Modified y-type molecular sieve and preparation method therefor, and hydrocracking catalyst

Abstract

A modified Y-type molecular sieve and a preparation method therefor, and a hydrocracking catalyst. The preparation method comprises: in a liquid phase system, subjecting an organic compound to a first reaction with a Y-type molecular sieve to obtain a modified Y-type molecular sieve A, wherein the organic compound comprises one or a combination of more than two of amidino, benzyl and sulfydryl functional groups; and in an acidic liquid phase system, subjecting the modified Y-type molecular sieve A to a second reaction, and then carrying out roasting treatment to obtain the modified Y-type molecular sieve, wherein the mass ratio of the Y-type molecular sieve to the organic compound is 3-12.5:1. The preparation method is safe and harmless, and the surface of the obtained molecular sieve is of a tunneled structure, so that the molecular sieve has good catalytic activity.

Description

A modified Y-type molecular sieve and its preparation method, and hydrocracking catalyst Technical Field

[0001] The present invention belongs to the field of molecular sieve modification, and in particular relates to a modified Y-type molecular sieve, a preparation method thereof, and a hydrocracking catalyst. Background Art

[0002] Y-type molecular sieves are synthetic molecular sieves with a supercage formed by a β-cage and a hexagonal prism cage. They are composed of 18 four-membered rings, four six-membered rings, and four twelve-membered rings, resulting in a structure with a pore diameter of 0.74 nm and an inner diameter of 1.2 nm. Due to its rich pore structure, it possesses a large number of cracking active sites required for solid acid catalysts. While the hydrothermal stability of Y-type molecular sieves with low silicon-aluminum ratios affects their subsequent performance, modified Y-type molecular sieves with high silicon-aluminum ratios exhibit excellent hydrothermal and acid stability. Therefore, modified Y-type molecular sieves play an irreplaceable role as catalytic materials in oil refining processes such as catalytic cracking and hydrocracking. There are three main methods for modifying Y-type molecular sieves: high-temperature hydrothermal, chemical, and a combination of high-temperature hydrothermal and chemical methods. The high-temperature hydrothermal method is simple and easy to use, and it can produce some secondary pores. The aluminum removed from the framework does not leave the molecular sieve, but remains in various forms within the pores of the molecular sieve. This results in an irrational pore distribution and significant loss of crystallinity. The chemical method is to treat it with chemical reagents to dealuminate the skeleton part. This method can be divided into two categories: one is dealumination and siliconization, that is, while dealumination is carried out with chemical reagents, silicon atoms fill the dealumination position, which can maintain a high degree of crystallinity. The typical methods are SiCl4 gas phase dealumination and siliconization and (NH4)2SiF6 liquid phase dealumination and siliconization; the other is to use inorganic acid or organic acid to react with molecular sieve for simple dealumination. Inorganic acid dealumination such as HCl, HNO3, H2SO4, citric acid only relies on H + Dealumination results in a significant decrease in crystallinity.

[0003] CN106608643B addresses the problem that the total acid content of the molecular sieve decreases during the hydrothermal superstabilization process, which affects the cracking activity or selectivity. A modification method for a Y-type molecular sieve with a high framework silicon-aluminum ratio, good stability, and the ability to appropriately increase the number of acid centers is provided. The method specifically comprises: (1) activating the NaY-type molecular sieve with a polyhydric alcohol at 80-200°C for 1-10 hours to obtain slurry A; (2) cooling the slurry A and mixing it with an organic base to obtain slurry B; (3) adding a silicon source and an aluminum source in the order of first adding the silicon source and then adding the aluminum source, and aging the mixture to obtain slurry C; (4) hydrothermally crystallizing the slurry C and recovering the product. This technology activates the molecular sieve with a polyhydric alcohol to Si-OH and Al-OH, and then adds a silicon source and an aluminum source to re-hydrothermally crystallize it. The purpose is to increase the initial silicon-aluminum ratio and acid content of the NaY-type molecular sieve, but does not achieve external modification of the molecular sieve pores.

