Modified Y-type molecular sieve as well as preparation method and application thereof

Abstract

The invention provides a modified Y-type molecular sieve as well as a preparation method and application thereof. The modified Y-type molecular sieve is obtained by modifying a Y-type molecular sieve with a nitrogen-containing organic matter and then carrying out heat treatment, the mass content of nitrogen-containing organic matters in the modified Y-type molecular sieve is greater than or equal to 8%; the heat treatment is carried out in an inert atmosphere, and the temperature of the heat treatment is 280-350 DEG C; the nitrogen-containing organic matter is at least one of amino acid and amidino functional group-containing compounds. According to the present invention, the nitrogen-containing organic matter is adopted to modify the Y-type molecular sieve, and then heat treatment is performed at the temperature of 280-350 DEG C, such that the positive effect is provided for passivating the strong acid center of the Y-type molecular sieve, and the beneficial effect of shortening the initial reaction period of the hydrocracking catalyst can be achieved when the modified Y-type molecular sieve is applied to the hydrocracking catalyst; the effect of passivating the sulfurized hydrocracking catalyst in the prior art can be achieved, and the starting time of a hydrocracking device is shortened.

Description

Technical Field

[0001] The present invention belongs to the field of molecular sieve modification, and particularly relates to a modified Y molecular sieve and a preparation method thereof, as well as an application in the field of hydrocracking technology. Background Art

[0002] The hydrocracking technology can process heavy and inferior atmospheric and vacuum distillates to produce high-quality naphtha, kerosene, diesel, lubricating base oil, ethylene raw materials for cracking, etc., and is one of the most important processing means in current refining technologies. The hydrogenation active centers of hydrocracking catalysts are generally provided by sulfided metal centers such as Ni, Mo, W, etc., and the cracking active centers are generally provided by amorphous silica-alumina and molecular sieves.

[0003] The Y molecular sieve has a supercage surrounded by β cages and hexagonal prismatic cages, which is composed of 18 four-membered rings, 4 six-membered rings and 4 twelve-membered rings, forming a structural pore orifice diameter of 0.74 nm and an inner diameter of 1.2 nm. Due to its rich pore structure and a large number of cracking active centers required for solid acid catalysts, when applied to hydrocracking reactions, its pore structure and acid distribution will have a great impact on the selectivity, cracking activity and product distribution of the catalyst. Since the Y-type molecular sieve with a low silica-alumina ratio has relatively poor hydrothermal stability, the modified high-silica-alumina Y-type molecular sieve can have good hydrothermal stability and acid stability. The high-silica-alumina Y-type molecular sieve is mainly obtained by two methods: direct synthesis method and post-treatment modification. The direct synthesis method requires the use of expensive templates, has a long crystallization time, and a relatively low yield, which greatly increases the production cost; the post-treatment modification method mainly performs dealumination and desilication treatment on the molecular sieve framework through one or several of conventional acid, alkali and hydrothermal treatments, generating a large number of secondary mesoporous structures. Currently, the modified Y molecular sieve with a high silica-alumina ratio is mainly used in hydrocracking catalysts. However, in the hydrogenation reaction process of hydrocracking catalysts containing Y molecular sieves, in the initial stage of the reaction, it will show strong cracking activity and produce a relatively high proportion of light components. Therefore, during the start-up process of industrial plants, the sulfided hydrocracking catalyst needs to be passivated again to reduce the generation of unnecessary light components and shorten the start-up period.

[0004] CN 105621444 A discloses a modified Y molecular sieve and a preparation method thereof. Aiming at the problem that the conventional modification method in the modification process of Y molecular sieve simultaneously removes aluminum from the inside out, reducing the number of acid centers and affecting the activity, a modified molecular sieve with a higher silica-alumina ratio on the surface layer than the bulk phase and a preparation method thereof are provided. The modified Y molecular sieve is obtained by subjecting NaY molecular sieve to ammonium exchange, hydrothermal treatment, acid modification, adsorbing unsaturated olefins and then performing a carbon deposition reaction in an oxygen atmosphere, and then acid modification again. In this technical solution, unsaturated olefins are used as adsorbents for modification, and unsaturated olefins are usually hazardous chemicals, and there are limitations in the processing process.

