Selectivity To Light Olefins Research Articles

Boosting CO2 hydrogenation of Fe-based monolithic catalysts via 3D printing technology-induced heat/mass-transfer enhancements

The direct transformation of CO2 into valuable chemicals with the aid of sustainable energy-generated H2 has attracted enormous interest owing to the integrated functions of carbon elimination and non-fossil fuel-derived products supply. As one of the most promising catalysts for CO2 hydrogenation, the chemical properties of Fe-based catalysts, such as electronic structure and coordination environment, have been widely studied. However, the mass/heat transfer effects in Fe-based catalysts are also crucial to the targeted product selectivity and catalytic stability, but have been rarely investigated due to the lack of facile fabrication protocols. Herein, we precisely fabricate and tailor the architecture of the Fe-based monolithic catalysts by a direct ink writing (DIW)-type three-dimensional (3D) printing technology under the guidance of the computationally controlled printing procedure. The Fe-based monolithic catalyst with spiral-type architecture delivers extremely high light olefins selectivity (52.6%) and space time yield (STY, 451.8 gCH2 kgcat−1 h−1) from CO2 hydrogenation. Based on the mass-transfer simulation, the spiral-structured channels in the Fe-based monolithic catalyst lower the coverage of intermediates and products on the catalytic interface due to the optimal mass-transfer effect, thus maximizing the utilization of active sites and timely terminating the carbon-chain growth. More in-depth, the density functional theoretical (DFT) simulations verify that the relatively electron-rich catalytic interface with low intermediate coverage could facilitate the desorption of olefins and decelerate the C-C coupling step, which synergistically guarantee the enhanced light olefins synthesis performance. Furthermore, the enhanced heat-transfer effect endowed by the 3D architecture prolongs the life-time of catalyst by avoiding undesirable active site aggregation and carbon deposition. The powerful strategy for catalyst fabrication not only provides a new concept of regulating the CO2 hydrogenation performance of Fe-based catalysts but also holds a great promise to spread into other catalytic systems for targeted synthesis.

Catalytic Cracking of Fischer-Tropsch Wax on Different Zeolite Catalysts

Fisher-Tropsch synthesis (FTS) is a promising method to make alternative hydrocarbons from biomass or other resources. Upgrading the primary FTS products is of considerable interest. Cracking FT wax is economically attractive to produce light olefins. Herein, the effects of the zeolite type, Si/Al ratio of ZSM-5, and reaction condition on the catalytic cracking of FT wax were investigated. It was found that the pore structure and acid properties of zeolites had a significant impact on the product selectivity. USY was beneficial for the production of gasoline and diesel, while β was suitable for the production of propylene and butenes, and ZSM-5 was conductive to producing ethylene and propylene. Increasing the Si/Al ratio of ZSM-5 can suppress the hydrogen transfer reaction and increase the selectivity of light olefins. When the Si/Al ratio of ZSM-5 was 140, the mass yields of ethylene, propylene, and butenes were 6.40%, 26.83%, and 20.10%, respectively.

Syngas to FCC-like gasoline range hydrocarbons with upgraded light olefin selectivity catalyzed by readily synthesized Fe-MOF

The global trend toward sustainability is due to the growing demand for synthetic chemicals and fuels relying on fossil crude oil with the associated concerns of climate change. The Fischer-Tropsch synthesis (FTS) process is a key sustainable pathway for supplying light olefins, gasoline, and other petrochemicals using green hydrogen and energy. Here we report a simple, green, cost-effective synthesis strategy to prepare an iron-based metal–organic framework (Fe-BTC MOF) at room temperature with a remarkable porous structure analogous to the commercially available Basolite F300. The catalyst shows a 97% syngas conversion to gasoline-range hydrocarbons (C5-C12) at high temperatures, with a selectivity of 48.3%, yield of 28%, low methane selectivity (15.5%) and low C13+ selectivity (1%). In addition, the catalyst is 29% selective to light olefin (C2-C4=), yielding 17%, besides an olefin/paraffin ratio (O/P) of 4.3 with 81% olefin selectivity of the C2-C4 fraction. The resulting gasoline is equivalent to gasoline produced by Fluid Catalytic Cracking (FCC) of crude oil. The highest C5-C12 selectivity reached 63.6%, yielding 12% at 29% CO conversion. The Fe-BTC/C catalyst showed excellent stability for time on stream >100 h and a high gas hourly space velocity (GHSV) value of 20000 mL g-1cat h−1 with an Fe-time yield of 165 µmolCO g-1Fe s−1. The prepared Fe-BTC catalyst, with a 2-fold larger pore volume than the previously prepared Fe-MIL-88B catalyst, has a higher olefin production capability by 2-fold, 7-fold higher O/P for the light fraction and 2.3-fold higher C5+ selectivity. The sustainable synthesis of catalysts with improved porous structure may significantly foster FTS technology for being economically practical to be scaled up and commercialized for national fuel and olefin production projects.

