Preparation method for preparing ZSM-5 molecular sieve through kaolin in-situ crystallization and application of ZSM-5 molecular sieve

Abstract

The invention discloses a method for preparing a ZSM-5 molecular sieve by in-situ crystallization of kaolin and application of the ZSM-5 molecular sieve. A catalytic cracking catalyst for petroleum hydrocarbons mainly depends on ZSM-5 molecular sieves as active components, so that a green synthesis mode for developing a molecular sieve catalyst with good performance is very important. The preparation method comprises the following steps: uniformly stirring a NaZSM-5 molecular sieve, kaolin, water glass, aluminum hydroxide, silica sol, magnesium chloride and the like, performing spray granulation, performing segmented roasting to activate aluminum and silicon elements in the kaolin, and finally adding sodium hydroxide and ethanol for dynamic crystallization, pickling and roasting to obtain the molecular sieve. The molecular sieve can be used as an active component in light hydrocarbon cracking, has a rich pore structure and a larger specific surface area, is beneficial for oil-gas components to enter pores of the molecular sieve, is short in diffusion path, is higher in mass transfer rate in the reaction process, can quickly diffuse out a generated product, and can more effectively improve the conversion rate of the reaction. In a catalytic cracking reaction, the molecular sieve has better reaction stability while increasing the yield of ethylene and diene.

Description

Technical Field

[0001] The present invention relates to a preparation method and application of in-situ crystallization of ZSM-5 molecular sieve using kaolin as raw material, belonging to the category of catalysts. Background Art

[0002] Light olefins are important basic organic chemical raw materials in the chemical industry. With the rapid development of industries such as petrochemical industry and light industry, the demand for light olefins is increasing continuously. The catalytic cracking technology uses molecular sieve catalysts and existing FCC catalytic cracking reactors, which can better adjust the yields of ethylene and propylene, and become an effective way to increase the production of light olefins. The catalyst can reduce the reaction activation energy in the catalytic cracking reaction, enhance the raw material adaptability, and have selectivity, and can control the product distribution to a certain extent. Therefore, the performance and synthesis cost of the catalyst are the key to the catalytic cracking technology. ZSM-5 molecular sieve has become the most attractive catalyst due to its unique pore structure, adjustable acidity and good hydrothermal stability. With the proposal of the concept of green refining and sustainable development, many people are committed to developing simple, cheap and environmentally friendly strategies to prepare ZSM-5 with highly mesoporous or macroporous and high zeolite properties. Kaolinite is a cheap natural clay mineral, rich in reserves in some countries and regions, with main elements of aluminum and silicon, and is a good silicon source and alumina source for synthesizing ZSM-5. The zeolite molecular sieve obtained by the in-situ crystallization technology of kaolin has high hydrothermal stability and reduces the production cost at the same time.

[0003] CN202410638760 discloses a modified molecular sieve, its preparation method and application. After mixing a silicon source, an aluminum source and a calcium source under alkaline conditions, crystallization and calcination are carried out to obtain an intermediate; the intermediate is ion-exchanged with an ammonium salt, and a modified ZSM-5 molecular sieve is obtained after calcination. The molecular sieve has a microporous and mesoporous structure, and the Ca element in calcium oxide is evenly distributed in the pore structure of the molecular sieve, reducing the density of acid sites in the molecular sieve, making the acid distribution in the molecular sieve more uniform, inhibiting the hydrogen transfer reaction, improving the diolefin selectivity, and improving the coke resistance of the molecular sieve.

[0004] CN202311219756 discloses a preparation method of a catalyst composition, including the following steps: mixing a ZSM-5 molecular sieve, kaolin, a binder and an optional modifier evenly to obtain microspheres; crystallizing and calcining the microspheres under the action of a template agent to form a catalyst composition, and also provides a catalyst composition, its use and a reaction device for preparing it. When the prepared catalyst is used in the light hydrocarbon cracking reaction, it can greatly improve the yields of ethylene and propylene, and at the same time take into account the yield of aromatics.

