A multi-level pore y molecular sieve, a preparation method and application thereof

Abstract

The application relates to the technical field of molecular sieves, and discloses a kind of hierarchical pore Y molecular sieves and its preparation method and application, the method comprises the following steps: (1) mixing silicon source, aluminum source, alkali and water to obtain a mixture, the mixture is subjected to static crystallization to obtain a crystallization liquid; (2) the crystallization liquid is subjected to solid-liquid separation to obtain a parent Y molecular sieve and a synthesis mother liquor; (3) part of the synthesis mother liquor is diluted with water to a pH of 9-13 to obtain a first synthesis mother liquor, the first synthesis mother liquor is stirred with the parent Y molecular sieve at 70-90 DEG C, and solid-liquid separation is performed to obtain a first solid phase and a first liquid phase; (4) part of the synthesis mother liquor and / or the first liquid phase is aged to obtain a second synthesis mother liquor, and the second synthesis mother liquor is mixed with the first solid phase and subjected to first hydrothermal crystallization. In the method, not only the silicon and aluminum contained in the synthesis mother liquor are utilized, but also the synthesis mother liquor is used as a pore-forming agent, which provides a new idea for the green synthesis of molecular sieves and the resource utilization of the synthesis mother liquor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molecular sieve, in particular to a hierarchical Y molecular sieve and a preparation method and application thereof. BACKGROUND

[0002] Mesoporous molecular sieve is developed in recent years, which has large specific surface area, relatively large pore size and regular pore structure, can handle large volume molecules, and is a good shape-selective catalyst. Constructing hierarchical molecular sieve with micropore and mesopore has a positive effect on strengthening molecular sieve intracrystalline diffusion. At present, the synthesis of hierarchical molecular sieve mainly includes bottom-up method and top-down method. The bottom-up method refers to that the multi-layer structure of micropore and mesopore is prepared at the same time, mainly including hard template method, soft template method and kinetic control method; the top-down method, also known as post-treatment method, is to selectively remove silicon or aluminum in the framework of the existing molecular sieve by acid, alkali or water vapor treatment, to produce cavities, thereby forming intracrystalline mesopore. The top-down method mainly includes desilication method and dealumination method, which has lower cost and higher efficiency compared with the bottom-up method, but has the defects of structure collapse and stability reduction of the treated molecular sieve.

[0003] The synthesis of molecular sieve produces a large amount of synthesis mother liquor, in which a large amount of unreacted raw materials are remained. Direct discharge will not only cause resource waste, but also cause certain impact on the environment. The recovery and treatment of the synthesis mother liquor after the synthesis of molecular sieve is the only way to green synthesis of molecular sieve and resource utilization of the mother liquor. At present, the utilization of the synthesis mother liquor is mostly to utilize the unreacted raw materials to crystallize again, so as to improve the utilization rate of raw materials. However, there is little research on other uses of the synthesis mother liquor. Therefore, it has certain practical significance to expand the use of the synthesis mother liquor. SUMMARY

[0004] The present application aims to solve the problem of recycling of synthesis mother liquor, and provides a hierarchical Y molecular sieve and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose, the present application provides a preparation method of hierarchical Y molecular sieve, which comprises the following steps:

[0006] (1) mixing a silicon source, an aluminum source, a base and water to obtain a mixture, and performing static crystallization on the mixture to obtain a crystallization liquid;

[0007] (2) performing solid-liquid separation on the crystallization liquid to obtain a parent Y molecular sieve and a synthesis mother liquor;

[0008] (3) diluting part of the synthesis mother liquor with water to pH 9-13 to obtain a first synthesis mother liquor, and stirring the first synthesis mother liquor with the parent Y molecular sieve at 70-90℃, and separating the solid phase from the liquid phase to obtain a first solid phase and a first liquid phase;

[0009] (4) aging part of the synthesis mother liquor and / or the first liquid phase to obtain a second synthesis mother liquor, and mixing the second synthesis mother liquor with the first solid phase and then performing hydrothermal crystallization.

[0010] Preferably, in step (1), the molar ratio of the silicon source (calculated as SiO2), the aluminum source (calculated as Al2O3), the alkali source (calculated as the corresponding alkali metal oxide), the silicon source, the aluminum source, the alkali, and water is 10-18:0.9-1.3:3-6.5:150-240.

[0011] Preferably, in step (1), the static crystallization conditions include a temperature of 80-120℃ and a time of 2-5 days.

