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Syngas conversion is a useful technology for converting nonpetroleum carbon resources into chemicals such as olefins. Iron- and cobalt-based catalysts, as two major categories, have been extensively studied in Fischer–Tropsch synthesis to olefins (FTO) reactions. Although both iron and cobalt catalysts have shown distinct merits and shortcomings, they are also complementary in their properties and catalytic performances when combined with each other. Herein, Na-modified CoFe bimetallic catalysts were fabricated using a co-precipitation method. It was found that there was a synergistic effect between Co and Fe that promoted a CO dissociation rate and carburization, and an appropriate Co/Fe ratio was conducive to improvements in their catalytic performances. The desired olefins selectivity reached 66.1 C% at a CO conversion of 37.5% for a Co2Fe1 catalyst, while the methane selectivity was only 4.3 C%. In addition, no obvious deactivation was found after nearly 160 h, indicating their potential industrial application. [ABSTRACT FROM AUTHOR]

Syngas conversion provides an important platform for efficient utilization of various carbon-containing resources such as coal, natural gas, biomass, solid waste and even CO2. Various value-added fuels and chemicals including paraffins, olefins and alcohols can be directly obtained from syngas conversion via the Fischer–Tropsch Synthesis (FTS) route. However, the product selectivity control still remains a grand challenge for FTS due to the limitation of Anderson–Schulz–Flory (ASF) distribution. Our previous works showed that, under moderate reaction conditions, Co2C nanoprisms with exposed (101) and (020) facets can directly convert syngas to olefins with low methane and high olefin selectivity, breaking the limitation of ASF. The application of Co2C-based nanocatalysts unlocks the potential of the Fischer–Tropsch process for producing olefins. In this feature article, we summarized the recent advances in developing highly efficient Co2C-based nanocatalysts and reaction pathways for direct syngas conversion to olefins via the Fischer–Tropsch to olefin (FTO) reaction. We mainly focused on the following aspects: the formation mechanism of Co2C, nanoeffects of Co2C-based FTO catalysts, morphology control of Co2C nanostructures, and the effects of promoters, supports and reactors on the catalytic performance. From the viewpoint of carbon utilization efficiency, we presented the recent efforts in decreasing the CO2 selectivity for FTO reactions. In addition, the attempt to expand the target products to aromatics by coupling Co2C-based FTO catalysts and H-ZSM-5 zeolites was also made. In the end, future prospects for Co2C-based nanocatalysts for selective syngas conversion were proposed. [ABSTRACT FROM AUTHOR]

As is well known, CO2 is an attractive renewable C1 resource and H2 is a cheap and clean reductant. Combining CO2 and H2 to prepare building blocks for high-value-added products is an attractive yet challenging topic in green chemistry. A general and selective rhodium-catalyzed hydroformylation of alkenes using CO2/H2 as a syngas surrogate is described here. With this protocol, the desired aldehydes can be obtained in up to 97% yield with 93/7 regioselectivity under mild reaction conditions (25 bar and 80 °C). The key to success is the use of a bifunctional Rh/PTA catalyst (PTA: 1,3,5-triaza-7-phosphaadamantane), which facilitates both CO2 hydrogenation and hydroformylation. Notably, monodentate PTA exhibited better activity and regioselectivity than common bidentate ligands, which might be ascribed to its built-in basic site and tris-chelated mode. Mechanistic studies indicate that the transformation proceeds through cascade steps, involving free HCOOH production through CO2 hydrogenation, fast release of CO, and rhodium-catalyzed conventional hydroformylation. Moreover, the unconventional hydroformylation pathway, in which HCOOAc acts as a direct C1 source, has also been proved to be feasible with superior regioselectivity to that of the CO pathway. [ABSTRACT FROM AUTHOR]

