Metal in-situ modified ZSM-5 molecular sieve as well as preparation method and application thereof

Abstract

The invention discloses a metal in-situ modified ZSM-5 molecular sieve and a preparation method and application thereof.The preparation method comprises the following steps that S1, metal ion salt and weak base are dissolved in water to obtain a first mixed solution, and the weak base is one or more of urea, ammonia water, ammonium carbonate and ammonium bicarbonate; reacting the first mixed solution with carbon monoxide gas under high pressure to obtain a carbonylation metal precursor; mixing an aluminum source, a silicon source, a template agent and water to obtain a second mixed solution; s2, carrying out mixed reaction on the carbonyl metal precursor and a second mixed solution to obtain gel; s3, carrying out crystallization reaction on the gel, and then washing, drying and roasting to obtain the metal in-situ modified ZSM-5 molecular sieve material. The molecular sieve material obtained by the invention is of a nano block stacked structure, metal active components are uniformly dispersed, and the molecular sieve material has excellent hydrothermal resistance and has the advantages of high activity, good selectivity and the like when being used as a naphtha catalytic cracking catalyst.

Description

Technical Field

[0001] The present invention relates to a metal in-situ modified ZSM-5 molecular sieve, a preparation method thereof and an application thereof, belonging to the field of molecular sieve synthesis and catalytic application. Background Art

[0002] As important basic raw materials in the petrochemical industry, ethylene and propylene are mainly prepared by steam cracking method in tubular furnaces; the cracking raw materials include naphtha, light naphtha, ethane, liquefied petroleum gas, etc. However, with the sharp increase in the demand for propylene derivatives, the output of propylene co-produced by thermal cracking method can no longer meet the growing needs of the domestic and international markets for propylene. At the same time, the steam thermal cracking method itself has many deficiencies. Therefore, on the basis of optimizing the resource allocation of cracking raw materials, adopting new processes and new technologies to replace the traditional steam thermal cracking technology for producing light olefins has become an inevitable trend in the development of this field. Processes such as light hydrocarbon catalytic cracking have gradually emerged and developed in recent years, alleviating the market demand for propylene to a certain extent.

[0003] For refineries, due to the rise of large-scale refining and chemical integration enterprises, the refining capacity is greatly excessive, resulting in a supply-demand imbalance in the oil product market. Therefore, converting low-value oil products into high-value chemical products or chemical intermediates has become an inevitable trend. Light hydrocarbon catalytic cracking to produce light olefins is a process technology with great market prospects, which can crack alkanes, olefins, and naphthenes below C10 into ethylene, propylene, and light aromatics BTX under the action of a catalyst, reducing the gasoline output to a certain extent, converting it into high-value light olefin resources, and increasing the profitability of enterprises.

[0004] The ZSM-5 molecular sieve has a unique shape-selective catalytic effect and is widely used as a catalyst in production processes such as catalytic cracking. It has a three-dimensional cross-linked pore structure. The pores along the a-axis are straight pores with a cross-sectional size usually of 0.54×0.56 nm, while the pores along the b-axis are zigzag pores with a cross-sectional size of 0.51×0.56 nm; the pore openings of the ZSM-5 molecular sieve are composed of ten-membered rings, and its size is between small-pore zeolites and large-pore zeolites. Among them, compared with the cracking of macromolecules, naphtha cracking requires higher reaction activity, and a certain modification method can be used for the ZSM-5 molecular sieve to achieve this purpose. Due to problems such as easy aggregation and difficult dispersion of metal salts, post-treatment methods such as impregnation are currently mostly used to modify the molecular sieve, and it is still difficult to obtain a metal-modified molecular sieve catalyst with good dispersion of active components. Summary of the Invention

[0005] In view of the above problems, the present invention provides a metal in-situ modified ZSM-5 molecular sieve, a preparation method thereof and an application. The method of the present invention can realize in-situ modification of the ZSM-5 molecular sieve, improve the metal ion dispersion degree, and at the same time can avoid the agglomeration of metal ions under alkaline conditions, which is beneficial to its catalytic application in naphtha cracking and the like.

