Low-temperature Fischer-Tropsch synthesis iron-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to a low-temperature Fischer-Tropsch synthesis iron-based catalyst and a preparation method and application thereof. The catalyst is composed of Fe, Co, Si, K and a Sr-modified carrier M, wherein the carrier is activated carbon, carbon nanotubes, graphene, aluminum oxide, titanium dioxide or diatomite. The preparation method comprises the steps of carrier calcination, Sr precipitation, deposition and calcination, compounding of Fe / Co and potassium-silicon source silica sol, drying and reduction. The catalyst is used for Fischer-Tropsch synthesis under the conditions of 240-270 DEG C and 3.0-6.0 MPa through pre-reduction (selective carburization), can effectively reduce byproducts while improving CO conversion and selectivity, and has stability and amplification suitability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of low-temperature Fischer-Tropsch synthesis, and relates to a low-temperature Fischer-Tropsch synthesis iron-based catalyst and a preparation method and application thereof. BACKGROUND

[0002] Fischer-Tropsch synthesis reaction refers to a reaction in which synthesis gas (H2+CO) is converted into hydrocarbons and other chemicals under the action of a catalyst at a certain temperature and pressure. In the 1950s, the South African SASOL Company realized commercial application of low-temperature Fischer-Tropsch synthesis and high-temperature Fischer-Tropsch synthesis by using the patent technology of the German Ruhr Company. The reaction temperature of the low-temperature Fischer-Tropsch synthesis technology is between 210-280℃, the catalysts are a precipitated iron catalyst and a cobalt-based catalyst, and the reactor forms are a fixed bed reactor and a slurry bed reactor. The iron-based catalyst, as one of the main catalysts for Fischer-Tropsch synthesis, has advantages of abundant resources and low cost, and has been widely applied in industrial production. However, the traditional iron-based catalyst has problems of a complex preparation process, low activity and poor stability, which limit its application in Fischer-Tropsch synthesis. Therefore, it is of important industrial significance to find a method capable of improving the activity and stability of the iron-based catalyst.

[0003] The low-temperature Fischer-Tropsch synthesis iron-based catalyst has been developed for decades, and technical developers all over the world continue to improve the catalyst formula and preparation method, and many new useful additives are added to the Fe-Cu-K-SiO2 system to improve the catalyst performance. The Fe-Mn-Cu-K-SiO2 developed by the Synthesia Oil Development Company, the Fe-Cu-K-SiO2 developed by the Yanzhou Mining Company, the Fe-Co-Cu-K-SiO2 developed by the Shenhua Company and the like are relatively representative. 2- In order to further improve the activity and stability of the catalyst, researchers improve the mechanical strength of the catalyst by adding one or more structural additives. For example, the patents CN107913714B, CN1245255C, CN101293206A, CN101298046A and CN105478128B respectively add one or more rare earth metals, alkaline earth metals and other transition metal additives to improve the activity of the catalyst by the synergistic effect between the additives. However, the existing low-temperature Fischer-Tropsch synthesis iron-based catalyst still has many performance needs to be improved, such as activity, byproduct selectivity, C 5+ product selectivity, stability and wear resistance. SUMMARY

[0004] The application provides a low-temperature Fischer-Tropsch synthesis iron-based catalyst and a preparation method and application thereof, and aims to solve the problems that the traditional Fe-based catalyst is easy to appear and selectivity is high, The problems of insufficient chain growth, unstable active phase and short service life. The catalyst is based on a Sr-modified carrier M, and the active components include Fe, Co, Si and K. The construction of the catalyst is the synergistic combination of the pre-alkaline sites of the carrier and the active metals. Without changing the basic conditions of the low-temperature Fischer-Tropsch process, the synergistic regulation of the key surface site density, the formation of the active phase and the side reaction path is realized. The preparation steps of the catalyst include carrier calcination and purification, Sr deposition and calcination to obtain a Sr-modified carrier, the introduction of Fe salt, Co salt and potassium silicate sol, drying and high-temperature reduction to obtain the target catalyst. The catalyst is used for low-temperature Fischer-Tropsch synthesis after pre-reduction treatment, realizes the efficient conversion of synthesis gas to liquid fuel and high-carbon hydrocarbon products, and has the characteristics of high activity, low by-product selectivity and high stability. 5+ Product selectivity, high stability.