[0005] CN106608643B discloses a method for modifying Y-type molecular sieve. Aiming at the deficiency that the total acid amount of the molecular sieve decreases during the hydrothermal ultra-stabilization process of the molecular sieve, which affects the cracking activity or selectivity, a method for modifying Y-type molecular sieve with a high framework silicon-aluminum ratio, good stability, and an appropriate increase in the number of acid centers is provided. Specifically, it includes: (1) activating the NaY molecular sieve with polyhydric alcohol at 80-200 °C for 1-10 h to obtain slurry A; (2) cooling 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 adding the silicon source first and then the aluminum source, and subjecting the mixture to aging treatment to obtain slurry C; (4) performing hydrothermal crystallization on slurry C and recovering the product. In this technical solution, the molecular sieve is activated by polyhydric alcohol into Si-OH and Al-OH, and then a silicon source and an aluminum source are added to make it undergo hydrothermal crystallization again. The purpose is to increase the initial silicon-aluminum ratio and acid amount of the NaY molecular sieve, and the external pore structure modification of the molecular sieve is not achieved.

[0006] CN110498424B discloses a method for modifying Y molecular sieve. Aiming at the problem of uneven dealumination existing in the chemical dealumination method, a method for modifying Y molecular sieve with a uniform aluminum distribution is provided. Specifically, it includes: performing ammonium exchange treatment on NaY molecular sieve to obtain NH 4 Y molecular sieve, contacting the obtained NH 4 Y molecular sieve with a salt solution containing alkali metal ions and / or a salt solution containing alkaline earth metal ions, after filtration, washing, and drying, contacting the obtained product with an acid solution, and recovering the product to obtain the modified Y molecular sieve; this technical solution mainly utilizes the steric hindrance generated by NH 4 + ions to promote the enrichment of alkali metals outside the molecular sieve and stabilize the framework, and then uniformly dealuminating with an acid solution.

[0007] CN105498686B discloses a method for modifying molecular sieve to improve adsorption performance. Aiming at the problems of poor adsorption effect and desorption and reuse of the molecular sieve, a method for modifying the molecular sieve is provided. Specifically, it includes: loading or exchanging the molecular sieve with a soluble metal salt or heteropolyacid, etc., and using the modified molecular sieve to adsorb 2-heptanone in the cyclohexanone finished product; this technology aims to enhance the adsorption and desorption performance of the molecular sieve, and does not perform directional modulation on the pore structure of the molecular sieve, thereby changing its performance in the hydrogenation reaction.

[0008] Therefore, further research on the modification of Y molecular sieve is still needed in this field. Summary of the Invention

[0009] The main object of the present invention is to provide a modified Y-type molecular sieve, its preparation method and application, so as to overcome the defects that when the existing modified Y-type molecular sieve is used in a hydrocracking catalyst, the acidity of the catalyst is too strong in the initial stage of the reaction, and the initial activation period is relatively long, etc.

[0010] To achieve the above object, the present invention provides a modified Y-type molecular sieve, which is obtained by modifying a Y-type molecular sieve with a nitrogen-containing organic compound and then performing heat treatment; the mass content of the nitrogen-containing organic compound in the modified Y-type molecular sieve is greater than or equal to 8%; the heat treatment is carried out in an inert atmosphere, and the temperature of the heat treatment is 280-350 °C; the nitrogen-containing organic compound is at least one of an amino acid and a compound containing a guanidyl functional group.

[0011] For the modified Y-type molecular sieve of the present invention, before and after washing the modified Y-type molecular sieve with water, the content of the nitrogen-containing organic compound in the modified Y-type molecular sieve remains unchanged.

[0012] For the modified Y-type molecular sieve of the present invention, the nitrogen-containing organic compound is one or more of arginine, phenylalanine, methionine, ethylamidine hydrochloride, benzamidine hydrochloride, and 3-(formamidothio)-1-propanesulfonic acid.

