Preparation methods and applications of Fe-Zr based catalysts

Abstract

This invention relates to the field of catalyst preparation technology, specifically to a method for preparing a Fe-Zr-based catalyst, comprising: preparing a mixed solution of MOF(Zr), MOF(Fe), iron salt, and zirconium salt, a gelatin solution, and an auxiliary salt solution; mixing the mixed solution with the gelatin solution to obtain a mixed colloid; cooling the mixed colloid obtained in step S2 to obtain a mixed gel; adding ammonia water to the top of the mixed gel obtained in step S3 and allowing it to react; placing the gel segment after the reaction in step S4 in water, and after the gel has fully transformed into a colloid, performing an initial centrifugation separation on the colloid; subsequently, washing and separating the precipitate obtained from the initial centrifugation separation multiple times; adding the precipitate obtained in step S5 to the auxiliary salt solution prepared in step S1, stirring thoroughly, drying and calcining to obtain Fe 100 Zr x B y O z Catalyst. The preparation process of this invention is simple and low-cost, and it improves the performance of FTO reaction.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and more specifically to a method for preparing an Fe-Zr-based catalyst and its application. Background Technology

[0002] Ethylene, propylene, and butene (hereinafter referred to as low-carbon olefins) are important basic raw materials for petrochemical energy. Currently, their production mainly relies on petroleum steam cracking and catalytic cracking technologies. Given my country's resource distribution of abundant coal, scarce oil, and limited natural gas, developing non-petroleum pathways for producing low-carbon olefins is of great significance to my country's energy security. In recent years, the process of producing low-carbon olefins from syngas via methanol has gradually matured and achieved significant success in industrialization. However, the one-step syngas-to-low-carbon-olefins (FTO) process is still in the experimental research stage, but it has attracted widespread attention worldwide due to its advantages such as short process route, low energy consumption, and wide availability of raw materials.

[0003] Despite the numerous advantages of the FTO process and its significant strategic importance, application prospects, and economic competitiveness in the energy landscape, the synthesis of highly efficient catalysts for the FTO process remains a critical issue that urgently needs to be addressed. CN 103212399 A discloses an M / ZrO2 catalyst (M = one or more of Fe, Mn, La, Ce, and K) prepared via co-precipitation and impregnation methods, exhibiting a CO single-pass conversion >55%, C2-C4 olefins accounting for more than 50 wt% of the total hydrocarbon distribution, and CO2 selectivity below 15%. CN 105854885A discloses a preparation method involving the precipitation of the active component Fe and an auxiliary agent, followed by the precipitation of Zr. The resulting catalyst significantly improves CO conversion and low-carbon olefin selectivity while reducing C5+ selectivity, consistent with our group's previous research findings (CN 110433812 A). CN106607047 A discloses an iron-based catalyst containing a certain proportion of zirconium oxide, exhibiting a CO conversion rate greater than 95% and C2-C4 olefins accounting for more than 60% of the total hydrocarbon distribution. CN 106607058A discloses a multi-metal catalyst with the chemical formula Fe100AaBbOx, where A is either Ti or Zr, and B is an alkali metal. Results show that its CO conversion rate is greater than 96%, C2-C4 olefins account for more than 70 wt% of the total hydrocarbon distribution, and C5+ accounts for more than 15% of the total hydrocarbon distribution. CN 106345514A discloses a catalyst composed of a zirconium-based solid solution, a dual-microporous zeolite molecular sieve, and a metal oxide, exhibiting a CO single-pass conversion rate between 16.0% and 44.0%, C2-C4 olefins accounting for more than 70% of the total hydrocarbon distribution, and C5+ selectivity less than 5.0%. CN 109092321A discloses a Fe alloy with ZrO2 as the inert component. 100 Zrx B y O z The catalyst has a CO conversion rate of over 92%, with C2-C4 olefins accounting for more than 70% of the total hydrocarbon distribution, and it also exhibits good stability.

[0004] In recent years, although some progress has been made in the research of FTO process catalysts, from an overall technical perspective, there are still two main shortcomings:

[0005] (1) Poor reactivity (including severe carbon deposition and deactivation, low CO conversion rate, poor selectivity for low carbon olefins, etc.).