[0006] The present invention provides a preparation method of a metal in-situ modified ZSM-5 molecular sieve, comprising the following steps:

[0007] S1. Dissolve a metal ion salt and a weak base in water to obtain a first mixed solution, wherein the weak base is one or more of urea, ammonia water, ammonium carbonate and ammonium bicarbonate; react the first mixed solution with carbon monoxide gas under high pressure to obtain a carbonylated metal precursor;

[0008] Mix an aluminum source, a silicon source, a template agent and water to obtain a second mixed solution;

[0009] S2. Mix and react the carbonylated metal precursor and the second mixed solution to obtain a gel;

[0010] S3. Carry out a crystallization reaction on the gel, and then wash, dry and calcine it to obtain a metal in-situ modified ZSM-5 molecular sieve material.

[0011] Preferably, in step S1, the metal in the metal ion salt is one or more of iron, cobalt and nickel.

[0012] Preferably, in step S1, the temperature of the reaction is 40-90 °C and the pressure is 2-15 MPa.

[0013] Preferably, in step S1, the molar ratio of the metal ion salt to the carbon monoxide gas is 1:1-50.

[0014] Preferably, in step S1, the aluminum source is one or more of aluminum sulfate, sodium meta-aluminate and aluminum hydroxide; the silicon source is one or more of silica sol, silica gel and fumed silica; the template agent is one or more of tetraalkylammonium hydroxide, n-butylamine and triethylamine.

[0015] Preferably, in step S2, the molar ratio of the metal in the carbonylated metal precursor to the template agent in the second mixed solution is (0.001-0.1):(0.1-0.5).

[0016] Preferably, in step S3, the temperature of the crystallization reaction is 150-200 °C and the constant temperature crystallization time is 12-96 h.

[0017] The present invention provides a metal in-situ modified ZSM-5 molecular sieve material obtained by the preparation method as described above, which has a nano-block stacked structure.

[0018] The present invention provides the application of the above-mentioned in-situ metal-modified ZSM-5 molecular sieve material as a catalyst in the catalytic cracking of naphtha.

[0019] Preferably, the catalyst is subjected to an aging treatment, and the reaction temperature of the catalytic cracking is 600-630 °C.

[0020] If the metal characteristics can be introduced in-situ to construct a dehydrogenation-cracking bifunctional catalyst, the metal component realizes dehydrogenation, converts alkanes into olefins, and the olefins are further converted on the cracking component to generate other hydrocarbon products. By introducing a new active site metal, the reaction path is changed, and the energy barrier for alkane activation is reduced, thereby improving the conversion rate and the yield of target products.

[0021] Compared with the prior art, the present invention provides a method for in-situ metal-modifying ZSM-5 molecular sieve and its material. First, a specific carbonylated metal precursor is obtained, and then the ZSM-5 molecular sieve material is modified in-situ. The obtained in-situ metal-modified ZSM-5 molecular sieve material does not need to be further modified by post-treatment with alkali metals. The modified molecular sieve material prepared by the present invention has a morphology of a stacked nano-block structure, and the metal active components are evenly dispersed. It has excellent hydrothermal resistance, and has the advantages of high activity and good selectivity when used as a catalyst for naphtha catalytic cracking. Brief Description of the Drawings

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a scanning electron microscope (SEM) image of the molecular sieve material in Example 1;

[0024] Figure 2 It is an SEM image of the molecular sieve in Comparative Example 1;

[0025] Figure 3 It is an X-ray diffraction (XRD) pattern of the molecular sieve materials in Comparative Example 1 and Example 1. Detailed Embodiments

[0026] In order to further understand the present invention below, the preferred embodiments of the present invention will be described in conjunction with the examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0027] The present invention provides a preparation method for in-situ modification of ZSM-5 molecular sieve with metal, comprising the following steps:

[0028] S1. Dissolve a metal ion salt and a weak base in water to obtain a first mixed solution, wherein the weak base is one or more of urea, ammonia water, ammonium carbonate, and ammonium bicarbonate; react the first mixed solution with carbon monoxide gas under high pressure to obtain a carbonylated metal precursor;

[0029] Mix an aluminum source, a silicon source, a template agent, and water to obtain a second mixed solution;

[0030] S2. Mix and react the carbonylated metal precursor and the second mixed solution to obtain a gel;

[0031] S3. Perform a crystallization reaction on the gel, and then wash, dry, and calcine it to obtain a metal in-situ modified ZSM-5 molecular sieve material.

[0032] The method of the present invention can achieve in-situ modification of ZSM-5 molecular sieve, improve the dispersion degree of metal ions, and facilitate its catalytic applications in naphtha cracking and the like.

