Method for preparing ZSM-5 molecular sieve from kaolin and application of ZSM-5 molecular sieve in preparation of olefin from methanol
By using acid washing and hydrothermal treatment with kaolin as raw material, the problem of high synthesis cost of molecular sieves was solved, realizing low-cost and green synthesis of ZSM-5 molecular sieves, which showed excellent olefin selectivity in methanol-to-olefins reaction.
Patent Information
- Application Number
- CN202511297506.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-11
- Publication Date
- 2025-12-19
AI Technical Summary
Existing molecular sieve synthesis methods are costly and complex, making it difficult to achieve green and low-cost zeolite synthesis. Furthermore, traditional kaolin-based molecular sieve synthesis requires the addition of external silicon sources and template agents.
ZSM-5 molecular sieves were synthesized using kaolin as the sole raw material through a two-step heating method involving acid washing and dealumination followed by heat treatment and hydrothermal treatment. The silica-alumina ratio was controlled by acid washing of kaolin, reducing costs and achieving template-free synthesis.
A low-cost synthesis of ZSM-5 molecular sieve was achieved, which exhibits good olefin conversion selectivity in methanol-to-olefins reactions and has advantages over traditional methods.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a method for preparing ZSM-5 molecular sieves from kaolin and application of the ZSM-5 molecular sieves in methanol-to-olefins. BACKGROUND
[0002] Molecular sieves, also known as zeolites, are porous materials with inherent microporosity, high thermal stability, acidity and redox sites, and have excellent catalytic, adsorptive, separation and ion exchange properties. Therefore, zeolites can be widely used in the fields of petroleum refining, petrochemicals, fine chemicals and household chemicals closely related to energy and the environment, which is an important reason for the long-term development of zeolite synthesis technology. Among various types of molecular sieves, ZSM-5 molecular sieves are widely used as catalysts or catalyst carriers due to their unique pore structure and adjustable acidity.
[0003] However, many current molecular sieve synthesis methods often face problems of high cost and complex process. In today's era of rapid technological development, green chemistry has become an inevitable mainstream direction in the chemical industry, and the route of green synthesis of zeolites has become the focus of current catalytic chemistry research. Considering the large-scale application of zeolites in the chemical industry, if the problems of environment, safety and efficiency can be solved at the same time, the green synthesis route will be an ideal choice. A sustainable green route can optimize the synthesis process of zeolites, making it simple, efficient and less harmful to the environment.
[0004] Kaolin, as a mineral resource containing abundant silicon and aluminum, can be regarded as a favorable raw material for preparing zeolites. The strategy of synthesizing molecular sieves from kaolin not only reduces environmental pollution, but also realizes sustainable and low-cost synthesis of zeolites.
[0005] In the prior art, ZSM-5 molecular sieves can be prepared by in-situ crystallization of kaolin, but most of the preparation methods use kaolin and an external silicon source as raw materials for synthesizing molecular sieves and most of them need to add a template or seeds. Therefore, developing a method for synthesizing molecular sieves without a template using kaolin or other low-cost aluminosilicate minerals as the only raw material has become one of the problems to be solved in the field. SUMMARY
[0006] To solve the above problems, the application discloses a method for preparing ZSM-5 molecular sieves from kaolin, comprising the following steps:
[0007] The kaolin is calcined and acid-washed to remove aluminum to obtain acid-washed kaolin;
[0008] The acid-washed kaolin and the alkali are put into water and stirred to obtain a first mixed solution;
[0009] The first mixed solution is heat-treated to obtain a second mixed solution;
[0010] The second mixed solution is subjected to hydrothermal treatment to obtain the molecular sieve. In the application, kaolin is used as the only raw material for synthesizing ZSM-5 molecular sieve without a template agent, and the acid-washed kaolin is obtained by using the method of acid washing to remove aluminum, and is used as the active kaolin molecular sieve synthesis raw material that can regulate the silicon-aluminum ratio, and the method of using kaolin as a single silicon-aluminum source for synthesizing molecular sieve is realized by using the two-step heating synthesis method of heat treatment and hydrothermal treatment, thereby reducing the synthesis cost of the molecular sieve.