[0006] (2) The catalyst is expensive or contains toxic substances. Different metals in the catalyst play different roles in the reaction process, but the presence of expensive metals or toxic substances will increase the cost of the catalyst or cause environmental pollution, such as platinum, chromium, vanadium, etc. Summary of the Invention

[0007] To address the aforementioned technical problems in existing technologies, this invention provides a method for preparing Fe-Zr-based catalysts. By using MOF structures as guides, the carboxyl and hydroxyl groups in the organic functional groups achieve anchoring of external metal ions, resulting in controllable structures for both MOF metal ions and external metal ions. Using gelatin as a dispersant, and leveraging non-equilibrium ordered diffusion mechanisms and Ostwald ripening, the diffusion rate of external metal ions and crystal growth are controlled, achieving controllable size of the nano-ZrO2 and nano-Fe2O3 systems. The Fe catalyst prepared by this method... 100 Zr x B y O z After activation, the catalyst exhibits characteristics such as high CO conversion rate, high selectivity for low-carbon olefins, low C5+ selectivity, and strong stability.

[0008] The technical solutions of the present invention are as follows:

[0009] A method for preparing an Fe-Zr-based catalyst includes the following steps:

[0010] S1. Prepare a mixed solution of MOF(Zr), MOF(Fe), iron salt, zirconium salt, gelatin solution, and auxiliary salt solution;

[0011] S2. Mix the mixed solution with the gelatin solution to obtain a mixed colloid;

[0012] S3. Cool the mixed colloid obtained in S2 to obtain a mixed gel;

[0013] S4. Add ammonia water to the top of the mixed gel obtained in S3 and let it stand to react;

[0014] S5. Place the gel segment after the reaction in S4 in water. After the gel is fully converted into a colloid, perform the first centrifugation separation on the colloid. Then, wash and separate the precipitate obtained from the first centrifugation separation multiple times.

[0015] S6. Add the precipitate obtained in S5 to the auxiliary salt solution prepared in S1, stir thoroughly, dry and calcine to obtain Fe. 100 Zr x B y O z catalyst.

[0016] As a further technical solution, the MOF(Zrα) is one or a mixture of Uio-66, Uio-66-NH2, MOF-801, MOF-808, NU-1000, MOF-867, PCN-777, and MOF-545; the auxiliary salt is one or a mixture of sodium salt, potassium salt, magnesium salt, manganese salt, and zinc salt; and the MOF(Fe) is one or a mixture of MIL-100, MIL-101, MIL-101-NH2, MIL-53, and MIL-88.

[0017] As a further technical solution, in step S1, the zirconium salt solution is one of zirconium oxychloride and zirconium nitrate, or a mixture thereof; the auxiliary salt solution is one of potassium hydroxide, potassium carbonate, potassium nitrate, potassium acetate, sodium hydroxide, sodium carbonate, sodium nitrate, sodium acetate, magnesium nitrate, magnesium acetate, magnesium formate, manganese nitrate, zinc acetate, and zinc nitrate, or a mixture thereof.

[0018] As a further technical solution, in step S1, the temperature range for preparing the mixed solution and gelatin solution is 40–70°C; the concentrations of MOF(Zr), MOF(Fe), iron salt, and zirconium salt are 0.01–0.12 mol / L, 0.0084–0.24 mol / L, 0.01–0.12 mol / L, and 0.005–0.144 mol / L, respectively.

[0019] As a further technical solution, in step S2, the mixing temperature range is 40-70℃, and the mixing time is 3-24h.

[0020] As a further technical solution, in step S3, the cooling temperature of the mixed colloid is 5-30°C.

[0021] As a further technical solution, in step S4, the mass percentage of ammonia water is 0.3-5%, the volume of ammonia water is 5-50% of the volume of the mixed gel, and the standing reaction time is 10-72 hours.

[0022] As a further technical solution, in step S6, the stirring time is 2-24 hours, the drying temperature is 120°C, the drying time is 10-30 hours, the calcination temperature is 450-650°C, and the calcination time is 3-24 hours.

[0023] As a further technical solution, in step S6, the Fe100ZrxByOz catalyst, B is one of K, Na, Mg, Mn, and Zn; when B is K, Na, or Zn, the value of y ranges from 1 to 10; when B is Mg or Mn, the value of y ranges from 1 to 100; the value of x ranges from 50 to 120; and z is the total number of oxygen atoms required to satisfy the oxidation states of each element in the catalyst.

[0024] This invention also discloses Fe 100 Zr x B y O z Application of catalysts in the one-step synthesis of low-carbon olefins from syngas.

