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A Ru single-atom (Ru SA) catalyst supported on activated carbon was adopted to synthesize 3-pentanone with 83.3% selectivity via heterogeneous ethylene hydroformylation, while 52.1% ethane selectivity was obtained for Ru nanoparticles (Ru NPs). The atomically dispersed Ru species with oxidation state (Ruδ+) and Ru-C4O coordination structure were identified as the active sites for efficient C–C coupling to generate 3-pentanone, while metallic Ru nanoparticles exhibited high activity for ethylene hydrogenation to ethane. Density functional theory (DFT) calculation revealed that the energy barrier of the direct coupling of C2H5CO* with C2H5* to form 3-pentanone on Ru SA was much lower than that on Ru NPs. As a result, the formation of 3-pentanone over Ru SA was more favourable than propanal, which was admittedly generated via coupling of C2H5CO* and H*. This strategy may provide a potential green route for the one-pot synthesis of 3-pentanone with high atomic economy. [ABSTRACT FROM AUTHOR]

Selective synthesis of higher oxygenates (linear α‐alcohols and α‐aldehydes, C2+ OH) from syngas is highly attractive but remains challenging owing to the low C2+ OH selectivity and low catalytic stability. Herein we introduce a multifunctional catalyst composed of CoMn and CuZnAlZr oxides that dramatically increased the oxygenates selectivity to 58.1 wt %, where more than 92.0 wt % of the produced oxygenates are C2+ OH. Notably, the total selectivity to value‐added chemicals including oxygenates and olefins reached 80.6 wt % at CO conversion of 29.0 % with high stability. The appropriate component proximity can effectively suppress the formation of the undesired C1 products, and the selectively propulsion of reaction network by synergetic effect of different components contributes to the enhanced selectivity to higher oxygenates. This work provides an alternative strategy for the rational design of new catalysts for direct conversion of syngas into higher oxygenates with co‐production of olefins. A stable multifunctional catalyst composed of CoMn oxides and CuZnAlZr oxides was developed for direct conversion of syngas to higher oxygenates and olefins with a total selectivity of 80.6 wt % at a CO conversion of 29.0 %. The interaction manner of the two components plays a crucial role in suppressing C1 products formation and enhancing the selectivity to higher oxygenates. [ABSTRACT FROM AUTHOR]

Controlling product selectivity still remains as a grand challenge for syngas conversion to fuels and chemicals. Herein, ZnO modified CoMn-based catalysts were prepared for direct higher oxygenates synthesis via syngas conversion, and the role of Zn promoter on catalytic behaviour and structure evolution was investigated comprehensively. It was found that the addition of Zn greatly reduced the particle size of active phases including Co and Co 2 C. Specially, the Zn promoter facilitated the formation of Co 2 C species, thus effectively tuning the surface ratio of Co/Co 2 C and strengthening the function for CO associative adsorption and insertion for oxygenates product formation. As a result, the oxygenates selectivity was enhanced to 39.1 wt% over ZnO-promoted CoMn-based catalyst, where more than 96.0 wt% of the produced oxygenates are C 2+ products. In addition, Zn promoter can weaken the chain growth ability, leading to the increase of low carbon chain products. [Display omitted] • The addition of Zn promoter greatly reduced the particle size of Co and Co 2 C. • Zn promoter facilitated the formation of Co 2 C. • CO associative adsorption was strengthened for oxygenates formation with Zn addition. • The selectivity of oxygenates was enhanced to 39.1 wt% for Zn-promoted CoMn-based catalyst. [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]

The influence of impregnation sequences on the structure and performance of the Ru-based catalysts for olefins synthesis from syngas via Fischer-Tropsch reaction (FTO) was investigated. Among the catalysts studied, Na-Ru/SiO 2 (Na was impregnated before Ru) exhibited the highest CO conversion (43.5 %) and olefins yield (33.9 %). In contrast, Ru-Na/SiO 2 (Ru was impregnated before Na) showed the lowest CO conversion (26.6 %) and olefins yield (19.8 %). Characterization analysis indicated that Na-Ru/SiO 2 exhibited higher Ru dispersion. In addition, the structural configuration of Na-Ru/SiO 2 was found to enhance CO adsorption capabilities to create a C*-rich localized chemical environment, thereby increasing catalytic activity and olefins production. This study demonstrates a straightforward and effective approach to optimize Ru utilization for the design of Ru-based FTO catalysts. [Display omitted] • The effect of impregnation sequence over Ru-based FTO catalysts was investigated. • Na-Ru/SiO 2 exhibited the highest CO conversion and olefins yield. • High Ru dispersion was obtained on Na-Ru/SiO 2. • An effective method to enhance Ru utilization for FTO reaction was provided. [ABSTRACT FROM AUTHOR]