[0011] Preferably, the Al content in the first mixed solution ranges from 0.2wt% to 4wt%;
[0012] The Si content ranges from 2wt% to 10wt%. In the application, the acid-washed kaolin is mixed with the alkali after the residual material of the acid-washed kaolin, which substantially plays the role of alkali dissolution, so that the Al and Si can be dissolved into the first mixture, and there is a certain residual unit, which provides a material basis for obtaining the ZSM-5 molecular sieve by subsequent heat treatment and hydrothermal treatment.
[0013] Preferably, the mass fraction of Al in the acid-washed kaolin is 2-20wt%.
[0014] Preferably, the calcination is performed as follows: the calcination temperature is 500-1100℃; and the calcination activation time is not less than 2h.
[0015] Preferably, the acid washing to remove aluminum is performed as follows: the calcined kaolin is placed in 3-15 times the mass of inorganic acid for not less than 1h, and then is washed and dried, the drying temperature is 60-100℃, and the drying time is 6-24h.
[0016] Preferably, the inorganic acid is hydrochloric acid, and the HCl concentration in the hydrochloric acid is 0.1-10mol / L.
[0017] Preferably, the alkali in the first mixed solution is NaOH, the mass ratio of NaOH to acid-washed kaolin is 0.05-1, the mass ratio of water to acid-washed kaolin is 5-10, and the stirring time is not less than 30min.
[0018] Preferably, the heating time of the heat treatment is 2-12h, and the temperature is 80-100℃.
[0019] Preferably, the heating time of the hydrothermal treatment is 20-72h, and the temperature is 120-200℃.
[0020] Preferably, the process after the hydrothermal treatment further includes a cleaning and drying process:
[0021] The hydrothermal product is flushed into a centrifuge tube with water, and then is subjected to centrifugation operation.
[0022] After washing, dry in an oven, drying temperature 60-100℃, time 6-24h, then grind the collected solid powder to obtain ZSM-5 molecular sieve.
[0023] In another aspect, the application discloses the application of the ZSM-5 molecular sieve prepared by the method of the application in the preparation of olefins from methanol (MTO). The ZSM-5 molecular sieve prepared by the method of the application has good effects on the selectivity of olefin conversion in MTO, and has certain advantages compared with traditional commercial molecular sieves.
[0024] The application can bring the following beneficial effects:
[0025] 1. The application uses kaolin as the only raw material for synthesizing ZSM-5 molecular sieve without a template, uses acid washing to remove aluminum to obtain acid-washed kaolin as an active kaolin molecular sieve synthesis raw material that can regulate the silicon-aluminum ratio, and uses a two-step heating synthesis method of heat treatment and hydrothermal treatment to realize the synthesis of molecular sieve by using kaolin as a single silicon-aluminum source of molecular sieve, thereby reducing the synthesis cost of molecular sieve.
[0026] 2. The application uses acid-washed kaolin first, and then mixes the residual material after acid washing of kaolin with alkali, which essentially plays a role of alkali dissolution, so that Al and Si can be dissolved into the first mixture, and there will be certain residual units to provide a material basis for obtaining ZSM-5 molecular sieve through subsequent heat treatment and hydrothermal treatment.
[0027] 3. The ZSM-5 molecular sieve prepared by the method of the application has good effects on the selectivity of olefin conversion in MTO, and has certain advantages compared with traditional commercial molecular sieves. DETAILED DESCRIPTION
[0028] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application, and do not limit the application in any way. In the drawings:
[0029] Figure 1 It is an XRD pattern of No. 1 molecular sieve.
[0030] Figure 2 It is an SEM pattern of No. 1 molecular sieve.
[0031] Figure 3 It is an SEM pattern of No. 2 molecular sieve. DETAILED DESCRIPTION
[0032] To clearly illustrate the technical features of the application, the application will be described in detail below with reference to specific embodiments and in conjunction with the accompanying drawings.
[0033] The application discloses a method for preparing ZSM-5 molecular sieve from kaolin, comprising the following steps:
[0034] S1, roasting kaolin and performing aluminum removal by acid washing to obtain acid-washed kaolin;
[0035] The roasting is performed at a roasting temperature of 500-1100 DEG C and for not less than 2 h.