[0005] According to a first aspect of the present application, a low-temperature Fischer-Tropsch synthesis iron-based catalyst is provided, the active components of the catalyst include Fe, Co, Si, K and a carrier M, the carrier M is a Sr-modified carrier, and the carrier is selected from one or more of activated carbon, carbon nanotubes, graphene, alumina, titanium dioxide and diatomite; The components satisfy the mass ratio of Fe:Co:Si:K:M=30:(2-9):(10-30):(1-5):30, and Sr accounts for 0.1-20% of the weight of the carrier M.

[0006] In some technical solutions, the Si and K sources are potassium silicate sol.

[0007] According to a second aspect of the present application, a preparation method of the above-mentioned low-temperature Fischer-Tropsch synthesis iron-based catalyst is further provided, which comprises the following steps: S1, high-temperature calcination of the carrier to remove impurities to obtain a carrier M0; S2, loading Sr on the carrier M0 by a deposition method, drying and calcining to obtain a Sr-modified carrier M1; S3, adding Fe salt, Co salt and potassium silicate sol to deionized water to obtain a first solution S1; S4, adding the Sr-modified carrier M1 to the first solution S1 and stirring and ultrasonicating to obtain a mixture M2; S5, continuously stirring at a certain temperature until drying to obtain a solid M3; S6, drying and high-temperature reduction of the solid M3 to obtain the catalyst.

[0008] In some technical solutions, in step S2, The deposition method is a precipitation deposition method. The Sr source was ammonium bicarbonate as the precipitant, the Sr concentration in the slurry was 10-20%, the precipitation temperature was 25-80℃, the precipitation pH was 8.5-9.0, and the aging time was 2-4 h.

[0009] In some technical solutions, the calcination temperature in step S1 is 300–500℃, and the time is 4–6 h; and / or; The drying in step S2 and / or step S6 is air drying in an oven at a temperature of 80–150°C for a time of 1–30 h; and / or, In step S2, the calcination temperature is 300–600℃, the heating rate is 0.5–2℃ / min, and the calcination time is 4–10 h; and / or, The stirring temperature in step S5 is 25–80℃, and the stirring time is 12–24 h; and / or, The high-temperature reduction temperature in step S6 is 300–750℃, the heating rate is 0.5–2℃ / min, and the reduction time is 4–10 h.

[0010] In some technical solutions, the Fe salt and Co salt are one or more of the corresponding metal nitrates, sulfates and hydrochlorides; The precipitant used in step S2 is selected from one or more of hydroxides, carbonates, and bicarbonates.

[0011] According to a third aspect of the present invention, an application of a low-temperature Fischer-Tropsch synthesis iron-based catalyst is further provided. The catalyst described above, or the catalyst prepared by the method described above, is used in the low-temperature Fischer-Tropsch synthesis. The application steps are as follows: The catalyst is subjected to pre-reduction treatment; Syngas is converted into hydrocarbon products under low-temperature Fischer-Tropsch synthesis conditions.

[0012] In some technical solutions, the pre-reduction conditions are: the reducing gas is... The flow rate was 350–800 mL / min, the reduction pressure was 0.5–2.4 MPa, the reduction temperature was 240–270℃, the reduction time was 20–32 h, and the heating rate was 2℃ / min.

[0013] Some technical solutions also include carburizing the catalyst, with the carburizing conditions being: the carburizing gas being CO and... The flow rate is 350–800 mL / min, the carburizing pressure is 0.5–2.4 MPa, the carburizing temperature is 240℃, the carburizing time is 20–32 h, and the heating rate is 2℃ / min.

[0014] In some technical solutions, the low-temperature Fischer-Tropsch synthesis reaction conditions are as follows: the reaction gas is... CO reacts with inert gas Ar at a pressure of 3.0–6.0 MPa and a temperature of 240–270 °C. The molar ratio with CO is 2:1.

[0015] The present invention, by employing the above technical solution, has at least the following beneficial effects: 1. This invention employs a "Sr-support" pre-modification strategy to pre-position basic sites at the support scale, significantly enhancing the dissociation ability of CO molecules at the iron carbide precursor site and reducing the promoting effect of surface hydroxyl groups and acidic sites on WGS side reactions, thereby enabling... Under the common ratio of / CO=2 / 1, Generation is effectively suppressed, and the probability of chain growth is increased. Selectivity is thus improved. Compared with the approach of simply adding alkali to the catalyst surface (such as post-impregnation with K or alkaline earth), the present invention first applies alkali to the support and then introduces the Fe / Co / Si / K sequence design, so that the strong base sites and metal / carbide active centers form a stable and repeatable spatial coupling relationship at the microscale, which is more conducive to the initiation and continuation of C–C bond growth under low temperature conditions.