A green route for one−pot synthesis of acetals by tandem hydroformylation−acetalization of olefins using supported Rh−based catalysts was developed. Experimental results demonstrated that suitable Rh loading (1 wt%) with appropriate reaction temperature (120 °C) and reaction time (8 h) were favorable for the formation of acetals, and a high acetals selectivity of 94.6% was achieved. More importantly, the selectivity to valuable linear products was enhanced in this tandem catalysis. Based on the catalytic mechanism study, highly dispersed RhOx nanoparticles and abundant acid sites on the supports were responsible for the hydroformylation and acetalization, respectively. One-pot synthesis of acetals directly from olefins with high selectivity was achieved over heterogeneous bifunctional catalysts via tandem hydroformylation-acetalization. [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]

Because lower olefins (C2=–C4=) are important bulk petrochemicals, their direct production from CO2 hydrogenation is highly attractive. However, the selectivity towards C2=–C4= by the modified Fischer–Tropsch synthesis is restricted to 56.7 % with high undesired methane selectivity. Here, a series of bifunctional catalysts containing In2O3‐ZnZrOx oxides and various SAPO‐34 zeolites with different crystal sizes (0.4–1.5 μm) and pore structures was developed for the production of lower olefins by CO2 hydrogenation. The C2=–C4= selectivity reached as high as 85 % among all hydrocarbons with very low CH4 selectivity of only 1 % at a CO2 conversion of 17 %. This demonstrated that the small crystal size, hierarchical pore structure, and appropriate amount of Brønsted acid sites of SAPO‐34 endowed the bifunctional catalysts with high C2=–C4= selectivity. This work shows an efficient way for developing bifunctional catalysts for direct CO2 hydrogenation to lower olefins. [ABSTRACT FROM AUTHOR]

An atomically economical green protocol for the hydrofunctionalization of olefins to higher aliphatic alcohols with 100% anti-Markovnikov regioselectivity was developed via visible-light photocatalytic coupling. This method employs cheap, readily available and abundant methanol as both the C1 feedstock and the hydrogen source under visible light irradiation over CdS photocatalyst. A wide scope of olefin substrates could be hydrofunctionalized successfully to the corresponding higher alcohols with high selectivity. Besides alcohol, acetone and acetonitrile can also couple with olefins to generate the corresponding hydrofunctionalization products, suggesting promising potential industrial application. Hydrofunctionalization of olefins to value-added chemicals with high selectivity was achieved via visible-light photocatalytic cross-coupling. [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]

Inspired by the nature fractal structure, a novel honeycomb fractal micro-reactor was designed and applied to intensify both heat and mass transfer in the exothermic conversion of syngas to olefins. The results show that the honeycomb fractal micro-reactor provides more even distribution of temperature profiles, a narrower reactant residence time distribution, and relative smaller pressure drop per unit length, compared with parallel straight microchannel reactor and mini-fixed bed reactor under the same reaction conditions. Owning to the reinforcement of flow separation and convergence in the honeycomb structure, the contact between reactants and catalyst particles were enhanced, leading to a better heat and mass transfer. Under the current range of temperature, pressure and standard GHSV, the honeycomb fractal micro-reactor leads to supreme CO conversion and lower olefins yield. [ABSTRACT FROM AUTHOR]

A green strategy was developed for the synthesis of various value-added chemicals using methanol, acetonitrile, acetic acid, acetone and ethyl acetate as the hydrogen source by coupling them with olefins over heterogeneous photocatalysts. A radical coupling mechanism was proposed for the hydrofunctionalization of olefins with methanol to higher aliphatic alcohols over the Pt/TiO2 catalyst as the model reaction. C–H bond cleavage and C–C bond formation between photogenerated radicals and terminal olefins were accomplished in a single reaction at high efficiency. Our approach is atomically economical with high anti-Markovnikov regioselectivity and promising application potential under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Highly dispersed FeMn nanoparticles were encapsulated with a carbon layer to form a core–shell structure. This catalyst (FeMn@C) exhibited distinguished catalytic activity, high light-olefin selectivity (40.6%) and superior stability in the Fischer–Tropsch synthesis. Furthermore, it was revealed that the carbon layer facilitated the formation of χ-Fe5C2 with suitable particle size, which is responsible for the enhanced catalytic activity. In particular, the core–shell structure of FeMn@C could also influence the distribution of hydrocarbons and the catalyst stability due to the confinement effect. [ABSTRACT FROM AUTHOR]