[0036] The aluminum removal by acid washing is performed by placing the roasted kaolin in 3-15 times the mass of inorganic acid for not less than 1 h, and then performing washing and drying at a temperature of 60-100 DEG C for 6-24 h; the inorganic acid is hydrochloric acid, and the HCl concentration in the hydrochloric acid is 0.1-10 mol / L.
[0037] The mass fraction of Al in the acid-washed kaolin is 2-20 wt%.
[0038] S2, stirring the acid-washed kaolin and alkali in water to obtain a first mixed solution;
[0039] The alkali in the first mixed solution is NaOH, the mass ratio of the NaOH to the acid-washed kaolin is 0.05-1, the mass ratio of water to the acid-washed kaolin is 5-10, and the stirring time is not less than 30 min.
[0040] The Al content in the first mixed solution ranges from 0.2 wt% to 4 wt%, and the Si content ranges from 2 wt% to 10 wt%.
[0041] S3, performing heat treatment on the first mixed solution to obtain a second mixed solution;
[0042] The heating time of the heat treatment is 2-12 h, and the temperature is 80-100 DEG C.
[0043] S4, performing hydrothermal treatment on the second mixed solution to obtain a molecular sieve.
[0044] The heating time of the hydrothermal treatment is 20-72 h, and the temperature is 120-200 DEG C.
[0045] S5, performing cleaning and drying after the hydrothermal treatment:
[0046] The hydrothermal product is poured into a centrifugal tube by using water, and then centrifugal operation is performed;
[0047] After cleaning, the product is placed in a drying oven for drying at a temperature of 60-100 DEG C for 6-24 h, and then the obtained solid powder is collected to obtain a ZSM-5 molecular sieve.
[0048] The application relates to application of a molecular sieve prepared according to a method for preparing ZSM-5 molecular sieve from kaolin in MTO olefin adsorption separation.
[0049] In order to characterize the effectiveness of the preparation method, the following experiment was conducted:
[0050] Example 1:
[0051] S101: roasting and acid washing kaolin to remove aluminum to obtain acid-washed kaolin;
[0052] The roasting is performed at a roasting temperature of 500 DEG C and a roasting activation time of 2h.
[0053] The acid washing to remove aluminum is performed as follows: the roasted kaolin is placed in 3-15 times the mass of hydrochloric acid with a HCl concentration of 0.1 mol / L, continuous stirring is conducted for 1h, then washing with water is conducted, and drying is conducted at a temperature of 60 DEG C for 24h.
[0054] The mass fraction of Al in the acid-washed kaolin is 20wt%.
[0055] S102: stirring the acid-washed kaolin and alkali in water to obtain a first mixed solution;
[0056] The alkali in the first mixed solution is NaOH, the mass ratio of the NaOH to the acid-washed kaolin is 0.05, the mass ratio of water to the acid-washed kaolin is 5, and the stirring time is 30min.
[0057] The Al content in the first mixed solution ranges from 4wt%; the Si content ranges from 2wt%.
[0058] S103: heat treating the first mixed solution to obtain a second mixed solution;
[0059] The heating time of the heat treatment is 2h, and the temperature is 100 DEG C.
[0060] S104: hydrothermally treating the second mixed solution to obtain a molecular sieve.
[0061] The heating time of the hydrothermal treatment is 20h, and the temperature is 200 DEG C.
[0062] S105: cleaning and drying after the hydrothermal treatment:
[0063] The hydrothermal product is flushed into a centrifugal tube with water, and centrifugal operation is conducted;
[0064] After cleaning, the product is placed in a drying oven for drying at a temperature of 60 DEG C for 24h, and then the obtained solid powder is ground and collected to obtain a ZSM-5 molecular sieve, which is recorded as No.1 molecular sieve. Figure 1 andFigure 2 As shown.
[0065] The molecular sieve No. 1 was heated and stirred with 1 mol / L ammonium chloride solution at a temperature of 80℃ for 5h, and repeated three times of centrifugal drying, and then the powder obtained by heating at 550℃ for 6h was H-ZSM-5. The molecular sieve obtained by the above method was activated at 500℃ for 2h in a nitrogen atmosphere in a MTO fixed bed device, and then the methanol to olefin reaction was carried out at 450℃. The gaseous product after reaction was analyzed offline by a gas chromatograph with a thermal conductivity detector and a flame ionization detector, and methane was used as an internal standard. The conversion rate was 100%, and the selectivity of C2-C4 olefins was analyzed. See Table 1 for details.