[0004] CN110498424B addresses the problem of uneven dealumination in chemical dealumination and provides a method for modifying a Y-type molecular sieve with uniform aluminum distribution. The method comprises: subjecting a NaY-type molecular sieve to ammonium exchange to obtain an NH4Y-type molecular sieve; contacting the obtained NH4Y-type molecular sieve with a salt solution containing alkali metal ions and / or a salt solution containing alkaline earth metal ions; filtering, washing, and drying the obtained product; contacting the obtained product with an acid solution; and recovering the product to obtain a modified Y-type molecular sieve. The technical solution mainly utilizes NH4 + The steric hindrance generated by the ions promotes the enrichment of alkali metals on the outside of the molecular sieve and stabilizes the skeleton, and then the acid solution is used for uniform dealumination. The main purpose is to enhance the dealumination degree of the molecular sieve bulk phase without involving the modification of the molecular sieve surface morphology.

[0005] CN105498686B addresses the issues of poor adsorption performance and desorption and reuse of molecular sieves, and provides a molecular sieve modification method. The method specifically comprises: loading or exchanging the molecular sieve with a soluble metal salt or heteropolyacid, and using the modified molecular sieve to adsorb 2-heptanone in the cyclohexanone product. This technology aims to enhance the adsorption and desorption performance of the molecular sieve, without directionally modifying the molecular sieve pore structure to change its surface structure.

[0006] Summary of the Invention

[0007] In order to solve the above-mentioned problems in the prior art, the present invention aims to provide a modified Y-type molecular sieve and a preparation method thereof. The preparation method is safe and harmless, and the resulting molecular sieve has a tunnel structure on its surface and has good catalytic activity.

[0008] In order to achieve the above-mentioned object, according to one aspect, the present invention provides a method for preparing a modified Y-type molecular sieve, which comprises:

[0009] In a liquid phase system, an organic substance is reacted with a Y-type molecular sieve to obtain a modified Y-type molecular sieve A; wherein the organic substance has one or a combination of two or more of amidine, benzyl, and thiol functional groups;

[0010] In an acidic liquid phase system, the modified Y-type molecular sieve A undergoes a second reaction, followed by calcination to obtain the modified Y-type molecular sieve;

[0011] Wherein, the mass ratio of the Y-type molecular sieve to the organic matter is 3-12.5:1.

[0012] In the first reaction, the preparation method of the present invention completes the first step of modification of the modified Y-type molecular sieve. The specific functional groups in the organic matter (including one or a combination of more than two amidine, benzyl, and thiol functional groups) react with the surface structure of the molecular sieve to form a stable organic matter-Y-type molecular sieve structure, which can have a positive impact on the subsequent chemical treatment process.

[0013] The pore structure of the Y-type molecular sieve can be divided into a microporous structure formed by its crystal configuration and a mesoporous structure formed by the accumulation of molecular sieve particles. In terms of microporous structure, the pore size in the Y-type molecular sieve crystal is 0.74nm, which is about the length of 5 CC bonds. In the process of organic matter reacting with the surface structure of the molecular sieve, it will significantly block the microporous channels in the Y-type molecular sieve, resulting in a significant reduction in the mass transfer performance of the original microporous structure. In terms of mesoporous structure, the size of the stacked pores formed by the Y-type molecular sieve is usually around 10-15nm, and the reaction of organic matter with the surface of the molecular sieve has almost no effect on the mass transfer performance of the mesoporous structure. Therefore, by adsorbing organic matter through the Y-type molecular sieve, the subsequent acid treatment process can be made more likely to occur at the mesoporous channel position of the Y-type molecular sieve.

[0014] Organic modification in the present invention can produce beneficial effects in three aspects: Y-type molecular sieve micropores, mesopores, and the outer surface of molecular sieves. First, in terms of micropores, the adsorption of organic matter can achieve the protection of the microporous structure of Y-type molecular sieves, reduce the loss of crystallinity caused by chemical modification, and thus cause the catalyst long-term operation life to be not guaranteed. Second, in terms of mesopores, it is possible to achieve directional regulation of molecular sieve mesoporous channel structure, enhance channel structure connectivity. Third, in terms of the outer surface of molecular sieves, it is possible to carry out skeleton structure destruction on the outer surface of molecular sieves, so as to produce a certain tunnel structure. The generation of the tunnel structure is conducive to the preparation of catalysts, so that nearly spherical non-supported active phases fall into tunnels, so as to promote the degree of combination of non-supported active phases and Y-type molecular sieves, to achieve the purpose of promoting non-supported catalyst activity, selectivity.

[0015] The mass ratio of the Y-type molecular sieve to the organic matter is 3-12.5:1. Carrying out the first reaction according to this ratio is conducive to achieving the beneficial effects brought about by the modification of the organic matter.