[0005] As can be seen from the above invention, hierarchical pore ZSM-5 can significantly improve the selectivity of diolefins in the catalytic reaction of light hydrocarbon cracking, reduce coke, and the catalyst prepared by synthesizing ZSM-5 molecular sieve with natural kaolin as the raw material has a greater improvement in the diolefin yield for the light hydrocarbon cracking reaction. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a preparation method and application of in-situ crystallization of ZSM-5 molecular sieve with kaolin as the raw material. Using natural kaolin, a natural material with rich resources and low price, as the raw material, ZSM-5 molecular sieve is synthesized by the in-situ crystallization method. The preparation process is simple and the cost is low. The molecular sieve is used in the light hydrocarbon cracking reaction, and has good reaction stability while improving the ethylene and diolefin yields.

[0007] In the first aspect, the present invention provides a preparation method for in-situ crystallization of ZSM-5 molecular sieve with kaolin as the raw material. The specific preparation steps are as follows:

[0008] (1) Add kaolin and water of the same mass to the reaction tank, start stirring, and ensure that the stirring speed is not less than 100 r / min. Add aluminum hydroxide to the above slurry, slowly add a certain proportion of hydrochloric acid solution, and beat the slurry for not less than 1 h to mix evenly for later use.

[0009] (2) Add NaZSM-5 molecular sieve to water glass, beat and disperse evenly for later use.

[0010] (3) Add the slurry in step (1) to the slurry in step (2), and the standby time of the slurry in step (1) should not exceed 2 h. Filter, wash and re-beat the mixed slurry, transfer the slurry into a ball mill and grind for 2 h, add silica sol and magnesium chloride, and continue to stir for 30 min for spray granulation.

[0011] (4) After segmental temperature-controlled calcination, transfer it to a pressure reactor, add sodium hydroxide and ethanol, and perform dynamic crystallization for 24 h. After pickling the product, impregnate it with an equal mass of sodium dihydrogen phosphate solution, dry it, and calcine it to obtain the molecular sieve.

[0012] Preferably, the finally prepared product is ZSM-5 molecular sieve, and the Al2O3:SiO2 of the ZSM-5 molecular sieve is 1:(35 - 50).

[0013] Preferably, the addition ratio of kaolin in step (1) is 20 - 28 wt% of the total Al2O3 mass of the finally prepared catalyst in terms of the mass of Al2O3; the addition ratio of aluminum hydroxide is 72 - 80 wt% of the total Al2O3 mass of the finally prepared catalyst in terms of the mass of Al2O3.

[0014] Preferably, the addition ratio of hydrochloric acid in step (1) is determined by the pH of the mixed slurry, and the pH of the slurry should be controlled between 2.0 and 3.0.

[0015] Preferably, the addition ratio of sodium silicate in step (2) is 50 - 70 wt% of the mass of SiO2 in the finally prepared catalyst in terms of the mass of SiO2, where the concentration of SiO2 is 370 - 390 g / L and the concentration of Na2O is 120 - 130 g / L.

[0016] Preferably, the addition ratio of NaZSM-5 molecular sieve in step (2) is 5 wt% of the mass of SiO2 in the finally prepared catalyst in terms of the mass of SiO2.

[0017] Preferably, the amount of washing water for the mixed slurry in step (3) is 5 times the dry basis mass of the mixed slurry. After washing, the filter cake is slurried to ensure a solid content of about 30%.

[0018] Preferably, the operating frequency of the ball mill in step (3) is 30 Hz / h, the mass ratio of alumina balls to the slurry is 1:1, and the diameter of the balls is selected to be 3 - 4 mm.

