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As a clean fossil energy and chemical feedstock, development of breakthrough strategies for direct conversion of methane (CH4) into various chemicals under mild reaction conditions is highly desired. Herein, Rh/ZSM‐5 catalyst was reported to convert CH4 to oxygenates with molecular oxygen (O2) in the presence of CO at low temperature with promising catalytic performance. The oxygenates productivity reached as high as 5638.0 μmol gcat.−1 h−1. Structure characterization confirmed the existence of highly dispersed Rh2O3 nanoparticles with an average diameter of 2.4 nm in the Rh/ZSM‐5 catalyst. Based on control experiments and mechanism study, it was suggested that CO plays a pivotal role over the Rh/ZSM‐5 catalyst to boost direct oxidation of methane. CO participates in water‐gas‐shift reaction to produce in‐situ H species, which enables to form *OH, *OOH and H2O2 active species by reacting with O2. The as‐obtained *OH, *OOH and H2O2 species will thus render high activity for methane oxidation. [ABSTRACT FROM AUTHOR]

Selective oxidation of methane to oxygenates using low‐cost and environment‐friendly molecular oxygen (O2) under mild reaction conditions is a promising strategy but still remains grand challenge. It is of great importance to accelerate the activation of O2 to generate highly active oxygen species, such as hydroxyl peroxide and hydroxyl species to improve catalytic performance for selective oxidation of methane. Selective oxidation of methane using O2 by coupling with in situ generation of hydrogen peroxide via tandem catalysis ensures the easy formation of active oxygen species for methane activation, leading to high oxygenates productivity under mild conditions. In this concept, we summarized the recent progresses for selective oxidation of methane to oxygenates using O2 based on tandem catalysis by coupling with in situ generation of hydrogen peroxide. The remaining challenges and future perspectives for selective oxidation of methane to oxygenates via tandem catalysis were also proposed. [ABSTRACT FROM AUTHOR]

Highly selective conversion of methane to oxygenates with O2 as a green oxidant remains a great challenge. It is still difficult to suppress the generation of COx (x=1, 2) as undesired by‐products due to unavoidable overoxidation reaction. Hence, tungsten‐doped (W‐doped) TiO2 photocatalysts were designed with a tunable band structure for photocatalytic oxidation of methane to C1 oxygenates using O2 at low temperature (30 °C). The W‐doping effectively modified the electronic and band structure of pristine TiO2 to enhance photocatalytic performance. Liquid oxygenates productivity could reach as high as 12.2 mmol g−1 with high selectivity of 99.4 %. Moreover, COx selectivity was effectively decreased from 21.2 % over TiO2 to 0.6 % for W‐doped catalyst. Detailed characterizations further disclosed that W‐doping not only enhanced light absorption, but also promoted the separation of photo‐generated carriers to improve methane conversion. This work provides new insights into the design of highly efficient photocatalysts for methane oxidation. [ABSTRACT FROM AUTHOR]

Selective oxidation of methane to oxygenates with O2 under mild conditions remains a great challenge. Here we report a ZSM‐5 (Z‐5) supported PdCu bimetallic catalyst (PdCu/Z‐5) for methane conversion to oxygenates by reacting with O2 in the presence of H2 at low temperature (120 °C). Benefiting from the co‐existence of PdO nanoparticles and Cu single atoms via tandem catalysis, the PdCu/Z‐5 catalyst exhibited a high oxygenates yield of 1178 mmol g−1Pd h−1 (mmol of oxygenates per gram Pd per hour) and at the same time high oxygenates selectivity of up to 95 %. Control experiments and mechanistic studies revealed that PdO nanoparticles promoted the in situ generation of H2O2 from O2 and H2, while Cu single atoms not only accelerated the activation of H2O2 for the generation of abundant hydroxyl radicals (⋅OH) from H2O2 decomposition, but also enabled the homolytic cleavage of CH4 by ⋅OH to methyl radicals (⋅CH3). Subsequently, the ⋅OH reacted quickly with the ⋅CH3 to form CH3OH with high selectivity. [ABSTRACT FROM AUTHOR]