[0033] In the in-situ modification method of the embodiment of the present invention, the metal ion salt can be dissolved in water in beaker A, and a weak base solution is preferably added dropwise thereto and stirred evenly. The obtained first mixed solution is transferred into a reaction kettle, sealed, and carbon monoxide gas is introduced as a carbonylation agent to react under a certain high pressure condition to obtain a carbonylated metal precursor.

[0034] In the embodiment of the present invention, the metal ion salt is a soluble salt, and the metal is preferably one or more of iron (Fe), cobalt (Co), and nickel (Ni) used in combination, specifically it can be ferric chloride, cobalt chloride, or nickel chloride. The weak base solution is a solution of one or a mixture of several of urea, ammonia water, ammonium carbonate, and ammonium bicarbonate, preferably a urea solution or an ammonium carbonate solution. The molar ratio of the metal ion salt, the weak base, and the solvent water can be 1:(1 - 100):(10 - 100); 15 g of water can be added to beaker A, a certain mass of the metal ion salt is stirred and dissolved, and then preferably 10 g of a urea solution (concentration 50%) is added dropwise and stirred evenly.

[0035] In the embodiment of the present invention, the mixed and dissolved liquid is transferred into a reaction kettle, sealed, and CO gas is introduced for reaction. The reaction is carried out under high pressure, and the carbonylated metal precursor can be obtained through sufficient reaction. Preferably, the temperature of the reaction is 40 - 90 °C, the pressure is 2 - 15 MPa, preferably 6 - 15 MPa; the time can be 12 - 96 h, such as 24 h, 30 h, etc. The molar ratio of the metal ion salt, CO gas, weak base, and solvent water can be 1:(1 - 50)(1 - 100):(10 - 200), and further 1:(5 - 40)(1 - 100):(10 - 200). The carbonylated metal precursor is mainly a metal carbonyl compound, such as Fe(CO) 5 , Ni(CO) 4 . The metal precursor in this application is a metal carbonyl compound generated from inorganic substances, with a smaller molecule and easier to disperse evenly.

[0036] Moreover, in the embodiment of the present invention, a certain amount of water, aluminum source, silicon source, and template agent can be added to beaker B, and quickly stirred and mixed evenly to obtain a second mixed solution. Among them, the aluminum source is preferably one or more of aluminum sulfate, sodium aluminate, and aluminum hydroxide, and more preferably one or a mixture of aluminum sulfate and aluminum hydroxide. The silicon source is preferably one or more of silica sol, silica gel, and white carbon black, and more preferably one or a mixture of silica sol and white carbon black. Silica sol is a colloidal solution in which silicon dioxide (SiO 2 ) particles are dispersed in water, and it can be heated and solidified into silica gel. White carbon black mainly refers to precipitated silica, fumed silica, and ultrafine silica gel, which are porous powders. The template agent can regulate the pore structure of the molecular sieve, and is preferably one or more of tetraalkylammonium hydroxides (tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide), n-butylamine, and triethylamine, and further one or a mixture of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0037] In the embodiment of the present invention, the solution of the carbonylated metal precursor can be slowly added to beaker B for mixing, stirred evenly, and reacted at room temperature (such as 20 - 30 °C) to obtain a gel. The gel mainly is a hydrated colloidal state of silicon oxide and aluminum oxide, and the specific composition (molar ratio) is: metal ion: SiO 2 : Al 2 O 3 : template agent: H 2 O = (0.001 - 0.1):1:(0.001 - 0.05):(0.1 - 0.5):(5 - 50), and further (0.005 - 0.1):1:(0.001 - 0.05):(0.2 - 0.5):(10 - 40).

[0038] After obtaining the gel, the embodiment of the present invention can transfer it into a crystallization reactor (abbreviated as crystallization kettle), carry out crystallization reaction under certain conditions, and obtain the metal in-situ modified ZSM-5 molecular sieve of the present invention after water washing, drying and calcination.

[0039] In the embodiment of the present invention, the crystallization reaction conditions include: the temperature is 150-200 °C, preferably 160-190 °C, and the constant temperature crystallization time is 12-96 h, preferably 24-48 h of constant temperature. The embodiment of the present invention further crystallizes at 170 °C for 24 h, then after cooling, centrifuging and washing, the obtained sample is dried overnight at 60-80 °C and calcined at 500-600 °C, and finally a metal-containing ZSM-5 molecular sieve material is obtained.

