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The direct CO2 Fischer–Tropsch synthesis (CO2-FTS) process has been proven as one of the indispensable and effective routes in CO2 utilization and transformation. Herein, we present a core-shell structured Na/Fe@Co bimetallic catalyst to boost CO2 conversion and light hydrocarbon (C2 to C4) selectivity, as well as inhibit the selectivity of CO. Compared to the Na/Fe catalyst, our Na/Fe@CoCo-3 catalyst enabled 50.3% CO2 conversion, 40.1% selectivity of light hydrocarbons (C2-C4) in all hydrocarbon products and a high olefin-to-paraffin ratio (O/P) of 7.5 at 330 °C and 3.0 MPa. Through the characterization analyses, the introduction of CoCo Prussian Blue Analog (CoCo PBA) not only increased the reducibility of iron oxide (Fe2O3 to Fe3O4), accelerated the formation of iron carbide (FexCy), but also adjusted the surface basic properties of catalysts. Moreover, the trace Co atoms acted as a second active center in the CO2-FTS process for heightening light hydrocarbon synthesis from CO hydrogenation. This work provides a novel core-shell structured bimetallistic catalyst system for light hydrocarbons, especially light olefin production from CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

BACKGROUND: Syngas conversion to olefins via Fischer‐Tropsch Synthesis (FTs) route and then subsequently into aromatics (syngas−olefins−aromatics (SOA)) was considered a promising industrialization route due to its ability to match reaction temperatures between syngas to olefins (300–400 °C) and olefins to aromatics (300–500 °C). In this reaction route, the syngas to olefin process can be efficiently and easily realized by Fe‐based FTs catalysts. However, the aromatization process occurring over the zeolite catalyst was still considered a big challenge due to zeolites' complex topology, variable morphology, and elusive acidic properties. RESULTS: A series of ZSM‐5 zeolites with different morphologies, including nano ellipsoid, nano cube, nano aggregate, nano bead, and nano pile were successfully synthesized. The effects of the ZSM‐5 zeolite's morphology and reaction temperature on the aromatics synthesis from syngas based on a modified FTs route were systematically studied. CONCLUSION: In all the studied ZSM‐5 zeolites, the nano cube ZSM‐5 zeolite (Z5‐NC) zeolite had the best aromatization ability. The hybrid catalyst combination of FeMnK&Z5‐NC obtained the highest xylene selectivity of 12% (2.8% + 9.2%), and its total aromatics selectivity was also the highest (42.5%). The study on reaction temperature suggested that a higher reaction temperature (320–360 °C) could efficiently impede the formation of CO2. However, the selectivity of aromatics was restrained to around 44% at higher temperatures because a high temperature facilitated the hydrocracking of higher hydrocarbons, leading to the increase of the selectivity of lighter CH4 and paraffin. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

As a century‐old classical reaction, Fischer‐Tropsch (F‐T) synthesis is undergoing new developments especially in its applications of producing jet fuel, olefins, aromatics and oxygenated chemicals, which are completely different from the conventional F‐T product, gasoline, diesel and wax. Producing above new products is not obeying famous ASF distribution law, requiring revolutionary design of new F‐T catalysts and reaction pathways. A mass of new research directions on F‐T synthesis for these liquid fuels and high‐value chemicals are successfully proposed. This review spotlights recent new advances based on F‐T synthesis for non‐automotive applications, and discusses its new possible directions in future. Going beyond cars: This Minireview spotlights recent new advances based on Fischer‐Tropsch synthesis for non‐automotive applications, such as jet fuel, olefins, aromatics and oxygenated chemicals, which are completely different from the conventional Fischer‐Tropsch product, and discusses its new possible directions in future. [ABSTRACT FROM AUTHOR]