[0012] Preferably, in step (2), the parent Y molecular sieve has a SiO2 / Al2O3 ratio of >5.

[0013] Preferably, in step (3), the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor is 10-25:100.

[0014] Preferably, in step (3), the stirring time is 1-5h.

[0015] Preferably, in step (4), the aging conditions include a temperature of 50-75℃ and a time of 2-5h.

[0016] Preferably, in step (4), the mixing conditions include a temperature of 60-90℃ and a time of 3-9h.

[0017] Preferably, in step (4), the first hydrothermal crystallization conditions include a temperature of 90-110℃ and a time of 20-50h.

[0018] Preferably, the method further comprises:

[0019] stirring the product obtained by the first hydrothermal crystallization with the first synthesis mother liquor at 70-90℃, and separating the solid phase from the liquid phase to obtain a second solid phase;

[0020] mixing the second solid phase with the second synthesis mother liquor and then performing second hydrothermal crystallization.

[0021] The second aspect of the application provides a method for preparing a hierarchical-pore Y molecular sieve, which comprises the following steps:

[0022] (1) mixing a silicon source, an aluminum source, a base and water to obtain a mixture, and subjecting the mixture to static crystallization to obtain a crystallization liquid;

[0023] (2) diluting the crystallization liquid with water to a pH of 9-13 in the system, stirring at 70-90°C, and then subjecting to solid-liquid separation to obtain Y molecular sieve and a synthesis mother liquor;

[0024] (3) subjecting the synthesis mother liquor to aging, and then mixing with the Y molecular sieve and subjecting to hydrothermal crystallization.

[0025] Preferably, in step (1), the molar ratio of the silicon source (calculated as SiO2), the aluminum source (calculated as Al2O3), the base source (calculated as the corresponding alkali metal oxide), and water is 10-18:0.9-1.3:3-6.5:150-240.

[0026] Preferably, in step (1), the static crystallization is carried out at a temperature of 80-120°C for 2-5 days.

[0027] Preferably, in step (3), the aging is carried out at a temperature of 50-75°C for 2-5h.

[0028] Preferably, in step (3), the mixing is carried out at a temperature of 60-90°C for 3-9h.

[0029] Preferably, in step (3), the hydrothermal crystallization is carried out at a temperature of 90-110°C for 20-50h.

[0030] The third aspect of the present application provides a hierarchical-pore Y molecular sieve prepared by the method as described above.

[0031] The fourth aspect of the present application provides a catalyst, wherein the catalyst uses the hierarchical-pore Y molecular sieve as described above as a carrier.

[0032] The fifth aspect of the present application provides an application of the catalyst as described above in the field of heavy aromatic hydrocarbon lightening.

[0033] The method provided by the present application can reasonably utilize the synthesis mother liquor, not only the silicon and aluminum contained in the synthesis mother liquor, but also the synthesis mother liquor as a pore-forming agent, so as to utilize the alkalinity in the synthesis mother liquor, and further make full use of the synthesis mother liquor, which provides a new idea for green synthesis of molecular sieve and resource utilization of synthesis mother liquor. DETAILED DESCRIPTION

[0034] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0035] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numerical range recited herein is intended to include all sub-ranges of the same numbers (i.e., every subset of numbers within the indicated range). For ranges containing one or more endpoints, the endpoints are included in the range. For ranges containing no endpoints, the range is intended to include all values and / or sub-ranges of the same numbers (i.e., every number falling within the range).

[0036] The present application provides a method for preparing a hierarchical pore Y molecular sieve, which comprises the following steps:

[0037] (1) mixing a silicon source, an aluminum source, a base and water to obtain a mixture, and subjecting the mixture to static crystallization to obtain a crystallization liquid;

[0038] (2) subjecting the crystallization liquid to solid-liquid separation to obtain a parent Y molecular sieve and a synthesis mother liquor;

[0039] (3) diluting part of the synthesis mother liquor with water to a pH of 9-13 to obtain a first synthesis mother liquor, and stirring the first synthesis mother liquor with the parent Y molecular sieve at 70-90°C, and subjecting to solid-liquid separation to obtain a first solid phase and a first liquid phase;

[0040] (4) subjecting part of the synthesis mother liquor and / or the first liquid phase to aging to obtain a second synthesis mother liquor, and mixing the second synthesis mother liquor with the first solid phase and subjecting to first hydrothermal crystallization.

