Advances in the Development of Novel Cobalt Fischer−Tropsch Catalysts for Synthesis of Long-Chain Hydrocarbons and Clean Fuels

Reductive coupling of CO with magnesium anthracene complexes: formation of magnesium enediolates

Two β-diketiminato-magnesium anthracene complexes, [{(^ArNacnac)Mg}₂(μ-C₁₄H₁₀)] (^ArNacnac = [HC(MeCNAr)₂]^-, Ar = mesityl (Mes) or 2,6-diethylphenyl (Dep)) react with 1 atm. CO at room temperature to give tetra-magnesium enediolate complexes [{(^ArNacnac)Mg}₄(O₂C₁₆H₁₀)₂] via coupling of two molecules of CO with the anthracenediyl fragment. Similarly, reaction of magnesium anthracene, [Mg(THF)₃(C₁₄H₁₀)], with CO afforded a low isolated yield of a tetra-magnesium complex bearing both dianthraceneylenediolate and dibenzocyclohepteneolateyl ligands. The presented reactions represent very rare examples of magnesium alkyl carbonylations that occur under mild conditions, and in the absence of catalysts.

Enhanced Electrochemical Reduction of CO2 to CO on Ag/SnO2 by a Synergistic Effect of Morphology and Structural Defects

Silver (Ag)-based materials are considered to be promising materials for electrochemical reduction of CO₂ to produce CO, but the selectivity and efficiency of traditional polycrystalline Ag materials are insufficient; there still exists a great challenge to explore novel modified Ag based materials. Herein, a nanocomposite of Ag and SnO₂ (Ag/SnO₂ ) for efficient reduction of CO₂ to CO is reported. HRTEM and XRD patterns clearly demonstrated the lattice destruction of Ag and the amorphous SnO₂ in the Ag/SnO₂ nanocomposite. Electrochemical tests indicated the nanocomposite containing 15% SnO₂ possesses highest catalytic selectivity featured by a CO faradaic efficiency (FE) of 99.2% at -0.9 V versus reversible hydrogen electrode (vs RHE) and FE>90% for the CO product at a wide potential range from -0.8 V to -1.4 V vs RHE. Experimental characterization and analysis showed that the high catalytic performance is attributed to not only the branched morphology of Ag/SnO₂ nanocomposites (NCs), which endows the maximum exposure of active sites, but also the special adsorption capacity of abundant defect sites in the crystal for *COOH (the key intermediate of CO formation), which improves the intrinsic activity of the catalyst. But equally important, the existed SnO₂ also plays an important role in inhibiting hydrogen evolution reaction (HER) and anchoring defect sites. This work demonstrates the use of crystal defect engineering and synergy in composite to improve the efficiency of electrocatalytic CO₂ reduction reaction (CO₂ RR).

Single-Pulse Shock Tube Experimental and Kinetic Modeling Study on Pyrolysis of a Direct Coal Liquefaction-Derived Jet Fuel and Its Blends with the Traditional RP-3 Jet Fuel

A basic understanding of the high-temperature pyrolysis process of jet fuels is not only valuable for the development of combustion kinetic models but also critical to the design of advanced aeroengines. The development and utilization of alternative jet fuels are of crucial importance in both military and civil aviation. A direct coal liquefaction (DCL) derived liquid fuel is an important alternative jet fuel, yet fundamental pyrolysis studies on this category of jet fuels are lacking. In the present work, high-temperature pyrolysis studies on a DCL-derived jet fuel and its blend with the traditional RP-3 jet fuel are carried out by using a single-pulse shock tube (SPST) facility. The SPST experiments are performed at averaged pressures of 5.0 and 10.0 bar in the temperature range around 900-1800 K for 0.05% fuel diluted by argon. Major intermediates are obtained and quantified using gas chromatography analysis. A flame-ionization detector and a thermal conductivity detector are used for species identification and quantification. Ethylene is the most abundant product for the two fuels in the pyrolysis process. Other important intermediates such as methane, ethane, propyne, acetylene, and 1,3-butadiene are also identified and quantified. The pyrolysis product distributions of the pure RP-3 jet fuel are also performed. Kinetic modeling is performed by using a modern detailed mechanism for the DCL-derived jet fuel and its blends with the RP-3 jet fuel. Rate-of-production analysis and sensitivity analysis are conducted to compare the differences of the chemical kinetics of the pyrolysis process of the two jet fuels. The present work is not only valuable for the validation and development of detailed combustion mechanisms for alternative jet fuels but also improves our understanding of the pyrolysis characteristics of alternative jet fuels.