Graphical abstract Morphology control of Co 2 C nanostructures via reduction process was developed for direct production of lower olefins from syngas. The structure-performance of the as-obtained Co 2 C nanoprisms and nanospheres were investigated based on kinetic study and DFT calculations. Highlights • Morphology control of Co 2 C nanostructures via reduction process was developed. • Co 2 C nanoprisms or nanospheres can be obtained by controlling the reduction process. • The structure-performance of the as-obtained Co 2 C nanoprisms and nanospheres was investigated. • Co 2 C nanoprisms possessed higher activity and lower methane selectivity than Co 2 C nanospheres. • The product distribution of Co 2 C nanoprisms deviated from the ASF law. Abstract Fischer-Tropsch to olefins (FTO) is recognized as a surface-catalyzed structure-sensitive reaction, and the catalytic performance is strongly influenced by the morphology and exposed facets of the active phase. Here we report the effect of the reduction process on the morphology of the active phase and the catalytic performance for FTO over the CoMn catalyst. For the catalysts reduced by 10% CO-300 °C, 10% H 2 -300 °C and 10% H 2 -250 °C, Co 2 C nanoprisms were formed after reaching the steady state. However, for the catalysts reduced by CO-300 °C and 10% H 2 -400 °C, Co 2 C nanospheres were found instead. Both Co 2 C nanoprisms and nanospheres were present for the spent sample reduced by 10% H 2 -350 °C. Kinetic study found Co 2 C nanospheres to possess higher activation energy, and are more sensitive to hydrogen than Co 2 C nanoprisms. Density functional theory (DFT) calculations were also performed to clarify the structure-performance relationship of Co 2 C nanostructures for syngas conversion. [ABSTRACT FROM AUTHOR]

Selective conversion of syngas to olefins has aroused extensive attention while some challenges still existed such as high CO 2 selectivity. Herein, a series of hydrophobic FeMnO x @SiO 2 -y-(CH 3) 3 (y represents SiO 2 weight percent of the catalyst) catalysts with various SiO 2 shell content were synthesized for Fischer-Tropsch to olefins (FTO). During the activation process, high hydrophobic SiO 2 -coating content catalysts suppressed the reduction/carburization of iron species to iron carbide. During FTO reaction, iron carbide of low hydrophobic SiO 2 -coating content catalysts was re-oxidized while it was stabilized for high hydrophobic SiO 2 -coating content catalysts. The trade-off among CO 2 , CH 4 selectivity and SiO 2 -coating content was reflected as an increasing trend relationship, while olefins selectivity exhibited a decreasing trend. Additionally, a desirable hydrophobic SiO 2 -coating (8.2 wt%) catalyst apparently suppressed CO 2 formation (4.7 C%) with high olefins selectivity (54.6 C%) at CO conversion of 50.7%. This study provides an efficient approach to inhibit CO 2 formation of Fe-based FTO catalyst. [Display omitted] • Controllable hydrophobic SiO 2 shell of FeMnO x @SiO 2 catalysts were synthesized for FTO reaction. • The hydrophobic SiO 2 shell significantly decreased CO 2 selectivity by suppressing WGS reaction. • The hydrophobic SiO 2 shell content and olefins selectivity is reflected as a decreasing trend. [ABSTRACT FROM AUTHOR]

The calcination pretreatment of SiO 2 support exhibited a significant effect on the structure-performance of supported Co 2 C-based catalyst for Fischer-Tropsch to olefins. [Display omitted] • Effect of thermal pretreatment of SiO 2 support on FTO performance was investigated. • Promising FTO performance was achieved if SiO 2 support was pretreated at 990 °C. • The morphology of Co 2 C nanostructures can be tuned by controlling pretreatment of support. • The Si OH content affects metal-support interaction and morphology of Co 2 C. SiO 2 supported Co 2 C-based catalysts were used for Fischer-Tropsch to olefins (FTO), and the effect of thermal pretreatment of SiO 2 support under different temperatures on the Co 2 C morphology and catalytic performance was investigated. It was found that the interaction between cobalt and support was weakened when SiO 2 was pretreated at high temperature (990 °C) due to the decreased content of surface Si OH groups. The relative weak interaction between cobalt and support benefited the formation of cobalt manganese composite oxide after calcination and reduction, and thus promoted the generation of Co 2 C nanoprisms with promising FTO performance. In contrast, for the SiO 2 support pretreated at 350 °C or 650 °C, the strong interaction between cobalt and support led to phase separation of cobalt and manganese. As a result, only Co 2 C nanospheres were generated which displayed low activity and high methane selectivity. [ABSTRACT FROM AUTHOR]