[0019] Preferably, the addition ratio of silica sol in step (3) is 20 - 30 wt% of the mass of SiO2 in the finally prepared catalyst in terms of the mass of SiO2; the addition ratio of magnesium chloride is 0.5 - 2 wt% of the dry basis mass of the final catalyst in terms of the mass of Mg 2+ .

[0020] Preferably, in step (4), the staged calcination is controlled to be calcined at 600 °C for 0.5 h, 750 °C for 1.0 h, and 900 °C for 1.0 h.

[0021] Preferably, the addition ratio of sodium hydroxide in step (4) is (0.12 - 0.15):1 in terms of the mass ratio of Na + to the mass of Si in the system. The addition ratio of ethanol to the mass of Si in the system is 1.5:1. The solution used for pickling is a hydrochloric acid solution with a mass fraction of 4%, and the amount of hydrochloric acid used is 1.2 wt% of the dry basis mass of the finally prepared catalyst. Sodium dihydrogen phosphate is an aqueous solution with a pH value of 3.3 - 3.�, and the addition ratio is 0.7 wt% of the dry basis of the finally prepared catalyst.

[0022] In a second aspect, the present invention provides a catalyst, which includes a carrier, a binder, and an active component.

[0023] Preferably, the carrier is selected from kaolin.

[0024] Preferably, the binder is selected from any one or more of aluminum sol, silica sol, acidified pseudo-boehmite, or phosphoaluminate.

[0025] Preferably, the active component is the molecular sieve involved above.

[0026] Preferably, after the mixture of the carrier, binder and active component is stirred evenly, spray molded, then calcined and washed with water, the catalyst is obtained.

[0027] Preferably, the catalyst comprises, by weight, 20 - 45 wt% of the carrier, 15 - 30 wt% of the binder and 30 - 50 wt% of the active component.

[0028] Preferably, the calcination temperature is 500 - 600 °C; the calcination time is 2 - 4 h; the water consumption for washing is 5 times the dry - basis mass of the catalyst; the drying temperature is 140 - 180 °C, and the drying time is 2 - 4 h. Specific Embodiments

[0029] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application and does not limit the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0030] The water glass, silica sol, NaZSM - 5, hydrochloric acid, magnesium chloride, sodium hydroxide, disodium hydrogen phosphate, aluminophosphate gel, and HZSM - 5 zeolite used are all industrial - grade and are taken from Qingdao Huicheng Environmental Protection Technology Group Co., Ltd.

[0031] The kaolin is produced by China Kaolin Company, and the loss on ignition is 22.5 wt%;

[0032] The Al(OH)3 is produced by Langfang Pengcai Fine Chemical Co., Ltd., with a content of 99.7 wt%;

[0033] The water glass contains 26.91 wt% of silicon oxide and 8.82 wt% of sodium oxide;

[0034] The silica sol has a mass concentration of 30.5%;

[0035] The NaZSM - 5 zeolite has a loss on ignition of 22.5 wt%, wherein the silicon oxide content is 88.45 wt% and the sodium oxide content is 5.33 wt%;

[0036] The magnesium chloride contains Mg 2+ with a mass concentration of 9.0%;

[0037] The sodium hydroxide has a mass concentration of 40%;

[0038] The absolute ethanol is produced by Jinan Hongcheng Chemical Co., Ltd., with a content of 99.9 wt%;

[0039] The disodium hydrogen phosphate has a mass concentration of 12.2%;

[0040] Hydrochloric acid, mass concentration 4.0%;

[0041] Phosphoaluminate glue, mass concentration 43.3%;

[0042] HZSM-5 zeolite, loss on ignition 22.8 wt%.

[0043] Example 1:

[0044] (1) Add 105.9 g of kaolin and the same mass of water to the reaction tank, start stirring, and ensure that the stirring speed is not less than 100 r / min. Add 121.7 g of aluminum hydroxide to the above slurry, and adjust the pH value of the mixture to 2 with dilute hydrochloric acid with a concentration of 4 wt%. Beat the slurry for not less than 1 h, mix evenly, and set aside for use.