Zeolite synthesis involved use of large volumes of solvent that resulted in waste and enhanced production costs. In our study, we selected a solvent‐free synthesis route that involved mixing, grinding and crystallization at various times creating Fe@Silicalite‐1. This synthesis method produced a hierarchical in‐situ microporous crystal morphology with Fe particles caged inside zeolite displaying a high gasoline (C5‐C11) selectivity of 66.0% with a relatively low CO2 and CH4 selectivity (18.5% and 10.0%, respectively) in Fischer‐Tropsch synthesis. Prolonged crystallization time of 72 h and other subsequent procedures contributed to zeolite structure and performance. Iron moieties were appropriately immobilized over silicalite support. The characterization results were correlated with the zeolite activity and selectivity. This novel zeolite at its best possesses all the potential to be advanced in other related material synthesis because of its expedient procedure, characteristics and worthwhile outcomes. As a result of solvent‐free synthesis route, this Fe@Silicalite‐1 zeolite containing hierarchical in‐situ microporous crystal structure in union with Fe particles entrapped within zeolite contributed largely to gasoline product distribution of Fischer‐Tropsch synthesis reaction. The remarkable high gasoline selectivity of 66.0% has been achieved by this zeolite as a result of its intrinsic properties. [ABSTRACT FROM AUTHOR]

Jet fuel is not easy to synthesize by the biomass-to-liquid (BTL) process owing to the limitation of the Anderson-Schulz-Flory (ASF) hydrocarbon distribution law in Fischer-Tropsch synthesis (FTS) with biomass-derived syngas (CO+H2). Here, we realized an anti-ASF distribution to selectively produce jet fuel from biomass on a large scale by addition of small amounts of 1-olefin, a FTS product, into syngas, enhancing jet fuel selectivity in hydrocarbons up to 64% and that in oil product to as high as 91%. The Co/SiO2 catalyst (300 g) was loaded into a flow-type three-phase reactor and 120h continuous operation was conducted by using the real-time on-line biomass- derived syngas from an entrained bed gasifier of biomass (240 kgday-1) of Mitsubishi Heavy Industries, Ltd. The production rate of liquid oil reached 720 gkgcat -1h-1. The structure of the fresh and used catalyst was characterized in detail, accompanied with lab-scale data on reaction performance and catalyst properties. The stable technology process from biomass gasification to FTS, stable catalyst structure, and novel design of 1-olefin addition are the key to success in selectively converting biomass to jet fuel on a large scale. [ABSTRACT FROM AUTHOR]

A hierarchically spherical Co based zeolite catalyst with aggregated nanorods structure (simplified as Co/AN-Z) was prepared by an in-situ self-assembly crystallization route of Co/SBA-15 under hydrothermal synthesis environment. The obtained Co/AN-Z catalyst with uniformly sized zeolite microspheres with 0.5–1 μm was evaluated for improved Fischer–Tropsch synthesis (FTS) reaction activity and isoparaffin selectivity. The selectivities of isoparaffin and C 5-11 hydrocarbons were higher with a narrower product distribution as well as CH 4 and C 12+ selectivities were lower on the Co/AN-Z catalyst than those on the commercial HZSM-5 supported Co catalyst (Co/HZSM-5) for FTS reaction. The demonstrated route of the hierarchically spherical Co based zeolite catalyst can be extended to synthesize bifunctional catalyst and expected to find a new approach for tandem reaction. [ABSTRACT FROM AUTHOR]

In this paper, a new Co/ZrO 2 –SiO 2 catalyst with specific bimodal structure was developed and applied for jet fuel direct synthesis from syngas in Fischer–Tropsch synthesis (FTS) with varied 1-olefins as additives. In a slurry-phase reaction process, 1-olefins as additives were introduced into reaction system to enhance the selectivity of jet-fuel-like hydrocarbons (C 8 –C 16 ), at the same time suppressing the formation of light hydrocarbons including CH 4 and CO 2 . The new FTS reactions, due to the co-fed 1-olefins, showed anti-Anderson–Schulz–Flory (anti-ASF) law product distribution. Among all the co-fed mixed 1-olefins, 1-decene and 1-tetradecene mixed with the volume ratio of 1:1, exhibited the highest selectivity of jet-fuel-like hydrocarbons. This new Co/ZrO 2 –SiO 2 bimodal catalyst had specific bimodal structure, which realized its excellent catalytic performances in the FTS reaction, because the large pores provided efficient pathways for reactants and products diffusion, and high metal dispersion was obtained by the newly formed small pores with enhanced active surface area. [ABSTRACT FROM AUTHOR]

