Methane Oxidation to Methanol

Chemical Reviews, Год журнала: 2022, Номер 123(9), С. 6359 - 6411

Опубликована: Дек. 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.

Язык: Английский

---

A priori control of zeolite phase competition and intergrowth with high-throughput simulations

Science, Год журнала: 2021, Номер 374(6565), С. 308 - 315

Опубликована: Сен. 16, 2021

Selectivity control in zeolite synthesis Zeolites are widely used many industrial applications, but despite decades of research, their still relies on trial-and-error approaches. Complex nucleation mechanisms and topological diversity lead to strong phase competition, complicating the issue rational design synthesis. Using atomistic simulations, literature mining, human-computer interaction, synthesis, characterization, Schwalbe-Koda et al . developed a computational strategy that enables priori selectivity (see Perspective by Chaikittisilp Okubo). This approach uses several metrics for designing organic structure–directing agents crystallize target zeolites with controlled competition intergrowth. These results may have profound implications materials science community if this method is shown be successful practically useful uncommon zeolites. —YS

Язык: Английский

---

Competition between Mononuclear and Binuclear Copper Sites across Different Zeolite Topologies

JACS Au, Год журнала: 2024, Номер 4(1), С. 197 - 215

Опубликована: Янв. 4, 2024

A key challenge for metal-exchanged zeolites is the determination of metal cation speciation and nuclearity under synthesis reaction conditions. Copper-exchanged zeolites, which are widely used in automotive emissions control potential catalysts partial methane oxidation, have particular evidenced a wide variety Cu structures that observed to change with exposure conditions, zeolite composition, topology. Here, we develop predictive models CHA, MOR, BEA, AFX, FER topologies using interatomic potentials, quantum chemical calculations, Monte Carlo simulations interrogate this vast configurational compositional space. Model predictions rationalize experimentally differences between Cu-zeolites wide-body literature, including populations, structural variations, methanol per yields. Our results show both topological features commonly Al-siting biases MOR increase population binuclear sites, explaining small mononuclear sites these materials relative other such as CHA BEA. Finally, machine learning classification model determine preference form or at different Al configurations 200 international database. reveal several extreme ends vs spectrum, highlighting synthetic options realization strong preferences.

Язык: Английский

---

Dynamic Evolution of Zeolite Framework and Metal-Zeolite Interface

ACS Catalysis, Год журнала: 2022, Номер 12(9), С. 5060 - 5076

Опубликована: Апрель 14, 2022

Zeolites and metal-zeolites are a class of porous materials that have been widely utilized in industry. So far, several fundamental questions relating to the dynamic evolution zeolite framework metal-zeolite interface remain unanswered. Contrary classical view zeolites as static, rigid, changeless material, atoms foreign metals can dynamically interconvert under pretreatment or reaction conditions, making it difficult identify real active centers mechanisms. With development characterization techniques theoretical calculations, more profound understanding at atomic scale has achieved. This critical Review will feature recent progress metal-zeolites, mainly focusing on T–O–T bonds breaking formation, metal valence state transformation, phase evolution, migration. We compare these proposed mechanisms analyze their suitability distinct experimental conditions. highlight identification sites catalytic mechanism should be cautious consider Finally, we summarize usages limitations different characteristic techniques, propose some future research directions about hope bridge gaps between knowledge achieved characterizations nature guide zeolite-based synthesis, modification, application.

Язык: Английский

---

Effects of Al distribution in the Cu-exchanged AEI zeolites on the reaction performance of continuous direct conversion of methane to methanol

Applied Catalysis B Environment and Energy, Год журнала: 2023, Номер 325, С. 122395 - 122395

Опубликована: Янв. 11, 2023

Язык: Английский

---

Mechanisms and site requirements for NO and NH3 oxidation on Cu/SSZ-13

Applied Catalysis B Environment and Energy, Год журнала: 2024, Номер 346, С. 123726 - 123726

Опубликована: Янв. 15, 2024

Язык: Английский

---

Exploring the Impact of Active Site Structure on the Conversion of Methane to Methanol in Cu‐Exchanged Zeolites

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(23)

Опубликована: Апрель 4, 2024

Abstract In the past, Cu‐oxo or ‐hydroxy clusters hosted in zeolites have been suggested to enable selective conversion of methane methanol, but impact active site's stoichiometry and structure on methanol production is still poorly understood. Herein, we apply theoretical modeling conjunction with experiments study these two factors partial oxidation Cu‐exchanged zeolite SSZ‐13. Phase diagrams developed from first‐principles suggest that Cu‐hydroxy dimers are stabilized when O 2 N used activate catalyst, respectively. We confirm predictions experimentally determine a stepwise process, can convert twice as much compared Cu‐hydroxyl dimers. Our models rationalize how Cu‐di‐oxo up molecules while Cu‐di‐hydroxyl only one molecule per catalytic cycle. These findings imply Cu clusters, at least oxo group hydroxyl groups needed This simple structure–activity relationship allows intuitively understand potential small oxygenated hydroxylated transition metal methanol.