[0066] Example 2:
[0067] S201, calcining kaolin to obtain acid-washed kaolin by removing aluminum;
[0068] The calcination is carried out as follows: the calcination temperature is 1100℃, and the calcination activation time is 2h.
[0069] The acid-washing to remove aluminum is carried out as follows: the calcined kaolin is placed in 15 times the mass of hydrochloric acid with a HCl concentration of 10 mol / L, and continuously stirred for 1h, then washed with water and dried at a temperature of 100℃ for 6h.
[0070] The mass fraction of Al in the acid-washed kaolin is 2wt%.
[0071] S202, stirring the acid-washed kaolin with alkali in water to obtain a first mixture;
[0072] The alkali in the first mixture is NaOH, the mass ratio of NaOH to acid-washed kaolin is 1, and the mass ratio of water to acid-washed kaolin is 10; the stirring time is 30min.
[0073] The Al content in the first mixture ranges from 0.2wt%, and the Si content ranges from 2wt%.
[0074] S203, heat treating the first mixture to obtain a second mixture;
[0075] The heating time of the heat treatment is 12h, and the temperature is 80℃.
[0076] S204, hydrothermally treating the second mixture to obtain a molecular sieve.
[0077] The heating time of the hydrothermal treatment is 72h, and the temperature is 120℃.
[0078] S205, cleaning and drying after hydrothermal treatment:
[0079] The hydrothermal product is washed into a centrifuge tube with water, and then centrifuged;
[0080] After washing, it is dried in an oven at 100°C for 6h, and then the obtained solid powder is ground to obtain ZSM-5 molecular sieve, which is recorded as No. 2 molecular sieve. The SEM is shown in Figure 2
[0081] The No. 2 molecular sieve is heated and stirred with a 1 mol / L ammonium chloride solution at 80°C for 5h, and the centrifugation and drying are repeated three times, and then the powder obtained by heating at 550°C for 6h is H-ZSM-5. The molecular sieve obtained by the above method is activated at 500°C for 2h in a MTO fixed bed device under a nitrogen atmosphere, and then a methanol to olefin reaction is carried out at 450°C. The gaseous product after the reaction is analyzed offline by a gas chromatograph with a thermal conductivity detector and a flame ionization detector, and methane is used as an internal standard. The conversion rate is 100%, and the selectivity of C2-C4 olefins is analyzed. See Table 1 for details.
[0082] The comparison is as follows:
[0083] Comparative Example 1:
[0084] S301: Al is removed from kaolin by acid washing to obtain acid-washed kaolin;
[0085] The acid washing for removing Al is carried out as follows: the kaolin is placed in 15 times the mass of hydrochloric acid, the HCl concentration in the hydrochloric acid is 10 mol / L, continuous stirring is carried out, the stirring time is 1h, then washing with water is carried out and then drying is carried out, the drying temperature is 100°C, and the drying time is 6h.
[0086] S302: The acid-washed kaolin is stirred with a base in water to obtain a first mixed solution;
[0087] The base in the first mixed solution is NaOH, the mass ratio of NaOH to acid-washed kaolin is 1, and the mass ratio of water to acid-washed kaolin is 10; the stirring time is 30min.
[0088] S303: The first mixed solution is heat treated to obtain a second mixed solution;
[0089] The heating time of the heat treatment is 12h, and the temperature is 80°C.
[0090] S304: The second mixed solution is hydrothermally treated to obtain a molecular sieve.
[0091] The heating time of the hydrothermal treatment is 72h, and the temperature is 120°C.
[0092] S305: Washing and drying are carried out after the hydrothermal treatment:
[0093] The hydrothermal product is washed into a centrifuge tube with water, and then centrifuged;
[0094] After washing, it is dried in an oven at 100℃ for 6h, and then the obtained solid powder is ground and collected. The solid powder is in a non-structured state and cannot be used in MTO, and the olefin conversion rate is extremely low.