A two-step method consisting of acid leaching and base leaching was developed and applied to create hierarchical pores on a general microporous Y zeolite. Characterization with BET and TEM on the texture, morphology and structure of the prepared hierarchical Y zeolite confirmed the co-existence of mesopores with zeolitic walls. The analysis results showed that the mesopore surface area and pore volume of the hierarchical zeolite Y (Y-AB x , A: acid leaching, B: base leaching, “ x ” represents for base leaching time) increased with increasing the base leaching time. The hierarchical zeolite Y supported Co as catalysts were employed to catalyze the hydrogenation of carbon monoxide to form hydrocarbons through Fischer–Tropsch synthesis (FTS) reaction. The CO conversion and C 5 – 11 selectivity on Co/Y-AB x catalysts increased significantly compared with those on the pristine Y supported Co catalyst. The isoparaffin selectivity of Co/Y-AB4 catalyst reached up to 52.3% and middle hydrocarbons became the main FTS products due to the optimized hydrocracking and isomerization function afforded by the hierarchical zeolite Y with the strong Brønsted acid/Lewis acid (B/L) ratio and textural property. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two new methods are presented for zeolite capsule catalyst preparation. [•] One is an improved hydrothermal synthesis process. [•] Another is an initially reported method without employing hydrothermal synthesis. [•] Zeolite capsule catalysts realize tandem catalytic synthesis with higher efficient. [ABSTRACT FROM AUTHOR]

Highlights: [•] We realize the controllable encapsulation of Co clusters inside CNTs channels. [•] The oxygen-containing functional groups are selectively removed. [•] The cobalt nanoparticles inside the CNTs channel reach up to 80%. [•] The Co/CNTs-650 catalyst exhibits high activity and C5+ selectivity. [ABSTRACT FROM AUTHOR]

Fused iron (FI), is a general Fischer-Tropsch synthesis (FTS) catalyst and can be used to convert syngas (CO+H2) into normal hydrocarbons. The syntheses of HZSM-5 or H-β zeolite-shell encapsulated catalysts for FTS have been reported previously, however, conventional zeolite-shell synthesis generally employs an organic template, which is neither economic nor environmentally benign. Here we report the synthesis, without using an organic template, of a millimeter-sized defect-free capsule catalyst covered by a MOR zeolite shell (thickness of 23 μm) on FI pellets. The capsule catalyst (HMOR/FI) exhibited excellent performance for FTS, greatly increasing the selectivity of middle isoparaffins. Compared with the pure FI catalyst, the CO conversion of the HMOR/FI capsule catalyst increased remarkably and the iso/ n ratio was almost 8 times that of the pure FI catalyst. This report provides an effective route to synthesize a capsule catalyst, which can reduce costs effectively and is also more environmentally benign than the current conventional zeolite-shell synthesis. [ABSTRACT FROM AUTHOR]

Abstract: Three kinds of H-ZSM-5 zeolite capsule catalysts were prepared on Ru/SiO2 catalyst pellets with different size. Characterization indicated that defect-free H-ZSM-5 capsule had been constructed on the Ru/SiO2 surface successfully. And small Ru/SiO2 pellet with large external surface was favorable for zeolite capsule growth under the same zeolite synthesis conditions. In the iso-paraffin direct synthesis via Fischer–Tropsch synthesis (FTS) reaction, zeolite capsule catalysts, especially the one with smaller pellet size, realized the higher iso-paraffin selectivity comparing with conventional FTS Ru/SiO2 catalyst, and physically mixed catalyst of Ru/SiO2 with H-ZSM-5 zeolite. [Copyright &y& Elsevier]