[0025] The beneficial effects of the technical solution of the present invention are as follows:

[0026] 1. By using the MOF structure as a guiding agent, the carboxyl and hydroxyl groups in the organic functional groups can anchor the added metal ions, achieving controllable structures for both the MOF metal ions and the added metal ions. After calcination, the metal clusters in the MOF material and the nano-metal particles generated on its surface undergo thermal decomposition or sublimation of the ligands and modulators, resulting in a significant synergistic effect and improved particle dispersion of nano-Fe2O3 and ZrO2, thus enhancing the FTO reactivity.

[0027] 2. This invention utilizes MOF(Zr) or MOF(Fe) as a guide agent, and leverages the restriction of anion and cation diffusion by the gel and the adsorption of metal cations by MOF materials to achieve controllable growth of nano-metal particles.

[0028] 3. The preparation process of this invention is simple, requires no high-end equipment, has low preparation cost, and produces no toxic substances. Attached Figure Description

[0029] The following figures illustrate exemplary embodiments of the present invention by way of example.

[0030] Figure 1 This is a flowchart of the preparation method of the Fe-Zr-based catalyst of the present invention;

[0031] Figure 2 For the present invention Fe 100 Zr 100 K5O z TEM image of the catalyst;

[0032] Figure 3 This is a stability test diagram of the catalyst prepared in an embodiment of the present invention. Detailed Implementation

[0033] The present invention will now be described in further detail.

[0034] The catalysts used in the existing one-step synthesis of low-carbon olefins from syngas have the following drawbacks: (1) poor reactivity (including low selectivity for low-carbon olefins, low synergistic effect, high CO2 selectivity, etc.); (2) expensive catalyst components or containing toxic substances. Various metals in the catalyst play different roles in the reaction process, but the presence of expensive metals or toxic substances will increase the cost of the catalyst or cause environmental pollution, such as platinum, chromium, vanadium, etc.

[0035] This invention utilizes the MOF structure as a guiding agent, leveraging the carboxyl and hydroxyl groups in the organic functional groups to anchor external metal ions, achieving structural control over both the MOF metal ions and the external metal ions. By using gelatin as a dispersant, and employing a non-equilibrium ordered diffusion mechanism and Ostwald ripening, the diffusion rate and crystal growth of the external metal ions are controlled, resulting in controllable size of the nano-ZrO2 and nano-Fe2O3 systems. After calcination, the metal clusters in the MOF material and the nano-metal particles formed on its surface, due to the thermal decomposition or sublimation of the ligands and modulators, exhibit significant synergistic effects and particle dispersion in the nano-Fe2O3 and ZrO2, thus improving the FTO reaction performance. The Fe2O3 prepared by this method... 100 Zr x B y O z After activation, the catalyst exhibits high CO conversion rate, high selectivity for low-carbon olefins, low C5+ selectivity, and strong stability. The preparation process is simple, requires no high-end equipment, has low preparation cost, and produces no toxic substances.

[0036] like Figure 1 As shown, the preparation method of the Fe-Zr-based catalyst of the present invention includes the following steps:

[0037] S1. Prepare a mixed solution of MOF(Zr), MOF(Fe), iron salt, zirconium salt, gelatin solution, and auxiliary salt solution;

[0038] S2. Mix the mixed solution with the gelatin solution to obtain a mixed colloid;

[0039] S3. Cool the mixed colloid obtained in S2 to obtain a mixed gel;

[0040] S4. Add ammonia water to the top of the mixed gel obtained in S3 and let it stand to react;

[0041] S5. Place the gel segment after the reaction in S4 in water. After the gel is fully converted into a colloid, perform the first centrifugation separation on the colloid. Then, wash and separate the precipitate obtained from the first centrifugation separation multiple times.

[0042] S6. Add the precipitate obtained in S5 to the auxiliary salt solution prepared in S1, stir thoroughly, dry and calcine to obtain Fe. 100 Zr x B y O z catalyst.

[0043] Fe 100 Zr 100 K5O z SEM images of the catalyst after in-situ activation, as shown below. Figure 2 As shown.

[0044] Example 1

[0045] 1. Solution A: Weigh 2.7g and 4.85g of MOF-801 and Fe(NO3)3·9H2O respectively, and add them to 200ml of 50℃ aqueous solution under ultrasonic vibration.

[0046] 2. Solution B: Weigh 50g of gelatin and pour it into 200ml of aqueous solution. Let it swell at room temperature for 10 hours, then heat it to 50℃ under ultrasonic vibration and let it dissolve for 3 hours.