[0016] Further preferably, the mass ratio of the Y-type molecular sieve to the organic matter is 5-10:1.

[0017] In some preferred embodiments of the present invention, the temperature of the first reaction is 20-50° C., and the time is 0.5-3 h.

[0018] More advantageously, the temperature of the first reaction is 20-45°C.

[0019] In some embodiments of the present invention, the solvent in the liquid phase system in the first reaction is water. Preferably, the solid-liquid mass ratio is 1:5-10. Preferably, the solid-liquid mass ratio is 1:10.

[0020] In some embodiments of the present invention, after the first reaction is completed, the preparation method further comprises:

[0021] The reaction product obtained from the first reaction is subjected to solid-liquid separation, washed and dried to obtain the modified Y-type molecular sieve A.

[0022] Preferably, the solid-liquid separation method is filtration.

[0023] In the preparation method of the present invention, the methods of solid-liquid separation, washing and drying may be conventional methods in the art.

[0024] It should be noted that after the first reaction, the above-mentioned solid-liquid separation, washing and drying treatments are optional. In some embodiments of the present invention, the system obtained after the first reaction can be directly used for the second reaction, further simplifying the process and reducing costs.

[0025] In some embodiments of the present invention, a washing treatment is performed after the first reaction, preferably a water washing treatment. In the first reaction of the present invention, the specific functional groups in the amino acid react with the surface structure of the molecular sieve to form a stable organic-Y-type molecular sieve structure. Therefore, water washing does not cause a change in the content of amino acids adsorbed on the modified Y-type molecular sieve A.

[0026] In some embodiments of the present invention, preferably, the temperature of the second reaction is 35-60° C., and the time is 0.5-4 h.

[0027] In some embodiments of the present invention, in the second reaction, the pH of the acidic liquid phase system is ≤1.

[0028] In some embodiments of the present invention, the acidic environment in the second reaction can be provided by organic acids and / or inorganic acids. For example, it can be oxalic acid, hydrochloric acid, citric acid, etc. Preferably, the concentration of the added acid is 0.1-1 mol / L. Since molecular sieves are oxides of silicon and aluminum, they are unstable in both acidic and alkaline media. In acidic media, the Si and Al elements in the molecular sieve framework react to form Al 3+ ions and Si 4+ Ions (under acidic conditions, the reaction performance of Al element to separate from the skeleton is higher than that of Si element). Through this etching action, pits are formed on the surface of the molecular sieve.

[0029] It should be noted that in the second reaction, the structure of the acid is not the main factor and is not immobilized on the molecular sieve.

[0030] In some embodiments of the present invention, preferably, after the second reaction, the slurry is filtered, washed, and dried. Preferably, the drying temperature is 80-120° C. and the drying time is 2-8 hours.

[0031] In some embodiments of the present invention, the organic compound is preferably one or a combination of two or more of arginine, phenylalanine, methionine, acetamidine hydrochloride, benzamidine hydrochloride, and 3-(carbamimidothio)-1-propanesulfonic acid. When the carbon chain length of the organic compound is greater than 5, it is easier for the organic compound to occupy the micropores and achieve pore plugging.

[0032] Similarly, through experiments in the development of the technology of the present invention, it was found that if amino acids with large molecular weight and steric hindrance are used to modify the molecular sieve, it is difficult for the larger molecular weight molecules to enter the micropores, and the modification process is more difficult to occur.

[0033] In some embodiments of the present invention, the calcination temperature is preferably 470-560°C for 3-6 hours. The calcination temperature only needs to be sufficient to completely burn off the modified amino acid. Typically, a treatment temperature greater than 500°C ensures the complete burning of all organic matter. However, some organic matter has a low decomposition temperature, and treatment at temperatures below 500°C may also be effective.

[0034] In the preparation method of the present invention, there is no additional limitation on the specific model of the Y-type molecular sieve. Common Y-type molecular sieves on the market, regardless of their silicon-aluminum ratio, are applicable to the modification method provided by the present invention.

[0035] According to another aspect of the present invention, there is provided a modified Y-type molecular sieve obtained according to the above-mentioned preparation method, the surface of which has a tunnel structure. In the preparation of the catalyst, the generation of the tunnel structure is conducive to making nearly spherical cluster pellets (non-supported active phase) fall into the tunnel, thereby improving the degree of combination of non-supported active phase and Y-type molecular sieve, reaching the purpose of improving non-supported catalyst activity and selectivity. The cluster pellet can have the effect of being a hydrocracking catalyst active phase after sulfurization.