Abstract: Three kinds of H-ZSM-5 zeolite capsule catalysts were prepared by a direct hydrothermal synthesis method, where directly synthesized H-ZSM-5 membrane was coated perfectly onto Co/SiO2 catalyst pellets of different sizes. SEM, EDS and XRD were used to characterize the catalyst morphology and to identify the H-ZSM-5 structure of zeolite capsules. Surface acidity and pore property of these catalysts were tested by NH3-TPD and gas adsorption. The results showed that smaller Co/SiO2 pellets with large external surfaces were favorable for zeolite capsule growth under the same synthesis conditions. The Fischer–Tropsch synthesis (FTS) reactions using the conventional FTS catalyst Co/SiO2 or the physically mixed catalyst of Co/SiO2 with H-ZSM-5, or the zeolite capsule catalysts were each conducted. The isoparaffins were selectively obtained on the capsule catalysts and the mixed catalyst. The capsule catalysts exhibited higher selectivity of isoparaffins than the mixed catalyst due to the space-confined effect and the shape-selective effect. Especially, capsule catalysts with smaller sizes showed higher CO conversion and higher isoparaffin selectivity. Changing the substrate pellet size could control the capsule catalysts’ structure and their activity as well as their selectivity. [Copyright &y& Elsevier]

Bimodal catalyst support is a widely applied concept in solid catalysts but until now the supported metal on the bimodal support has no satisfied dispersion and the average metal particle size is generally larger than the pore size of small pores (mesopores) of the bimodal structure, lowering the power and significance of the bimodal structure. To overcome this problem, a novel ZrO 2 SiO 2 bimodal pore support with enlarged depth of small pores, was successfully fabricated though self-assembly of nanosized ZrSiO 4 inside pore of silica gel. Cobalt was finely dispersed on bimodal support by incipient-wetness impregnation. The bimodal support and catalyst were characterized by various techniques, such as BET, TEM, XRD, and TPR and H 2 -chemisorpion. The bimodal catalyst was applied in slurry-phase Fischer-Tropsch synthesis. Characterization results suggested that bimodal pore support processed larger BET surface than pristine silica gel, due to the newly formed small pores organized by packing of the ZrSiO 4 nanoparticles. The enlarged BET surface area leaded to good dispersion of cobalt species. More importantly, it was observed that the deep small pores could serve as traps for Co nanoparticles, preventing sintering and agglomeration due to confinement effect. Co/30 wt% ZrO 2 -Q-50 and Co/20 wt% ZrO 2 -Q-100 bimodal catalyst with large BET surface and deep small pores exhibited excellent catalytic activity, and selectivity to heavy hydrocarbons due to high dispersion of cobalt and unique pore structure, while coexisting ZrO 2 promoted the reduction of finely-dispersed cobalt oxide nanoparticles. It is interesting to find that different from the conventional theory where small metallic particle lowers chain-growth probability, the trapped smaller Co particles inside deep small pores achieved higher chain-growth probability due to the facilitated re-adsorption of olefinic intermediates happening inside deep small pores. [ABSTRACT FROM AUTHOR]

Pd-promoted zeolite capsule catalyst (Co/Pd/SiO 2 -HZSM5) was developed by coating H-ZSM-5 zeolite shell over Pd-modified core catalyst (Co/Pd/SiO 2 ), and employed for direct synthesis of C 5 –C 11 iso-paraffins from syngas via Fischer-Tropsch synthesis (FTS). The roles of Pd promotion in structure and performance of the capsule catalyst for C 5 –C 11 iso-paraffins synthesis were deeply studied. Structure characterizations (XRD, FTIR, TPR, and XPS) indicated that the main cobalt species in Pd-promoted capsule catalyst was cobalt silicate, while Co 3 O 4 was the predominant cobalt species in un-promoted capsule catalyst (Co/SiO 2 -HZSM5). Evolution of cobalt species in the synthesis of Pd-promoted capsule catalyst revealed that Pd improved the formation of cobalt silicate in strong basic TPAOH solution during the hydrothermal synthesis of H-ZSM-5 zeolite shell. It was found that Pd not only promoted the reduction in cobalt oxides, but also improved the reduction in cobalt silicate, which could not be reduced under traditional reduction condition for cobalt-based FTS catalysts. Catalytic tests indicated that Pd-promoted capsule catalyst exhibited highly enhanced performance for C 5 –C 11 iso-paraffins synthesis with molar ratio of iso-paraffins to n -paraffins up to 1.03. Long-chain hydrocarbons were completely eliminated in the capsule catalyst as a consequence of spatial confinement effect of the H-ZSM-5 zeolite shell. The hydrogenation of olefins to paraffins, which was enhanced by Pd promotion, together with the hydrocracking and isomerization of primary hydrocarbons, contributed to the high selectivity of C 5 –C 11 iso-paraffins in Pd-promoted capsule catalyst. [ABSTRACT FROM AUTHOR]