Acid-driven architecture of hierarchical porous ZSM–5 with high acidic quantity and its catalytic cracking performance

Controllable synthesis of ZSM–5 zeolites with hierarchical pores and high acidities is an efficient way for cracking of naphtha to produce light olefins. Here, nanocrystalline ZSM-5 aggregates (NCs) with n(Si)/n(Al) of ∼18 were hydrothermally synthesized via acid hydrolysis of a silicon source for the cracking of n–pentane. Compared with conventional microporous ZSM–5 zeolite, NCs catalysts with preserved micropores and newly generated intercrystalline mesopores promote cracking conversion as well as selectivity of light olefins. Moreover, enhanced acidities with high Al concentration in zeolite benefit the conversion of n–pentane. Interestingly, it is found that with moderate amount of framework Fe, the strength of the Brønsted acid sites of the catalysts increases and Lewis acid sites are formed in zeolite, while maintaining the total acidities. Owing to the restricted bimolecular reaction of the olefins on the adjacent acid sites, the catalysts with an Al–Fe co–framework (NC–5Al–1Fe) affords increased yield of light olefins (ethylene and propylene) up to ∼40 wt% with enhanced catalytic stability after 16 h reaction at 600 °C.

Insight into the effect of F− on acidity of H-SAPO-18 and its catalytic performance for conversion of methanol to olefins

In this study, F− was added to the synthesis gel to regulate the acid property of SAPO-18 molecular sieve and enhance its catalytic performance for the methanol-to-olefin (MTO) reactions. The results indicate that adding an appropriate amount of F− during synthesis can increase the crystallinity of SAPO-18 molecular sieve and reduce the overall strong acid density and external surface acid content. The H-SAPO-18-I-20-0.0025 molecular sieve exhibits a much higher catalytic lifetime (1000 min) and light olefins selectivity (45.2% to propene and 96.1% to C2-5=) in MTO at 400 °C than those of the traditional H-SAPO-18-1-0. The results of the isotope labeling experiments, GC-MS, and 13C MAS NMR results provided direct evidence that the aromatic-based cycle contributes more to the conversion of methanol into light olefins, and hexamethylbenzene serves as the most abundant hydrocarbon species that produces propene via the paring route.

Insight into performance over IM-5, ZSM-5 and ZSM-11 zeolites for n-heptane cracking to light olefins in the absence & presence of steam

The three dimension (3D) 10-membered ring channels zeolite has a unique advantage in increasing light olefins for catalytic cracking reaction. Herein, zeolites IM-5, ZSM-5 and ZSM-11 were synthesized hydrothermally to achieve comparable texture properties and SiO2/Al2O3 ratios. The acid content and acid strength of the three zeolites were as follows: IM-5 > ZSM-5 > ZSM-11. Meanwhile, 1H DQ MAS NMR confirmed that there was a synergistic effect between Brønsted and Lewis acids in IM-5 zeolite. However, IM-5 zeolite with lots of strong BAS had an unexpected low TOF in n-heptane cracking. Furthermore, the light olefins selectivity was as follows: IM-5 > ZSM-11 > ZSM-5 at 550–650 ℃ in the absence of steam. IM-5 zeolite had the particular advantage in ethylene, and its selectivity was up to 44.9 %. After steam was introduced, the monomolecular cracking reaction, the aromatization of propylene and the deep cracking of C3 and C4 hydrocarbons were inhibited over the three zeolites. Steam could prolong the activity of IM-5 zeolite, but accelerate the deactivation of ZSM-5 and ZSM-11 zeolites. The primary cause for the rapid deactivation of ZSM-5 and ZSM-11 zeolites was dealuminization in steam, whereas for the IM-5 zeolite, it was the rapid formation of coke on its surface, thereby blocking its micropore channels.