Cu single atoms embedded in the C3N4 (Cu-SAs/C3N4) matrix exhibited high activity with 95% oxygenate selectivity for the direct conversion of methane at ambient temperature. The presence of abundant anchoring sites in C3N4 led to highly dispersed Cu–N4 moieties, which were suggested to be the underlying active sites for methane conversion. [ABSTRACT FROM AUTHOR]

Cobalt carbide (Co2C) exhibits strong facet effect for Fischer‐Tropsch to olefins (FTO) reaction. Herein, we report that the facet proportion of Co2C nanostructures can be tuned effectively by incorporating and altering the Mn content in the CoMn composite oxide as catalyst precursor. With the addition of Mn promoter, the Co2C nanoprisms with exposed (020) and (101) facets are generated under reaction conditions. In addition, the facet proportion of Co2C(020) facet can be effectively improved by enhancing the Mn/Co ratio. With the increase of facet proportion of Co2C(020)/Co2C(101) ratio, the as‐obtained Co2C nanoprisms exhibit higher intrinsic activity and lower methane selectivity during the syngas conversion process. Kinetic experiments also demonstrate that the apparent activation energy (Ea) for CO conversion is significantly reduced as increasing the facet proportion of Co2C(020). This work provides a simple and feasible way to tune the exposed facet proportion for the rational design of Co2C nanocatalyst for FTO reaction. [ABSTRACT FROM AUTHOR]

Direct conversion of methane to acetic acid with high activity and selectivity over non-noble metal-based catalysts under mild reaction conditions remains a grand challenge. Specifically, 1.2Ni-ZSM-5 with 88.9 % isolated Ni sites achieved a high acetic acid yield of 2920 μ mol/g cat. and a remarkable selectivity up to 82.3 % from methane oxidative carbonylation. Combined with high angle annular dark field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy analyses, it was revealed that the isolated Ni species with Ni-O 6 moieties anchored in the micropores of ZSM-5 were suggested to be the active sites. The isotopic labeling experiments and monitoring of reaction intermediates demonstrated that CH 3 COOH was formed via the direct coupling of methyl radicals and carbon monoxide molecules. This work suggests that the well-designed Ni sites can promote the transformation of CH 4 to C 2+ oxygenates instead of traditional C 1 oxygenates as main products. [Display omitted] • Non-noble Ni-based catalyst can promote the oxidative carbonylation of CH 4 to C 2+ oxygenates. • 2920 μ mol/g cat. of oxygenated products can be acquired with 82.3 % of CH 3 COOH selectivity. • The catalytic performance of Ni-ZSM-5 is comparable to these noble metal-based catalysts. • Isolated Ni sites anchored on zeolites was identified as active center. • The CH 3 COOH was formed via the direct coupling of ·CH 3 radicals and CO. [ABSTRACT FROM AUTHOR]

The effects of preparation methods of CoMn-based catalysts on the precursor phase of Co species, the morphology of Co 2 C nanostructures as well as the catalytic performance for Fischer-Tropsch to olefins were investigated. • The effects of preparation methods on CoMn catalysts were investigated. • Preparation methods influenced the precursor phase of Co species. • The interaction extent of Co and Mn influenced the reduction process. • Co x Mn 1-x O structure benefited for the formation of Co 2 C nanoprisms. • Co 2 C nanoprisms exhibited better FTO performance than nanospheres. The effects of preparation methods for CoMn-based catalysts on the precursor phase of Co species, the morphology of Co 2 C nanostructures as well as the catalytic performance for Fischer-Tropsch to olefins were investigated. Five catalysts prepared by precipitation and impregnation methods were compared in detail. CoMn spinel oxide was found in the calcined catalysts prepared by co-precipitation or sequential precipitation starting from the Co salt. However, Co 3 O 4 and MnO 2 were the major phases for the calcined catalysts prepared by sequential precipitation starting from the Mn salt or impregnation methods. During the syngas conversion process, Co 2 C nanoprisms with exposed facets of (101) and (020) were generated from CoMn spinel phase, and exhibited high CO conversion, low methane selectivity and high olefins selectivity. In contrast, Co 2 C nanospheres carburized from metallic Co or CoO were observed for the other samples with poorer FTO catalytic performance. [ABSTRACT FROM AUTHOR]