[0040] The present invention provides a metal in-situ modified ZSM-5 molecular sieve material obtained by the method as described above; the molecular sieve material has a nanostack stacking structure and the morphology of ZSM-5 molecular sieve nanoclusters, wherein the introduced metal ions have a high dispersion degree and excellent hydrothermal stability.

[0041] Exemplarily, the specific surface area of the metal in-situ modified ZSM-5 molecular sieve material is 436 m 2 / g, and the mesoporous specific surface area is 99 m 2 / g.

[0042] The present invention provides the application of the metal in-situ modified ZSM-5 molecular sieve material as described above as a catalyst in the catalytic cracking of naphtha.

[0043] Specifically, the 20-40 mesh molecular sieve catalyst as described above can be mixed evenly with quartz sand and loaded into a reaction tube for aging treatment; for example, the aging temperature is 700 °C, the water inlet is 0.1 mL / min, and the aging time is 60 min. After the aging is completed, the catalytic cracking performance is evaluated, and the reaction temperature is preferably 620 °C.

[0044] Based on the structure and performance of the molecular sieve material, the number of accessible active center sites increases, and at the same time it has good hydrothermal stability. As an application in the catalytic cracking of naphtha catalyst, it has high activity and good selectivity.

[0045] To better illustrate the present invention, further examples are given below by examples. In the examples, all the original reagents and materials can be obtained commercially, and the experimental methods without specifying specific experimental conditions are the conventional methods and conditions well-known in the art.

[0046] Example 1

[0047] (1) Add 4 g of water and 0.8 g of ferric chloride into beaker A. After stirring and dissolving, add 10 g of urea (50%) solution and stir evenly. Transfer the liquid into a 50 mL autoclave, seal it, and introduce CO gas. The reaction temperature is 80 °C, the reaction pressure is 10 MPa, and the carbonylated metal precursor is obtained after 24 h.

[0048] (2) Add 50 g of water, 1.05 g of aluminum hydroxide, 40 g of silica sol, and 8 g of tetrapropylammonium hydroxide into beaker B, and quickly stir and mix evenly. Slowly add 10 g of the carbonylated metal precursor solution into beaker B for mixing, stir evenly, and react at room temperature for 1 h to obtain a gel. The specific composition (molar ratio) of the gel is:

[0049] Metal ions: SiO 2 : Al 2 O 3 : Template agent: H 2 O is approximately 0.01:1:0.03:0.2:14.

[0050] (3) Load the gel into a crystallization kettle and crystallize at 170 °C for 24 h.

[0051] (4) After cooling, centrifuging, and washing, dry the obtained sample overnight at 80 °C and calcine it at 550 °C for 4 h to finally obtain a nano-cluster zeolite containing Fe metal (metal in-situ modified ZSM-5 zeolite material).

[0052] Example 2

[0053] (1) Add 10 g of water and 0.65 g of cobalt chloride into beaker A. After stirring and dissolving, add 10 g of urea (50%) solution and stir evenly. Transfer the liquid into a 50 mL autoclave, seal it, and introduce CO gas (the molar ratio of metal ion salt, CO gas, weak base, and solvent water is 1:21 (theoretical value):16:160). The reaction temperature is 70 °C, the reaction pressure is 10 MPa, and the carbonylated metal precursor is obtained after 24 h.

[0054] (2) Add 50 g of water, 1.05 g of aluminum hydroxide, 40 g of silica sol, and 8 g of tetrapropylammonium hydroxide into beaker B, and quickly stir and mix evenly. Slowly add 10 g of the carbonylated metal precursor solution into beaker B for mixing, stir evenly, and react at room temperature for 1 h to obtain a gel.

[0055] (3) Load the gel into a crystallization kettle and crystallize at 170 °C for 24 h.

[0056] (4) After cooling, centrifuging, and washing, dry the obtained sample overnight at 80 °C and calcine it at 550 °C for 4 h to finally obtain a nano-cluster zeolite containing Co metal.

[0057] Example 3

[0058] (1) Add 4 g of water and 0.6 g of nickel chloride to beaker A. After stirring and dissolving, add 10 g of urea (50%) solution dropwise and stir evenly. Transfer the liquid into a reaction kettle, seal it, and introduce CO gas (the molar ratio of metal ion salt, CO gas, weak base, and solvent water is 1:5 (theoretical value): 16:100). The reaction temperature is 50 °C, the reaction pressure is 2 MPa, and after 24 h, a metal carbonylation precursor is obtained.