[0013] To achieve the above object, the present invention also provides a preparation method of the above modified Y-type molecular sieve, which comprises the following steps:

[0014] Step 1, mixing a Y-type molecular sieve, a nitrogen-containing organic compound, and water, and reacting at 20-50 °C for 0.5-3 h;

[0015] Step 2, performing heat treatment and roasting on the modified Y-type molecular sieve obtained in Step 1 to obtain a modified Y-type molecular sieve.

[0016] For the preparation method of the modified Y-type molecular sieve of the present invention, in Step 1, the Y-type molecular sieve and water are mixed, and then mixed with the nitrogen-containing organic compound; in the mixture of the Y-type molecular sieve and water, the solid-liquid ratio is 1:5-10, and the mass ratio of the Y-type molecular sieve to the nitrogen-containing organic compound is 12.5-3:1.

[0017] For the preparation method of the modified Y-type molecular sieve of the present invention, in the heat treatment, part of the nitrogen-containing organic compound on the modified Y-type molecular sieve decomposes to generate CO 2 .

[0018] For the preparation method of the modified Y-type molecular sieve of the present invention, the mass ratio of the Y-type molecular sieve to the nitrogen-containing organic compound is 10-5:1.

[0019] For the preparation method of the modified Y-type molecular sieve of the present invention, the reaction temperature in Step 1 is 20-45 °C; the heat treatment temperature in Step 2 is 290-320 °C.

[0020] For the preparation method of the modified Y-type molecular sieve of the present invention, the roasting temperature is less than or equal to 550 °C, and the roasting time is 3-6 h.

[0021] To achieve the above object, the present invention further provides an application of the above modified Y-type molecular sieve in a hydrocracking catalyst.

[0022] Advantages of the present invention:

[0023] In the present invention, a nitrogen-containing organic compound is used to modify a Y-type molecular sieve, and then heat treatment is carried out at 280-350 °C, which has a positive effect on passivating the strong acid sites of the Y molecular sieve. Furthermore, when the modified Y-type molecular sieve is applied to a hydrocracking catalyst, it can shorten the initial activation period of the hydrocracking catalyst, achieve the passivation effect of the sulfided hydrocracking catalyst in the prior art, and shorten the start-up time of the hydrocracking unit. Description of the drawings

[0024] Figure 1 It is the ultraviolet-visible spectrogram of the aqueous solution in the initial stage of preparing the Y-A1 molecular sieve in Example 1 and the solution after washing the Y-A1 molecular sieve.

[0025] Figure 2 It is the release curve of CO in Example 2 of the Y-A2 molecular sieve under the condition of temperature rise. 2 of

[0026] Figure 3 It is the graph of the change in the product density at the initial stage of hydrocracking for the catalyst prepared in the example of the present invention and the catalyst prepared in the comparative example. Detailed implementation manners

[0027] The technical solution of the present invention will be described in detail below. The following implementation manners are carried out on the premise of the technical solution of the present invention, and the detailed implementation process is given. However, the protection scope of the present invention is not limited to the following implementation manners. For the structures or experimental methods without specific conditions noted in the following implementation manners, they are usually carried out according to conventional conditions.

[0028] The present invention provides a modified Y-type molecular sieve, which is obtained by modifying a Y-type molecular sieve with a nitrogen-containing organic compound and then performing heat treatment; the mass content of the nitrogen-containing organic compound in the modified Y-type molecular sieve is greater than or equal to 8%; the heat treatment is carried out in an inert atmosphere, and the temperature of the heat treatment is 280-350 °C; the nitrogen-containing organic compound is at least one of an amino acid and a compound containing a guanidino functional group.

[0029] The present invention uses a specific nitrogen-containing organic compound to modify a Y-type molecular sieve. The functional group of the nitrogen-containing organic compound tends to react with the surface structure of the Y molecular sieve. After washing the reacted Y-type molecular sieve, the content of the nitrogen-containing organic compound hardly changes, indicating that the specific functional group in the nitrogen-containing organic compound has reacted with the surface structure of the Y molecular sieve to form a stable organic compound-Y-type molecular sieve structure.