[0045] (2) Add 156.1 g of NaZSM-5 molecular sieve to 5581.9 g of water glass, beat and disperse evenly, and set aside for use.

[0046] (3) Add the slurry in step (1) to the slurry in step (2), and control the standby time of the slurry in step (1) not to exceed 2 h. Filter, wash, and re-beat the mixed slurry, transfer the slurry into a ball mill and grind for 2 h, add 1970.0 g of silica sol and 114.8 g of magnesium chloride, and continue to stir for 30 min for spray granulation.

[0047] (4) Roast the spray-dried dry powder at 600 °C for 0.5 h, 750 °C for 1.0 h, and 900 °C for 1.0 h, then transfer it to a pressure reactor, add 299.3 g of sodium hydroxide and 1496.3 g of ethanol, and carry out dynamic crystallization for 24 h. Dilute 118.6 g of sodium dihydrogen phosphate solution to the same mass as the product, pickle the product with 620.0 g of dilute hydrochloric acid, then transfer it to the diluted sodium dihydrogen phosphate solution for impregnation, dry, and roast to obtain this molecular sieve, denoted as A1.

[0048] (5) Soak 832.3 g of kaolin, 415.7 g of phosphoaluminate glue, and 1700 g of water for 30 minutes, then start stirring, add 800 g of the above A1 molecular sieve and 800 g of water to make a slurry and stir for 10 minutes. Continue to add 245.9 g of silica sol and stir for 30 minutes. Then spray-dry and form the obtained slurry, roast at 500 °C for 1 hour, wash with 5 times of water, and dry to obtain the catalytic cracking aid, denoted as CAT-1.

[0049] Example 2:

[0050] (1) Add 95.3 g of kaolin and the same mass of water to the reaction tank, start stirring, and ensure that the stirring speed is not less than 100 r / min. Add 124.8 g of aluminum hydroxide to the above slurry, and adjust the pH value of the mixture to 2.3 with dilute hydrochloric acid with a concentration of 4 wt%. Beat the slurry for not less than 1 h, mix evenly, and set aside for use.

[0051] (2) Add 177.9 g of NaZSM-5 molecular sieve to 6251.8 g of water glass, make a slurry and disperse it evenly for later use.

[0052] (3) Add the slurry in step (1) to the slurry in step (2), and control the standby time of the slurry in step (1) not to exceed 2 h. Filter press, wash and re-slurry the mixed slurry, transfer the slurry into a ball mill and grind for 2 h, add 2364.0 g of silica sol and 227.5 g of magnesium chloride, and continue stirring for 30 min for spray granulation.

[0053] (4) Roast the dry powder after spraying at 600 °C for 0.5 h, 750 °C for 1.0 h, and 900 °C for 1.0 h, then transfer it to a pressure reactor, add 369.4 g of sodium hydroxide and 1705.1 g of ethanol, and carry out dynamic crystallization for 24 h. Dilute 117.5 g of sodium dihydrogen phosphate solution to the same mass as the product, pickle the product with 614.3 g of dilute hydrochloric acid, then transfer it to the diluted sodium dihydrogen phosphate solution for impregnation, dry and roast to obtain this molecular sieve denoted as A2.

[0054] (5) Soak 832.3 g of kaolin, 415.7 g of phosphoaluminate gel and 1700 g of water for 30 minutes, then start stirring, add 800 g of the above A2 molecular sieve and 800 g of water to make a slurry and add it to the mixture and stir for 10 minutes. Continue to add 245.9 g of silica sol and stir for 30 minutes. Then spray dry and form the obtained slurry, roast at 500 °C for 1 hour, wash with 5 times of water, and dry to obtain the catalytic cracking aid denoted as CAT-2.