[0095] Comparative Example 2:
[0096] S401: Kaolin is calcined and acid-washed to remove aluminum to obtain acid-washed kaolin;
[0097] The calcination is performed at a calcination temperature of 1100℃ for 2h.
[0098] The acid-washing to remove aluminum is performed as follows: the calcined kaolin is placed in 15 times the mass of hydrochloric acid with a HCl concentration of 10mol / L, continuously stirred for 5h, then washed with water and dried at 100℃ for 6h.
[0099] The mass fraction of Al in the acid-washed kaolin is 1.2wt%.
[0100] S402: The acid-washed kaolin and alkali are stirred in water to obtain a first mixed solution;
[0101] The alkali in the first mixed solution is NaOH, the mass ratio of NaOH to acid-washed kaolin is 1, and the mass ratio of water to acid-washed kaolin is 10. The stirring time is 30min.
[0102] The Al content in the first mixed solution ranges from 0.1wt%, and the Si content ranges from 2wt%.
[0103] S403: The first mixed solution is heat-treated to obtain a second mixed solution;
[0104] The heating time of the heat treatment is 12h at a temperature of 80℃.
[0105] S404: The second mixed solution is hydrothermally treated to obtain a molecular sieve.
[0106] The heating time of the hydrothermal treatment is 72h at a temperature of 120℃.
[0107] S405: After the hydrothermal treatment, washing and drying are performed:
[0108] The hydrothermal product is washed into a centrifuge tube with water, and then centrifuged;
[0109] After washing, put into the oven to dry, drying temperature 100℃, time 6h, then grind the collected solid powder. The solid powder is non-shaped, mainly composed of quartz and amorphous structure. The olefin conversion rate is extremely low and cannot be used in MTO.
[0110] Comparative Example 3:
[0111] S501 calcine kaolin and acid wash to remove aluminum to obtain acid-washed kaolin;
[0112] The calcination is carried out as follows: calcination temperature is 1100℃; calcination activation time is 2h.
[0113] The acid washing to remove aluminum is carried out as follows: the calcined kaolin is placed in 15 times the mass of hydrochloric acid, the HCl concentration in the hydrochloric acid is 10mol / L, continuous stirring, stirring time 1h, then washed with water and dried, drying temperature is 100℃, time is 6h.
[0114] The mass fraction of Al in the acid-washed kaolin is 2wt%.
[0115] S502 put the acid-washed kaolin and alkali into water to obtain a first mixed solution by stirring;
[0116] The alkali in the first mixed solution is NaOH, the mass ratio of NaOH to acid-washed kaolin is 1, and the mass ratio of water to acid-washed kaolin is 10; the stirring time is 30min.
[0117] The Al content in the first mixed solution ranges from 0.2wt%; the Si content ranges from 2wt%.
[0118] S503 hydrothermal treatment of the first mixed solution to obtain a molecular sieve.
[0119] The heating time of the hydrothermal treatment is 72h, and the temperature is 120℃.
[0120] S504 washing and drying after hydrothermal treatment:
[0121] The hydrothermal product is washed into a centrifuge tube with water, and then centrifuged;
[0122] After washing, put into the oven to dry, drying temperature 100℃, time 6h, then grind the collected solid powder. The solid powder is non-shaped, mainly composed of quartz and amorphous structure. The olefin conversion rate is extremely low and cannot be used in MTO.
[0123] Comparative Example 4:
[0124] S601 calcine kaolin and acid wash to remove aluminum to obtain acid-washed kaolin;
[0125] The calcination is performed at a temperature of 1100℃ for 2h.
[0126] The acid washing is performed by placing the calcined kaolin clay in 15 times the mass of hydrochloric acid with a concentration of 10mol / L, continuously stirring for 1h, then washing with water and drying at a temperature of 100℃ for 6h.
[0127] The mass fraction of Al in the acid washed kaolin clay is 2wt%.
[0128] S602 placing the acid washed kaolin clay, alkali and tetrapropylammonium hydroxide into water to obtain a first mixture by stirring;
[0129] The alkali in the first mixture is NaOH, the mass ratio of NaOH to acid washed kaolin clay is 1, the mass ratio of water to acid washed kaolin clay is 10, and the mass ratio of tetrapropylammonium hydroxide to acid washed kaolin clay is 0.05; the stirring time is 30min.