[0030] The reacted Y-type zeolite is heat-treated at 280-350 °C, and the nitrogen-containing organic matter on the modified Y-type zeolite decomposes, releasing CO 2 . Among them, the removal of C element and the decomposed substances are nitrogen-containing organic matters that react with the surface structure of Y zeolite. The remaining substances mainly composed of N element can better modify the acidic sites of Y zeolite. Specifically, nitrogen element combines with the acidic centers of Y zeolite, occupying a certain amount of strong acid center sites on Y zeolite, producing the effect of passivating strong acid centers, realizing the regulation of strong acid centers and weak acid centers of Y zeolite, and then can reduce the initial activity of the hydrocracking catalyst, achieving the effect of passivating the sulfided hydrocracking catalyst in the prior art, and shortening the start-up time of the hydrocracking unit.

[0031] In the present invention, the Y zeolite is not particularly limited, and it can be prepared according to the prior art methods or can be a commercially available product.

[0032] In the present invention, the nitrogen-containing organic matter is at least one of amino acids and compounds containing amidino functional groups. The nitrogen-containing organic matter in the present invention is a non-hazardous chemical, and the modification process of Y zeolite is safe, environmentally friendly and convenient for production. In another embodiment, the nitrogen-containing organic matter also contains functional groups such as benzyl and mercapto. In yet another embodiment, the nitrogen-containing organic matter in the present invention is one or more of arginine, phenylalanine, methionine, ethylamidine hydrochloride, benzamidine hydrochloride, and 3-(formamidothio)-1-propanesulfonic acid.

[0033] The modification of Y-type zeolite with nitrogen-containing organic matter is, for example, reacting the nitrogen-containing organic matter and Y-type zeolite at 20-50 °C, and the reaction time is, for example, 0.5-3 h. After the reaction, the slurry is filtered, washed and dried. The drying temperature is, for example, 100-120 °C, and the drying time is, for example, 1-5 h.

[0034] In the present invention, the above-mentioned dried zeolite is heat-treated. The heat treatment is carried out in an inert atmosphere, and the heat treatment temperature is 280-350 °C, preferably 290-320 °C. During the heat treatment under this temperature condition, the nitrogen-containing organic matter in the modified Y-type zeolite decomposes, and can sequentially release H 2 O, CO 2 . The remaining substances mainly composed of N element can better modify the acidic sites of Y zeolite, realizing the regulation of strong acid centers and weak acid centers of Y zeolite.

[0035] In one embodiment, the present invention also provides a preparation method of the above-mentioned modified Y-type zeolite, including the following steps:

[0036] Step 1, mixing Y-type zeolite, nitrogen-containing organic matter and water, and reacting at 20-50 °C for 0.5-3 h;

[0037] Step 2: Heat-treat and calcine the Y-type molecular sieve modified in Step 1 to obtain a modified Y-type molecular sieve.

[0038] For the selection of Y-type molecular sieve and nitrogen-containing organic matter, it has been described in detail above and will not be elaborated here. In one embodiment, Step 1 is to mix the Y-type molecular sieve and water, and then mix with the nitrogen-containing organic matter. In the mixture of Y-type molecular sieve and water, the solid-liquid ratio is 1:5 to 10, and the mass ratio of Y-type molecular sieve to nitrogen-containing organic matter is 12.5 to 3:1, preferably 10 to 5:1.

[0039] In one embodiment, the reaction temperature of the mixture of Y-type molecular sieve, nitrogen-containing organic matter and water is 20 - 45 °C.

[0040] Heat-treat and calcine the Y-type molecular sieve modified in Step 1 to obtain a modified Y-type molecular sieve.

[0041] The heat treatment of the present invention is carried out in an inert atmosphere. The present invention does not particularly limit the type of inert atmosphere, such as nitrogen atmosphere, argon atmosphere, etc. The heat treatment temperature is 280 - 350 °C, preferably 290 - 320 °C. At this heat treatment temperature, the nitrogen-containing organic matter on the modified Y-type molecular sieve will decompose, resulting in weight loss, and the main component released during the weight loss process is CO 2 .