[0036] In the present invention, the design goal of the channels on the molecular sieve surface is to form a channel structure of not less than 20 nm on the molecular sieve surface, preferably between 20-40 nm.

[0037] According to another aspect of the present invention, a hydrocracking catalyst is provided, the raw material of which includes the above-mentioned modified Y-type molecular sieve.

[0038] In some embodiments of the present invention, preferably, the hydrocracking catalyst further comprises a non-supported active phase, alumina, and optionally amorphous silica-alumina, and the non-supported hydrocracking catalyst is obtained by mixing, shaping, drying, and calcining.

[0039] The present invention also provides a hydrocracking process, which is carried out using the hydrocracking catalyst provided by the present invention.

[0040] Compared with the prior art, the molecular sieve synthesized by the present invention has the following beneficial effects: the hydrocracking catalyst prepared by the modified Y-type molecular sieve of the present invention has a higher conversion rate, which means that the molecular sieve synthesized by the present invention has higher performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG1 shows a scanning electron microscope image of the modified Y1 molecular sieve according to Example 1 of the present invention.

[0042] FIG2 shows a scanning electron microscope image of the Y molecular sieve before modification according to Example 1 of the present invention.

[0043] FIG3 shows a scanning electron microscope image of the modified Y molecular sieve of Comparative Example 1 of the present invention.

[0044] FIG4 shows the UV spectra of the arginine solution and the water washing liquid of the Y-A2 molecular sieve in Example 2 of the present invention. DETAILED DESCRIPTION

[0045] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0046] The Y-type molecular sieve used in the examples of the present invention is HY molecular sieve (SiO2, Al2O3 molar ratio 10.7) produced by Nankai Catalyst Factory, hereinafter referred to as Y-type molecular sieve.

[0047] Example 1

[0048] 10 g of Y-type molecular sieve was weighed and added to 100 g of deionized water, stirred evenly, and then 1 g of 3-(carbamimidothio)-1-propanesulfonic acid and 1 g of benzamidine hydrochloride were added. The first reaction was carried out at 20° C. for 3 h. The formed slurry was then filtered, washed, and dried at 120° C. for 3 h to obtain modified Y-type molecular sieve A, which was recorded as Y-A1.

[0049] Weigh 9g of Y-A1 and add it to 90g of deionized water, stir evenly; then add 4g of oxalic acid, pH <1, and heat to 50℃ for reaction for 3h. Then filter and wash the slurry, dry it at 120℃ for 3h, and calcine it at 550℃ to obtain a modified Y-type molecular sieve, recorded as Y1 molecular sieve.

[0050] Scanning electron microscopy was used to characterize the molecular sieves before and after modification. Scanning electron micrographs of the modified Y1 and unmodified Y molecular sieves are shown in Figures 1 and 2, respectively. It can be clearly seen that, compared to the unmodified Y molecular sieve, the surface of the molecular sieve modified by the method of this example has a certain tunnel structure.

[0051] Example 2

[0052] 10 g of Y-type molecular sieve was weighed and added to 80 g of deionized water, stirred evenly, and then 1.5 g of arginine was added. The reaction was carried out at 25°C for 2 h. The formed slurry was filtered, washed, and dried at 120°C for 3 h to obtain modified Y-type molecular sieve A, which was recorded as Y-A2.

[0053] UV-visible spectroscopy was used to characterize the ability of water-washed Y-A2 molecular sieves to not cause changes in their organic matter content. As shown in Figure 4, 1.5g of arginine dissolved in 80g of water at the initial stage of preparation showed a clear UV-visible absorption spectrum; Y-A2 was added to 80g of water, stirred, and filtered to obtain the washed solution. It did not have a significant UV-visible absorption spectrum (as shown in Figure 4), indicating that the modified organic matter had reacted chemically with the molecular sieve, forming a stable organic matter-Y type molecular sieve structure. Therefore, it can be used for subsequent modification treatments in aqueous solution environments.

[0054] Weigh 9 g of Y-A2 and add it to 90 g of deionized water, stir evenly; then add 14.0 g of citric acid, heat to 60 ° C and react for 2 hours, filter and wash the slurry, dry at 120 ° C for 3 hours, and calcine at 550 ° C to obtain a modified Y-type molecular sieve, recorded as Y2 molecular sieve.