Fischer-Tropsch to olefins (FTO) with controllable iron carbide phase and high carbon utilization efficiency for Fe-based nanocatalyst attracts great interest but remains challenge. Herein, we report that the metastable Fe 7 C 3 phase can be effectively tailored by altering shell thickness of hydrophobic SiO 2 over a core-shell nanostructured FeZn@SiO 2 -c nanocatalyst. χ-Fe 5 C 2 was the dominated iron carbide phase for FeZnO x and FeZn@SiO 2 nanocatalysts, while numerous Fe 7 C 3 phases existed for hydrophobic FeZn@SiO 2 -c nanospheres. Compared with FeZnO x , the CO 2 selectivity of FeZn@ 4.1-SiO 2 -c decreased by > 70%, while 1.7-fold higher olefins selectivity was simultaneously obtained during syngas conversion process. The hydrophobic interface greatly suppressed the water-gas-shift reaction by promoting the quick diffusion of water, and the as-formed H 2 -lean and CO-rich local chemical environment benefits the formation of Fe 7 C 3 and olefins products. This work provides a promising strategy to design phase-stable Fe 7 C 3 with improvement of carbon efficiency for Fe-based nanocatalysts. [Display omitted] • Hydrophobic interfaces could regulate iron carbide phases. • Hydrophobic confined environment benefits the design of phase-stable Fe 7 C 3 carbide. • Fe 7 C 3 is a favorable active phase for Fischer-Tropsch to olefins (FTO). • Wettability environment affects WGS reaction activity and FTO performance. • Suppressed CO 2 selectivity, enhanced activity and olefins selectivity was obtained. [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]

The Fischer-Tropsch to olefins (FTO) process is a promising alternative non-petroleum route to produce value-added olefins. In this study, Co 2 C nanoprisms formed via the CoMn spinel structure were used as the active phase for the FTO reaction and the product distribution was thoroughly investigated. A break from the traditional ASF model was found with much lower methane selectivity than that predicted by the ideal ASF law. In addition, the as-obtained hydrocarbons were mainly concentrated in the range of C 2 to C 12 with the C 2-12 selectivity as high as 91% while the C 13+ selectivity as low as 5%, indicating a much narrower distribution, which was rarely observed in the FT reaction. Moreover, ∼86% of the hydrocarbon products were olefins with very high olefin to paraffin ratios, suggesting a promising route for the selective production of olefins directly from syngas. A modified ASF distribution model was proposed with three different chain growth probabilities to rationalize the non-ASF phenomenon. [ABSTRACT FROM AUTHOR]

Direct production of lower olefins (C 2 = −C 4 = : ethylene, propylene and butylene), basic carbon-based building blocks, from carbon dioxide (CO 2 ) hydrogenation is highly attractive, although the selectivity towards olefins has been too low. Here we present a series of bifunctional catalysts contained indium-zirconium composite oxides with different In:Zr atomic ratios and SAPO-34 zeolite, which can achieve a selectivity for C 2 = –C 4 = as high as 65–80% and that for C 2 –C 4 of 96% with only about 2.5% methane among the hydrocarbon products at CO 2 conversion of 15–27%. The selectivity of CO via the reverse water gas shift reaction is lower than 70%. The product distribution is completely different from that obtained via CO 2 -based Fischer-Tropsch synthesis and deviates greatly from the classical Anderson-Schulz-Flory distribution. The zirconium component plays a critical role in determining the physicochemical properties and catalytic performance of bifunctional catalysts. Catalyst characterization and density functional theory calculations demonstrate that the incorporation of a certain amount of zirconium can create more oxygen vacancy sites, stabilize the intermediates in CO 2 hydrogenation and prevent the sintering of the active nanoparticles, thus leading to significantly enhanced catalytic activity, selectivity of hydrocarbons and stability for direct CO 2 hydrogenation to lower olefins at the relatively high reaction temperature of 380 °C. [ABSTRACT FROM AUTHOR]