The bifunctional oxygen carrier K/LayCoxFe1-xO3 for the production of C2–C4 olefins via CO2 hydrogenation

Developing the bifunctional oxygen carrier with excellent oxygen mobility and catalytic activity is the key to chemical looping combustion coupled CO2 hydrogenation to light olefins. In this study, a series of K/LayCoxFe1-xO3 (x = 0, 0.2, 0.4, 0.6, y = 0.2, 0.4, 0.8) with oxygen vacancy-active metal dual active centers were constructed by the Co doping-La defect synergistic strategy to evaluate the oxygen release and catalytic performance. The results indicated that K/La0.4Co0.4Fe0.6O3 had high oxygen mobility, and its reduced state can be directly used for CO2 hydrogenation to light olefins (C2=-C4=). The selectivity of C2=-C4= was close to 30%, and the conversion rate of CO2 was 36%. Combined with various characterizations, the synergy of Co doping and La defects increased the oxygen vacancy and promoted the exsolved CoFe alloy under the reduction induction of chemical looping combustion. In situ DRIFTS reveals the dynamic equilibrium of the Formate-Methoxy mechanism and RWGS-FTS pathway. Oxygen vacancies are found to enhance the conversion of CO2 via the formate pathway, while metal active phases alter the product distribution by changing the evolution of intermediates. The Co7Fe3 and oxygen vacancy on K/La0.4Co0.4Fe0.6O3 promotes the formation of CHx∗ and C–C coupling through various intermediates, improving the selectivity of light olefins.

Effect of acidity and oxygen vacancy in Mn loaded SAPO-34 on CO2 hydrogenation to light olefin

In this paper, the interaction between metal catalyst and Mn-doped molecular sieve was proposed as a strategy to regulate the metal valence which influences acidic sites and promotes carbon dioxide adsorption during CO2 hydrogenation reaction. The ZnO-ZrO2/4%MnSAPO-34 catalyst displayed a stronger CO2 adsorption capacity and improved activity compared to the unmodified ZnO-ZrO2/SAPO-34 catalyst. Physical and chemical properties of the tested catalysts were explored using XRD, SEM-EDS, FT-IR, TEM, CO2-TPD, NH3-TPD and XPS. By fine tuning the Mn amount on SAPO-34 catalyst, the acidity which plays a crucial role in the selectivity of the light olefins, was controlled. Optimized conditions such as influence of catalyst composition and reaction temperature were also investigated. At 380 °C, 2.0 MPa, GHSV = 2400 h−1 and ZnO-ZrO2 to MnSAPO-34 mass ratio of 1, the selectivity of light olefins reached 83.2%, with a CO2 conversion of 17.3%.

Acid Treatment to Improve Total Light Olefins Selectivity of HZSM-5 Catalyst in Methanol to Olefins (MTO) Reaction

Acid Treatment to Improve Total Light Olefins Selectivity of HZSM-5 Catalyst in Methanol to Olefins (MTO) Reaction

Promotion effects of alkali metals on iron molybdate catalysts for CO2 catalytic hydrogenation

CO2 hydrogenation is an attractive way to store and utilize carbon dioxide generated by industrial processes, as well as to produce valuable chemicals from renewable and abundant resources. Iron catalysts are commonly used for the hydrogenation of carbon oxides to hydrocarbons. Iron-molybdenum catalysts have found numerous applications in catalysis, but have been never evaluated in the CO2 hydrogenation. In this work, the structural properties of iron-molybdenum catalysts without and with a promoting alkali metal (Li, Na, K, Rb, or Cs) were characterized using X-ray diffraction, hydrogen temperature-programmed reduction, CO2 temperature-programmed desorption, in-situ 57Fe Mossbauer spectroscopy and operando X-ray adsorption spectroscopy. Their catalytic performance was evaluated in the CO2 hydrogenation. During the reaction conditions, the catalysts undergo the formation of an iron (II) molybdate structure, accompanied by a partial reduction of molybdenum and carbidization of iron. The rate of CO2 conversion and product selectivity strongly depend on the promoting alkali metals, and electronegativity was identified as an important factor affecting the catalytic performance. Higher CO2 conversion rates were observed with the promoters having higher electronegativity, while low electronegativity of alkali metals favors higher light olefin selectivity.

A facile strategy to prepare ZSM-5-based composites with enhanced light olefin selectivity and stability in the HTO process.