[0042] The present invention does not particularly limit the calcination temperature, for example, it is less than or equal to 550 °C, and the calcination time is 3 - 6 h.

[0043] The mass content of nitrogen-containing organic matter in the modified Y-type molecular sieve obtained by the present invention is greater than or equal to 8%, for example, 8% - 30%.

[0044] The modified Y-type molecular sieve of the present invention can be used in hydrocracking catalysts, having high cracking activity and good selectivity. In one embodiment, the hydrocracking catalyst of the present invention includes the above-mentioned modified Y-type molecular sieve, metal components, alumina, and optionally amorphous silica-alumina. The present invention does not particularly limit the content of each component and the preparation method of the catalyst, and conventional methods in the art can be used.

[0045] The technical solution of the present invention will be further described in detail through specific examples below.

[0046] The Y molecular sieve used in the examples of the present invention is the Y molecular sieve (SiO 2 to Al 2 O 3 molar ratio 11.2) produced by Shanghai Xinian Petrochemical Auxiliary Co., Ltd., hereinafter referred to as Y molecular sieve.

[0047] Example 1:

[0048] Weigh 10 g of Y zeolite and add it to 100 g of deionized water. Stir evenly, then add 2 g of arginine, and carry out the reaction at room temperature of 20 °C for 3 h. Then, filter and wash the formed slurry, and dry it at 120 °C for 3 h to obtain the organically modified Y zeolite Y-A1; heat-treat the Y-A1 zeolite at 290 °C under a nitrogen atmosphere for 2 h, and calcine it to obtain the heat-treated organically modified Y1 zeolite.

[0049] Use ultraviolet-visible spectroscopy to characterize the arginine shedding of Y-A1 zeolite before and after water washing. The results are as Figure 1 shown. Water washing will not cause a change in the arginine content on the Y-A1 zeolite. Specifically, as Figure 1 shown, at the initial stage of preparation, 2 g of arginine is dissolved in 100 g of water, and at this time, the aqueous solution has an obvious ultraviolet-visible absorption spectrum; add the Y-A1 zeolite to 100 g of water, stir and then filter, and take the solution after water washing for ultraviolet-visible light determination. It does not have a significant ultraviolet-visible absorption spectrum, indicating that the structure of the modified Y zeolite is stable and water washing will not cause arginine to fall off from the Y zeolite.

[0050] Example 2:

[0051] Weigh 10 g of Y zeolite and add it to 80 g of deionized water. Stir evenly, then add 1 g of phenylalanine and 0.4 g of acetamidine hydrochloride, and carry out the reaction at room temperature of 25 °C for 3 h. Then, filter and wash the formed slurry, and dry it at 120 °C for 3 h to obtain the organically modified Y zeolite Y-A2; heat-treat the Y-A2 zeolite at 300 °C under a nitrogen atmosphere for 2 h, and calcine it to obtain the heat-treated organically modified Y2 zeolite.

[0052] Use a thermogravimetry-infrared-chromatography-mass spectrometry combined instrument to characterize the modified Y zeolite Y-A2, and focus on the release of CO 2 molecules under the condition of programmed temperature rise. Therefore, the combined instrument detects the release of molecules with a molecular mass of 44 with temperature change. The results are as Figure 2 shown. As Figure 2 shown, there is a release of CO 2 from 200 °C to 400 °C. This shows that under the heat treatment temperature of the present invention, the CO 2 in the nitrogen-containing organic matter is removed, which can provide conditions for nitrogen element modification of the Y zeolite.

[0053] Example 3:

[0054] Weigh 10 g of Y zeolite and add it to 60 g of deionized water. Stir evenly, then add 0.3 g of methionine, 0.3 g of benzamidine hydrochloride, and 0.23 g of 3-(formamidinothio)-1-propanesulfonic acid, and carry out the reaction at room temperature of 20 °C for 3 h. Then filter and wash the formed slurry, and dry it at 120 °C for 3 h to obtain the organically modified Y zeolite Y-A3; heat-treat the Y-A3 zeolite at 310 °C in a nitrogen atmosphere for 2 h, and calcine it to obtain the heat-treated organically modified Y3 zeolite.

