Recognizing the best catalyst for a reaction

Nature Reviews Chemistry, Год журнала: 2023, Номер 7(4), С. 287 - 295

Опубликована: Фев. 23, 2023

Язык: Английский

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Sustainable Energy Resources for Driving Methane Conversion

Advanced Energy Materials, Год журнала: 2023, Номер 13(36)

Опубликована: Авг. 13, 2023

Abstract The conversion of methane to value‐added chemicals by traditional reforming processes suffers from intensive energy consumption due its particularly strong C─H bonds. Thus, it is urgent optimize the driving force structure for accelerating integration sustainable energy. In this review, advances in energy‐driven are systematically summarized provide a scientific understanding operation/storage concepts, reactor design, technological maturity, system optimization, and remaining issues. Furthermore, essence, economic evaluations, balance, social impacts driven carefully discussed, paving path future course research development. Diversifying mix can play an important role industries, being used as crucial step transition energy, especially combination solar/nuclear with fossil fuels produce chemicals. Additionally, review intends bridge studies development, ultimate goal offering robust framework understand current status guidance design solutions greener future.

Язык: Английский

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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

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Continuous Synthesis of Methanol from Methane and Steam over Copper-Mordenite

ACS Catalysis, Год журнала: 2021, Номер 11(3), С. 1065 - 1070

Опубликована: Янв. 8, 2021

One-step methane-to-methanol conversion is a "dream reaction" for chemists. In this Letter, continuous direct of methane into methanol with steam under mild conditions using Cu(II)-exchanged mordenite reported. The production rate depended on the Si/Al ratio, Cu/Al presence Brønsted acid sites, and O2 concentration in feed. Cu-H-mordenite Cu-Na-mordenite showed comparable rates, but former provided higher selectivity. At given gave volcano plot as function selectivity decreased increasing ratio. These experimental data DFT calculation implied that binuclear copper species are more active than mononuclear oxide clusters favorable total oxidation.

Язык: Английский

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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

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Metal–Organic Framework-Encaged Monomeric Cobalt(III) Hydroperoxides Enable Chemoselective Methane Oxidation to Methanol

ACS Catalysis, Год журнала: 2022, Номер 12(18), С. 11159 - 11168

Опубликована: Авг. 31, 2022

Developing highly efficient catalysts for chemoselective oxidation of methane to methanol under mild conditions is a grand challenge. We report the successful design and synthesis heterogeneous single-site cobalt hydroxide catalyst [Ce-UiO-Co(OH)] supported by nodes cerium metal–organic framework (Ce-UiO-66 MOF), which in partial using hydrogen peroxide at 80 °C, giving an extraordinarily high yield 2166 mmol gcat–1 99% selectivity with turnover number 3250. The Ce-UiO-Co significantly more active selective than its iso-structural zirconium analogue Zr-UiO-Co conversion. Experimental computational studies suggest formation CoIII(η2-hydroperoxide) intermediate coordinating one μ4-O– two neutral carboxylate oxygens Ce4+ oxo within pores Ce-UiO-66, undergoes σ-bond metathesis C–H bond limiting step catalytic cycle. lower activation energy due electron-deficient nature ion Co(η2-O2H) species Ce-UiO nodes, promotes facile via metathesis. This MOF-based holds promise developing molecular electrophilic abundant metal functionalization saturated hydrocarbons.

Язык: Английский

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Confined Cu-OH single sites in SSZ-13 zeolite for the direct oxidation of methane to methanol

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Ноя. 24, 2023

Abstract The direct oxidation of methane to methanol (MTM) remains a significant challenge in heterogeneous catalysis due the high dissociation energy C-H bond and desorption methanol. In this work, we demonstrate breakthrough selective MTM by achieving space-time yield 2678 mmol molCu−1 h−1 with 93% selectivity continuous methane-steam reaction at 400 °C. superior performance is attributed confinement effect 6-membered ring (6MR) voids SSZ-13 zeolite, which host isolated Cu-OH single sites. Our results provide deeper understanding role Cu-zeolites conversion pave way for further improvement.

Язык: Английский

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Partially Bonded Aluminum Site on the External Surface of Post-treated Au/ZSM-5 Enhances Methane Oxidation to Oxygenates

ACS Catalysis, Год журнала: 2024, Номер 14(3), С. 1797 - 1807

Опубликована: Янв. 19, 2024

Au nanoparticles supported on the exterior surface of ZSM-5 zeolite (Au/ZSM-5) have shown ability to partially oxidize methane methanol and acetic acid. However, further improvements catalyst activity are required. This study investigates effect modifying acidic properties support through a desilication–recrystallization (DR) process Au/ZSM-5 catalysts toward oxidation. A DR treatment 24 h leads 50% higher oxygenate yield compared analogous prepared using untreated support. Characterization solid-state 27Al NMR FTIR adsorption pyridine 2,4,6-trimethylpyridine reveals that induces framework dealumination redistribution Brønsted acid sites external surface. Two-dimensional MQMAS identifies coordinated Al surface, correlating with yield. These help stabilize nanoparticles, enhancing stability for partial

Язык: Английский

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Water-participated mild oxidation of ethane to acetaldehyde

Nature Communications, Год журнала: 2024, Номер 15(1)

Опубликована: Март 22, 2024

Abstract The direct conversion of low alkane such as ethane into high-value-added chemicals has remained a great challenge since the development natural gas utilization. Herein, we achieve an efficient one-step to C 2 oxygenates on Rh 1 /AC-SNI catalyst under mild condition, which delivers turnover frequency high 158.5 h −1 . 18 O isotope-GC–MS shows that formation ethanol and acetaldehyde follows two distinct pathways, where oxygen water directly participate in acetaldehyde, respectively. In situ formed intermediate species radicals, hydroxyl vinyl groups, ethyl groups are captured by laser desorption ionization/time flight mass spectrometer. Density functional theory calculation activation barrier rate-determining step for is much lower than ethanol, leading higher selectivity all products.

Язык: Английский

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Synthetic Fuels Based on Dimethyl Ether as a Future Non-Fossil Fuel for Road Transport From Sustainable Feedstocks

Frontiers in Energy Research, Год журнала: 2021, Номер 9

Опубликована: Май 28, 2021

In this review we consider the important future of synthetic fuel, dimethyl ether (DME). We compare DME to two alternatives [oxymethylene (OME x ) and diesel through Fischer-Tropsch (FT) reactions]. Finally, explore a range methodologies processes for synthesis DME. is an alternative fuel use in compression ignition (CI) engines may be produced from waste feedstocks, thereby avoiding new fossil carbon entering supply chain. characterised by low CO 2 , NOx particulate matter (PM) emissions. Its high cetane number means it can used CI with minimal modifications. The key creating circular fuels economy integrating multiple streams into economically environmentally sustainable Therefore, also availability nature low-carbon hydrogen production. Reliable dioxide sources are essential if utilisation become commercially viable. location plants will depend on local ecosystems ideally should co-located or near emitters energy sources. Alternative liquid considered interesting medium term, while renewable electricity as reliable long-term solutions transport sector. carrier which able store at times power generation. chemistry individual steps within chain generally well known usually relies cheap Earth-abundant metal catalysts. thermodynamics these well-characterised. So overcoming challenge now expertise chemical engineers put fundamentals commercial practice. It that whole systems approach adopted interventions have detrimental unintended consequences unless close monitoring applied. This shows production has been achieved great promise, there considerable effort needed reach true net zero emissions sector, particularly long-haul road use, require timescales.

Язык: Английский

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