Sheet ZSM-5 molecular sieve as well as preparation method and application thereof
By synthesizing thin-film ZSM-5 molecular sieves in a one-pot process and using mineralizers and growth inhibitors to suppress the growth of the molecular sieves in the b-axis direction, the problem of catalyst deactivation of ZSM-5 molecular sieves was solved, achieving high efficiency and high selectivity in naphtha catalytic cracking.
Patent Information
- Application Number
- CN202510960125.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-10-28
Smart Images
Figure BDA0005495830290000081 
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Abstract
Description
Technical Field
[0001] This invention relates to the field of molecular sieve synthesis technology, and in particular to a thin-film ZSM-5 molecular sieve, its preparation method and application. Background Technology
[0002] Molecular sieves, with their unique three-dimensional framework, abundant pore structure, and tunable acidic sites, have found wide applications in catalysis, adsorption separation, and ion exchange. Among them, the MFI-type ZSM-5 molecular sieve features two intersecting 10-membered ring channels, with a straight channel along the b-axis and a sinusoidal channel along the a-axis. Its unique pore size distribution, ranging from 0.5 to 0.6 nm, enables it to exhibit excellent performance in the catalytic cracking of naphtha to produce ethylene and propylene.
[0003] However, these individual micropores, smaller than 2 nm, restrict the diffusion of macromolecular reactants within the crystal, leading to secondary reactions, coke formation, and catalyst deactivation. The axial length of the molecular sieve crystal can regulate the diffusion rate of molecules within the sieve channels, thus significantly impacting the catalytic performance of the molecular sieve. Compared to the sinusoidal channels along the a-axis, the straight channels along the b-axis are typically the primary diffusion pathway for reactions. Therefore, inhibiting the growth of the molecular sieve along the b-axis can shorten the diffusion path of reactant or product molecules, thereby improving diffusion efficiency and exhibiting excellent catalytic performance in naphtha catalytic cracking. Effectively inhibiting the growth of the molecular sieve along the b-axis is a hot topic of close research in this field. Summary of the Invention
[0004] In view of this, the technical problem to be solved by the present invention is to provide a thin sheet ZSM-5 molecular sieve, its preparation method and application. The thin sheet ZSM-5 molecular sieve provided by the present invention can be made into a catalyst, which can be used for the catalytic cracking of naphtha, and has better catalytic performance.
[0005] This invention provides a method for preparing thin-film ZSM-5 molecular sieves, comprising the following steps:
[0006] S1) Mix the aqueous solution of silicon source, mineralizer, aluminum source and seed crystal to obtain gel;
[0007] S2) The gel is mixed with a growth inhibitor, crystallized, and calcined to obtain thin-film ZSM-5 molecular sieve.
[0008] Preferably, the mineralizing agent includes at least one selected from urea, ammonium fluoride, and ammonium bromide;
[0009] The molar ratio of the silicon source to the mineralizer is 1:0.05 to 0.8;
[0010] The silicon source includes at least one of silica gel, tetraethyl orthosilicate, and neutral silica sol;
[0011] In the aqueous solution of the silicon source, the molar ratio of silicon source to water is 1:8 to 40;
[0012] The aluminum source includes at least one of aluminum isopropoxide, aluminum sulfate, and boehmite.
[0013] The molar ratio of the silicon source to the aluminum source is 1:0.01 to 0.033.
[0014] Preferably, the growth inhibitor includes at least one of L-carnitine, acetyl-L-carnitine, and ammonium carboxylate;
[0015] The molar ratio of the silicon source to the growth inhibitor is 1:0.05 to 0.8.
[0016] Preferably, the seed crystal is a ZSM-5 molecular sieve;
[0017] The mass of the seed crystal is 1% to 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0018] Preferably, the crystallization temperature is 160–180°C and the time is 72–96 h;
[0019] The calcination temperature is 500–700℃, and the time is 4–6 hours.
[0020] The present invention also provides a thin sheet ZSM-5 molecular sieve prepared by the preparation method described above.
[0021] This invention also provides a method for preparing a catalyst, comprising the following steps:
[0022] a) Kaolin, molecular sieve and binder are mixed and stirred to obtain a slurry; the molecular sieve is the thin-film ZSM-5 molecular sieve described above;
[0023] b) After ball milling the slurry, spray molding is performed to obtain microsphere particles;
[0024] c) The microspheres are calcined to obtain a catalyst.
[0025] Preferably, the mass ratio of kaolin, molecular sieve and binder is 20-60:30-50:10-30;
[0026] The roasting temperature is 450–550℃, and the time is 1.5–2.5 h.