In this study, the influence of different ZSM-5 composite materials (ASA, γ-alumina, η-Al2O3, SiO2, and attapulgite) and their performance in the n-hexane catalytic cracking process in a fixed bed microreactor at 550 °C under atmospheric pressure was studied. XRD, FT-IR spectroscopy, NH3-TPD, BET, FE-SEM, and TG analyses were performed to characterize the catalysts. The result of the n-hexane to olefin process indicated that the A2 catalyst (γ-alumina composition with ZSM-5) showed the highest conversion of 98.89%, highest propylene selectivity of 68.92%, highest yield of light olefins of 83.84%, and highest propylene to ethylene ratio of 4.34. The reason for the significant increase in all these factors and the lowest amount of coke in this catalyst is the use of γ-alumina, which increased the hydrothermal stability and resistance to deactivation, improved the acidic properties with a strong to weak acid ratio of 0.382, and increased the mesoporosity to 0.242. This study indicates the effect of the extrusion process and the composition and the major effect of the properties of this material on the physicochemical properties and distribution of the product.

Effect of Molecular Structure of C10 Hydrocarbons on Production of Light Olefins in Catalytic Cracking

The effect of the molecular structure of feedstock on the cracking reaction of C10 hydrocarbons to ethylene and propylene over H-ZSM-5 zeolite was investigated. To better compare the effect of decane on the production of light olefins, the thermal cracking and catalytic cracking performance of decane were first investigated. As a comparison, the thermal cracking and catalytic cracking of decane were studied by cracking over quartz sand and H-ZSM-5. Compared with the thermal cracking reaction over quartz sand, the catalytic cracking reaction of decane over H-ZSM-5 has a significantly higher conversion and light olefins selectivity, especially when the reaction temperature was lower than 600 °C. On this basis, the catalytic cracking reactions of decane and decene over H-ZSM-5 were further compared. It was found that decene with a double bond structure had high reactivity over H-ZSM-5 and was almost completely converted, and the product was mainly olefin. Compared with decane as feedstock, it has a lower methane yield and higher selectivity of light olefins. Therefore, decene was more suitable for the production of light olefins than decane. To this end, we designed a new light olefin production process. Through olefin cracking, the yield of light olefins in the product can be effectively improved, and the proportion of different light olefins such as ethylene, propylene and butene can be flexibly adjusted.

Crucial Role of Surface FeOx Components on Supported Fe-Based Nanocatalysts for CO2 Hydrogenation to Light Olefins

Currently, Fe-based catalysts show excellent catalytic performance in the hydrogenation of CO2 to produce light olefins. Despite numerous studies, the identification of the role of catalytically active components over Fe-based catalysts for CO2 hydrogenation is not quite clear. In this work, a series of ZrO2-supported cobalt-doped Fe-based catalysts were fabricated by a microliquid film reactor-assisted coprecipitation method. It was demonstrated that appropriately strong interactions between Fe-containing species and the ZrO2 support in catalyst precursors could facilitate the generation of a defective FeOx component upon reduction treatment and inhibit the carburization of metallic iron during the reaction. Among all Fe-based catalysts, the catalyst bearing a (Co + Fe)/ZrO2 mass ratio of 3:7 and a Co/Fe molar ratio of 1:9 achieved a highest light olefins selectivity of about 38% at 49% CO2 conversion under reaction conditions (i.e., 320 °C, 2.0 MPa, and 4800 mL·gcat–1·h–1), along with a high Fe time yield to light olefins of 9.2 μmolCO2·gFe–1·s–1 and a low CO selectivity of 4.7%. Comprehensive structural characterization and catalytic CO2 hydrogenation experiments clarified that the surface-dominant defect-rich FeOx component as catalytically active species substantially played a crucial role in governing the hydrogenation of CO2, mainly owing to their enhanced adsorption and binding ability for CO2 and the CO intermediate. This study offers a new strategy to design Fe-based catalysts and provides deep insight into the role of iron oxide species for CO2 hydrogenation to produce light olefins.