[0055] Example 3

[0056] 10 g of Y-type molecular sieve was weighed and added to 50 g of deionized water, stirred evenly, and then 0.6 g of methionine and 0.6 g of acetamidine hydrochloride were added. The reaction was carried out at 35 ° C for 1 hour. The formed slurry was filtered, washed, and dried at 120 ° C for 3 hours to obtain modified Y-type molecular sieve A, which was recorded as Y-A3.

[0057] Weigh 9g of Y-A3 and add it to 90g of deionized water, stir evenly; then add 1.87g of hydrochloric acid (concentration 36%), pH <1, and heat to 55°C for reaction for 1h, filter and wash the slurry, dry it at 120°C for 3h, and calcine it at 550°C to obtain a modified Y-type molecular sieve, recorded as Y3 molecular sieve.

[0058] Example 4

[0059] 10 g of Y-type molecular sieve was weighed and added to 100 g of deionized water, stirred evenly, and then 0.83 g of phenylalanine was added. The reaction was carried out at 45 ° C for 2 h. The formed slurry was filtered, washed, and dried at 120 ° C for 3 h to obtain modified Y-type molecular sieve A, which was recorded as Y-A4.

[0060] Weigh 9g of Y-A4 and add it to 90g of deionized water, stir evenly; then add 8.6g of citric acid, pH <1, and heat to 45℃ for reaction for 4h. Then filter and wash the slurry, dry it at 120℃ for 3h, and calcine it at 550℃ to obtain a modified Y-type molecular sieve, recorded as Y4 molecular sieve.

[0061] Comparative Example 1

[0062] Weigh 9 g of Y-type molecular sieve and add it to 90 g of deionized water, stir evenly, then add 14 g of citric acid, pH <1, and heat to 60 ° C for constant temperature. After reacting for 2 hours, the slurry is filtered, washed, dried at 120 ° C for 3 hours, and calcined at 550 ° C to obtain modified D1 molecular sieve.

[0063] Scanning electron microscopy was used to characterize the differences between the molecular sieves modified using the technical solution of the present invention and those modified using the solution. Scanning electron micrographs of the modified Y1 and D1 molecular sieves are shown in Figures 1 and 3, respectively. It can be clearly seen from the figures that the surface of the molecular sieve Y1 modified by the method of this embodiment produces a certain tunnel structure, while the molecular sieve D1 not modified by this method cannot achieve targeted etching of the surface of the molecular sieve by the acidic solution because the acidic solution can enter the micropores of the molecular sieve, resulting in a modified molecular sieve with no feature morphology.

[0064] Comparative Example 2

[0065] Weigh 9 g of Y-type molecular sieve and add it to 90 g of deionized water, stir evenly, then add 1.87 g of hydrochloric acid (concentration 36%), pH is <1, and heat to 55 ° C for constant temperature. After reacting for 1 hour, the slurry is filtered and washed, and dried at 120 ° C for 3 hours, and calcined at 550 ° C to obtain modified D2 molecular sieve.

[0066] Comparative Example 3

[0067] 10 g of Y-type molecular sieve was weighed and added to 100 g of deionized water, stirred evenly, and then 2 g of glucose was added. The reaction was carried out at 20 ° C for 2 h. The formed slurry was filtered, washed, and dried at 120 ° C for 3 h to obtain Y-D3 molecular sieve; the Y-D3 obtained in the previous step was subjected to the same water washing test as in Example 2, and 10 mL of the filtrate after washing was added to 10 mL of 0.05 mol / L iodine standard solution, and then 0.2 mol / L sodium hydroxide solution was slowly added dropwise until the solution was light yellow. The solution was found to be weakly acidic when tested with pH paper, indicating that the water washing liquid contained glucose. Therefore, this process failed to obtain a modified Y molecular sieve with stable adsorption.

[0068] The physical adsorption characterization results for the Y, Y1, Y2, Y3, Y4, D1, and D2 molecular sieves are shown in Table 1. The total specific surface area was calculated using the BET method. To ensure the validity of the BET equation, the BET specific surface area was obtained by selecting at least three points with a p / p0 ratio between 0.01 and 0.30, satisfying the BET equation's C value greater than 0. The mesoporous and microporous specific surface areas were characterized based on the BET specific surface area and calculated using the t-Plot method.