Hierarchical HZSM-5 zeolite with combined micropores and mesopores was synthesized by one-step approach with TPAOH and F127 as dual templates. The physical and acidic properties of the hierarchical HZSM-5 zeolite were characterized by XRD, N 2 adsorption–desorption isotherm, SEM, TEM, and NH 3 -TPD techniques. The hierarchical HZSM-5 zeolite exhibited a significantly higher mesopore surface area and larger mesopore volume than that of the conventional HZSM-5. The prepared hierarchical HZSM-5 and conventional HZSM-5 zeolite supported cobalt catalysts were evaluated via Fischer–Tropsch synthesis (FTS) reaction to tune product selectivity. Compared with the conventional catalyst, the CO conversion of FTS reaction on the present catalyst increased significantly. Meanwhile, the C 5 + selectivity and isoparaffin selectivity also increased. The C 5–11 hydrocarbons with a lot of isoparaffin and olefin had become the main FTS products due to the optimized hydrocracking and isomerization afforded by the hierarchical pore structure, different from the conventional FTS hydrocarbons which were mainly composed of normal paraffin. [ABSTRACT FROM AUTHOR]

Abstract: The different solvents were applied, such as acetic acid or ethanol, during preparation of Fischer–Tropsch synthesis (FTS) catalysts, to modify the surface properties of silica supports or as a solvent of cobalt precursors. The modification of silica supports by acetic acid or ethanol improves the reduction degree and dispersion of supported cobalt simultaneously, realizing higher catalytic activity, and the catalysts prepared from ethanol solution of cobalt precursor exhibit significant stability and activity in slurry phase FTS reaction during 100h. The obtained catalysts were characterized by XRD, TPR, in situ DRIFT and H2 chemisorption. [Copyright &y& Elsevier]

Abstract: Silica-supported cobalt (20wt%) catalysts were prepared by incipient-wetness impregnation of silica with different cobalt nitrate solutions. The catalyst prepared from dehydration ethanol solution exhibited stable and the highest activity, as well as significantly low methane selectivity. Cobalt crystalline size of the catalyst prepared from dehydrated ethanol was smaller than that of the catalyst prepared from aqueous solution, and existed two different size where the large particles showed low bulk density with cluster-like structure. But only larger clusters existed in the catalyst prepared from aqueous solution. The increased amount of active sites and more reactive adsorbed CO on the surface determined the highest activity of the catalyst prepared from dehydrated ethanol solution in liquid-phase Fischer-Tropsch synthesis (FTS) reaction. [Copyright &y& Elsevier]

[Display omitted] • Successfully prepared ZrO 2 @FeCu-K, which ZrO 2 as the core and FeCu as the shell. • ZrO 2 @FeCu-K shows the ability of increasing CO adsorption. • ZrO 2 @FeCu-K catalyst reaches the highest CO conversion and makes the product shift to the higher hydrocarbon. The Fischer-Tropsch (FT) synthesis, as an alternative route to produce high-quality liquid fuels and chemicals, has received considerable attention in recent years. In this work, a nano-sized capsule catalyst (ZrO 2 @FeCu) with ZrO 2 as a core and FeCu bimetallic oxide as a shell was fabricated by urea hydrolysis method. For comparison, FeCu@ZrO 2 capsule catalyst was synthesized by the sequential precipitation method. FeCu + ZrO 2 reference catalyst was obtained by physically mixing of FeCu and ZrO 2 samples. Besides, these catalysts with potassium (K) modification were realized by wetness impregnation method, and the catalysts are denoted as ZrO 2 @FeCu-K, FeCu@ZrO 2 -K, and FeCu + ZrO 2 -K, respectively. The structure-function relationship of the obtained catalysts was systematically clarified by means of a series of characterization techniques, such as BET, XRD, H 2 -TPR, CO-TPD, XPS, SEM and EDS mapping. Among these catalysts after reduction, ZrO 2 @FeCu-K exhibited the most excellent catalytic performance with 97 % CO conversion and 49 % α-olefins selectivity by promoted CO adsorption. [ABSTRACT FROM AUTHOR]