[0027] The present invention also provides a catalyst prepared by the preparation method described above.
[0028] The present invention also provides an application of the catalyst described above as a catalyst for naphtha catalytic cracking.
[0029] This invention provides a method for preparing sheet-like ZSM-5 molecular sieves, comprising the following steps: S1) mixing an aqueous solution of a silicon source, a mineralizing agent, an aluminum source, and a seed crystal to obtain a gel; S2) mixing the gel with a growth inhibitor, crystallizing, and calcining to obtain sheet-like ZSM-5 molecular sieves. This invention introduces a mineralizing agent and a growth inhibitor during the molecular sieve crystallization process, directly preparing sheet-like ZSM-5 molecular sieves in a one-pot method. On one hand, the growth inhibitor used in this invention can interact with the mineralizing agent to generate long-chain quaternary ammonium molecules, effectively inhibiting the growth direction of the ZSM-5 molecular sieve along the b-axis, which is beneficial for synthesizing sheet-like ZSM-5 molecular sieves. On the other hand, this invention employs a near-neutral synthesis scheme; the presence of the mineralizing agent provides a weakly alkaline environment to the synthesis system, and no Na is introduced during the synthesis. + No extra Na is needed + Elution step. This method is simple to operate and streamlined. The prepared thin-film molecular sieve has the characteristics of high specific surface area and short b-axis, which is beneficial to reducing the diffusion resistance of macromolecular substrates and products. Using this molecular sieve as the active component in naphtha cracking catalyst, it exhibits excellent conversion rate and diene selectivity in naphtha cracking reaction. The light hydrocarbon catalytic cracking catalyst prepared by this invention can improve the diffusion rate of reaction substrates and products, reaction conversion rate and diene selectivity, and is particularly suitable for refinery naphtha cracking to produce more dienes. Attached Figure Description
[0030] Figure 1 The XRD patterns of the thin-film ZSM-5 molecular sieves of Example 4 and Comparative Example 1 of the present invention are shown below.
[0031] Figure 2 The images show SEM images of the thin-film ZSM-5 molecular sieves of Example 4 and Comparative Example 1 of this invention. Detailed Implementation
[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0033] This invention provides a method for preparing thin-film ZSM-5 molecular sieves, comprising the following steps:
[0034] S1) Mix the aqueous solution of silicon source, mineralizer, aluminum source and seed crystal to obtain gel;
[0035] S2) The gel is mixed with a growth inhibitor, crystallized, and calcined to obtain thin-film ZSM-5 molecular sieve.
[0036] Regarding step S1):
[0037] An aqueous solution of silicon source, a mineralizing agent, an aluminum source, and a seed crystal are mixed to obtain a gel.
[0038] In some embodiments of the present invention, step S1) includes:
[0039] S1-1) Mix the aqueous solution of silicon source with the mineralizing agent to obtain a mixed solution;
[0040] S1-2) After mixing the mixed solution with the aluminum source, it is then mixed with the seed crystal to obtain a gel.
[0041] The silicon source is selected from at least one of silica gel, tetraethyl orthosilicate, and neutral silica sol. In the aqueous solution of the silicon source, the molar ratio of silicon source to water is 1:8 to 40.
[0042] The mineralizing agent is selected from at least one of urea, ammonium fluoride, and ammonium bromide. The molar ratio of the silicon source to the mineralizing agent is 1:0.05 to 0.8. The mineralizing agent is used to inhibit the growth of the b-axis of the molecular sieve.
[0043] The aluminum source is selected from at least one of aluminum isopropoxide, aluminum sulfate, and boehmite. The molar ratio of the silicon source to the aluminum source is 1:0.01 to 0.033.
[0044] The seed crystal is commercially available ZSM-5 molecular sieve.
[0045] The mass of the seed crystal is 1% to 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0046] Regarding step S2):
[0047] The gel was mixed with a growth inhibitor, crystallized, and calcined to obtain thin-film ZSM-5 molecular sieve.
[0048] In some embodiments of the present invention, the growth inhibitor is selected from at least one of L-carnitine, acetyl-L-carnitine, and ammonium carboxylate. The molar ratio of the silicon source to the growth inhibitor is 1:0.05 to 0.8.
[0049] In some embodiments of the present invention, the crystallization temperature is 160–180°C, and the time is 72–96 hours. The crystallization is carried out in a reaction vessel.
[0050] In some embodiments of the present invention, the crystallization process further includes filtration and drying. The filtration method may be vacuum filtration. The drying temperature is 90–110°C, for example, 100°C; the drying time is 10–14 hours, for example, 12 hours.