Effect of Temperature, Syngas Space Velocity and Catalyst Stability of Co-Mn/CNT Bimetallic Catalyst on Fischer Tropsch Synthesis Performance

The effect of reaction temperature, syngas space velocity, and catalyst stability on Fischer-Tropsch reaction was investigated using a fixed-bed microreactor. Cobalt and Manganese bimetallic catalysts on carbon nanotubes (CNT) support (Co-Mn/CNT) were synthesized via the strong electrostatic adsorption (SEA) method. For testing the performance of the catalyst, Co-Mn/CNT catalysts with four different manganese percentages (0, 5, 10, 15, and 20%) were synthesized. Synthesized catalysts were then analyzed by TEM, FESEM, atomic absorption spectrometry (AAS), and zeta potential sizer. In this study, the temperature was varied from 200 to 280 °C and syngas space velocity was varied from 0.5 to 4.5 L/g.h. Results showed an increasing reaction temperature from 200 °C to 280 °C with reaction pressure of 20 atm, the Space velocity of 2.5 L/h.g and H2/CO ratio of 2, lead to the rise of CO % conversion from 59.5% to 88.2% and an increase for C5+ selectivity from 83.2% to 85.8%. When compared to the other catalyst formulation, the catalyst sample with 95% cobalt and 5% manganese on CNT support (95Co5Mn/CNT) performed more stable for 48 h on stream.

Effect of the Nanostructured Zn/Cu Electrocatalyst Morphology on the Electrochemical Reduction of CO2 to Value-Added Chemicals

Zn/Cu electrocatalysts were synthesized by the electrodeposition method with various bath compositions and deposition times. X-ray diffraction results confirmed the presence of (101) and (002) lattice structures for all the deposited Zn nanoparticles. However, a bulky (hexagonal) structure with particle size in the range of 1–10 μm was obtained from a high-Zn-concentration bath, whereas a fern-like dendritic structure was produced using a low Zn concentration. A larger particle size of Zn dendrites could also be obtained when Cu²⁺ ions were added to the high-Zn-concentration bath. The catalysts were tested in the electrochemical reduction of CO₂ (CO₂RR) using an H-cell type reactor under ambient conditions. Despite the different sizes/shapes, the CO₂RR products obtained on the nanostructured Zn catalysts depended largely on their morphologies. All the dendritic structures led to high CO production rates, while the bulky Zn structure produced formate as the major product, with limited amounts of gaseous CO and H₂. The highest CO/H₂ production rate ratio of 4.7 and a stable CO production rate of 3.55 μmol/min were obtained over the dendritic structure of the Zn/Cu–Na200 catalyst at −1.6 V vs. Ag/AgCl during 4 h CO₂RR. The dissolution and re-deposition of Zn nanoparticles occurred but did not affect the activity and selectivity in the CO₂RR of the electrodeposited Zn catalysts. The present results show the possibilities to enhance the activity and to control the selectivity of CO₂RR products on nanostructured Zn catalysts.

Passivation of Co/Al2O3 Catalyst by Atomic Layer Deposition to Reduce Deactivation in the Fischer–Tropsch Synthesis

The present work explores the technical feasibility of passivating a Co/γ-Al2O3 catalyst by atomic layer deposition (ALD) to reduce deactivation rate during Fischer–Tropsch synthesis (FTS). Three samples of the reference catalyst were passivated using different numbers of ALD cycles (3, 6 and 10). Characterization results revealed that a shell of the passivating agent (Al2O3) grew around catalyst particles. This shell did not affect the properties of passivated samples below 10 cycles, in which catalyst reduction was hindered. Catalytic tests at 50% CO conversion evidenced that 3 and 6 ALD cycles increased catalyst stability without significantly affecting the catalytic performance, whereas 10 cycles caused blockage of the active phase that led to a strong decrease of catalytic activity. Catalyst deactivation modelling and tests at 60% CO conversion served to conclude that 3 to 6 ALD cycles reduced Co/γ-Al2O3 deactivation, so that the technical feasibility of this technique was proven in FTS.

