Bimetallic mofs-mediated morphology-controllable catalysts, methods of making, and uses thereof

Abstract

The application discloses a bimetallic MOFs mediated morphology controllable catalyst, a preparation method and application thereof, and the preparation method comprises the following steps: respectively adding iron salt, cobalt salt and an organic ligand into an organic solvent, then adding an alkaline adjusting agent and a surfactant; transferring the stirred solution into a reaction kettle to perform a solvothermal reaction, centrifuging the suspension after the reaction, washing and drying the suspension for multiple times to obtain a bimetallic organic framework (MOFs) precursor; and obtaining the catalyst after heat treatment of the bimetallic organic framework (MOFs) precursor in a gas atmosphere. The one-step solvothermal method is used to obtain the bimetallic MOFs, the size and morphology of the product are controlled through the alkaline adjusting agent, and the agglomeration of the catalyst nanoparticles can be reduced by adding the surfactant. The preparation method is simple, the specific surface area of the product is high, when the catalyst is used for preparing high-carbon hydrocarbons through catalytic hydrogenation of carbon dioxide, the carbon dioxide conversion rate is as high as 47.82%, the selectivity of the high-carbon hydrocarbons reaches 59.68%, the selectivity of the by-products carbon monoxide and methane is low, and the catalytic activity is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and particularly relates to a bimetallic MOFs-mediated morphology-controllable catalyst, a preparation method and application thereof. BACKGROUND

[0002] The combustion of fossil fuels leads to a large amount of carbon dioxide emissions, thereby causing a series of environmental problems. In order to solve this problem, people seek various methods for carbon dioxide capture and utilization. Carbon dioxide hydrogenation is not only conducive to alleviating the environmental problems caused by excessive carbon dioxide emissions, but also can generate high-value hydrocarbon chemicals. The improved Fischer-Tropsch (FT) reaction is an effective way, in which carbon dioxide and hydrogen are converted into intermediate CO through the RWGS reaction (active phase Fe3O4), and then the CO is converted into hydrocarbon substances through the FT reaction (active phase Fe5C2). However, the catalysts in this reaction have problems such as easy deactivation, difficult to control, and low activity. The reason is that the specific surface area of the catalysts is small. Therefore, it is essential to study the size and morphology of the catalysts in the carbon dioxide hydrogenation reaction. A large number of studies have shown that metal-organic frameworks (MOFs) are a kind of material with unique structure and high specific surface area formed by metal ions and organic ligands. Under suitable conditions, the porous structure and morphology of MOF crystals are retained during the conversion process, and porous metal oxides and porous metal oxide / carbon composite catalysts with rich structure and excellent performance can be obtained. Therefore, controlling the size and morphology of the catalysts is an important way to improve the activity of the catalysts.

[0003] CN115445669A provides a carbon dioxide hydrogenation catalyst prepared by mixing a metal and an acid-treated molecular sieve, but the carbon dioxide conversion rate of the catalyst in the reaction is low (20%). Patent CN114870886A provides a multifunctional catalyst (Na-Fe3O4 / ZSM-5) composed of a metal oxide and a molecular sieve. The catalyst has high high-carbon hydrocarbon selectivity (68.5%) and low methane selectivity (2.1%), but the carbon dioxide conversion rate is low (22.4%). Patent CN116899570A discloses a metal catalyst and a preparation method and application thereof. The preparation method of the patent is to pyrolyze the precursor in a hydrogen atmosphere or a nitrogen atmosphere to obtain the metal catalyst, which also has high hydrogenation activity for benzene, and the conversion rate of benzene is more than 80% at 180℃. The catalysts prepared by the above methods have low carbon dioxide conversion rate, complex preparation process, easy catalyst agglomeration, and poor stability.