[0130] S603 heat treating the first mixture to obtain a second mixture;
[0131] The heating time of the heat treatment is 12h at a temperature of 80℃.
[0132] S604 hydrothermally treating the second mixture to obtain a molecular sieve.
[0133] The heating time of the hydrothermal treatment is 72h at a temperature of 120℃.
[0134] S605 washing and drying after the hydrothermal treatment:
[0135] The hydrothermal product is poured into a centrifuge tube and centrifuged;
[0136] After washing, it is dried in an oven at a temperature of 100℃ for 6h, then the obtained solid powder is ground and collected to obtain a ZSM-5 molecular sieve, denoted as No. 6 molecular sieve.
[0137] The No. 6 molecular sieve is heated and stirred with a 1mol / L ammonium chloride solution at a temperature of 80℃ for 5h, centrifuged and dried repeatedly for three times, and then heated at 550℃ for 6h to obtain a powder of H-ZSM-5. The molecular sieve obtained by the above method is activated at 500℃ for 2h in a MTO fixed bed device under a nitrogen atmosphere, and then a methanol to olefin reaction is performed at 450℃. The gaseous product after the reaction is analyzed offline by a gas chromatograph with a thermal conductivity detector and a flame ionization detector, and methane is used as an internal standard. The conversion rate is 100%, and the selectivity of C2-C4 olefins is analyzed. See Table 1 for details.
[0138] In addition, the MTO selectivity of the commercially available ZSM-5 was determined, and the conversion rate of the commercially available ZSM-5 treated with the ammonium chloride solution, dried, and activated in the above manner was 100%. The selectivity test results are shown in Table 1.
[0139] Table 1: Olefin selectivity of methanol to olefins
[0140]
[0141] It can be seen that the molecular sieve synthesized by using kaolin as a raw material, controlling the silicon and aluminum content by moderate pickling and then alkali dissolution, has excellent olefin selectivity in the MTO reaction.
[0142] The above is only an embodiment of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of the claims of the present application.
Claims
1. A method for preparing ZSM-5 molecular sieve from kaolin, characterized in that: The method comprises the following steps: roasting kaolin and acid washing to remove aluminum to obtain acid-washed kaolin; putting the acid-washed kaolin and alkali into water to stir to obtain a first mixed solution; heat treating the first mixed solution to obtain a second mixed solution; hydrothermally treating the second mixed solution to obtain a molecular sieve.
2. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, characterized by: The Al content in the first mixed solution ranges from 0.2wt% to 4wt%. The Si content ranges from 2wt% to 10wt%.
3. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, wherein: The mass fraction of Al in the acid-washed kaolin is 2-20wt%.
4. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, characterized by: The roasting is performed at a temperature of 500-1100℃ for not less than 2h.
5. The method for preparing ZSM-5 molecular sieve from kaolin according to claim 1, characterized in that: the acid washing to remove aluminum is performed by putting the roasted kaolin into 3-15 times of inorganic acid for not less than 1h, then washing and drying at a temperature of 60-100℃ for 6-24h; the inorganic acid is hydrochloric acid with a HCl concentration of 0.1-10mol / L.
6. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, wherein: The alkali in the first mixed solution is NaOH, the mass ratio of NaOH to acid-washed kaolin is 0.05-1, the mass ratio of water to acid-washed kaolin is 5-10, and the stirring time is not less than 30min.
7. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, wherein: The heating time for the heat treatment is 2-12h at a temperature of 80-100℃.
8. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, wherein: The heating time for the hydrothermal treatment is 20-72h at a temperature of 120-200℃.
9. The method of preparing ZSM-5 zeolite from kaolin according to claim 1, wherein: After the hydrothermal treatment, the process further comprises cleaning and drying: putting the hydrothermal product into a centrifuge tube and performing centrifugation; after cleaning, putting into a drying oven at a temperature of 60-100℃ for 6-24h, then grinding and collecting the obtained solid powder to obtain ZSM-5 molecular sieve.
10. The application of ZSM-5 molecular sieve prepared by the method for preparing ZSM-5 molecular sieve from kaolin according to claims 1-9 in the methanol-to-olefin reaction.