[0051] In some embodiments of the present invention, the calcination temperature is 500-700°C, for example, 500°C; and the time is 4-6 hours, for example, 6 hours.
[0052] In some embodiments of the present invention, the mixing method described above can be stirring and mixing.
[0053] The present invention also provides a thin sheet ZSM-5 molecular sieve prepared by the preparation method described above.
[0054] In some embodiments of the present invention, the specific surface area of the thin-film ZSM-5 molecular sieve is not less than 413.45 m². 2 / g; micropore volume not less than 0.17cm³ 3 / g. The b-axis of the thin-film ZSM-5 molecular sieve does not exceed 55nm, such as 54nm, 45nm, 46nm, 40nm, 49nm, or 51nm.
[0055] This invention also provides a method for preparing a catalyst, comprising the following steps:
[0056] a) Kaolin, molecular sieve and binder are mixed and stirred to obtain a slurry; the molecular sieve is the thin-film ZSM-5 molecular sieve described above;
[0057] b) After ball milling the slurry, spray molding is performed to obtain microsphere particles;
[0058] c) The microspheres are calcined to obtain a catalyst.
[0059] In some embodiments of the present invention, the mass ratio of kaolin, molecular sieve, and binder is 20–60:30–50:10–30; for example, 60:40:26. The binder includes, but is not limited to, one or more of alumina sol, silica sol, acidified boehmite, water glass, and aluminum phosphate. In some embodiments, the binder is alumina sol and silica sol in a mass ratio of 0.8–1.2:0.8–1.2, for example, 1:1.
[0060] In some embodiments of the present invention, in step a), the raw materials for mixing and stirring further include phosphoric acid. The mass ratio of the kaolin, molecular sieve, binder and phosphoric acid is 20-60:30-50:10-30:5-10, for example 60:40:26:7.
[0061] In some embodiments of the present invention, the spray forming is performed in a spray dryer.
[0062] In some embodiments of the present invention, the calcination temperature is 450–550°C, for example 500°C; and the time is 1.5–2.5 h, for example 2 h.
[0063] The present invention also provides a catalyst prepared by the method described above.
[0064] This invention also provides an application of the catalyst described above as a catalyst for naphtha catalytic cracking. Specifically, it is used as a catalyst for the catalytic cracking of naphtha to produce ethylene and propylene.
[0065] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.
[0066] To further illustrate the present invention, the following detailed description of a thin-film ZSM-5 molecular sieve, its preparation method, and its application, in conjunction with embodiments, is provided by the present invention, but should not be construed as limiting the scope of protection of the present invention.
[0067] Example 1
[0068] 1) Add 30 mol of neutral silica sol from silicon source to 79 mol of water and stir to obtain solution A.
[0069] 2) Add 1 mol of mineralizing agent urea to solution A and stir to mix well to obtain solution B.
[0070] 3) Add 0.1 mol of aluminum source aluminum isopropoxide to solution B and stir to mix well to obtain gel C.
[0071] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0072] 5) After adding 1 mol of the growth inhibitor L-carnitine to gel D, transfer it to a reaction vessel and crystallize it at 160℃ for 96 h.
[0073] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 500℃ for 6h to obtain thin sheet ZSM-5 molecular sieve.
[0074] Example 2
[0075] 1) Add 30 mol of neutral silica sol from silicon source to 79 mol of water and stir to obtain solution A.
[0076] 2) Add 1.4 mol of mineralizing agent urea to solution A and stir to mix well to obtain solution B.
[0077] 3) Add 0.125 mol of aluminum source aluminum isopropoxide to solution B and stir to mix well to obtain gel C.
[0078] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0079] 5) After adding 1.4 mol of the growth inhibitor L-carnitine to gel D, transfer it to a reaction vessel and crystallize it at 160℃ for 96 h.
[0080] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 500℃ for 6h to obtain thin sheet ZSM-5 molecular sieve.
[0081] Example 3
[0082] 1) Add 30 mol of neutral silica sol from silicon source to 79 mol of water and stir to obtain solution A.
[0083] 2) Add 1.7 mol of mineralizing agent urea to solution A and stir to mix well to obtain solution B.
[0084] 3) Add 0.2 mol of aluminum source aluminum isopropoxide to solution B and stir to mix well to obtain gel C.
[0085] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0086] 5) After adding 1.7 mol of the growth inhibitor L-carnitine to gel D, transfer it to a reaction vessel and crystallize it at 160℃ for 96 h.
[0087] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 500℃ for 6h to obtain thin sheet ZSM-5 molecular sieve.