[0047] 3. Solution C: Weigh 0.07g of anhydrous K2CO3 and dissolve it in 100ml of water.

[0048] 4. Mix solution A and solution B, and mix them under ultrasonic vibration at 50°C for 5 hours to obtain a mixed colloid.

[0049] 5. Transfer the mixed colloid to a tubular reactor, allow it to cool naturally to room temperature and stabilize for 2 hours to obtain a mixed gel.

[0050] 6. Add 50 ml of 1% ammonia solution to the top of the mixed gel and let it stand to react.

[0051] 7. Four hours after adding ammonia, remove the gel segment from sampling port No. 2, close the sampling port, and push the upper interface of the lower gel upwards until it is in close contact with the lower interface of the upper gel. After that, take samples from sampling port No. 2 every 2 hours for a total of 6 times.

[0052] 8. The gel segments collected six times were placed in 300 ml of water at 70°C and ultrasonically agitated for 1 hour, followed by rapid centrifugation. The precipitate obtained from the first centrifugation was then ultrasonically agitated in 150 ml of water at 70°C and washed and centrifuged twice more. The centrifuged product was placed in solution C, stirred thoroughly for 2 hours, dried at 120°C for 15 hours, and then calcined at 550°C for 12 hours to obtain Fe. 100 Zr 100 K4O 352 catalyst.

[0053] Example 2

[0054] 1. Solution A: Weigh 6.7g and 4.87g of MOF-808 and anhydrous FeCl3 respectively, and add them to 300ml of 50℃ aqueous solution under ultrasonic vibration.

[0055] 2. Solution B: Weigh 50g of gelatin and pour it into 300ml of aqueous solution. Let it swell at room temperature for 10 hours, then heat it to 50℃ under ultrasonic vibration and let it dissolve for 3 hours.

[0056] 3. Solution C: Weigh 0.17g of anhydrous K2CO3 and dissolve it in 150ml of water.

[0057] 4. Mix solution A and solution B, and mix them under ultrasonic vibration at 50°C for 5 hours to obtain a mixed colloid.

[0058] 5. Transfer the mixed colloid to a tubular reactor, allow it to cool naturally to room temperature and stabilize for 2 hours to obtain a mixed gel.

[0059] 6. Add 50 ml of 1% ammonia solution to the top of the mixed gel and let it stand to react.

[0060] 7. Three hours after adding ammonia, take out the gel segment from sampling port 1, close the sampling port, and push the upper interface of the lower gel upwards until it is in close contact with the lower interface of the upper gel. Then, take samples from sampling port 1 every 2 hours for a total of 6 times.

[0061] 8. The gel segments collected six times were placed in 300 ml of water at 70°C and ultrasonically agitated for 1 hour, followed by rapid centrifugation. The precipitate obtained from the first centrifugation was then ultrasonically agitated in 150 ml of water at 70°C and washed and centrifuged twice more. The centrifuged product was placed in solution C, stirred thoroughly for 2 hours, dried at 120°C for 15 hours, and then calcined at 550°C for 12 hours to obtain Fe. 100 Zr 100 K4O 352 catalyst.

[0062] Example 3

[0063] 1. Solution A: Weigh 2.57g and 3.86g of MIL-100 and ZrOCl2·8H2O respectively, and add them to 200ml of 50℃ aqueous solution under ultrasonic vibration.

[0064] 2. Solution B: Weigh 50g of gelatin and pour it into 200ml of aqueous solution. Let it swell at room temperature for 10 hours, then heat it to 50℃ under ultrasonic vibration and let it dissolve for 3 hours.

[0065] 3. Solution C: Weigh 0.07g of anhydrous K2CO3 and dissolve it in 100ml of water.

[0066] 4. Mix solution A and solution B, and mix them under ultrasonic vibration at 50°C for 5 hours to obtain a mixed colloid.

[0067] 5. Transfer the mixed colloid to a tubular reactor, allow it to cool naturally to room temperature and stabilize for 2 hours to obtain a mixed gel.

[0068] 6. Add 50 ml of 1% ammonia solution to the top of the mixed gel and let it stand to react.

[0069] 7. Four hours after adding ammonia, remove the gel segment from sampling port No. 2, close the sampling port, and push the upper interface of the lower gel upwards until it is in close contact with the lower interface of the upper gel. After that, take samples from sampling port No. 2 every 2 hours for a total of 6 times.

