Atomically Dispersed Iron-Copper Dual-Metal Sites Synergistically Boost Carbonylation of Methane.

The direct liquid-phase oxidative carbonylation of methane, utilizing abundant natural gas, offers a mild and straightforward alternative. However, most catalysts proposed for this process suffer from low acetic acid yields due to few active sites and rapid C1 oxygenate generation, impeding their industrial feasibility. Herein, we report a highly efficient 0.1Cu/Fe-HZSM-5-TF (TF denotes template-free synthesis) catalyst featuring exclusively mononuclear Fe and Cu anchored in the ZSM-5 channels. Under optimized conditions, the catalyst achieved an unprecedented acetic acid yield of 40.5 mmol gcat -1 h-1 at 50 °C, tripling the previous records of 12.0 mmol gcat -1 h-1. Comprehensive characterization, isotope-labeled experiments and density functional theory (DFT) calculations reveal that the homogeneous mononuclear Fe sites are responsible for the activation and oxidation of methane, while the neighboring Cu sites play a key role in retarding the oxidation process, promoting C-C coupling for effective acetic acid synthesis. Furthermore, the methyl-group carbon in acetic acid originates solely from methane, while its carbonyl-group carbon is derived exclusively from CO, rather than the conversion of other C1 oxygenates. The proposed bimetallic catalyst design not only overcomes the limitations of current catalysts but also generalizes the oxidative carbonylation of other alkanes, demonstrating promising advancements in sustainable chemical synthesis.

Photocatalytic Multicomponent Annulation of Amide-Anchored 1,7-Diynes Enabled by Deconstruction of Bromotrichloromethane.

We present the first example of visible-light-mediated multicomponent annulation of 1,7-diynes by taking advantage of quadruple cleavage olf carbon-halogen bonds of BrCCl3 to generate a C1 synthon, which was adeptly applied to the preparation of skeletally diverse 3-benzoyl-quinolin-2(1H)-one acetates in moderate to good yields. Controlled experiments demonstrated that H2O acted as both oxygen and hydrogen sources, and gem-dichlorovinyl carbonyl compound exhibited as a critical intermediate in this process. The mechanistic pathway involves Kharasch-type addition/6-exo-dig cyclization/1,5-(SN")-substitution/elimination/binucleophilic 1,6-addition/proton transfer/tautomerization sequence.

Photodegradable polar-functionalized polyethylenes.

The degradation of plastics has attracted much attention from the global community. Polyethylenes (PEs), as the most abundant synthetic plastics, are most frequently studied. PE is non-degradable and non-polar because of the sole presence of the pure hydrocarbon components. Concurrent incorporation of both in-chain cleavable and functional groups into the PE chain is an effective pathway to overcome the non-degradable and non-polar issue; however, the method for achieving this pathway remains elusive. Here, we report a strictly non-alternating (>99%) terpolymerization of ethylene with CO and fundamental polar monomers via a coordination-insertion mechanism using late transition metal catalysts, which effectively prevents the formation of undesired chelates originating from both co-monomers under a low CO concentration. High-molecular-weight linear PEs with both in-chain isolated keto (>99%) and main-chain functional groups are prepared. The incorporation of key low-content isolated keto groups makes PEs photodegradable while retaining their desirable bulk material properties, and the introduction of polar functional groups considerably improves their surface properties.

Tuning Ionic Liquid-Based Catalysts for CO2 Conversion into Quinazoline-2,4(1H,3H)-diones.

Carbon capture and storage (CCS) and carbon capture and utilization (CCU) are two kinds of strategies to reduce the CO2 concentration in the atmosphere, which is emitted from the burning of fossil fuels and leads to the greenhouse effect. With the unique properties of ionic liquids (ILs), such as low vapor pressures, tunable structures, high solubilities, and high thermal and chemical stabilities, they could be used as solvents and catalysts for CO2 capture and conversion into value-added chemicals. In this critical review, we mainly focus our attention on the tuning IL-based catalysts for CO2 conversion into quinazoline-2,4(1H,3H)-diones from o-aminobenzonitriles during this decade (2012~2022). Due to the importance of basicity and nucleophilicity of catalysts, kinds of ILs with basic anions such as [OH], carboxylates, aprotic heterocyclic anions, etc., for conversion CO2 and o-aminobenzonitriles into quinazoline-2,4(1H,3H)-diones via different catalytic mechanisms, including amino preferential activation, CO2 preferential activation, and simultaneous amino and CO2 activation, are investigated systematically. Finally, future directions and prospects for CO2 conversion by IL-based catalysts are outlined. This review is benefit for academic researchers to obtain an overall understanding of the synthesis of quinazoline-2,4(1H,3H)-diones from CO2 and o-aminobenzonitriles by IL-based catalysts. This work will also open a door to develop novel IL-based catalysts for the conversion of other acid gases such as SO2 and H2S.