[0088] Example 4
[0089] 1) Add 30 mol of neutral silica sol from silicon source to 79 mol of water and stir to obtain solution A.
[0090] 2) Add 2 mol of mineralizing agent urea to solution A and stir to mix well to obtain solution B.
[0091] 3) Add 0.33 mol of aluminum source aluminum isopropoxide to solution B and stir to mix well to obtain gel C.
[0092] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0093] 5) After adding 2 mol of the growth inhibitor L-carnitine to gel D, transfer it to a reaction vessel and crystallize it at 160℃ for 96 h.
[0094] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 500℃ for 6h to obtain thin sheet ZSM-5 molecular sieve.
[0095] Example 5
[0096] 1) Add 10 mol of neutral silica sol from silicon source to 100 mol of water and stir to mix well to obtain solution A.
[0097] 2) Add 2 mol of mineralizing agent ammonium fluoride to solution A and stir to mix well to obtain solution B.
[0098] 3) Add 0.33 mol of aluminum sulfate source to solution B and stir to mix well to obtain gel C.
[0099] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 5% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0100] 5) After adding 2 mol of the growth inhibitor acetyl-L-carnitine to gel D, transfer it to a reaction vessel and crystallize it at 190℃ for 72 h.
[0101] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 700℃ for 3h to obtain thin sheet ZSM-5 molecular sieve.
[0102] Example 6
[0103] 1) Add 10 mol of neutral silica sol from silicon source to 100 mol of water and stir to mix well to obtain solution A.
[0104] 2) Add 2 mol of mineralizing agent ammonium bromide to solution A and stir to mix well to obtain solution B.
[0105] 3) Add 0.33 mol of aluminum source boehmite to solution B and stir to mix well to obtain gel C.
[0106] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 5% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0107] 5) After adding 2 mol of growth inhibitor ammonium carboxylate to gel D, transfer it to a reaction vessel and crystallize it at 190℃ for 72 h.
[0108] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 700℃ for 3h to obtain thin sheet ZSM-5 molecular sieve.
[0109] Comparative Example 1
[0110] 1) Add 30 mol of neutral silica sol from silicon source to 79 mol of water and stir to obtain solution A.
[0111] 2) Add 2 mol of mineralizing agent urea to solution A and stir to mix well to obtain solution B.
[0112] 3) Add 0.33 mol of aluminum source aluminum isopropoxide to solution B and stir to mix well to obtain gel C.
[0113] 4) Add seed crystals (commercially available ZSM-5 molecular sieve) to gel C, stir and mix well to obtain gel D; the mass of the seed crystals is 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
[0114] 5) Transfer gel D to a reaction vessel and crystallize at 150°C for 96 hours.
[0115] 6) The solid was filtered out from the crystallized molecular sieve, dried at 100℃ for 12h, and calcined at 500℃ for 6h to obtain thin sheet ZSM-5 molecular sieve.
[0116] Figure 1 The images show the XRD patterns of the thin-film ZSM-5 molecular sieves of Example 4 and Comparative Example 1 of this invention.
[0117] Figure 2 The images show SEM images of the thin-film ZSM-5 molecular sieves of Example 4 and Comparative Example 1 of this invention.
[0118] from Figure 1 As can be seen, compared with the standard MFI diffraction peak pattern, both Example 4 and Comparative Example 1 show characteristic diffraction peaks of the MFI phase, indicating that the materials prepared by both methods are ZSM-5 molecular sieves. Figure 2 It can be seen that the thin-film ZSM-5 molecular sieve prepared by the present invention has a distinct thin-film morphology.
[0119] The surface area and pore volume of the thin-film ZSM-5 molecular sieves prepared in Examples 1-4 and Comparative Example 1 were tested, and the results are shown in Table 1.
[0120] Table 1. Surface area and pore volume of the sheet ZSM-5 molecular sieves prepared in Examples 1-6 and Comparative Examples 1-5
[0121]
[0122] Based on the surface area and pore volume test results of molecular sieves, it can be seen that the specific surface area and micropore volume of the thin-film ZSM-5 molecular sieves prepared in Examples 1 to 6 are significantly higher than those of the sample synthesized in Comparative Example 1.
[0123] Application examples
[0124] Naphtha catalytic cracking:
[0125] The physical properties of naphtha are shown in Table 2.
[0126] Table 2 Physical properties of naphtha
[0127]
[0128] The thin-film ZSM-5 molecular sieves prepared in Examples 1-6 and Comparative Examples 1-5 were used as the active components of the catalyst. They were added sequentially in the following order: 600g kaolin, 130g alumina sol, 70g phosphoric acid, 400g ZSM-5 molecular sieve, and 130g silica sol. The mixture was stirred into a slurry, ball-milled, and then spray-dried to obtain microspheres. The microspheres were calcined at 500℃ for 2 hours to obtain the catalyst sample. The catalyst was evaluated using a fixed fluidized bed reactor.