[0070] 8. The gel segments collected six times were placed in 300 ml of water at 70°C and ultrasonically agitated for 1 hour, followed by rapid centrifugation. The precipitate obtained from the first centrifugation was then ultrasonically agitated in 150 ml of water at 70°C and washed and centrifuged twice more. The centrifuged product was placed in solution C, stirred thoroughly for 2 hours, dried at 120°C for 15 hours, and then calcined at 550°C for 12 hours to obtain Fe. 100 Zr 100 K4O 352 catalyst.

[0071] Example 4

[0072] 1. Solution A: Weigh 7.07g and 12.88g of MIL-53 and Zr(NO3)4·5H2O respectively, and add them to 300ml of 50℃ aqueous solution under ultrasonic vibration.

[0073] 2. Solution B: Weigh 50g of gelatin and pour it into 200ml of aqueous solution. Let it swell at room temperature for 10 hours, then heat it to 50℃ under ultrasonic vibration and let it dissolve for 3 hours.

[0074] 3. Solution C: Weigh 0.15g of anhydrous K2CO3 and dissolve it in 200ml of water.

[0075] 4. Mix solution A and solution B, and mix them under ultrasonic vibration at 50°C for 5 hours to obtain a mixed colloid.

[0076] 5. Transfer the mixed colloid to a tubular reactor, allow it to cool naturally to room temperature and stabilize for 2 hours to obtain a mixed gel.

[0077] 6. Add 50 ml of 1% ammonia solution to the top of the mixed gel and let it stand to react.

[0078] 7. Five hours after adding ammonia, remove the gel segment from sampling port 1, close the sampling port, and push the upper interface of the lower gel upwards until it is in close contact with the lower interface of the upper gel. After that, take samples from sampling port 1 every 2 hours for a total of 6 times.

[0079] 8. The gel segments collected six times were placed in 300 ml of water at 70°C and ultrasonically agitated for 1 hour, followed by rapid centrifugation. The precipitate obtained from the first centrifugation was then ultrasonically agitated in 150 ml of water at 70°C and washed and centrifuged twice more. The centrifuged product was placed in solution C, stirred thoroughly for 2 hours, dried at 120°C for 15 hours, and then calcined at 550°C for 12 hours to obtain Fe. 100 Zr 100 K4O 352 catalyst.

[0080] Comparative Example

[0081] 1. Weigh 10.0g of Fe(NO3)3·9H2O and add it to 150.0ml of deionized water to prepare an iron salt solution. Weigh 8.0g of ZrOCl2·8H2O and add it to 100.0ml of deionized water to prepare a zirconium salt solution. Weigh 0.1g of KCO3 and add it to 50ml of deionized water to prepare an auxiliary salt solution. Heat the iron salt solution, zirconium salt solution and auxiliary salt solution to 50℃.

[0082] 2. Add 15wt% ammonia solution dropwise to the zirconium salt solution at a rate of 100ml / h until the pH = 10.0. Maintain the pH = 10.0 and continue stirring (300r / min) for aging for 5h. Then filter and wash to bring the pH to 7, dry at 120℃ for 5h, and finally calcine at 600℃ for 8h to obtain ZrO2.

[0083] 3. First, add ZrO2 to an iron salt solution at 50℃ and stir rapidly (500 r / min) for 0.5 h. Then, adjust the stirring speed to 300 r / min, and add 15 wt% ammonia solution dropwise to the iron salt solution at a rate of 100 ml / h until pH = 9.0. At the titration endpoint, maintain pH = 9.0 and continue stirring for aging for 5 h. Finally, filter and wash to pH = 7, and then dry at 120℃ for 5 h to obtain ZrO2-FeO. x .

[0084] 4. ZrO2-FeO x Add the additive salt solution and stir rapidly (500 r / min) for 5 h. Stop stirring and transfer the solution to a drying oven, dry at 120 °C for 24 h, and then calcine at 550 °C for 12 h to obtain Zr. 100 Fe 100 K4O 352 catalyst.

[0085]

[0086]

[0087] Note: (1) Data is taken from the results at 30h;

[0088] (2) The data listed in the table are based on carbon balance, and the specific calculation formula is as follows:

[0089] CO conversion rate:

[0090] Hydrocarbon selectivity:

[0091] C2 O ~C4 O Selectivity:

[0092] C2 P ~C4 P Selectivity:

[0093] C5 + Selectivity: In the formula, This indicates the number of moles of carbon in imported CO. and This indicates the number of carbon moles in CO and CO2 in the exhaust gas, where i represents a specific hydrocarbon or CO2, and n (n = 1, 2, 3, 4) represents the stoichiometric number of carbon in the hydrocarbon or CO2.