Excess CO2 Reductions during CH3 COOH Formation from CH4 and CO2 under Periodic Operation: Downhill Side Reactions in an Uphill Target Reaction under Unsteady Conditions.

Acetic acid (CH3 COOH) formation from methane (CH4 ) and carbon dioxide (CO2 ) is an ideal reaction for chemical production, whereas this reaction possesses a severe thermodynamic limitation. To address this issue, it has been reported that periodic operation allowing a non-equilibrium condition can overcome the thermodynamic limitation. However, although an intrinsic issue of uphill reactions in non-equilibrium conditions generally is occurrence of unfavorable downhill reactions, this issue has seldom been discussed for the CH3 COOH formation under periodic operation. Herein, excess CO2 reductions were found to be the unfavorable downhill reactions possibly occurring in the reaction aiming at CH3 COOH formation under periodically operated CH4 and CO2 feeds. The reaction using an isotopic reactant (i. e., 13 CH4 ) unveiled that excess CO2 reductions to CO and even to CH3 moiety could occur, indicating importance of catalyst development. Furthermore, it was proposed that H2 O vapor introduction into the CO2 feed, which increased the CH3 COOH product, most likely facilitated the reverse reaction of the excess CO2 reductions and thereby is effective to hamper the unfavorable side reaction.

Applications of Zeolites to C1 Chemistry: Recent Advances, Challenges, and Opportunities.

C1 chemistry, which is the catalytic transformation of C1 molecules including CO, CO2 , CH4 , CH3 OH, and HCOOH, plays an important role in providing energy and chemical supplies while meeting environmental requirements. Zeolites are highly efficient solid catalysts used in the chemical industry. The design and development of zeolite-based mono-, bi-, and multifunctional catalysts has led to a booming application of zeolite-based catalysts to C1 chemistry. Combining the advantages of zeolites and metallic catalytic species has promoted the catalytic production of various hydrocarbons (e.g., methane, light olefins, aromatics, and liquid fuels) and oxygenates (e.g., methanol, dimethyl ether, formic acid, and higher alcohols) from C1 molecules. The key zeolite descriptors that influence catalytic performance, such as framework topologies, nanoconfinement effects, Brønsted acidities, secondary-pore systems, particle sizes, extraframework cations and atoms, hydrophobicity and hydrophilicity, and proximity between acid and metallic sites are discussed to provide a deep understanding of the significance of zeolites to C1 chemistry. An outlook regarding challenges and opportunities for the conversion of C1 resources using zeolite-based catalysts to meet emerging energy and environmental demands is also presented.

From Solar Energy to Fuels: Recent Advances in Light-Driven C1 Chemistry.

Catalytic C1 chemistry based on the activation/conversion of synthesis gas (CO+H2 ), methane, carbon dioxide, and methanol offers great potential for the sustainable development of hydrocarbon fuels to replace oil, coal, and natural gas. Traditional thermal catalytic processes used for C1 transformations require high temperatures and pressures, thereby carrying a significant carbon footprint. In comparison, solar-driven C1 catalysis offers a greener and more sustainable pathway for manufacturing fuels and other commodity chemicals, although conversion efficiencies are currently too low to justify industry investment. In this Review, we highlight recent advances and milestones in light-driven C1 chemistry, including solar Fischer-Tropsch synthesis, the water-gas-shift reaction, CO2 hydrogenation, as well as methane and methanol conversion reactions. Particular emphasis is placed on the rational design of catalysts, structure-reactivity relationships, as well as reaction mechanisms. Strategies for scaling up solar-driven C1 processes are also discussed.

Activation of Gold on Metal Carbides: Novel Catalysts for C1 Chemistry.

This article presents a review of recent uses of Au-carbide interfaces as catalysts for C1 Chemistry (CO oxidation, low-temperature water-gas shift, and CO2 hydrogenation). The results of density-functional calculations and photoemission point to important electronic perturbations when small two-dimensional clusters of gold are bounded to the (001) surface of various transition metal carbides (TiC, ZrC, VC, Ta C, and δ-MoC). On these surfaces, the C sites exhibited strong interactions with the gold clusters. On the carbide surfaces, the Au interacts stronger than on oxides opening the door for strong metal-support interactions. So far, most of the experimental studies with well-defined systems have been focused on the Au/TiC, Au/δ-MoC, and Au/ß-Mo2C interfaces. Au/TiC and Au/δ-MoC are active and stable catalysts for the low-temperature water-gas shift reaction and for the hydrogenation of CO2 to methanol or CO. Variations in the behavior of the Au/δ-MoC and Au/ß-Mo2C systems clearly show the strong effect of the metal/carbon ratio on the performance of the carbide catalysts. This parameter substantially impacts the chemical behavior of the carbide and its interaction with supported metals, up to the point of modifying the reaction rate and mechanism of C1 processes.