[0016] 2. The synergistic construction of Fe and Co in this invention is promoted with the assistance of Si and K. The formation and maintenance of the active phase of iron carbide are optimized, avoiding reliance solely on high temperatures or strong reducing conditions to achieve the target phase. This allows for a balance between high activity and durability within the low-temperature Fischer-Tropsch window of 240–270 °C. The introduction of Si contributes to the formation of a dispersed framework and crosslinked structure with moderate mechanical strength, while the electronic effects of K further stabilize iron carbide and inhibit methanation. Byproducts were effectively controlled; the synergistic results were manifested in CO2 conversion and... Selective, simultaneous improvement rather than one-sided optimization that results in a zero-sum game.

[0017] 3. The Sr modification in this invention synergistically regulates the surface electrical properties and wettability of the support, improving the anchoring strength and dispersion uniformity of Fe / Co / Si / K on different supports (activated carbon, carbon nanotubes, graphene, alumina, titanium dioxide, diatomaceous earth). This "platformized" support system gives this invention good adaptability: it achieves excellent thermal conductivity and mass transfer properties on carbon-based supports, and better mechanical strength and scalability on oxide and natural mineral supports; stable scale-up can be achieved in both fixed-bed and slurry-bed environments using the same construction approach, reducing performance fluctuations caused by differences in the support.

[0018] 4. The process window of this invention is clearly defined and can be industrially reproduced. The pH, aging and calcination conditions for Sr deposition, the sol-curing process of the Fe / Co / Si / K composite step, and the temperature-time-heating rate parameters for drying and high-temperature reduction are all systematically defined, which is beneficial for enterprises to conduct process control and quality consistency management during scale-up. The pre-reduction and optional carburizing operations provide an operable path for the "online forming / stabilization" of the active phase, reducing start-up fluctuations and shortening the time required to reach a stable production state.

[0019] 5. Because this invention suppresses WGS and excessive methanation at the source through the synergistic design of sites and phases, the unit Compared to similar cryogenic systems, this system achieves higher yields with the same energy consumption. The reduction in byproduct gases such as carbon dioxide and methane also decreases downstream separation load and recycling costs. Overall, it boasts superior energy and carbon efficiency, resulting in excellent economic and environmental benefits. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. These embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0021] Unless otherwise specified, all percentages used in the embodiments of the present invention are mass percentages.

[0022] Example 1 Weigh 20 g of activated carbon and calcine it at 300℃ for 6 h to obtain the carrier M0.

[0023] Measure 100 mL of 0.5 mol / L Sr(NO3)2 solution and 200 mL of 0.5 mol / L NH4HCO3 solution. Slowly add both solutions dropwise to the carrier M0 suspension at 80℃, maintaining the pH at around 8.5. After the addition is complete, age the suspension for 3 h. After aging, filter the solution, wash it with deionized water at 60℃ until neutral, dry it at 120℃ for 12 h, and then calcine it at 300℃ for 4 h to obtain M1.

[0024] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurry mixing to prepare a 100 mL solution, thus obtaining S1; M1 and S1 were mixed and sonicated for 30 min to obtain M2; M2 was stirred at 60 °C for 12 h to obtain M3; the solid M3 obtained above was dried in an oven at 120 °C for 24 h, and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst 1.

[0025] Example 2 20 g of carbon nanotubes were weighed and calcined at 400℃ for 6 h to obtain the carrier M0.

[0026] Measure 100 mL of 0.5 mol / L Sr(NO3)2 solution and 200 mL of 0.5 mol / L NH4HCO3 solution. Slowly add both solutions dropwise to the carrier M0 suspension at 80℃, maintaining the pH at around 8.5. After the addition is complete, age the suspension for 3 h. After aging, filter the solution, wash it with deionized water at 60℃ until neutral, dry it at 120℃ for 12 h, and then calcine it at 300℃ for 4 h to obtain M1.

[0027] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, which yielded S1. M1 and S1 were mixed and sonicated for 30 min to obtain M2. M2 was stirred at 60 °C for 12 h to obtain M3. The solid M3 obtained above was dried in an oven at 120 °C for 24 h and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst 2.

[0028] Example 3 20 g of graphene was weighed and calcined at 300℃ for 6 h to obtain the support M0.