[0004] Therefore, it is crucial to develop a carbon dioxide catalytic hydrogenation catalyst for preparing high-carbon hydrocarbons with simple preparation method, low energy consumption and high activity. SUMMARY

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a preparation and application of a bimetallic MOFs mediated morphology controllable catalyst, so as to solve the problems of complex preparation process, and inability to balance carbon dioxide conversion rate and high carbon hydrocarbon selectivity of the existing catalyst.

[0006] To solve the above problems, the technical scheme adopted by the present application is:

[0007] The preparation and application of a bimetallic MOFs mediated morphology controllable catalyst according to the present application is characterized by comprising the following steps:

[0008] Step 1, respectively add a transition metal compound and an organic ligand to an organic solvent, mix the two solutions after complete dissolution, add an alkaline adjusting agent and a surfactant to stir, and obtain a reaction liquid; the transition metal compound is a mixture comprising a first transition metal soluble salt and a second transition metal soluble salt;

[0009] Step 2, transfer the reaction liquid to a reaction kettle to perform a solvothermal reaction, and obtain a suspension;

[0010] Step 3, dry the suspension obtained in step 2) after centrifugation and multiple washing, and obtain a bimetallic organic framework precursor;

[0011] Step 4, perform heat treatment on the bimetallic organic framework precursor obtained in step 3) under a gas atmosphere, and obtain a bimetallic organic framework mediated catalyst.

[0012] As a preferred embodiment of the present application, the first transition metal soluble salt is selected from at least one of an iron salt and a hydrate of the iron salt.

[0013] As a preferred embodiment of the present application, the iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric sulfate.

[0014] As a preferred embodiment of the present application, the second transition metal soluble salt is selected from at least one of a cobalt salt, a manganese salt, a copper salt, a hydrate of the cobalt salt, a hydrate of the manganese salt, and a hydrate of the copper salt.

[0015] As a preferred embodiment of the present application, the second transition metal is selected from at least one of a cobalt salt and a hydrate of the cobalt salt.

[0016] As a preferred embodiment of the present application, the cobalt salt comprises at least one of cobalt nitrate, cobalt acetate, and cobalt sulfate.

[0017] As a preferred embodiment of the present application, the organic ligand is selected from at least one of terephthalic acid and trimesic acid.

[0018] As a preferred embodiment of the present application, the ratio of the amount of substance of the first transition metal soluble salt and the second transition metal soluble salt is (0.01-3):(1-2).

[0019] As a preferred embodiment of the present application, the organic solvent is at least one of N,N dimethylformamide (DMF), methanol, ethanol. Preferably, the organic solvent is N,N dimethylformamide (DMF).

[0020] As a preferred embodiment of the present application, the ratio of the total amount of substance of the transition metal compound, the amount of substance of the organic ligand, the amount of substance of the adjusting agent, and the amount of substance of the surfactant is 1:(0.5-1):(0.01-1):(0.001-0.01).

[0021] As a preferred embodiment of the present application, the basic adjusting agent is at least one of sodium hydroxide, potassium hydroxide, triethylamine, polyvinylpyrrolidone. Preferably, the basic adjusting agent is sodium hydroxide.

[0022] As a preferred embodiment of the present application, the surfactant includes at least one of ethylene glycol, glycerol, cetyltrimethylammonium bromide. Preferably, the surfactant is cetyltrimethylammonium bromide (CTAB).

[0023] As a preferred embodiment of the present application, the hydrothermal reaction temperature in step 2 is 110℃, and the hydrothermal time is 12-36h.

[0024] As a preferred embodiment of the present application, in step 3, the washing liquid used for washing is N,N dimethylformamide (DMF), ethanol solution and deionized water in sequence.

[0025] As a preferred embodiment of the present application, the bimetallic organic framework precursor is subjected to heat treatment in a gas atmosphere, and the heat treatment atmosphere includes at least one of nitrogen, argon, air, hydrogen, carbon monoxide or mixed gas. Preferably, the heat treatment atmosphere is mixed gas (first argon and then air).

[0026] The present application also provides a bimetallic MOFs mediated catalyst prepared according to the preparation method.