[0055] Comparative Example 1:

[0056] Weigh 10 g of Y zeolite and add it to 100 g of deionized water. Stir evenly, then add 2 g of arginine, and carry out the reaction at room temperature of 20 °C for 3 h. Then filter and wash the formed slurry, and dry it at 120 °C for 3 h, and then calcine it at 550 °C to obtain the unheat-treated organically modified D1 zeolite.

[0057] Comparative Example 2:

[0058] Weigh 10 g of Y zeolite and heat-treat it at 290 °C in a nitrogen atmosphere for 2 h, and then calcine it at 550 °C to obtain the heat-treated D2 zeolite.

[0059] The pyridine adsorption infrared characterization results of Y, Y1, Y2, Y3, D1, and D2 zeolites are shown in Table 1. At room temperature, pyridine is adsorbed on the zeolite surface, and then the system temperature is raised to 200 °C, and the peak areas of the infrared absorption peaks at wavenumbers of 1540 cm -1 and 1450 cm -1 are measured respectively, which represent the amounts of B acid sites and L acid sites in the total acid amount of the zeolite. The sum of the two amounts is the total acid amount; further, the system temperature is raised to 350 °C, and the peak areas of the infrared absorption peaks at wavenumbers of 1540 cm -1 and 1450 cm -1 are measured respectively, which represent the amounts of B acid sites and L acid sites in the strong acid sites of the zeolite. The sum of the two amounts is the total strong acid amount. From the data in Table 1, it can be seen that compared with the Y zeolite, the total acid amount and the total strong acid amount of the Y1, Y2, and Y3 zeolites in the examples of the present invention are both reduced to a certain extent, but the reduction amplitude of the total strong acid amount is greater, resulting in a significant reduction in the proportion of the total strong acid amount in the total acid amount. The total acid amount and the total strong acid amount of the D1 and D2 zeolites do not change much, and the proportion of the total strong acid amount in the total acid amount does not change significantly.

[0060] Table 1 Pyridine adsorption infrared characterization results of zeolites

[0061]

[0062] Weigh 7.2 g of alumina (dry basis 70%), 1.15 g of nitric acid (concentration 65%) and 50 g of deionized water to prepare a binder.

[0063] Weigh 5 g of Y1, Y2, Y3, D1, and D2 molecular sieves respectively, and mix them evenly with 10.7 g of alumina (dry basis 70%), 25 g of amorphous silica-alumina (dry basis 70%) and the above binder, extrude into pellets, dry at 120 °C for 4 h, and calcine in a nitrogen atmosphere at 550 °C for 3 h to obtain the support; weigh 13.3 g of ammonium metatungstate (purity 90 wt%) and 13.58 g of nickel nitrate (purity 25 wt%) to prepare a 30 mL metal salt solution, and impregnate 50 g of the above formed support with equal volume respectively, dry at 120 °C for 3 h, and calcine in a nitrogen atmosphere at 500 °C for 3 h to obtain hydrocracking catalysts CAT-1, CAT-2, CAT-3, CAT-D1, and CAT-D2. Use the prepared CAT-1, CAT-2, CAT-3, CAT-D1, and CAT-D2 catalysts to evaluate the performance of a refinery's straight-run diesel and straight-run kerosene mixed diesel refined oil as raw materials in a 100 ml pilot-scale evaluation device. Among them, the actual loading amount of the catalyst is 60 mL.