[0069] As can be seen from the data in Table 1, the mesopore specific surface area of ​​Y1, Y2, Y3, and Y4 molecular sieves is improved to a certain extent compared with that of Y molecular sieve, indicating that the method of the present invention can achieve directional regulation of the mesopore channel structure of the molecular sieve and enhance the connectivity of the channel structure. The micropore specific surface area of ​​Y1, Y2, Y3, and Y4 molecular sieves is not much different from that of Y molecular sieve, but the micropore specific surface area of ​​D1 and D2 molecular sieves is greatly reduced, indicating that the adsorption of amino acid organic matter in the method of the present invention can protect the micropore structure of Y-type molecular sieve.

[0070] Table 1

[0071] The relative crystallinity results of Y, Y1, Y2, Y3, Y4, D1, and D2 molecular sieves are shown in Table 2. As can be seen from the data in Table 2, Y1, Y2, Y3, and Y4 molecular sieves have higher relative crystallinity than D1 and D2 molecular sieves. This shows that the method of the present invention can protect the structure of Y-type molecular sieves by adsorption of amino acid organic compounds, reducing the loss of crystallinity caused by chemical modification.

[0072] Table 2

[0073] Weigh 10g of Y1, Y2, Y3, Y4, D1, and D2 molecular sieves respectively, mix them evenly with 60g of alumina, 30g of non-supported active phase, and 2g of sesbania powder, wet mix them with nitric acid aqueous solution, and then extrudate them. The molded products are dried at 120°C for 4h and calcined at 500°C for 3h to obtain hydrocracking catalysts CAT-Y1, CAT-Y2, CAT-Y3, CAT-Y4, CAT-D1, and CAT-D2, respectively. The prepared catalysts are prepared using straight-run diesel as raw material at 340°C, 8.0MPa, a hydrogen-to-oil ratio of 800, and a space velocity of 4.5h. -1 Catalyst evaluation experiments were carried out under the conditions of , and the test results are shown in Table 3. The conversion rate is the mass fraction of the fraction below 180 ° C in the total products.

[0074] Table 3

[0075] It can be seen from the evaluation results of each catalyst in Table 3 that the hydrocracking catalyst prepared using the molecular sieve synthesized by the present invention has a higher conversion rate than that prepared by the comparative technology, which means that the molecular sieve synthesized by the present invention has higher performance.

[0076] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a modified Y-type molecular sieve, wherein: include: In a liquid phase system, an organic substance is first reacted with a Y-type molecular sieve to obtain a modified Y-type molecular sieve A; wherein the organic substance has one or a combination of two or more of amidine, benzyl, and thiol functional groups; In an acidic liquid phase system, the modified Y-type molecular sieve A undergoes a second reaction, and then undergoes a calcination treatment to obtain the modified Y-type molecular sieve; Wherein, the mass ratio of the Y-type molecular sieve to the organic matter is 3-12.5:

1.

2. The preparation method according to claim 1, wherein The mass ratio of the Y-type molecular sieve to the organic matter is 5-10:

1.

3. The preparation method according to claim 1, wherein The temperature of the first reaction is 20-50°C and the time is 0.5-3h.

4. The preparation method according to claim 1, wherein After the first reaction is completed, the preparation method further comprises: The reaction product obtained by the first reaction is subjected to solid-liquid separation, washing and drying to obtain the modified Y-type molecular sieve A.

5. The preparation method according to claim 1, wherein The temperature of the second reaction is 35-60°C and the time is 0.5-4h.

6. The preparation method according to claim 1, wherein In the second reaction, the pH of the acidic liquid phase system is ≤1.

7. The preparation method according to claim 1, wherein The organic matter is one or a combination of two or more of arginine, phenylalanine, methionine, acetamidine hydrochloride, benzamidine hydrochloride, and 3-(carbamimidothio)-1-propanesulfonic acid.

8. The preparation method according to claim 1, wherein The calcination temperature is 470-560°C and the calcination time is 3-6 hours.

9. A modified Y-type molecular sieve obtained by the preparation method according to any one of claims 1 to 8.

10. A hydrocracking catalyst, wherein: The raw material comprises the modified Y-type molecular sieve described in claim 9.

11. A hydrocracking process, which is carried out using the hydrocracking catalyst according to claim 10.

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