[0027] The present application also provides an application of the bimetallic MOFs mediated catalyst in the preparation of high-carbon hydrocarbon compounds through carbon dioxide hydrogenation reaction.

[0028] As a preferred embodiment of the present application, the application is carried out according to the following steps:

[0029] The catalyst is loaded in a fixed bed reactor;

[0030] The catalyst needs to be reduced and activated under a hydrogen atmosphere before the mixed gas reaction. The reduction temperature is 300-500 DEG C, and it needs to be carried out under normal pressure. After the reduction is completed, the temperature is reduced to below 100 DEG C, and then the mixed gas is switched to carry out the catalytic reaction to obtain high carbon hydrocarbon compounds; the temperature of the catalytic reaction is 250-400 DEG C, the reaction pressure is 1-5 MPa, the reaction volume space velocity is 1500-6000 h -1 , the mixed gas is a mixture of H2, CO2 and N2, the volume fraction of H2 in the mixed gas is 65-75%, the volume fraction of CO2 is 20-25%, the volume fraction of N2 is 5-10%, and the sum of the volume fractions of the components is equal to 100%.

[0031] As preferred in the present application, the high carbon hydrocarbon compounds are hydrocarbon substances with a carbon atom number of 5 or more.

[0032] Compared with the prior art, the present application has the following beneficial effects:

[0033] (1) The preparation method of the present application is simple, and a one-step solvothermal synthesis method is used to synthesize the catalyst;

[0034] (2) Compared with a single iron-based metal organic framework, by adjusting the molar ratio of iron and cobalt, the component content of the catalyst is optimized, and the synergistic effect between the two metals can make the carbon dioxide hydrogenation reaction have higher conversion rate and high carbon hydrocarbon selectivity;

[0035] (3) The present application provides a preparation and application of a bimetallic MOFs mediated morphology controllable catalyst, and an alkaline adjusting agent is added during the preparation process to control the size and morphology of the product. The deprotonation of the alkaline adjusting agent can quickly generate many small crystal seeds to accelerate the nucleation process, and then smaller products are obtained;

[0036] (4) The addition of a surfactant during the preparation process can prevent the rapid growth of the crystal, uniformly disperse the crystal nucleus, effectively reduce the agglomeration between the catalysts, and thus obtain monodisperse, more uniform micro-nano MOFs, increase the specific surface area of the catalyst and the dispersion degree between the active components, and finally improve the performance of the catalyst

[0037] (5) The present application provides a preparation and application of an iron-cobalt bimetallic MOFs mediated catalyst, which uses a unique MOFs structure as a precursor, and pyrolysis under suitable conditions can obtain a catalyst with rich structure and excellent performance. The traditional heat treatment of MOFs is usually direct pyrolysis in an inert atmosphere or air atmosphere, and the heat treatment of MOFs in the present application is multi-step pyrolysis (first pyrolysis under inert gas to obtain carbon-coated highly dispersed metal or metal oxide particles, and then calcination under air atmosphere to obtain metal oxide with high crystallinity). BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 XRD pattern of FeCo-MOFs mediated catalyst under nitrogen atmosphere at different ratios.

[0039] Figure 2 SEM image of bimetallic MOFs prepared by adding basic regulator and surfactant. DETAILED DESCRIPTION

[0040] The above specific examples illustrate the embodiments of the present application, and those skilled in the art can easily understand other advantages and effects of the present application from the disclosure of the specification. The present application can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details in the specification based on different views and applications without departing from the spirit of the present application.

[0041] It should be noted that the process equipment or device not specifically mentioned in the following examples is the conventional equipment or device in the art.

[0042] In addition, it should be understood that the one or more method steps mentioned in the present application do not exclude that there can be other method steps before and after the combination steps or other method steps can be inserted between the explicitly mentioned steps, unless otherwise stated; it should also be understood that the combination connection relationship between the one or more devices / apparatuses mentioned in the present application does not exclude that there can be other devices / apparatuses before and after the combination devices / apparatuses or other devices / apparatuses can be inserted between the two explicitly mentioned devices / apparatuses, unless otherwise stated. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool to identify each method step, and is not intended to limit the arrangement order of each method step or to limit the scope of the present application, and the change or adjustment of the relative relationship without substantial change of the technical content is also regarded as the scope of the present application that can be implemented.