[0055] Example 3:

[0056] (1) Add 81.2 g of kaolin and the same mass of water to the reaction tank, start stirring, and ensure that the stirring speed is not less than 100 r / min. Add 126.4 g of aluminum hydroxide to the above slurry, and adjust the pH value of the mixture to 2.6 with dilute hydrochloric acid with a concentration of 4% by weight. Make a slurry for not less than 1 h, mix evenly for later use.

[0057] (2) Add 199.3 g of NaZSM-5 molecular sieve to 6921.6 g of water glass, make a slurry and disperse it evenly for later use.

[0058] (3) Add the slurry in step (1) to the slurry in step (2), and control the standby time of the slurry in step (1) not to exceed 2 h. Filter press, wash and re-slurry the mixed slurry, transfer the slurry into a ball mill and grind for 2 h, add 2558.0 g of silica sol and 331.7 g of magnesium chloride, and continue stirring for 30 min for spray granulation.

[0059] (4) The dry powder after spraying is calcined at 600 °C for 0.5 h, 750 °C for 1.0 h, and 900 °C for 1.0 h, and then transferred to a pressure reactor. Add 445.7 g of sodium hydroxide and 1910.2 g of ethanol, and carry out dynamic crystallization for 24 h. Dilute 114.2 g of sodium dihydrogen phosphate solution to the same mass as the product. After pickling the product with 597.1 g of dilute hydrochloric acid, transfer it to the diluted sodium dihydrogen phosphate solution for impregnation, drying, and calcination to obtain this molecular sieve denoted as A3.

[0060] (5) Soak 832.3 g of kaolin, 415.7 g of aluminophosphate gel, and 1700 g of water for 30 minutes, then start stirring. Add 800 g of the above A3 molecular sieve and 800 g of water to make a slurry and stir for 10 minutes. Continue to add 245.9 g of silica sol and stir for 30 minutes. Then spray-dry and form the obtained slurry, calcine at 500 °C for 1 hour, wash with 5 times the amount of water, and dry to obtain the catalytic cracking aid denoted as CAT-3.

[0061] Example 4:

[0062] (1) Add 70.6 g of kaolin and the same mass of water to the reaction tank, start stirring, and ensure that the stirring speed is not less than 100 r / min. Add 127.9 g of aluminum hydroxide to the above slurry, and adjust the pH value of the mixture to 3 with dilute hydrochloric acid with a concentration of 4% by weight. Carry out pulping for not less than 1 h and mix evenly for standby.

[0063] (2) Add 221.0 g of NaZSM-5 molecular sieve to 7814.7 g of water glass, make a slurry and disperse it evenly for standby.

[0064] (3) Add the slurry in step (1) to the slurry in step (2), and control the standby time of the slurry in step (1) not to exceed 2 h. Filter, wash, and re-pulp the mixed slurry, transfer the slurry to a ball mill for grinding for 2 h, add 2955.0 g of silica sol and 433.8 g of magnesium chloride, and continue to stir for 30 min for spray granulation.

[0065] (4) The dry powder after spraying is calcined at 600 °C for 0.5 h, 750 °C for 1.0 h, and 900 °C for 1.0 h, and then transferred to a pressure reactor. Add 529.4 g of sodium hydroxide and 2117.6 g of ethanol, and carry out dynamic crystallization for 24 h. Dilute 112 g of sodium dihydrogen phosphate solution to the same mass as the product. After pickling the product with 585.6 g of dilute hydrochloric acid, transfer it to the diluted sodium dihydrogen phosphate solution for impregnation, drying, and calcination to obtain this molecular sieve denoted as A4.

[0066] (5) Soak 832.3 g of kaolin, 415.7 g of aluminophosphate gel, and 1700 g of water for 30 minutes. Then start stirring, add 800 g of the above A4 molecular sieve and 800 g of water to make a slurry and stir for 10 minutes. Continuously add 245.9 g of silica sol and stir for 30 minutes. Then spray-dry and form the obtained slurry, calcine it at 500 °C for 1 hour, wash it with 5 times the amount of water, and dry it to obtain a catalytic cracking aid denoted as CAT-4.