CO2 hydrogenation to light olefins using In2O3 and SSZ-13 catalyst − Understanding the role of zeolite acidity in olefin production

With the aim to explore the effect of acidic properties of zeolites in tandem catalysts on their performance for CO2 hydrogenation, two types of SSZ-13 zeolites with similar bulk composition, but different arrangements of framework Al, were prepared. Their morphology, pore structure, distribution of framework Al, surface acid strength and density, were explored. The results showed that SSZ-13 zeolites with isolated aluminum distribution could be successfully synthesized, however, they contained structural defects. During calcination, the framework underwent dealumination, resulting in weaker Brønsted acidity and lower crystallinity. The morphologies were, however, well preserved. Compared with the SSZ-13 zeolites, synthesized conventionally, these low acidity SSZ-13 zeolites with isolated aluminum were good zeolite components in bifunctional catalysts for CO2 hydrogenation to light olefins. By combining with In2O3, they exhibited better catalytic performance for light olefin production during CO2 hydrogenation at low temperatures. Na+ cation exchange was used to adjust the Brønsted acid site (BAS) density with only minor changes to the cavity structure. Comparative experiments established that the BAS density of the zeolite, rather than the framework Al distribution (BAS distribution), overwhelmingly affected catalyst stability and product selectivity. A higher acid density reduced the selectivity for light olefins, while lower acid density tended to form inert coke species leading to rapid deactivation. The ideal amount of BAS density in the bifunctional catalyst was approximately 0.25 mmol/g, which exhibited 70% selectivity for light olefins among hydrocarbons, and 74% selectivity for CO without deactivation, after 12 h reaction at 325 ℃ and 10 bar.

Disentangling the activity-selectivity trade-off in catalytic conversion of syngas to light olefins.

Breaking the trade-off between activity and selectivity has been a long-standing challenge in the field of catalysis. We demonstrate the importance of disentangling the target reaction from the secondary reactions for the case of direct syngas conversion to light olefins by incorporating germanium-substituted AlPO-18 within the framework of the metal oxide-zeolite (OXZEO) catalyst concept. The attenuated strength of the catalytically active Brønsted acid sites allows enhancing the targeted carbon-carbon coupling of ketene intermediates to form olefins by increasing the active site density while inhibiting secondary reactions that consume the olefins. Thus, a light-olefins selectivity of 83% among hydrocarbons and carbon monoxide conversion of 85% were obtained simultaneously, leading to an unprecedented light-olefins yield of 48% versus current reported light-olefins yields of ≤27%.

Facilely adjusting acidity features of zeolites by steaming treatment for enhanced methanol conversion to aromatics: A mechanism study

In this contribution, the effects of the steaming treatment on the acidity and aluminum structure of ZSM-5 were systematically investigated by using different types of zeolite catalysts. The relationships between the acid properties and the catalytic performance of the methanol-to-aromatics (MTA) reaction were also elucidated. The results revealed that different kinds of acid sites showed varied stability during the steaming treatment. Especially for Brønsted acid sites (BAS), the reduction of the acid site was highly related to the stability of different distributed framework Al sites (Alsingle > Alpairs) and the existence of non-framework species (“neutralization” by the EFAL and ZnO). Additionally, the presence of the extra-framework aluminum (EFAl) and metal compensation ions could enhance the stability of the zeolite framework Si-O(H)-Al. Besides, it was found that the reduction degree in the content of the Zn-LAS (LAS = Lewis acid sites) was less than the Al-LAS. The effects of steaming treatment on acid properties over zeolites with different particle sizes were also explored. Furthermore, the catalytic performance for the MTA reaction showed that the stability of the ZSM-5 catalyst was significantly enhanced after the steaming treatment. Moreover, the reduction in the proportion of the Alpairs sites may inhibit the hydrogen-transfer aromatization process of alkenes, while the increase of the Alsingle species enhanced the cracking process of higher olefins, leading to the reduction of aromatics selectivity and the increase of light olefins selectivity, respectively.

Unraveling the role of GaZrOx structure and oxygen vacancy in bifunctional catalyst for highly active and selective conversion of syngas into light olefins

The direct conversion of syngas to light olefins (STO) over metal oxide-zeolite (OX-ZEO) bifunctional catalyst has aroused wide interest. However, due to unmatched reaction temperature for CO conversion to oxygenated hydrocarbons over metal oxide (200–300 °C) and C−C coupling reaction over zeolite (350–450 °C), it is still a great challenge to achieve both high light olefins selectivity and high CO conversion; moreover, the reaction mechanism needs to be further studied. Herein, the Ga-Zr oxide is taken as a probe oxide to mix with SAPO-34 zeolite for STO. A high light olefins selectivity of 88.6% is achieved at an extremely high CO conversion of 51.6% with a stable activity for 200 h. The incorporation of Ga into ZrO2 generates the GaZrOx solid solution structure with abundant concentration of oxygen vacancy and hydroxy group, the strong synergetic effect between Ga and Zr in GaZrOx benefits the CO activation and CH3O* formation at high temperatures (280–430 °C), providing a compatible temperature match for C−C coupling over SAPO-34. The GaZrOx is a promising and potential catalyst for industrial application in direct conversion of syngas to olefins, aromatics, and liquid fuels.