[0043] The present application will be further described below in conjunction with specific embodiments, but the protection scope of the present application is not limited to this.

[0044] Example 1

[0045] Step 1, 0.025 mol of iron trichloride hexahydrate (FeCl3·6H2O) and 0.025 mol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) were dissolved in 60 mL of DMF, 0.025 mol of terephthalic acid was dissolved in 60 mL of DMF, after complete dissolution, the two solutions were mixed and stirred for 10 min, 5 mL of sodium hydroxide solution (concentration of 4 mol / L) was added dropwise to the mixed solution and stirred for 10 min, finally 0.001 mol of cetyltrimethylammonium bromide (CTAB) was added to the solution to obtain the reaction solution;

[0046] Step 2, the reaction solution was transferred to a reaction kettle and reacted at 110℃ for 36h, the obtained suspension was centrifuged (at a speed of 6000rmp for 5min), washed and dried to obtain the bimetallic organic framework precursor; when washing, the washing product was sequentially washed with DMF, anhydrous ethanol and deionized water for three times, and then dried in an oven at 70℃ for 12h, finally obtaining the bimetallic organic framework precursor Fe1Co1-MOF;

[0047] Step 3, the bimetallic organic framework precursor was placed in a tube furnace, inert gas N2 was introduced, and heated to 500℃ at a heating rate of 5℃ / min for 3h to obtain the bimetallic MOFs mediated Fe1Co1@C catalyst.

[0048] Example 2

[0049] The preparation method of this example is basically the same as that of example 1, the difference is that the molar ratio of the first transition metal soluble salt and the second transition metal soluble salt is different, in this example, the molar ratio of the first transition metal soluble salt and the second transition metal soluble salt is 3:2, that is, the amount of iron trichloride hexahydrate is changed from 0.025mol to 0.03mol, and the amount of cobalt nitrate hexahydrate is changed from 0.025mol to 0.02mol, and the rest of the process is exactly the same.

[0050] The product obtained in this example is a bimetallic organic framework Fe3Co2-MOF, that is, a bimetallic MOFs mediated Fe3Co2@C catalyst.

[0051] Example 3

[0052] The preparation method of this example is basically the same as that of example 1, the difference is that the molar ratio of the first transition metal soluble salt and the second transition metal soluble salt is different, in this example, the molar ratio of the first transition metal soluble salt and the second transition metal soluble salt is 2:1, that is, the amount of iron trichloride hexahydrate is changed from 0.025mol to 0.007mol, and the amount of cobalt nitrate hexahydrate is changed from 0.025mol to 0.003mol, and the rest of the process is exactly the same.

[0053] The product obtained in this example is a bimetallic organic framework Fe2Co1-MOF, that is, a bimetallic MOFs mediated Fe2Co1@C catalyst.

[0054] Example 4

[0055] The preparation method of this comparative example is basically the same as that of example 2, except that the ratio of the total amount of substance of the transition metal compound, the amount of substance of the organic ligand, the amount of substance of the alkaline adjusting agent, and the amount of substance of the surfactant is different. In this example, the ratio of the total amount of substance of the transition metal compound, the amount of substance of the organic ligand, the amount of substance of the alkaline adjusting agent, and the amount of substance of the surfactant is 1:0.5:0.01:0.001, and the rest of the process is exactly the same.

[0056] Example 5

[0057] The preparation method of this comparative example is basically the same as that of example 2, except that the ratio of the total amount of substance of the transition metal compound, the amount of substance of the organic ligand, the amount of substance of the alkaline adjusting agent, and the amount of substance of the surfactant is different. In this example, the ratio of the total amount of substance of the transition metal compound, the amount of substance of the organic ligand, the amount of substance of the alkaline adjusting agent, and the amount of substance of the surfactant is 1:1:0.03:0.005, and the rest of the process is exactly the same.