[0067] Comparative Example 1:

[0068] (1) First, soak 832.3 g of kaolin, 415.7 g of aluminophosphate gel, and 1700 g of water for 30 minutes. Then start stirring, ensure that the pulping time is not less than 8 hours, and denote it as Slurry A1. Pulp 777.2 g of ZSM-5 molecular sieve and 800 g of water for later use, and denote it as Slurry A2. Add Slurry A2 to Slurry A1 and stir for 10 minutes. Continuously add 245.9 g of silica sol and stir for 30 minutes.

[0069] (2) Then spray-dry and form the obtained slurry, calcine it at 500 °C for 1 hour to obtain a catalytic cracking aid denoted as CAT-5.

[0070] Respectively, subject the catalytic cracking aids CAT-1 to CAT-4 prepared in Preparation Examples 1 to 4 of the present invention to 100% steam aging at 800 °C for 17 hours on a fixed-bed aging device. Then evaluate them on an ACE device. The properties of the feedstock oil used for evaluation are shown in Table 1.

[0071] Respectively, conduct X-ray fluorescence spectroscopy tests, abrasion tests, bulk density tests, specific surface area tests, and pore volume tests on the catalysts prepared in Preparation Examples 1 to 4 of the present invention and Comparative Example 1. The test results are shown in Table 2.

[0072] Carry out catalytic cracking on the same feedstock oil using the same method as in Examples 1 to 4, except that use the CAT-5 prepared in Comparative Example 1 to replace the catalytic cracking catalyst prepared in the examples of the present invention. The evaluation results are listed in Table 3.

[0073] Table 1 Properties of the feedstock oil:

[0074]

[0075]

[0076] Table 2 Physical property indexes of the catalysts:

[0077]

[0078] Table 3 Evaluation results:

[0079]

[0080] As can be seen from Table 2 and Table 3, compared with the comparative examples, the total yield of ethylene and propylene in the examples of the present invention increases, and the diolefin yield is significantly improved. This may be because the molecular sieve of the present invention has a larger pore volume, which is conducive to the entry of oil and gas components into its pores, with a short diffusion path, a faster mass transfer rate during the reaction, and the generated products can diffuse out quickly, more effectively improving the conversion rate of the reaction; the diolefin selectivity also has a large improvement, which benefits from the rich pore structure and larger specific surface area of the molecular sieve of the present invention. Moreover, the catalyst of the example shows better mechanical properties in the abrasion test, indicating that the catalytic cracking catalyst prepared by the present invention, preferably, has better reaction stability while increasing the diolefin yield and has good application value.

Claims

1. A preparation method for in-situ crystallization of kaolin to prepare ZSM-5 molecular sieve, and the specific steps are as follows: (1) Add kaolin and the same mass of water into the reaction tank, start stirring, and ensure that the stirring speed is not less than 100 r / min. Add aluminum hydroxide into the above slurry, slowly add a certain proportion of hydrochloric acid solution, beat the pulp for not less than 1 h, mix evenly, and set aside; (2) Add NaZSM-5 molecular sieve into water glass, beat and disperse evenly, and set aside; (3) Add the slurry in step (1) into the slurry in step (2), and the standby time of the slurry in step (1) should be controlled not to exceed 2 h. Filter, wash, and re-beat the mixed slurry, transfer the slurry into a ball mill and grind for 2 h, add silica sol and magnesium chloride, and continue stirring for 30 min for spray granulation; (4) After segmental temperature-controlled calcination, transfer it into a pressure reactor, add sodium hydroxide and ethanol, and carry out dynamic crystallization for 24 h. After pickling the product, impregnate it with an equal mass of sodium dihydrogen phosphate solution, dry it, and obtain the molecular sieve after calcination.