[0029] Measure 100 mL of 0.5 mol / L Sr(NO3)2 solution and 200 mL of 0.5 mol / L NH4HCO3 solution. Slowly add both solutions dropwise to the carrier M0 suspension at 80℃, maintaining the pH at around 8.5. After the addition is complete, age the suspension for 3 h. After aging, filter the solution, wash it with deionized water at 60℃ until neutral, dry it at 120℃ for 12 h, and then calcine it at 300℃ for 4 h to obtain M1.

[0030] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, which yielded S1. M1 and S1 were mixed and sonicated for 30 min to obtain M2. M2 was stirred at 60 °C for 12 h to obtain M3. The solid M3 obtained above was dried in an oven at 120 °C for 24 h and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst 3.

[0031] Example 4 Referring to Example 2, the difference is that the 100 mL Sr(NO3)2 solution in Example 2 was replaced with 140 mL Sr(NO3)2 solution, and the other preparation conditions were the same as in Example 2, thus obtaining catalyst 4.

[0032] Example 5 Referring to Example 2, the difference is that the 100 mL Sr(NO3)2 solution in Example 2 was replaced with 180 mL Sr(NO3)2 solution, and the other preparation conditions were the same as in Example 2, thus obtaining catalyst 5.

[0033] Example 6 Referring to Example 2, the difference is that the 100 mL Sr(NO3)2 solution in Example 2 was replaced with 220 mL Sr(NO3)2 solution, and the other preparation conditions were the same as in Example 2, to obtain catalyst 6.

[0034] Example 7 Referring to Example 2, the difference is that 20 g of carbon nanotubes in Example 2 were replaced with 20 g of alumina, and the other preparation conditions were the same as in Example 2, resulting in catalyst 7.

[0035] Example 8 Referring to Example 2, the difference is that 20 g of carbon nanotubes in Example 2 were replaced with 20 g of titanium dioxide, and the other preparation conditions were the same as in Example 2, to obtain catalyst 8.

[0036] Example 9 Referring to Example 2, the difference is that 20 g of carbon nanotubes in Example 2 were replaced with 20 g of diatomaceous earth, and the other preparation conditions were the same as in Example 2, resulting in catalyst 9.

[0037] Example 10 Referring to Example 2, the difference is that 40.4 g Fe(NO3)3·9H2O in Example 2 was replaced with 60.6 g Fe(NO3)3·9H2O, and the other preparation conditions were the same as in Example 2, to obtain catalyst 10.

[0038] Example 11 Referring to Example 2, the difference is that 1.38 g Co(NO3)2·6H2O in Example 2 was replaced with 2.76 g Co(NO3)2·6H2O, and the other preparation conditions were the same as in Example 2, thus obtaining catalyst 11.

[0039] Example 12 Referring to Example 2, the difference is that the 4.76 g potassium silicon source silica sol in Example 2 was replaced with 9.52 g potassium silicon source silica sol, and the other preparation conditions were the same as in Example 2, to obtain catalyst 12.

[0040] Example 13 Referring to Example 2, the difference is that the 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol in Example 2 were replaced with 60.6 g Fe(NO3)3·9H2O, 2.76 g Co(NO3)2·6H2O and 9.52 g silica sol, and the other preparation conditions were the same as in Example 2, thus obtaining catalyst 13.

[0041] Comparative Example 1 20 g of carbon nanotubes were weighed and calcined at 400℃ for 6 h to obtain the carrier M0.

[0042] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, thus obtaining S1; M0 and S1 were mixed and sonicated for 30 min to obtain M1; M1 was stirred at 60 °C for 12 h to obtain M2; the solid M2 obtained above was dried in an oven at 120 °C for 24 h, and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst A1.

[0043] Comparative Example 2 Weigh 20 g of alumina and calcine it at 400℃ for 6 h to obtain the carrier M0.

[0044] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, which yielded S1. M0 and S1 were mixed and sonicated for 30 min to obtain M1. M1 was stirred at 60 °C for 12 h to obtain M2. The solid M2 obtained above was dried in an oven at 120 °C for 24 h and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst A2.

[0045] Comparative Example 3 20 g of titanium dioxide was weighed and calcined at 400℃ for 6 h to obtain the support M0.

[0046] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution to obtain S1; M0 and S1 were mixed and sonicated for 30 min to obtain M1; M1 was stirred at 60 °C for 12 h to obtain M2; the solid M2 obtained above was dried in an oven at 120 °C for 24 h, and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst A3.

[0047] Comparative Example 4 20 g of carbon nanotubes were weighed and calcined at 400℃ for 6 h to obtain the carrier M0.