Tuning Fischer-Tropsch synthesis products of metallic Co-based catalysts from paraffins to value-added olefins chemicals attracts great attention but remains challenging. Herein, we succeed in designing the carbon layers confined cobalt metal core-shell nanocatalyst (Co@C) via a reduction-carburization-pyrolysis (RCP) pretreatment of Co/SiO 2 , which exhibits highly efficient for Fischer-Tropsch to olefins (FTO) with negligible Water-Gas-Shift activity. At 250 °C and 5 bar, 56.4 % of olefins selectivity and limited CO 2 selectivity (5.8 %) are achieved for Mn-promoted Co@C nanocatalyst with at least 200 h of stability running. The electronic effect of carbon layers and Mn promoter as well as the confinement structure tailor the local chemical environment and weaken the hydrogenation ability of Co metal sites, thus improving the selectivity toward olefins while largely reducing the formation of CH 4 and CO 2. This work develops an effective strategy for the rational design of highly active and stable metallic Co-based FTO catalysts with high carbon efficiency. [Display omitted] • Carbon layers encapsulating Co metallic nanoparticles (Co@C) was successfully designed. • Reduction-carburization-pyrolysis (RCP) strategy was effective in fabricating Co@C structure. • Co@C nanocatalyst was favorable for olefins production instead of paraffins during FTS process. • Features of negligible WGSR activity and high carbon efficiency were observed for Co@C nanocatalyst. • Both electronic effect of carbon layers and Mn promoter could weaken hydrogenation ability of Co metal. [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]

Co 2 C nanoprisms exhibit promising catalytic performance for Fischer-Tropsch synthesis to olefins (FTO) but with high CO 2 selectivity (>40%). Herein, silica-coated CoMn-based catalyst was designed to limit CO 2 production and remained Co 2 C nanoprisms as active sites unchanged. With a desired coating amount of silica, CO 2 selectivity was significantly suppressed to 15.1 C% while enhancing olefins selectivity from 39.7 C% to 58.8 C%, which also shows at least 160 h of stability. It is suggested the silica-coating not only reduces the adsorption capacity of H 2 O, but also promotes the fast transfer of H 2 O away from active sites due to the higher adsorption energy of H 2 O on SiO 2 surface, thus suppressing water-gas-shift-reaction (WGSR) activity. Moreover, the sodium promoter can counteract the H 2 -enrichment effect caused by SiO 2 -coating and largely restrain CH 4 formation and olefins hydrogenation. This work provides an effective strategy to suppress CO 2 formation and enhance the carbon efficiency of FTO process. [Display omitted] • WGSR-resistant CoMnAl@SiO 2 catalyst was prepared for FTO with low CO 2 selectivity. • H 2 O can easily transfer from Co 2 C surface to adjacent hydrophilic SiO 2 sites. • SiO 2 -coating prevents the reabsorption of water on Co 2 C site for further WGSR. • Alkali metals counteract H 2 -enrichment effect of SiO 2 and largely improve O/P ratio. • Low CO 2 emission improved activity, olefins selectivity and carbon-efficiency of FTO. [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]