[0094] (3) The activation condition is: mass space velocity Temperature: 320℃, Pressure: 1.0MPa, Time: 3h, Activation gas volume composition: CO (20%) / N2 (80%).

[0095] (4) The reaction conditions are: Temperature: 300℃, Pressure: 2.0MPa, Syngas volume composition: CO (10%) / H2 (20%) / N2 (70%), Syngas H2:CO molar ratio = 2.

[0096] like Figure 3 The figures shown are stability test graphs of the catalysts prepared in Examples 1, 2, 3, 4, and Comparative Example 1.

[0097] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for preparing an Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas, characterized in that, The following steps are involved: S1. Prepare mixed solutions of MOF(Zr) and iron salt or MOF(Fe) and zirconium salt, gelatin solution, and auxiliary salt solution respectively; S2. Mix the mixed solution with the gelatin solution to obtain a mixed colloid; S3. Cool the mixed colloid obtained in S2 to obtain a mixed gel; S4. Add ammonia water to the top of the mixed gel obtained in S3 and let it stand to react; S5. Place the gel segment after the reaction in S4 in water. After the gel is fully converted into a colloid, perform the first centrifugation separation on the colloid. Then, wash and separate the precipitate obtained from the first centrifugation separation multiple times. S6. Add the precipitate obtained in S5 to the auxiliary salt solution prepared in S1, stir thoroughly, dry and calcine to obtain Fe. 100 Zr x B y O z catalyst; In step S1, the MOF(Zr) is one or a mixture of UiO-66, UiO-66-NH2, MOF-801, MOF-808, NU-1000, MOF-867, PCN-777, and MOF-545; the auxiliary salt is one of sodium salt, potassium salt, magnesium salt, manganese salt, and zinc salt; and the MOF(Fe) is one or a mixture of MIL-100, MIL-101, MIL-101-NH2, MIL-53, and MIL-88. In step S6, the Fe 100 Zr x B y O z The catalyst, B is one of K, Na, Mg, Mn, Zn; when B is K, Na or Zn, the value of y ranges from 1 to 10, and when B is Mg or Mn, the value of y ranges from 1 to 100; the value of x ranges from 50 to 120; z is the total number of oxygen atoms required to satisfy the oxidation states of each element in the catalyst.

2. The method for preparing the Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas as described in claim 1, characterized in that, In step S1, the zirconium salt is one of zirconium oxychloride and zirconium nitrate, or a mixture thereof; the auxiliary salt is one of potassium carbonate, potassium nitrate, potassium acetate, sodium carbonate, sodium nitrate, sodium acetate, magnesium nitrate, magnesium acetate, magnesium formate, manganese nitrate, zinc acetate, and zinc nitrate.

3. The method for preparing the Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas as described in any one of claims 1-2, characterized in that, In step S1, the temperature range for preparing the mixed solution and gelatin solution is 40–70°C; the concentrations of MOF(Zr), MOF(Fe), iron salt, and zirconium salt are 0.01–0.12 mol / L, 0.0084–0.24 mol / L, 0.01–0.12 mol / L, and 0.005–0.144 mol / L, respectively.

4. The method for preparing the Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas as described in claim 3, characterized in that, In step S2, the mixing temperature range is 40–70℃, and the mixing time is 3–24h.

5. The method for preparing the Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas as described in claim 4, characterized in that, In step S3, the cooling temperature of the mixed colloid is 5–30°C.

6. The method for preparing the Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas as described in claim 5, characterized in that, In step S4, the mass percentage of ammonia is 0.3-5%, the volume of ammonia is 5-50% of the volume of the mixed gel, and the standing reaction time is 10-72 hours.

7. The method for preparing the Fe-Zr-based catalyst for one-step synthesis of low-carbon olefins from syngas as described in any one of claims 4-6, characterized in that, In step S6, the stirring time is 2-24 hours, the drying temperature is 120°C, the drying time is 10-30 hours, the calcination temperature is 450-650°C, and the calcination time is 3-24 hours.

8. Fe prepared by the preparation method according to any one of claims 1-7 100 Zr x B y O z Application of catalysts in the one-step synthesis of low-carbon olefins from syngas.

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