[0048] Take 300 mL of 0.5 mol / L Sr(NO3)2 solution and 200 mL of 0.5 mol / L NH4HCO3 solution. Add both solutions slowly dropwise to the carrier M0 suspension at 80℃, maintaining the pH at around 8.5. After the addition is complete, age the suspension for 3 h. After aging, filter the suspension, wash it with deionized water at 60℃ until neutral, dry it at 120℃ for 12 h, and then calcine it at 300℃ for 4 h to obtain M1.

[0049] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, which yielded S1. M1 and S1 were mixed and sonicated for 30 min to obtain M2. M2 was stirred at 60 °C for 12 h to obtain M3. The solid M3 obtained above was dried in an oven at 120 °C for 24 h and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst A4.

[0050] Comparative Example 5 Weigh 20 g of alumina and calcine it at 400℃ for 6 h to obtain the carrier M0.

[0051] Take 300 mL of 0.5 mol / L Sr(NO3)2 solution and 200 mL of 0.5 mol / L NH4HCO3 solution. Add both solutions slowly dropwise to the carrier M0 suspension at 80℃, maintaining the pH at around 8.5. After the addition is complete, age the suspension for 3 h. After aging, filter the suspension, wash it with deionized water at 60℃ until neutral, dry it at 120℃ for 12 h, and then calcine it at 300℃ for 4 h to obtain M1.

[0052] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, which yielded S1. M1 and S1 were mixed and sonicated for 30 min to obtain M2. M2 was stirred at 60 °C for 12 h to obtain M3. The solid M3 obtained above was dried in an oven at 120 °C for 24 h and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst A5.

[0053] Comparative Example 6 20 g of titanium dioxide was weighed and calcined at 400℃ for 6 h to obtain the support M0.

[0054] Take 300 mL of 0.5 mol / L Sr(NO3)2 solution and 200 mL of 0.5 mol / L NH4HCO3 solution. Add both solutions slowly dropwise to the carrier M0 suspension at 80℃, maintaining the pH at around 8.5. After the addition is complete, age the suspension for 3 h. After aging, filter the suspension, wash it with deionized water at 60℃ until neutral, dry it at 120℃ for 12 h, and then calcine it at 300℃ for 4 h to obtain M1.

[0055] 40.4 g Fe(NO3)3·9H2O, 1.38 g Co(NO3)2·6H2O and 4.76 g potassium silicon source silica sol were added to deionized water and dissolved by slurrying to prepare a 100 mL solution, which yielded S1. M1 and S1 were mixed and sonicated for 30 min to obtain M2. M2 was stirred at 60 °C for 12 h to obtain M3. The solid M3 obtained above was dried in an oven at 120 °C for 24 h and then reduced in a hydrogen reduction furnace at 600 °C for 6 h to obtain catalyst A6.

[0056] Test Example 1 (1) The pre-reduction conditions are: the reducing gas is H2, the flow rate of the reducing gas is 350 mL / min, the reduction pressure is 2.4 MPa, the reduction temperature is 240℃, the reduction time is 20 h, and the heating rate is 2℃ / min.

[0057] (2) The carburizing reaction conditions are as follows: the carburizing reaction gas is CO+H2, the flow rate of the carburizing reaction gas is 350 mL / min, the carburizing pressure is 2.4 MPa, the carburizing reaction temperature is 240℃, the carburizing reaction time is 24 h, and the heating rate is 2℃ / min.

[0058] (3) The catalyst is used in the low-temperature Fischer-Tropsch synthesis reaction under the following conditions: the reaction atmosphere is H2, CO and Ar (the molar ratio of H2 to CO is 2:1), the reaction pressure is 3.0 MPa, and the reaction temperature is 240℃.

[0059] The reaction performance results of the catalysts prepared in the examples are shown in Table 1.

[0060] Table 1. Reaction performance of catalysts

[0061] Implementation results: Experiments have verified that loading iron-based catalysts onto Sr-modified supports increases the concentration and intensity of basic sites on the catalyst surface. CO molecules, being somewhat acidic, tend to adsorb onto these basic sites. Stronger basicity helps weaken the C≡O bond, promoting its dissociation. Therefore, the introduction of Sr significantly increases CO conversion. Furthermore, stronger CO dissociation and adsorption provide more starting points for chain growth (C1 species), which is beneficial for C… 5+ The generation of .