Biosugarcane-based carbon support for high-performance iron-based Fischer-Tropsch synthesis

Exploiting new carbon supports with adjustable metal-support interaction and low price is of prime importance to realize the maximum active iron efficiency and industrial-scale application of Fe-based catalysts for Fischer-Tropsch synthesis (FTS). Herein, a simple, tunable, and scalable biochar support derived from the sugarcane bagasse was successfully prepared and was first used for FTS. The metal-support interaction was precisely controlled by functional groups of biosugarcane-based carbon material and different iron species sizes. All catalysts synthesized displayed high activities, and the iron-time-yield of Fe₄/C_bio even reached 1,198.9 μmol g_Fe⁻¹ s⁻¹. This performance was due to the unique structure and characteristics of the biosugarcane-based carbon support, which possessed abundant C−O, C=O (η¹(O) and η²(C, O)) functional groups, thus endowing the moderate metal-support interaction, high dispersion of active iron species, more active ε-Fe₂C phase, and, most importantly, a high proportion of Fe_xC/Fe_surf, facilitating the maximum iron efficiency and intrinsic activity of the catalyst.

•

A kind of carbon support, derived from the sugarcane bagasse, is prepared

•

This biochar catalyst reaches an excellent FTY value in Fischer-Tropsch synthesis

•

Functional groups and Fe species sizes regulate metal-support interactions

•

Superior performance is due to abundant functional groups and ε-Fe₂C

Chasing the Mond Cation: Synthesis and Characterization of the Homoleptic Nickel Tetracarbonyl Cation and its Tricarbonyl-Nitrosyl Analogue

130 years after Mond discovered the first homoleptic carbonyl complex Ni(CO)₄, we report on a [Ni(CO)₄]^.+ salt as the first synthesis of any homoleptic nickel carbonyl cation in the condensed phase. It was prepared by oxidation of nickel metal with the synergistic oxidant Ag[F{Al(OR^F)₃}₂]/0.5 I₂ (R^F=C(CF₃)₃) in CO atmosphere. This D_2d‐symmetric metalloradical represents the last missing entry among the structurally characterized homoleptic carbonyl cations of Groups 6 to 11. Additionally, the nickel tricarbonyl‐nitrosyl cation [Ni(CO)₃(NO)]⁺ was obtained by usage of NO[F{Al(OR^F)₃}₂] and all products were fully characterized by means of IR, Raman, NMR/EPR, single crystal and powder XRD.

Precisely Engineering Architectures of Co/C Sub-Microreactors for Selective Syngas Conversion

Fischer-Tropsch synthesis (FTS) is an effective route to produce olefins, gasoline, diesel, and oxygenates from syngas (CO + H₂ ). However, it still remains a challenge for regulating the product distribution of FTS. Here, a series of Co/C sub-microreactors with precise designed nanoarchitectures are synthesized for selective syngas conversion. Through a combination of surface protection-assisted etching and following carbonization process, Co/C sub-microreactors with solid cube, double-shelled hollow box, and hollow box architectures, namely, Co/C-Cube, Co/C-DBox, Co/C-Box can be obtained. In FTS, comparing with solid Co/C-Cube, double-shelled hollow structured Co/C-DBox is inclined to grow long-chain hydrocarbon products, whereas hollow structured Co/C-Box avails the formation of short-chain hydrocarbon chemicals. Therefore, shape selective catalysis and controlled product distribution of FTS are realized by tuning the architectures of Co/C sub-microreactors. It is expected to fundamentally unravel the heterogeneous catalytic process via upfront designing and precisely regulating the architectures of micro/nanoreactors.

Boosting the synthesis of value-added aromatics directly from syngas via a Cr2O3 and Ga doped zeolite capsule catalyst

Even though the transformation of syngas into aromatics has been realized via a methanol-mediated tandem process, the low product yield is still the bottleneck, limiting the industrial application of this technology. Herein, a tailor-made zeolite capsule catalyst with Ga doping and SiO2 coating was combined with the methanol synthesis catalyst Cr2O3 to boost the synthesis of value-added aromatics, especially para-xylene, from syngas. Multiple characterization studies, control experiments, and density functional theory (DFT) calculation results clarified that Ga doped zeolites with strong CO adsorption capability facilitated the transformation of the reaction intermediate methanol by optimizing the first C-C coupling step under a high-pressure CO atmosphere, thereby driving the reaction forward for aromatics synthesis. This work not only reveals the synergistic catalytic network in the tandem process but also sheds new light on principles for the rational design of a catalyst in terms of oriented conversion of syngas.