[0058] Example 6

[0059] The preparation method of this example is basically the same as that of example 2, except that the inert gas in step 4 is different. In this example, the inert gas is argon, and the rest of the process is exactly the same.

[0060] The product obtained in this example is a bimetallic MOFs mediated Fe3Co2@C(Ar) catalyst.

[0061] Example 7

[0062] The preparation method of this example is basically the same as that of example 2, except that the way of heat treatment of the bimetallic organic framework precursor under a gas atmosphere is different. In this example, the bimetallic organic framework precursor is calcined in air, heated to 500°C at a rate of 5°C / min for 3h, and the rest of the process is exactly the same.

[0063] The product obtained in this example is a bimetallic MOFs mediated Fe3Co2-KQ catalyst.

[0064] Example 8

[0065] The preparation method of this example is basically the same as that of example 2, except that the way of heat treatment of the bimetallic organic framework precursor under a gas atmosphere is different. In this example, the bimetallic organic framework Fe3Co2-MOF prepared in step 3 is heat treated by a multi-step pyrolysis method, and the rest of the process is exactly the same.

[0066] The multi-step pyrolysis method in this example is operated according to the following method:

[0067] First, the bimetallic organic framework precursor Fe3Co2-MOF was placed in a tube furnace and argon was introduced for pyrolysis, the pyrolysis temperature was 500℃, the pyrolysis time was 3h, and the pyrolysis product was obtained;

[0068] Then, the pyrolyzed product was calcined in air, heated to 500℃ at a heating rate of 5℃ / min for 3h, and the bimetallic MOFs mediated Fe3Co2-Ar-KQ catalyst was obtained.

[0069] Comparative Example 1

[0070] The preparation method of this comparative example is basically the same as that of Example 1, except that the transition metal compound in Example 1 is replaced by iron chloride hexahydrate, and the rest of the process is exactly the same.

[0071] The product obtained in this comparative example is a metal organic framework Fe-MOF, and a MOFs mediated Fe@C catalyst is obtained.

[0072] Comparative Example 2

[0073] The preparation method of this comparative example is basically the same as that of Example 1, except that the transition metal compound in Example 1 is replaced by cobalt nitrate hexahydrate, and the rest of the process is exactly the same.

[0074] The product obtained in this comparative example is a metal organic framework Co-MOF, and a MOFs mediated Co@C catalyst is obtained.

[0075] Comparative Example 3

[0076] The preparation method of this comparative example is basically the same as that of Example 1, except that the modifier in step 1 is changed from 5ml of sodium hydroxide solution with a concentration of 4mol / L to 5ml of acetic acid with a concentration of 4mol / L. The product obtained in this comparative example is a bimetallic MOFs mediated Fe3Co2@C catalyst (acetic acid).

[0077] Comparative Example 4

[0078] The preparation method of this comparative example is basically the same as that of Example 1, except that no alkaline modifier and surfactant are added in step 1, and the rest of the process is exactly the same.

[0079] Phase characterization

[0080] The ARL SCINTAG X'TRA X-ray diffractometer produced by Thermo Fischer Company of the United States was used to characterize the crystal structure and phase composition of the catalyst, with Cu Kα ray (wavelength 0.154056 nm) as the X-ray source. The tube voltage was 40 kV, the tube current was 40 mA, the scanning step was 0.02, and the scanning range was 20-70°. The X-ray diffractometer was used to analyze the phase composition of the catalyst.

[0081] Morphology characterization:

[0082] SEM characterization was observed by field emission scanning electron microscopy at an accelerating voltage of 5 kV using a Zeiss G500 scanning electron microscope to observe the surface morphology structure of the sample at different magnifications. The sample preparation process was as thin as possible, and since the sample had poor conductivity, gold spraying treatment for 120 s was required before shooting to better assist electron microscopy imaging. The specific reagent preparation and test steps were carried out according to the instruction manual.