[0059] (2) Add 50 g of water, 1.05 g of aluminum hydroxide, 40 g of silica sol, and 8 g of tetrapropylammonium hydroxide to beaker B. Stir quickly to mix evenly. Slowly add 10 g of the metal carbonylation precursor solution to beaker B for mixing, stir evenly, and react at room temperature for 1 h to obtain a gel.

[0060] (3) Load the gel into a crystallization kettle and crystallize at 170 °C for 24 h.

[0061] (4) After cooling, centrifuging, and washing, the obtained sample is dried overnight at 80 °C and calcined at 550 °C for 4 h to finally obtain a nickel-containing metal nanocluster molecular sieve.

[0062] Example 4

[0063] (1) Add 4 g of water and 0.8 g of ferric chloride to beaker A. After stirring and dissolving, add 10 g of urea (50%) solution dropwise and stir evenly. Transfer the liquid into a reaction kettle, seal it, and introduce CO gas (the ratio is the same as in Example 1, and the type of aluminum source has changed). The reaction temperature is 80 °C, the reaction pressure is 10 MPa, and after 24 h, a metal carbonylation precursor is obtained.

[0064] (2) Add 80 g of water, 2.3 g of aluminum sulfate, 12 g of white carbon black, and 8 g of tetrapropylammonium hydroxide to beaker B. Stir quickly to mix evenly. Slowly add 10 g of the metal carbonylation precursor solution to beaker B for mixing, stir evenly, and react at room temperature for 1 h to obtain a gel.

[0065] (3) Load the gel into a crystallization kettle and crystallize at 170 °C for 24 h.

[0066] (4) After cooling, centrifuging, and washing, the obtained sample is dried overnight at 80 °C and calcined at 550 °C for 4 h to finally obtain an iron-containing metal nanocluster molecular sieve.

[0067] Comparative Example 1

[0068] Use industrial molecular sieve, which is the original powder of ZSM-5 molecular sieve with a silica-alumina ratio of 30 and is not metal-modified.

[0069] Comparative Example 2

[0070] Using the same industrial molecular sieve as in Comparative Example 1, the impregnation method was adopted, and 0.1 wt% Fe metal modification was carried out using ferric chloride metal salt.

[0071] The molecular sieve samples of Example 1 were tested for specific surface area, etc., and the results are as follows.

[0072] Table 1 Test results of molecular sieve surface area and pore volume

[0073]

[0074] According to Table 1, the mesoporous specific surface area and mesoporous pore volume of the obtained nanocluster molecular sieve are significantly increased compared with those of the molecular sieve before modification.

[0075] For the morphology of the modified molecular sieve in Example 1, see Figure 1 , it can be seen from the morphology diagram that compared with Figure 2 the molecular sieve of Comparative Example 1, the molecular sieve prepared in the example has a nanocluster morphology, the molecular sieve contains more mesoporous structures, the specific surface area and pore volume of the molecular sieve increase, the accessible active center sites increase, and it has good hydrothermal stability at the same time.

[0076] Figure 3 is the XRD result of the molecular sieve materials of Comparative Example 1 and Example 1. It can be determined that both are pure-phase ZSM-5 molecular sieves through the diffraction peak positions, and the crystallization intensities are basically the same.

[0077] The modified molecular sieves of the above examples and comparative examples were applied to the cracking reaction of naphtha. To simultaneously investigate the hydrothermal stability of the molecular sieve, 0.80 g of 20-40 mesh molecular sieve catalyst was mixed evenly with 5.00 g of quartz sand of the same particle size, filled into a reaction tube for aging treatment, the aging temperature was 700 °C, the water inlet was 0.1 mL / min, and the aging time was 60 min. After the aging was completed, the catalytic cracking performance was evaluated. The reaction temperature was 620 °C, and the flow rates of naphtha and nitrogen were 0.2 mL / min and 30 mL / min, respectively.

[0078] The properties of its naphtha raw material are shown in Table 2, and the catalytic cracking performance is shown in Table 3.

[0079] Table 2 Raw material properties

[0080]

[0081]

[0082] Note: Cnum - number of carbon atoms, nP - normal paraffin, iP - isoparaffin, O - olefin, N - naphthene, A - aromatic hydrocarbon Csum - sum of each hydrocarbon under this carbon atom;

[0083] The test method is well-known, gasoline PONA composition.