[0129] The test methods for catalytic evaluation of fixed fluidized bed reactors are as follows:
[0130] Prepare 200g of catalyst and add it to a fixed fluidized bed reactor. Set the system temperature to 630℃, nitrogen flow rate to 200mL / min, and water flow rate to 6g / min. After gasification and heating with nitrogen, reflux the oil pump for 1 min, then introduce 20g of oil. React for 8 min, strip for 20 min, then heat to 750℃ and regenerate for 120 min. Regeneration is then complete. After the reaction, record the water, oil, and gas flow rates. Analyze the refinery gas and collect the liquid product.
[0131] The catalytic results are shown in Table 3.
[0132] Table 3. Catalytic cracking effect of naphtha
[0133]
[0134] As shown in Table 3, the catalyst samples prepared by the thin-film ZSM-5 molecular sieves in Examples 1-6 of this invention exhibit higher catalytic conversion rates, diene yields, and lower coke yields compared to Comparative Example 1. This is because the ZSM-5 molecular sieves prepared in Examples 1-6 have higher specific surface areas and shorter b-axis. In naphtha cracking, the shorter b-axis increases the mass transfer rate between the reaction substrate and products in the molecular sieve channels, improving catalytic conversion while inhibiting secondary reactions of product molecules, which is beneficial for improving diene selectivity and suppressing coke formation.
[0135] Furthermore, in Examples 1-4, as the silica-alumina ratio of the molecular sieve decreased, the naphtha cracking conversion rate and diene yield gradually increased, indicating that increasing the number of modified acidic sites in the molecular sieve is beneficial for improving the conversion rate and diene yield. In Examples 4-6, however, the silica-alumina ratio of the molecular sieve remained unchanged; only the raw materials were altered, which had little impact on the performance of the molecular sieve.
[0136] The descriptions of the above embodiments are merely illustrative of the methods and core ideas of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for preparing thin-film ZSM-5 molecular sieves, comprising the following steps: S1) Mix the aqueous solution of silicon source, mineralizer, aluminum source and seed crystal to obtain gel; S2) The gel is mixed with a growth inhibitor, crystallized, and calcined to obtain thin-film ZSM-5 molecular sieve.
2. The preparation method according to claim 1, characterized in that, The mineralizing agent includes at least one of urea, ammonium fluoride and ammonium bromide; The molar ratio of the silicon source to the mineralizer is 1:0.05 to 0.8; The silicon source includes at least one of silica gel, tetraethyl orthosilicate, and neutral silica sol; In the aqueous solution of the silicon source, the molar ratio of silicon source to water is 1:8 to 40; The aluminum source includes at least one of aluminum isopropoxide, aluminum sulfate, and boehmite. The molar ratio of the silicon source to the aluminum source is 1:0.01 to 0.
033.
3. The preparation method according to claim 1, characterized in that, The growth inhibitor includes at least one of L-carnitine, acetyl-L-carnitine, and ammonium carboxylate. The molar ratio of the silicon source to the growth inhibitor is 1:0.05 to 0.
8.
4. The preparation method according to claim 1, characterized in that, The seed crystal is ZSM-5 molecular sieve; The mass of the seed crystal is 1% to 10% of the total mass of SiO2 in the silicon source and Al2O3 in the aluminum source.
5. The preparation method according to claim 1, characterized in that, The crystallization temperature is 160–180°C, and the time is 72–96 h; The calcination temperature is 500–700℃, and the time is 4–6 hours.
6. The thin-film ZSM-5 molecular sieve prepared by the preparation method according to any one of claims 1 to 5.
7. A method for preparing a catalyst, comprising the following steps: a) Kaolin, molecular sieve and binder are mixed and stirred to obtain a slurry; the molecular sieve is the thin-film ZSM-5 molecular sieve as described in claim 6; b) After ball milling the slurry, spray molding is performed to obtain microsphere particles; c) The microspheres are calcined to obtain a catalyst.
8. The preparation method according to claim 7, characterized in that, The mass ratio of the kaolin, molecular sieve and binder is 20-60:30-50:10-30; The roasting temperature is 450–550℃, and the time is 1.5–2.5 h.
9. The catalyst prepared by the method according to any one of claims 7 to 8.
10. The application of the catalyst according to claim 9 as a naphtha catalytic cracking catalyst.