[0083] The performance of the catalysts prepared in Examples 1-8 and Comparative Examples 1-4 was evaluated, and the specific method was as follows:

[0084] The catalyst performance test was carried out in a fixed bed reactor. 0.5 mL of catalyst with a size of 60-100 mesh and 5.5 mL of quartz sand with the same mesh size were uniformly mixed and then loaded into the isothermal zone of the fixed bed reactor. The reaction conditions were as follows: temperature 300°C, reaction pressure 1 MPa, reaction volume space velocity 3000 h -1 , and the volume fraction ratio of the mixed reaction gas H2 / CO2 / N2 was 69% / 23% / 8%, with N2 as the internal standard gas for gas chromatographic analysis. The carbon dioxide, carbon monoxide and methane in the gas phase products were quantitatively analyzed by online gas chromatography with a TCD detector, and the carbon hydrocarbon compounds in the gas products were quantitatively analyzed by online gas chromatography with an FID detector. Finally, the carbon dioxide conversion rate and the selectivity of each product were calculated. The carbon dioxide hydrogenation performance test results are shown in the table.

[0085] Table 1 Performance test of different catalysts

[0086]

[0087] In Comparative Example 1-2, the single-metal organic framework containing only Fe or Co prepared by the solvothermal method was pyrolyzed under an inert atmosphere, and the obtained catalysts were used for carbon dioxide hydrogenation. However, the catalysts prepared by the solvothermal method had a low specific surface area and a low catalytic activity. Figure 1As can be seen from the XRD patterns in the table, the single metal Fe or Co respectively presents the diffraction peaks of Fe2O3 or Co3O4, and has a high crystallinity, but the catalytic performance of the single metal component is low. In order to improve the catalytic performance of the single metal Fe or Co catalyst, the double metal MOFs mediated double metal catalysts with different iron-cobalt ratios are prepared by the solvothermal synthesis method. In Examples 1-3, the component content of the MOFs mediated catalyst is changed by adjusting the iron-cobalt ratio, and after the iron-cobalt double metal MOFs are pyrolyzed by N2, the diffraction peaks of CoFe2O4 appear, indicating that the metal Fe and Co interact strongly to form an iron-cobalt alloy. As can be known from the evaluation results, the catalytic performance is best when the iron-cobalt ratio is 3:2. After the double metal MOFs with high specific surface area and positive dodecahedral spindle structure are heat treated, the original porosity and morphology are maintained. Whether the regulator is added will directly affect the coordination ability of the metal and the ligand during the formation of the double metal MOFs, as compared in Examples 1-3 and Comparative Examples 3-4. By adding the regulator and the surfactant, the morphology of the catalyst can be controlled. In Examples 1-8, the NaOH added by protonation accelerates the nucleation process of the crystal nucleus, and relatively small-sized products are obtained. In addition, the addition of the surfactant can prevent the rapid generation of the crystal nucleus, uniformly disperse the crystal nucleus, effectively reduce the agglomeration between the catalysts, so that the monodisperse, more uniform micro-nano MOFs are obtained, the specific surface area of the catalyst is increased, and the dispersion degree between the active components is increased, and finally the performance of the catalyst is improved.

[0088] In Examples 6-8, the atmosphere and the mode of heat treatment of the double metal MOFs are different. The traditional heat treatment of the metal organic framework is directly pyrolyzed under an inert atmosphere or an air atmosphere, and in the present application, a multi-step pyrolysis mode is adopted (firstly, the carbon-coated highly dispersed metal or metal oxide particles are obtained by pyrolysis under an inert gas, and then the metal oxide with high crystallinity is prepared by calcining under an air atmosphere).