Tuning the Crystal Phase to Form MnGaOx -Spinel for Highly Efficient Syngas to Light Olefins.

The oxide-zeolite (OXZEO) catalyst design concept has been demonstrated in an increasing number of studies as an alternative avenue for direct syngas conversion to light olefins. We report that face-centered cubic (FCC) MnGaOx -Spinel gives 40 % CO conversion, 81 % light olefins selectivity, and a 0.17 g gcat -1 h-1 space-time yield of light olefins in combination with SAPO-18. In comparison, solid solution MnGaOx (characterized by Mn-doped hexagonal close-packed (HCP) Ga2 O3 ) with a similar chemical composition gives a much inferior activity, i.e., the specific surface activity is one order of magnitude lower than the spinel oxide. Photoluminescence (PL), in situ Fourier-transform infrared (FT-IR), and density functional theory (DFT) calculations indicate that the superior activity of MnGaOx -Spinel can be attributed to its higher reducibility (higher concentration of oxygen vacancies) and the presence of coordinatively unsaturated Ga3+ sites, which facilitates the dissociation of the C-O bond via a more efficient ketene-acetate pathway to light olefins.

Tuning the Crystal Phase to Form MnGaOx‐Spinel for Highly Efficient Syngas to Light Olefins

AbstractThe oxide–zeolite (OXZEO) catalyst design concept has been demonstrated in an increasing number of studies as an alternative avenue for direct syngas conversion to light olefins. We report that face‐centered cubic (FCC) MnGaOx‐Spinel gives 40 % CO conversion, 81 % light olefins selectivity, and a 0.17 g gcat−1 h−1 space‐time yield of light olefins in combination with SAPO‐18. In comparison, solid solution MnGaOx (characterized by Mn‐doped hexagonal close‐packed (HCP) Ga2O3) with a similar chemical composition gives a much inferior activity, i.e., the specific surface activity is one order of magnitude lower than the spinel oxide. Photoluminescence (PL), in situ Fourier‐transform infrared (FT‐IR), and density functional theory (DFT) calculations indicate that the superior activity of MnGaOx‐Spinel can be attributed to its higher reducibility (higher concentration of oxygen vacancies) and the presence of coordinatively unsaturated Ga3+ sites, which facilitates the dissociation of the C−O bond via a more efficient ketene–acetate pathway to light olefins.

Green synthesis of Cu-Mo promoted Fe catalyst for production of the gaseous and liquid fuels through Fischer-Tropsch synthesis

Designing a novel Fe catalyst with improved selectivity to light olefins and heavier hydrocarbons attracts great attention for Fischer-Tropsch synthesis (FTS) as an alternative clean energy resource. In this work, a highly efficient Cu-Mo promoted Fe catalysts supported on activated carbon with engineered features from biomass were synthesized and tested for FTS under relevant industrial conditions (300 °C, 2 MPa, and 2000 h−1). Optimization of the Fe, Mo, and Cu loadings led to a significant increase in CO conversion (from 46.7% for unpromoted to 78.8% for Cu-Mo promoted catalysts). Light olefin selectivity for the promoted catalysts was remarkably enhanced to 33.2% and 25.0% for Cu and Mo-promoted catalysts, respectively. The improved selectivity to light olefin can be attributed to the weakened basicity of iron sites for promoted catalysts. Improved C5+ selectivity on the other hand, can be assigned to the contribution of Fe carbides with higher C:Fe ratio in the structure of the optimized catalyst. The presence of Mo carbides was confirmed by XPS, XRD, and XANES results, manifesting the contribution of Mo in the catalytic activity of the optimized catalyst. The superior selectivity to both light olefins and C5+ hydrocarbons disclosed that the prepared catalyst could be an ideal candidate for industrial iron-based FTS catalyst in future to modulate the products distribution.