Layered Double Hydroxide Quantum Dots for Use in a Bifunctional Separator of Lithium-Sulfur Batteries

Functional separators, which are chemically modified and coated with nanostructured materials, are considered an effective and economical approach to suppressing the shuttle effect of lithium polysulfide (LiPS) and promoting the conversion kinetics of sulfur cathodes. Herein, we report cobalt-aluminum-layered double hydroxide quantum dots (LDH-QDs) deposited with nitrogen-doped graphene (NG) as a bifunctional separator for lithium-sulfur batteries (LSBs). The mesoporous LDH-QDs/NG hybrids possess abundant active sites of Co²⁺ and hydroxide groups, which result in capturing LiPSs through strong chemical interactions and accelerating the redox kinetics of the conversion reaction, as confirmed through X-ray photoelectron spectroscopy, adsorption tests, Li₂S nucleation tests, and electrokinetic analyses of the LiPS conversion. The resulting LDH-QDs/NG hybrid-coated polypropylene (LDH-QDs/NG/PP) separator, with an average thickness of ∼17 μm, has a high ionic conductivity of 2.67 mS cm^-1. Consequently, the LSB cells with the LDH-QDs/NG/PP separator can deliver a high discharge capacity of 1227.48 mAh g^-1 at 0.1C along with a low capacity decay rate of 0.041% per cycle over 1200 cycles at 1.0C.

Cobalt Carbide Nanocatalysts for Efficient Syngas Conversion to Value-Added Chemicals with High Selectivity

Syngas conversion is a key platform for efficient utilization of various carbon-containing resources including coal, natural gas, biomass, organic wastes, and even CO₂. One of the most classic routes for syngas conversion is Fischer-Tropsch synthesis (FTS), which is already available for commercial application. However, it still remains a grand challenge to tune the product distribution from paraffins to value-added chemicals such as olefins and higher alcohols. Breaking the selectivity limitation of the Anderson-Schulz-Flory (ASF) distribution has been one of the hottest topics in syngas chemistry.Metallic Co⁰ is a well-known active phase for Co-catalyzed FTS, and the products are dominated by paraffins with a small amount of chemicals (i.e., olefins or alcohols). Specifically, a cobalt carbide (Co₂C) phase is typically viewed as an undesirable compound that could lead to deactivation with low activity and high methane selectivity. Although iron carbide (Fe_xC) can produce olefins with selectivity up to ∼60%, the fraction of methane is still rather high, and the required high reaction temperature (300-350 °C) typically causes coke deposition and fast deactivation. Recently, we discovered that Co₂C nanoprisms with preferentially exposed facets of (020) and (101) can effectively produce olefins from syngas conversion under mild reaction conditions with high selectivity. The methane fraction was limited within 5%, and the product distribution deviated greatly from ASF statistic law. The catalytic performances of Co₂C nanoprisms are completely different from that reported for the traditional FT process, exhibiting promising potential industrial application.This Account summarizes our progress in the development of Co₂C nanoprisms for Fischer-Tropsch synthesis to olefins (FTO) with remarkable efficiencies and stability. The underlying mechanism for the observed unique catalytic behaviors was extensively explored by combining DFT calculation, kinetic measurements, and various spectroscopic and microscopic investigation. We also emphasize the following issues: particle size effect of Co₂C, the promotional effect of alkali and Mn promoters, and the role of metal-support interaction (SMI) in fabricating supported Co₂C nanoprisms. Specially, we briefly review the synthetic methods for different Co₂C nanostructures. In addition, Co₂C can also be applied as a nondissociative adsorption center for higher alcohol synthesis (HAS) via syngas conversion. We also discuss the construction of a Co⁰/Co₂C interfacial catalyst for HAS and demonstrate how to tune the reaction network and strengthen CO nondissociative adsorption ability for efficient production of higher alcohols. We believe that the advances in the development of Co₂C nanocatalysts described here present a critic step to produce chemicals through the FTS process.