Nano-sized zeolites (NZs) were anchored on the layered double hydroxide consisting of cobalt and aluminum (Co-Al-LDH) using a solvent-free synthesis method (denoted as Co-Al-LDO-NZs). During the synthesis process, Co-Al-LDH was not only employed as a substrate for the growth of nano-sized zeolites but also acting as Al sources to participate in the formation of acid sites in the zeolite. The well-designed catalyst was used as a bifunctional catalyst for highly selective production of gasoline-range hydrocarbons from syngas through Fischer-Tropsch (FT) synthesis. Benefiting from the unique architecture of Co-Al-LDO-NZs, long-chain hydrocarbons formed on the active FT catalyst could diffuse to the zeolites surface, where hydrocracking and isomerization occurred. Furthermore, different from the traditional zeolite-supported FT catalyst, the nanoscale zeolite in Co-Al-LDO-NZs efficiently suppressed the over-cracking of hydrocarbons, lowering the selectivity of undesirable light hydrocarbons (CH 4 and C 2 –C 4 alkanes). [ABSTRACT FROM AUTHOR]

The catalysts with high activity and selectivity, especially the latter, play a key role in Fischer–Tropsch synthesis technology. Herein, a novel Fe-based confinement catalyst, Fe 2 O 3 encapsulated in TiO 2 nanotubes, was prepared by a method of vacuum-assisted impregnation. The catalyst presented an excellent yield of oil phase hydrocarbons and C 5+ selectivity due to the confinement effect. This interesting phenomenon was discussed from the view of the restrained molecular movement and enhanced readsorption of short-chain α-olefins in the confined space of TiO 2 nanotube channels. The results over this novel confinement catalyst revealed a promising research prospect on adjusting the product distribution to long-chain hydrocarbons for Fe-based Fischer–Tropsch catalyst. [ABSTRACT FROM AUTHOR]

A novel iron-based micro-capsule catalyst with interior Fe/Silica core and exterior H-ZSM-5 shell was synthesized via in-situ crystallization route on Fe/SBA-15 catalyst by using steam-assisted crystallization (SAC) process and evaluated for direct synthesis of middle isoparaffin from syngas in a fixed-bed reactor. Structure characterization indicated that the size of micro-capsule catalyst was about 1–2 μm. According to activity test results, original Fe/SBA-15 catalyst exhibited a low selectivity of isoparaffin as 8.2%. But the as-prepared micro-capsule catalyst achieved an excellent performance for isoparaffin synthesis with the selectivity up to 46.5%. Meanwhile, the physical mixture catalyst (Fe/SBA-15 and H-ZSM-5) exhibited lower isoparaffin selectivity with 33.9% than that of the micro-capsule catalyst. The spatial confinement effect of the micro-capsule catalyst played an important role for the high selectivity of isoparaffin synthesis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microwave assembling nitrogen-regulated graphene supported iron were fabricated. • N atom could effectively anchor iron, promoting small-size iron species formation. • The size of the iron nanoparticles could be regulated by adjusting microwave time. • Pyridinic-N and pyrrolic-N promoted the formation of alkene-rich hydrocarbons. Facile preparation of highly efficient iron-based catalysts is vital to improve the performance of Fischer-Tropsch synthesis (FTS), a sustainable process for converting non-petroleum carbon resources to valuable hydrocarbons. In this work, a convenient preparation for nitrogen-regulated graphene supported iron nanoparticles, with the assistant of microwave treatment, was developed. Thereinto, the nitrogen-containing groups in graphene support were introduced by NH 3 ·H 2 O treatment. By comparison with ordinary calcination, microwave treatment could significantly shorten the heating time to few seconds, and promote the reduction of iron species. The existence of a small number of nitrogen-containing groups could effectively anchor iron species, and improve the dispersion of iron species. Meanwhile, the duration length of NH 3 ·H 2 O treatment time could regulate the content of N configuration (pyridinic-N and pyrrolic-N). The size of supported iron species from 120 nm to 10 nm could be well controlled via increasing microwave time from 0 to 14 s. For N-regulated graphene supported iron catalysts, evenly dispersed small particles of iron species, improved surface reduction behavior and reasonable N configuration all promoted FTS. Under relevant industrial conditions (320 °C, 2.0 MPa, 5 g h mol−1), the optimized 15%Fe/AG(12 h)-W(10) catalyst achieved CO conversion as high as 97.2% and C 5+ selectivity of 40.0% while maintaining a mild CO 2 selectivity (28.2%). The superior preparation and catalytic performance disclosed that the catalyst could be one of ideal candidates for industrial iron-based FTS catalysts in future. [ABSTRACT FROM AUTHOR]