Язык: Английский

---

Direct Methane to Methanol Conversion: An Overview of Non‐Syn Gas Catalytic Strategies

The Chemical Record, Год журнала: 2025, Номер unknown

Опубликована: Янв. 16, 2025

Abstract Direct methane to methanol conversion is a dream reaction in industrial chemistry, which takes inspiration from the biological production catalysed by monooxygenase enzymes (MMOs). Over years, extensive studies have been conducted on this topic bioengineering MMOs, and tailoring methods isolate MMOs active form. Similarly, remarkable achievements noted other activation strategies such as use of heterogeneous catalysts or molecular catalysts. In review, we outline metabolism performed methanotrophs detail latest advancements site structures catalytic mechanisms both types MMOs. Also, recent progress bioinspired approaches using various catalysts, especially first‐row transition metal zeolites mechanistic insights are discussed. addition, complexes “Periana catalyst” for through methyl ester formation presence strong acids also detailed. Compared zeolites‐mediated field, utilisation application still its nascent phase further research required overcome limitations these effectively.

Язык: Английский

---

Kinetic Model for the Reduction of Cu^II Sites by NO + NH₃ and Reoxidation of NH₃-Solvated Cu^I Sites by O₂ and NO in Cu-SSZ-13

ACS Catalysis, Год журнала: 2022, Номер 12(11), С. 6418 - 6433

Опубликована: Май 16, 2022

In this work, a kinetic model is developed for the reduction of CuII sites by NO + NH3 and reoxidation NH3-solvated CuI O2 in Cu-SSZ-13. Fourier transform infrared (FTIR) spectroscopy spatially resolved capillary inlet mass spectrometry (SpaciMS) measurements during transient reactor experiments are utilized to identify rate parameters associated with RHC (reduction half-cycle), proposed occur via two distinct pathways involving adsorbed gas-phase NH3. The resulting validated using spatiotemporal N2 covering wide range temperatures (200–450 °C) space velocities (53 000–640 000 h–1). N2O formation observed modeled RHC, quantitative validation under standard selective catalytic (SCR) conditions. Experimentally measured enthalpic entropic changes adsorption on (ZCu(NH3)2) complexes [Kamasamudram, K. Catal. Today 2010, 151(3–4), 212−222], along activation energies estimated computationally intercage diffusion ZCu(NH3)2 [Paolucci, C. Science 2017, 357(6 354), 898−903], incorporated into mean field low-temperature oxidation half-cycle (OHC). Significant release isothermal sites, attributed desorption ligands from dimers (Z2Cu2(NH3)4O2). Reduction these dimeric leads consumption one NO/CuII, contradicting expected stoichiometry. Inclusion global Arrhenius titration Z2Cu2(NH3)4O2 provides accurate representations SCR reduced oxidized catalysts, predicting between 150 250 °C as function hydrothermal aging. Deactivation at high pressures, superoxo amino (ZCu(NH3)3OO*) [Negri, J. Am. Chem. Soc. 2020, 142(37), 15884−15896]. redox presented here foundational description active site SCR, combining recent kinetic, spectroscopic, computational findings mechanism over

Язык: Английский

---

Relationships among the Catalytic Performance, Redox Activity, and Structure of Cu-CHA Catalysts for the Direct Oxidation of Methane to Methanol Investigated Using In Situ XAFS and UV–Vis Spectroscopies

ACS Catalysis, Год журнала: 2022, Номер 12(4), С. 2454 - 2462

Опубликована: Фев. 3, 2022

Catalytic reaction systems for the direct conversion of methane to methanol have been previously developed using Cu zeolites. Among these materials, Cu-CHA has reported show relatively high catalytic performance during CH4–O2–H2O mixtures, although this activity varies with composition. In present study, four catalysts having different compositions and levels were prepared, redox properties local structures specimens analyzed in situ X-ray absorption fine structure UV–vis diffuse reflectance spectroscopies conjunction a mixture. The relationships between rates materials activities (as reflected turnover frequency (TOF) CH4 oxidation) assessed, analysis showed that reduction rate was highly correlated activity. data also suggested Cu2+ is associated activation C–H bonds CH4, which rate-determining step overall reaction. effects on selectivity CH3OH, TOF value, studied. Those samples proportions ions coordinated six-membered rings (Z2Cu) CHA framework exhibited higher than [CuOH]+ eight-membered (ZCuOH), values former not those latter because slower species. catalyses can be attributed difference Cu2Ox active formed Z2Cu-rich ZCuOH-rich samples.

Язык: Английский

---