[0089] Therefore, in the process of preparing the catalyst, the iron-cobalt alloy or the double metal oxide is formed by adjusting the component ratio of the iron-cobalt double metal, the morphology and size of the catalyst are controlled by adding the alkaline regulator and the surfactant, and the double metal organic framework precursor is obtained by multi-step pyrolysis, so that the conversion rate of carbon dioxide and the selectivity of high-carbon hydrocarbon are increased, which are 47.82% and 59.68%, respectively.

[0090] The above examples are intended to be illustrative and not exclusive. Various modifications to the methods, compositions, and processes of the application described herein, as well as alternatives to the various steps of the methods, are apparent to those of skill in the art without departing from the scope and spirit of the application. Although the application has been described in connection with specific preferred embodiments, it should be understood that the application as claimed should not be construed as limited to the described embodiments. Indeed, various modifications of the described modes of carrying out the application that are obvious to those skilled in the art are intended to be within the scope of the application.

Claims

1. A method for preparing bimetallic MOF-mediated morphology-controllable catalysts, characterized in that, Includes the following steps: Step 1: Add the transition metal compound and the organic ligand to the organic solvent respectively. After they are completely dissolved, mix the two solutions, add an alkaline regulator and a surfactant, and stir to obtain a reaction solution. The transition metal compound is a mixture containing ferric chloride hexahydrate and cobalt nitrate hexahydrate. Step 2: Transfer the reaction solution to a reaction vessel for reaction. The resulting suspension is centrifuged, washed multiple times, and dried to obtain the bimetallic organic framework precursor Fe3Co2-MOF. Step 3: The bimetallic organic framework precursor obtained in Step 2 is subjected to heat treatment in a gas atmosphere to obtain a bimetallic MOF-mediated catalyst; wherein, the heat treatment includes: firstly, the bimetallic organic framework precursor Fe3Co2-MOF is placed in a tube furnace and argon gas is introduced for pyrolysis at a temperature of 500℃ for 3 hours to obtain pyrolysis products; then, the pyrolysis products are calcined in air at a heating rate of 5℃ / min to 500℃ for 3 hours.

2. The method for preparing the bimetallic MOFs-mediated morphology-controllable catalyst according to claim 1, characterized in that: The ratio of the total amount of the transition metal compound, the amount of the organic ligand, the amount of the regulator, and the amount of the surfactant is 1:(0.5~1):(0.01~1):(0.001~0.01).

3. The method for preparing the bimetallic MOFs-mediated morphology-controllable catalyst according to claim 1, characterized in that: The alkalinity regulator includes at least one of sodium hydroxide, potassium hydroxide, triethylamine, and polyvinylpyrrolidone; the surfactant includes at least one of ethylene glycol, glycerol, and hexadecyltrimethylammonium bromide.

4. A bimetallic MOF-mediated morphology-controllable catalyst obtained by the preparation method according to any one of claims 1 to 3.

5. The application of a bimetallic MOFs-mediated morphology-controllable catalyst as described in claim 4 in the preparation of high-carbon hydrocarbon compounds by catalytic hydrogenation of carbon dioxide.

6. The application according to claim 5, characterized in that, The application is carried out in the following steps: Before the mixed gas reaction, the catalyst needs to be reduced and activated under a hydrogen atmosphere at a temperature of 300–500 °C under normal pressure. After reduction, the temperature is lowered to below 100 °C before switching to a mixed gas to carry out the catalytic reaction and obtain high-carbon hydrocarbon compounds. The catalytic reaction temperature is 250–400 °C, the reaction pressure is 1–5 MPa, and the reaction volume hourly space velocity is 1500–6000 h⁻¹. -1 The mixed gas is a mixture of three gases: H2, CO2, and N2. The volume fraction of H2 in the mixed gas is 65-75%, the volume fraction of CO2 is 20-25%, and the volume fraction of N2 is 5-10%, and the sum of the volume fractions of each component is equal to 100%.

7. The application according to claim 5, characterized in that: The high-carbon hydrocarbon compounds are hydrocarbons with ≥5 carbon atoms.

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