• High selectivity to desired amines (93.2%) was obtained over 0.5Rh 1 /HAP catalyst. • Atomically dispersed Rh on HAP support was confirmed. • Single-atom Rh ensured high activity for hydroformylation step and tandem process. • A wide scope corresponding amines can be obtained with satisfactory yields. Tandem hydroaminomethylation is an efficient and green route for one-pot synthesis of amines directly from olefins. Herein, heterogeneous hydroxyapatite (HAP) supported single-atom Rh catalyst was prepared and used for tandem hydroaminomethylation of olefins. Characterization techniques confirmed the atomic dispersion of Rh species on HAP. Up to 99% conversion of 1-hexene with high selectivity to the desired amines (93.2%) was obtained over 0.5Rh 1 /HAP catalyst. Mechanism study demonstrated that the first hydroformylation step during the tandem catalytic process was rate-determining. Compared with the Rh nanoparticles on other oxide supports (Mg 3 Al, MgO and Al 2 O 3), the atomically dispersed Rh sites on HAP ensured the high hydroformylation activity, thereby guaranteed the outstanding catalytic performance for the total tandem process. Furthermore, various corresponding amines can be obtained with satisfactory yields over 0.5Rh 1 /HAP catalyst from a wide scope of olefins or amines substrates. [Display omitted] [ABSTRACT FROM AUTHOR]

• The catalytic performance for HAS was dramatically improved by doping Rh or Ru. • The C-rich and H-lean chemical environment was effectively tuned. • The Rhδ+ (or Ruδ+) species benefited the formation and stable existence of Co 2 C. • Synergistic effect of Co 2 C, Co0 and Rhδ+ (or Ruδ+) boosted CO insertion. • Olefins relay coupling promoted the production of oxygenates. Higher alcohols synthesis (HAS) from syngas with high selectivity attracts great attention but remains challenging. Herein, we reported an effective strategy by tuning chemical environment and synergistic relay reaction to promote the production of higher alcohols. CO insertion rate was greatly enhanced by introducing Rh or Ru component to CoMn oxides. The catalytic activity and oxygenates selectivity increased dramatically over the as-obtained Rh-CoMn or Ru-CoMn catalyst, while the fraction of C 2+ OH in oxygenates maintained >92 %. Multiple studies demonstrated the highly dispersed Rhδ+ or Ruδ+ species not only effectively tuned the chemical environment and facilitated the stable existence of Co 2 C, but also catalyzed the coupling of syngas and in-situ generated olefins to produce extra oxygenates via hydroformylation route. The synergistic effect of Co0, Co 2 C and Rhδ+ (or Ruδ+) species, as well as the promotional effect of olefins relay reaction contributed to the enhancement in both higher alcohols selectivity and CO conversion. [ABSTRACT FROM AUTHOR]

The active sites in M/TiO 2 were carefully tuned for photocatalytic cyanation of olefins with high atom efficiency and regioselectivity. • The active sites in M/TiO 2 were tuned by delicate manipulation of metal kinds, metal loading amount and pretreatment process. • The reduced Pt species and surface oxygen defects were considered as active sites. • High metal dispersion and suitable oxygen defects on TiO 2 were favorable for catalytic performance. • A radical-initiated reaction mechanism for photocatalytic cyanation of olefins was proposed. The detailed structure of active sites plays an important role for the determination of catalytic performance. Herein, catalytic active sites of M/TiO 2 for photocatalytic cyanation of olefins are tuned by delicate manipulation of the metal kinds, metal loading amount and pretreatment processes. It was found that the 0.1% Pt/P25 catalyst reduced at 300 °C possessed high metal dispersion and suitable oxygen defects on TiO 2 , and thus exhibited the best catalytic performance with high specific speed of time yield and high selectivity. A wide scope of olefin substrates could be converted to the corresponding nitriles with high atom efficiency and anti-Markovnikov regioselectivity under mild conditions for the optimized Pt/P25 catalyst. The reaction mechanism based on radical coupling of acetonitrile and olefins was also discussed. This approach offers an environmental-friendly platform for the selective activation of C-H bonds of acetonitrile and will bring potential applications for hydrofunctionalization of olefins. [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]