For Fe-based Fischer-Tropsch synthesis catalyst, how to decrease CO 2 formation is a big challenge. In this work, a capsule catalyst (FeMn@HZSM-5) with FeMn as core and HZSM-5 as shell was prepared and used for Fischer-Tropsch to olefins (FTO) reaction, compared with bare FeMn catalyst and several hybrid catalysts by physically mixing FeMn and HZSM-5 in different ways. Among these catalysts, the FeMn@HZSM-5 capsule catalyst showed the best catalytic performance with the highest light olefins selectivity and the lowest CO 2 selectivity. Compared with FeMn catalyst, the CO 2 selectivity of FeMn@HZSM-5 catalyst decreased more than 10%. However, the CO 2 selectivity of other physically mixing catalysts was similar to that of bare FeMn catalyst, indicating that randomly adding HZSM-5 had no effect on depressing the CO 2 formation. Benefiting from the HZSM-5 shell, the FeMn@HZSM-5 capsule catalyst could effectively affect the diffusion of H 2 O and thus suppress the water-gas shift reaction in FTO reaction. [Display omitted] • A capsule catalyst with FeMn as core and HZSM-5 as shell was used for FTO reaction. • Compared with FeMn, the CO 2 selectivity of FeMn@HZSM-5 decreased more than 10%. • The HZSM-5 shell structure suppresses the water-gas shift reaction in FTO reaction. [ABSTRACT FROM AUTHOR]

The catalytic performance of CO 2 hydrogenation to liquid fuels over a bifunctional catalyst can be efficiently enhanced via simply tuning the microenvironment properties of ZSM-5 zeolite. [Display omitted] • K-Fe/C and tailor-made ZSM-5 are coupled together for CO 2 hydrogenation. • Surface acid properties of ZSM-5 can be regulated through different ion-exchange strategies. • Alkali K+ ions are effective in reducing strong acids, boosting up C 5+ hydrocarbon selectivity. Catalytic conversion of greenhouse CO 2 into valuable chemicals or fuels is highly attractive in terms of sustainable development. The chemical inertness of CO 2 molecules and high kinetic barriers for C–C propagation hinder its efficient utilization. Here we report a bifunctional catalyst composed of K-Fe/C and zeolite that efficiently produced liquid fuels via simply tuning the microenvironment properties of ZSM-5 zeolite. The catalysts are characterized by Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), X-ray diffractometer (XRD), temperature programmed desorption (NH 3 -TPD), X-ray photoelectron spectroscopy (XPS). K-Fe/C catalyst is mainly responsible for the formation of olefins, while ZSM-5 catalyst is mainly responsible for olefin secondary reaction, such as aromatization, isomerization, and cracking reaction. Surface acid properties of ZSM-5 can be well regulated through different ion-exchange strategies (NH 4 +, K+, Na+, Mg2+, Cu2+, Cs2+, La3+, Ce2+, Mn2+), in which the strong surface acid properties of ZSM-5 are eliminated with the utilization of K+-ion exchange strategy and then it presents a high C 5+ selectivity by suppressing the light saturated hydrocarbons formation. This work provides new insights or facile catalyst treatment for the efficient production of liquid fuels from CO 2 hydrogenation via tuning surface microenvironment properties of ZSM-5 zeolite. [ABSTRACT FROM AUTHOR]