Design of Cobalt Fischer-Tropsch Catalysts for the Combined Production of Liquid Fuels and Olefin Chemicals from Hydrogen-Rich Syngas

Adjusting hydrocarbon product distributions in the Fischer-Tropsch (FT) synthesis is of notable significance in the context of so-called X-to-liquids (XTL) technologies. While cobalt catalysts are selective to long-chain paraffin precursors for synthetic jet- and diesel-fuels, lighter (C_10-) alkane condensates are less valuable for fuel production. Alternatively, iron carbide-based catalysts are suitable for the coproduction of paraffinic waxes alongside liquid (and gaseous) olefin chemicals; however, their activity for the water-gas-shift reaction (WGSR) is notoriously detrimental when hydrogen-rich syngas feeds, for example, derived from (unconventional) natural gas, are to be converted. Herein the roles of pore architecture and oxide promoters of Lewis basic character on CoRu/Al₂O₃ FT catalysts are systematically addressed, targeting the development of catalysts with unusually high selectivity to liquid olefins. Both alkali and lanthanide oxides lead to a decrease in turnover frequency. The latter, particularly PrO _x , prove effective to boost the selectivity to liquid (C_5-10) olefins without undesired WGSR activity. In situ CO-FTIR spectroscopy suggests a dual promotion via both electronic modification of surface Co sites and the inhibition of Lewis acidity on the support, which has direct implications for double-bond isomerization reactivity and thus the regioisomery of liquid olefin products. Density functional theory calculations ascribe oxide promotion to an enhanced competitive adsorption of molecular CO versus hydrogen and olefins on oxide-decorated cobalt surfaces, dampening (secondary) olefin hydrogenation, and suggest an exacerbated metal surface carbophilicity to underlie the undesired induction of WGSR activity by strongly electron-donating alkali oxide promoters. Enhanced pore molecular transport within a multimodal meso-macroporous architecture in combination with PrO _x as promoter, at an optimal surface loading of 1 Pr_at nm^-2, results in an unconventional product distribution, reconciling benefits intrinsic to Co- and Fe-based FT catalysts, respectively. A chain-growth probability of 0.75, and thus >70 C% selectivity to C₅₊ products, is achieved alongside lighter hydrocarbon (C_5-10) condensates that are significantly enriched in added-value chemicals (67 C%), predominantly α-olefins but also linear alcohols, remarkably with essentially no CO₂ side-production (<1%). Such unusual product distributions, integrating precursors for synthetic fuels and liquid platform chemicals, might be desired to diversify the scope and improve the economics of small-scale gas- and biomass-to-liquid processes.

A combined theoretical/experimental study highlighting the formation of carbides on Ru nanoparticles during CO hydrogenation

Formation of stable carbides during CO bond dissociation on small ruthenium nanoparticles (RuNPs) is demonstrated, both by means of DFT calculations and by solid state ¹³C NMR techniques. Theoretical calculations of chemical shifts in several model clusters are employed in order to secure experimental spectroscopic assignations for surface ruthenium carbides. Mechanistic DFT investigations, carried out on a realistic Ru₅₅ nanoparticle model (∼1 nm) in terms of size, structure and surface composition, reveal that ruthenium carbides are obtained during CO hydrogenation. Calculations also indicate that carbide formation via hydrogen-assisted hydroxymethylidyne (COH) pathways is exothermic and occurs at reasonable kinetic cost on standard sites of the RuNPs, such as 4-fold ones on flat terraces, and not only in steps as previously suggested. Another novel outcome of the DFT mechanistic study consists of the possible formation of μ₆ ruthenium carbides in the tip-B₅ site, similar examples being known only for molecular ruthenium clusters. Moreover, based on DFT energies, the possible rearrangement of the surface metal atoms around the same tip-site results in a μ-Ru atom coordinated to the remaining RuNP moiety, reminiscent of a pseudo-octahedral metal center on the NP surface.

Stochastic Kinetics of Nanocatalytic Systems

Catalytic reaction events occurring on the surface of a nanoparticle constitute a complex stochastic process. Although advances in modern single-molecule experiments enable direct measurements of individual catalytic turnover events occurring on a segment of a single nanoparticle, we do not yet know how to measure the number of catalytic sites in each segment or how the catalytic turnover counting statistics and the catalytic turnover time distribution are related to the microscopic dynamics of catalytic reactions. Here, we address these issues by presenting a stochastic kinetics for nanoparticle catalytic systems. We propose a new experimental measure of the number of catalytic sites in terms of the mean and variance of the catalytic event count. By considering three types of nanocatalytic systems, we investigate how the mean, the variance, and the distribution of the catalytic turnover time depend on the catalytic reaction dynamics, the heterogeneity of catalytic activity, and communication among catalytic sites. This work enables accurate quantitative analyses of single-molecule experiments for nanocatalytic systems and enzymes with multiple catalytic sites.