[0062] The introduction of Sr into the support can enhance surface basicity, which helps suppress the water-gas shift reaction. Although WGS is unavoidable in iron-based FT (and is sometimes used to adjust the H2 / CO ratio), excessive WGS consumes CO to produce worthless CO2, reducing carbon efficiency. The basicity of Sr can moderately inhibit WGS activity.

[0063] Furthermore, the preparation method proposed in this invention is simple and easy to implement, with mild process conditions, requiring no complex equipment or operations, and is suitable for industrial production. At the same time, the required raw materials are readily available and inexpensive, making it highly economical.

[0064] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-temperature Fischer-Tropsch synthesis iron-based catalyst, characterized in that, The active components of the catalyst include Fe, Co, Si, K and support M, wherein the support M is an Sr-modified support, and the support is selected from one or more of activated carbon, carbon nanotubes, graphene, alumina, titanium dioxide and diatomaceous earth. The components, by mass ratio, satisfy the following: Fe : Co : Si : K : M = 30 : (2-9) : (10-30) : (1-5) : 30, and Sr accounts for 0.1-20% of the weight of the carrier M.

2. The low-temperature Fischer-Tropsch synthesis iron-based catalyst according to claim 1, characterized in that, The Si and K are derived from potassium-silicon silica sol.

3. A method for preparing a low-temperature Fischer-Tropsch synthesis iron-based catalyst as described in claim 2, characterized in that, Includes the following steps: S1. The carrier is calcined at high temperature to remove impurities, resulting in carrier M0; S2. Sr is loaded onto support M0 by precipitation deposition method, dried and calcined to obtain Sr modified support M1; S3. Fe salt, Co salt and potassium silica sol are added to deionized water to prepare the first solution S1; S4. Add Sr-modified carrier M1 to the first solution S1 and stir and sonicate to obtain mixture M2; S5. Stir continuously at a certain temperature until dry to obtain solid M3; S6. The solid M3 is dried and reduced at high temperature to obtain the catalyst.

4. The preparation method according to claim 3, characterized in that, In step S2, use The Sr source was ammonium bicarbonate as the precipitant, the Sr concentration in the slurry was 10-20%, the precipitation temperature was 25-80℃, the precipitation pH was 8.5-9.0, and the aging time was 2-4 h.

5. The preparation method according to claim 3, characterized in that, In step S1, the calcination temperature is 300–500℃ and the time is 4–6 h; and / or; The drying in step S2 and / or step S6 is air drying in an oven at a temperature of 80–150°C for a time of 1–30 h; and / or, In step S2, the calcination temperature is 300–600℃, the heating rate is 0.5–2℃ / min, and the calcination time is 4–10 h; and / or, The stirring temperature in step S5 is 25–80℃, and the stirring time is 12–24 h; and / or, The high-temperature reduction temperature in step S6 is 300–750℃, the heating rate is 0.5–2℃ / min, and the reduction time is 4–10h.

6. The preparation method according to claim 3, characterized in that, The Fe salt and Co salt are one or more of the nitrates, sulfates and hydrochlorides of the corresponding metals; The precipitant used in step S2 is selected from one or more of hydroxides, carbonates, and bicarbonates.

7. An application of a low-temperature Fischer-Tropsch synthesis iron-based catalyst, characterized in that, The catalyst prepared using the catalyst according to claim 1 or 2, or the preparation method provided by any one of claims 3 to 6, is used in low-temperature Fischer-Tropsch synthesis, and the application steps are as follows: The catalyst is subjected to pre-reduction treatment; Syngas is converted into hydrocarbon products under low-temperature Fischer-Tropsch synthesis conditions.

8. The application according to claim 7, characterized in that, The pre-reduction conditions are: reducing gas is The flow rate is 350–800 mL / min, the reduction pressure is 0.5–2.4 MPa, the reduction temperature is 240–270 °C, the reduction time is 20–32 h, and the heating rate is 2 °C / min.

9. The application according to claim 7, characterized in that, This also includes carburizing the catalyst, with the carburizing conditions being: the carburizing gas being CO and The flow rate is 350–800 mL / min, the carburizing pressure is 0.5–2.4 MPa, the carburizing temperature is 240℃, the carburizing time is 20–32 h, and the heating rate is 2℃ / min.

10. The application according to claim 7, characterized in that, The low-temperature Fischer-Tropsch synthesis reaction conditions are as follows: the reaction gas is... CO reacts with inert gas Ar at a pressure of 3.0–6.0 MPa and a temperature of 240–270 °C. The molar ratio with CO is 2:1.

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