[0084] Table 3 Product Distribution

[0085] Item Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Dry gas / wt% 21.38 20.60 20.93 22.15 16.92 18.78 Liquefied gas / wt% 23.83 24.30 23.46 23.23 19.95 19.89 Gasoline / wt% 51.99 52.63 52.93 52.15 60.49 58.21 Diesel / wt% 1.46 1.47 1.74 1.15 1.89 1.68 Heavy oil / wt% 0.14 0.16 0.21 0.17 0.11 0.18 Coke / wt% 1.10 0.84 0.76 1.15 0.64 1.26 Ethane / wt% 4.46 4.76 4.84 3.99 2.68 3.56 Ethylene / wt% 13.39 12.54 12.72 13.57 8.37 9.84 Propane / wt% 2.10 2.55 2.71 2.65 1.68 2.05 Propylene / wt% 14.92 15.06 14.83 14.48 12.54 13.67

[0086] The current evaluation results show that the modified molecular sieve prepared by the method of Example 1 has relatively high yields of ethylene and propylene for naphtha cracking. Combining the characteristics of in-situ introduction of metals, a dehydrogenation-cracking bifunctional catalyst is constructed. The metal component realizes dehydrogenation, converting alkanes into olefins, and the olefins are further converted into other hydrocarbon products on the cracking component. By introducing new active-site metals, the reaction path is changed and the energy barrier for alkane activation is reduced, thereby improving the conversion rate and the yield of target products. Compared with the post-impregnation modified molecular sieve, the in-situ introduced metal has a better binding degree with the framework, is not prone to agglomeration and shedding during hydrothermal treatment, and exhibits better hydrothermal stability and diolefin selectivity.

[0087] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a metal in-situ modified ZSM-5 molecular sieve, characterized in that: The following steps are involved: S1, dissolving a metal ion salt and a weak base in water to obtain a first mixed solution, wherein the weak base is one or more of urea, ammonia water, ammonium carbonate and ammonium bicarbonate; reacting the first mixed solution with carbon monoxide gas under high pressure to obtain a carbonyl metal precursor; Mixing an aluminum source, a silicon source, a template and water to obtain a second mixed solution; S2, mixing the carbonyl metal precursor and the second mixed solution to obtain a gel; S3, subjecting the gel to a crystallization reaction, and then washing, drying and calcining to obtain a metal in-situ modified ZSM-5 molecular sieve material.

2. The method for preparing the metal in-situ modified ZSM-5 molecular sieve according to claim 1, characterized in that: In step S1, the metal in the metal ion salt is one or more of iron, cobalt and nickel.

3. The method for preparing the metal in-situ modified ZSM-5 molecular sieve according to claim 1, characterized in that: In step S1, the reaction temperature is 40-90°C and the pressure is 2-15 MPa.

4. The method for preparing the metal in-situ modified ZSM-5 molecular sieve according to claim 1, characterized in that: In step S1, the molar ratio of the metal ion salt to the carbon monoxide gas is 1:1-50.

5. The method for preparing the metal in-situ modified ZSM-5 molecular sieve according to any one of claims 1 to 4, characterized in that: In step S1, the aluminum source is one or more of aluminum sulfate, sodium aluminate and aluminum hydroxide; the silicon source is one or more of silica sol, silica gel and white carbon black; and the template is one or more of tetraalkylammonium hydroxide, n-butylamine and triethylamine.

6. The method for preparing the metal in-situ modified ZSM-5 molecular sieve according to claim 5, characterized in that: In step S2, the molar ratio of the metal in the carbonyl metal precursor to the template in the second mixed solution is (0.001-0.1): (0.1-0.5).

7. The method for preparing the metal in-situ modified ZSM-5 molecular sieve according to claim 5, characterized in that: In step S3, the temperature of the crystallization reaction is 150-200° C., and the constant temperature crystallization time is 12-96 hours.

8. The metal in-situ modified ZSM-5 molecular sieve material obtained by the preparation method according to any one of claims 1 to 7, having a nano-block stacking structure.

9. Use of the metal in-situ modified ZSM-5 molecular sieve material as claimed in claim 8 as a catalyst in catalytic cracking of naphtha.

10. The use according to claim 9, characterized in that: The catalyst is subjected to aging treatment, and the reaction temperature of the catalytic cracking is 600-630°C.

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