[0064] The catalyst sulfidation conditions are as follows: hydrogen pressure 7.0 MPa, hydrogen-oil ratio 500:1, the reactor temperature is increased from room temperature to 150 °C at a heating rate of 20 °C / h, after the temperature reaches 150 °C and continues to be kept constant for 1 h, start to inject sulfiding oil (3% CS 2 + straight-run diesel) at an injection rate of 72 g / h, after keeping the temperature constant for 1 h, increase the temperature to 230 °C at a heating rate of 20 °C / h, keep the temperature constant at 230 °C for 6 h, increase the temperature to 330 °C at a heating rate of 10 °C / h, and after keeping the temperature constant at 330 °C for 4 h, switch to the raw material oil, and the space velocity is 2.0 h -1 .

[0065] Monitor the relationship between the density of the product and time after switching the raw material oil as Figure 3 shown (the density of the raw material oil is 0.836 g / cm 3 ). It can be seen from the figure that for the catalyst prepared by the method of the present invention, the density change of the product is relatively low in the initial stage of operation, indicating that the method of the present invention has a good effect in passivating the molecular sieve and shortening the initial activation period of the hydrocracking catalyst. After the catalyst evaluation days reach 14 days, the density of the hydrocracking products catalyzed by the catalyst of the present invention and the comparative catalyst remains at the same level, indicating that the catalyst of the present invention ensures the cracking activity of the catalyst on the basis of realizing the passivation of the molecular sieve, which means that the molecular sieve synthesized by the method of the present invention has higher application value.

[0066] 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 can make various corresponding changes and modifications according to the present invention. However, these corresponding changes and modifications should fall within the protection scope of the claims of the present invention.

Claims

1. A modified Y-type molecular sieve, characterized in that, it is obtained by modifying a Y-type molecular sieve with a nitrogen-containing organic compound and then performing heat treatment; the mass content of the nitrogen-containing organic compound in the modified Y-type molecular sieve is greater than or equal to 8%; the heat treatment is carried out in an inert atmosphere, and the temperature of the heat treatment is 280-350 °C; the nitrogen-containing organic compound is at least one of an amino acid and a compound containing a guanidino functional group.

2. The modified Y-type molecular sieve according to claim 1, characterized in that, before and after washing the modified Y-type molecular sieve with water, the content of the nitrogen-containing organic compound in the modified Y-type molecular sieve remains unchanged.

3. The modified Y-type molecular sieve according to claim 1, characterized in that, the nitrogen-containing organic compound is one or more of arginine, phenylalanine, methionine, ethylamidine hydrochloride, benzamidine hydrochloride, and 3-(formamidothio)-1-propanesulfonic acid.

4. A method for preparing the modified Y-type molecular sieve according to any one of claims 1-3, characterized in that, comprises the following steps: Step 1, mixing a Y-type molecular sieve, a nitrogen-containing organic compound, and water, and reacting at 20-50 °C for 0.5-3 h; Step 2, performing heat treatment and roasting on the modified Y-type molecular sieve obtained in Step 1 to obtain the modified Y-type molecular sieve.

5. The method for preparing the modified Y-type molecular sieve according to claim 4, characterized in that, in Step 1, the Y-type molecular sieve and water are mixed, and then mixed with the nitrogen-containing organic compound; in the mixture of the Y-type molecular sieve and water, the solid-liquid ratio is 1:5-10, and the mass ratio of the Y-type molecular sieve to the nitrogen-containing organic compound is 12.5-3:

1.

6. The method for preparing the modified Y-type molecular sieve according to claim 4, characterized in that, During the heat treatment, some of the nitrogen-containing organic substances on the modified Y-type molecular sieve decompose to generate CO 2 .

7. The method for preparing the modified Y-type molecular sieve according to claim 5, characterized in that, the mass ratio of the Y-type molecular sieve to the nitrogen-containing organic compound is 10-5:

1.

8. The method for preparing the modified Y-type molecular sieve according to claim 4, characterized in that, the reaction temperature in Step 1 is 20-45 °C; the heat treatment temperature in Step 2 is 290-320 °C.

9. The method for preparing the modified Y-type molecular sieve according to claim 4, characterized in that, the roasting temperature is less than or equal to 550 °C, and the roasting time is 3-6 h.

10. Application of the modified Y-type molecular sieve according to any one of claims 1-3 in a hydrocracking catalyst.

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