Two-Dimensional Layered Double Hydroxides for Reactions of Methanation and Methane Reforming in C1 Chemistry.

CH4 as the paramount ingredient of natural gas plays an eminent role in C1 chemistry. CH4 catalytically converted to syngas is a significant route to transmute methane into high value-added chemicals. Moreover, the CO/CO2 methanation reaction is one of the potent technologies for CO2 valorization and the coal-derived natural gas production process. Due to the high thermal stability and high extent of dispersion of metallic particles, two-dimensional mixed metal oxides through calcined layered double hydroxides (LDHs) precursors are considered as the suitable supports or catalysts for both the reaction of methanation and methane reforming. The LDHs displayed compositional flexibility, small crystal sizes, high surface area and excellent basic properties. In this paper, we review previous works of LDHs applied in the reaction of both methanation and methane reforming, focus on the LDH-derived catalysts, which exhibit better catalytic performance and thermal stability than conventional catalysts prepared by impregnation method and also discuss the anti-coke ability and anti-sintering ability of LDH-derived catalysts. We believe that LDH-derived catalysts are promising materials in the heterogeneous catalytic field and provide new insight for the design of advance LDH-derived catalysts worthy of future research.

Design and Synthesis of Powerful Capsule Catalysts Aimed at Applications in C1 Chemistry and Biomass Conversion.

Tandem catalytic reaction is a promising strategy to improve the utilization efficiency of energy and resources. The conventional hybrid catalysts cannot readily realize the precisely controlled synthesis of target products due to the unrestricted, open reaction environment. Assembling the hybrid catalyst with multiple active sites into core-shell structured capsule catalyst is one of the most effective ways to enhance the selectivity of desired products during a tandem catalysis process, because the core-shell structure offers a space-confined reaction field and synergistic effect. This review describes our recent progresses on the design and synthesis of core-shell structured zeolite capsule catalysts developed for C1 chemistry and biomass conversion. The various synthesis methods for constructing the well-defined zeolite capsule catalysts are described in detail. The applications of the capsule catalysts in catalysis, including the middle isoparaffins synthesis from syngas, one-step synthesis of dimethyl ether, and liquid-phase tandem reaction of glycerol conversion, are discussed, respectively. Our perspectives regarding the challenges and opportunities for future research in the field are also provided.

Europium Oxybromide Catalysts for Efficient Bromine Looping in Natural Gas Valorization.

The industrialization of bromine-mediated natural gas upgrading is contingent on the ability to fully recycle hydrogen bromide (HBr), which is the end form of the halogen after the activation and coupling of the alkanes. Europium oxybromide (EuOBr) is introduced as a unique catalytic material to close the bromine loop via HBr oxidation, permitting low-temperature operation and long lifetimes with a stoichiometric feed (O2 :HBr=0.25)-conditions at which any catalyst reported to date severely deactivates because of excessive bromination. Besides, EuOBr exhibits unparalleled selectivity to methyl bromide in methane oxybromination, which is an alternative route for bromine looping. This novel active phase is finely dispersed on appropriate carriers and scaled up to technical extrudates, enhancing the utilization of the europium phase while preserving the performance. This catalytic system paves the way for sustainable valorization of stranded natural gas via bromine chemistry.

Selective Production of Carbon Monoxide via Methane Oxychlorination over Vanadyl Pyrophosphate.

A catalytic process is demonstrated for the selective conversion of methane into carbon monoxide via oxychlorination chemistry. The process involves addition of HCl to a CH4 -O2 feed to facilitate C-H bond activation under mild conditions, leading to the formation of chloromethanes, CH3 Cl and CH2 Cl2 . The latter are oxidized in situ over the same catalyst, yielding CO and recycling HCl. A material exhibiting chlorine evolution by HCl oxidation, high activity to oxidize chloromethanes into CO, and no ability to oxidize CO, is therefore essential to accomplish this target. Following these design criteria, vanadyl pyrophosphate (VPO) was identified as an outstanding catalyst, exhibiting a CO yield up to approximately 35 % at 96 % selectivity and stable behavior. These findings constitute a basis for the development of a process enabling the on-site valorization of stranded natural-gas reserves using CO as a highly versatile platform molecule.