Effects of Structure and Particle Size of Iron, Cobalt and Ruthenium Catalysts on Fischer–Tropsch Synthesis

This review emphasizes the importance of the catalytic conversion techniques in the production of clean liquid and hydrogen fuels (XTF) and chemicals (XTC) from the carbonaceous materials including coal, natural gas, biomass, organic wastes, biogas and CO2. Dependence of the performance of Fischer–Tropsch Synthesis (FTS), a key reaction of the XTF/XTC process, on catalyst structure (crystal and size) is comparatively examined and reviewed. The contribution illustrates the very complicated crystal structure effect, which indicates that not only the particle type, but also the particle shape, facets and orientation that have been evidenced recently, strongly influence the catalyst performance. In addition, the particle size effects over iron, cobalt and ruthenium catalysts were carefully compared and analyzed. For all Fe, Co and Ru catalysts, the metal turnover frequency (TOF) for CO hydrogenation increased with increasing metal particle size in the small size region i.e., less than the size threshold 7–8 nm, but was found to be independent of particle size for the catalysts with large particle sizes greater than the size threshold. There are some inconsistencies in the small particle size region for Fe and Ru catalysts, i.e., an opposite activity trend and an abnormal peak TOF value were observed on a Fe catalyst and a Ru catalyst (2 nm), respectively. Further study from the literature provides deeper insights into the catalyst behaviors. The intrinsic activity of Fe catalysts (10 nm) at 260–300 °C is estimated in the range of 0.046–0.20 s−1, while that of the Co and Ru catalysts (7–70 nm) at 220 °C are 0.1 s−1 and 0.4 s−1, respectively.

Kinetics and Selectivity Study of Fischer–Tropsch Synthesis to C5+ Hydrocarbons: A Review

Fischer–Tropsch synthesis (FTS) is considered as one of the non-oil-based alternatives for liquid fuel production. This gas-to-liquid (GTL) technology converts syngas to a wide range of hydrocarbons using metal (Fe and Co) unsupported and supported catalysts. Effective design of the catalyst plays a significant role in enhancing syngas conversion, selectivity towards C5+ hydrocarbons, and decreasing selectivity towards methane. This work presents a review on catalyst design and the most employed support materials in FTS to synthesize heavier hydrocarbons. Furthermore, in this report, the recent achievements on mechanisms of this reaction will be discussed. Catalyst deactivation is one of the most important challenges during FTS, which will be covered in this work. The selectivity of FTS can be tuned by operational conditions, nature of the catalyst, support, and reactor configuration. The effects of all these parameters will be analyzed within this report. Moreover, zeolites can be employed as a support material of an FTS-based catalyst to direct synthesis of liquid fuels, and the specific character of zeolites will be elaborated further. Furthermore, this paper also includes a review of some of the most employed characterization techniques for Fe- and Co-based FTS catalysts. Kinetic study plays an important role in optimization and simulation of this industrial process. In this review, the recent developed reaction rate models are critically discussed.

Insight into the Influence of the Graphite Layer and Cobalt Crystalline on a ZIF-67-Derived Catalyst for Fischer-Tropsch Synthesis

Due to the special framework structure, ZIF-67 is a promising material as the precursor to prepare the Co@C catalysts with high cobalt loading and superior cobalt dispersion. Unfortunately, these Co@C-X catalysts exhibit not only unsatisfied activity but also high CH₄ selectivity. This limited its further application due to the lack of in-depth analysis of the reasons behind it. In this work, the Co@C-X catalysts were prepared by pyrolyzing the ZIF-67 precursor at different temperatures. A series of characterizations were conducted to explore the behavior of the graphite carbon coated on cobalt species, realizing that the role of active Co sites on these Co@C catalysts was restricted by the graphite carbon layer since it suppressed the adsorption and activation of syngas on Co sites. TEOS was introduced to suppress the aggregation of cobalt species and more active sites were exposed after the graphite carbon layer was eliminated. As a result, the FTS performance was greatly improved by a factor of 5. The effect of O₂ concentration on the microcrystalline size of Co and the reconfinement effect of SiO₂ were investigated. The model catalyst was prepared and the key factors determining CH₄ selectivity of the ZIF-67-derived Co@C catalyst were revealed. This provides a good basis for rational designing ZIF-67-derived Co-based FTS catalysts.