2. The preparation method according to claim 1, characterized in that: The finally prepared product is a ZSM-5 molecular sieve catalyst, and the Al2O3:SiO2 of the ZSM-5 molecular sieve is 1:(35 - 50).

3. The preparation method according to claim 1, wherein: In step (1), the addition ratio of kaolin based on the mass of Al2O3 is 20 - 28 wt% of the total Al2O3 mass of the finally prepared catalyst; the addition ratio of aluminum hydroxide based on the mass of Al2O3 is 72 - 80 wt% of the total Al2O3 mass of the finally prepared catalyst.

4. The preparation method according to claim 1, characterized in that: In step (1), the addition ratio of hydrochloric acid is determined by the pH of the mixed slurry, and the pH of the slurry should be controlled between 2.0 and 3.

0.

5. The preparation method according to claim 1, characterized in that: In step (2), the addition ratio of water glass based on the mass of SiO2 is 50 - 70 wt% of the SiO2 mass of the finally prepared catalyst, where the concentration of SiO2 is 370 - 390 g / L and the concentration of Na2O is 120 - 130 g / L.

6. The preparation method according to claim 1, characterized in that: In step (2), the addition ratio of NaZSM-5 molecular sieve based on the mass of SiO2 is 5 wt% of the SiO2 mass of the finally prepared catalyst.

7. The preparation method according to claim 1, characterized in that: In step (3), the washing water consumption of the mixed slurry is 5 times the dry basis mass of the mixed slurry. After washing, beat the filter cake to ensure that the solid content is about 30%.

8. The preparation method according to claim 1, characterized in that: In step (3), the operating frequency of the ball mill is 30 Hz / h, the mass ratio of the alumina balls used to the slurry mass is 1:1, and the diameter of the balls is selected to be 3 - 4 mm.

9. The preparation method according to claim 1, wherein: In step (3), the addition ratio of silica sol is 20-30 wt% of the mass of SiO2 in the finally prepared catalyst in terms of the mass of SiO2; the addition ratio of magnesium chloride is 0.5-2 wt% of the mass of the finally prepared catalyst dry basis in terms of the mass of Mg 2+ of the finally prepared catalyst dry basis in terms of the mass of Mg 10. The preparation method according to claim 1, characterized in that: In step (4), the segmental calcination is controlled to be calcined at 600 °C for 0.5 h, 750 °C for 1.0 h, and 900 °C for 1.0 h.

11. The preparation method according to claim 1, wherein: In step (4), the addition ratio of sodium hydroxide is (0.12 - 0.15):1 based on the mass of Na + to the mass of Si in the system. The addition ratio of ethanol is 1.5:1 to the mass of Si in the system. The pickling solution used is a hydrochloric acid solution with a mass fraction of 4%, and the hydrochloric acid dosage is 1.2 wt% of the dry basis mass of the finally prepared catalyst. Sodium dihydrogen phosphate is an aqueous solution with a pH value of 3.3 - 3.8, and the addition ratio is 0.7 wt% of the dry basis mass of the finally prepared catalyst.

12. A catalyst, characterized in that: It includes a carrier, a binder, and an active component; the carrier is selected from kaolin; the binder is selected from any one or more of aluminosol, silica sol, acidified pseudo-boehmite, or phosphoaluminate; the active component is the molecular sieve described in claim 1. The specific preparation steps are as follows: After stirring the mixture of the carrier, the binder, and the active component evenly, spray forming, calcining, washing with water, and drying, the catalyst is obtained. The calcination temperature is 500 - 600 °C; the calcination time is 2 - 4 h; the water consumption for washing with water is 5 times the dry basis mass of the catalyst; the drying temperature is 140 - 180 °C, and the drying time is 2 - 4 h.

13. The catalyst according to claim 12, wherein: The catalyst, by weight, comprises 20-45 wt% of a carrier, 15-30 wt% of a binder, and 30-50 wt% of an active component.

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