for development toward practical applications. However, scarcity real-space imaging low-atomic-number (LAN) materials due to electron-beam sensitivity zeolites has led continuous debates regarding exact LAN configurations. Here, a low-damage high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) technique employed direct visualization and (Cu) species in ZSM-5 zeolite frameworks. The structures Cu are revealed based on evidence also proved by complementary spectroscopy results. correlation between characteristic size Cu/ZSM-5 their oxidation methane methanol reaction properties unveiled. As result, mono-Cu stably anchored Al pairs inside channels identified as key structure higher C1 oxygenates yield selectivity methane. Meanwhile, local topological flexibility rigid frameworks induced agglomeration revealed. This work exemplifies combination characterization serves complete arsenal revealing relationships supported metal-zeolite catalysts.

Language: Английский

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Retrofitting Zr-Oxo Nodes of UiO-66 by Ru Single Atoms to Boost Methane Hydroxylation with Nearly Total Selectivity

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(24), P. 13169 - 13180

Published: June 6, 2023

Direct selective oxidation of methane (DSOM) to high value-added oxygenates under mild conditions is attracting considerable interest. Although state-of-the-art supported metal catalysts can improve conversion, it still challenging avoid the deep oxygenates. Here, we develop a highly efficient metal-organic frameworks (MOFs)-supported single-atom Ru catalyst (Ru1/UiO-66) for DSOM reaction using H2O2 as an oxidant. It endows nearly 100% selectivity and excellent turnover frequency 185.4 h-1 production The yield order magnitude higher than that on UiO-66 alone several times nanoparticles or other conventional Ru1 catalysts, which show severe CO2 formation. Detailed characterizations density functional theory calculations reveal synergistic effect between electron-deficient site electron-rich Zr-oxo nodes Ru1/UiO-66. responsible activation CH4 via resulting Ru1═O* species, while undertake formation oxygenic radical species produce In particular, retrofitted by prune excess inactive O2 more •OH helping suppress over-oxidation

Language: Английский

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Synergy of heterogeneous Co/Ni dual atoms enabling selective C–O bond scission of lignin coupling with in-situ N-functionalization

Journal of Energy Chemistry, Journal Year: 2024, Volume and Issue: 92, P. 16 - 25

Published: Jan. 14, 2024

Language: Английский

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Fe binuclear sites convert methane to acetic acid with ultrahigh selectivity

Chem, Journal Year: 2022, Volume and Issue: 8(6), P. 1658 - 1672

Published: March 2, 2022

Language: Английский

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