[0041] The present application does not limit the specific selection of the silicon source in step (1), as long as it can provide SiO2. In a specific embodiment, the silicon source can be silica sol and / or water glass.

[0042] The present application also does not limit the specific selection of the aluminum source in step (1), which can be a conventional aluminum source in the art. In a specific embodiment, the aluminum source can be one or two or more of sodium metaaluminate, aluminum oxide, aluminum hydroxide, aluminum isopropoxide, aluminum 2-butylate, aluminum chloride, aluminum sulfate and aluminum nitrate.

[0043] The present application does not particularly limit the base in step (1), which can be a base commonly used in the preparation of Y molecular sieves. In a specific embodiment, the base is selected from one or two or more of sodium hydroxide, potassium hydroxide and cesium hydroxide.

[0044] The present application does not limit the time and temperature of mixing in step (1), as long as the raw material components can be uniformly mixed. In a specific embodiment, in step (1), the mixing process comprises: uniformly mixing the silicon source, the aluminum source, the base and distilled water, and stirring at room temperature to form a gel-like mixture. In a specific embodiment, room temperature refers to 25-30°C.

[0045] In the preferred embodiment, in step (1), the molar ratio of the silicon source (calculated as SiO2), the aluminum source (calculated as Al2O3), the alkali source (calculated as the corresponding alkali metal oxide), the silicon source, the aluminum source, the alkali and water is 10-18:0.9-1.3:3-6.5:150-240.

[0046] In the preferred embodiment, in step (1), the conditions for static crystallization include a temperature of 80-120°C and a time of 2-5 days. By static crystallization of the gel, a parent Y molecular sieve with micropores is synthesized.

[0047] In the preferred embodiment, in step (2), the parent Y molecular sieve has a silicon-to-aluminum ratio (SiO2 / Al2O3) > 5. Specifically, the silicon-to-aluminum ratio refers to the molar ratio of SiO2 and Al2O3.

[0048] In step (3) of the present application, the synthesis mother liquor is used as a pore-forming agent to etch the silicon on the Y molecular sieve using the high alkalinity in the synthesis mother liquor, to obtain a Y molecular sieve with a mesoporous structure. The synthesis mother liquor obtained in the synthesis of the Y molecular sieve has very strong alkalinity (pH > 14), and in order to make the etching rate appropriate and finally obtain a multi-level pore Y molecular sieve with stable structure, in step (3) of the present application, the synthesis mother liquor is first diluted with water to a pH of 9-13, and then stirred with the parent Y molecular sieve to etch the parent Y molecular sieve.

[0049] In the preferred embodiment, in step (3), the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor is 10-25:100. Further preferably, in step (3), the stirring time is 1-5 h.

[0050] In the preferred embodiment, in step (4), the aging conditions include a temperature of 50-75°C and a time of 2-5 h.

[0051] In the preferred embodiment, in step (4), the mixing conditions include a temperature of 60-90°C and a time of 3-9 h.

[0052] In the preferred embodiment, in step (4), the first hydrothermal crystallization conditions include a temperature of 90-110°C and a time of 20-50 h.

[0053] In the preferred embodiment, in step (4), the mass ratio of the first solid phase to the second synthesis mother liquor is 10-30:100.

[0054] In the method, the synthesis mother liquor is used as a pore forming agent in step (3) and as a synthesis raw material in step (4), so that the alkalinity in the synthesis mother liquor can be reasonably utilized, the silicon and aluminum contained in the synthesis mother liquor can be utilized, the substances in the synthesis mother liquor can be fully utilized, and the method has certain industrial application potential and can promote the green synthesis of molecular sieves.

[0055] In the method, the alkaline treatment is performed in step (3) and the recrystallization treatment is performed in step (4). The present application does not limit the specific number of alkaline treatment and recrystallization treatment, and the actual needs can be designed. When the alkaline treatment and recrystallization treatment are performed for multiple times, the mesopore content can be increased, but the framework can be damaged. Therefore, in the preferred embodiment, the alkaline treatment and hydrothermal crystallization are performed for two times. Specifically, the method further comprises: stirring the product obtained by the first hydrothermal crystallization (i.e., the molecular sieve subjected to the pore forming and recrystallization process once) with the first synthesis mother liquor at 70-90°C, and performing solid-liquid separation to obtain a second solid phase; and performing second hydrothermal crystallization on the second solid phase mixed with the second synthesis mother liquor to obtain the hierarchical pore Y molecular sieve. In this way, the mesopore content of the prepared hierarchical pore Y molecular sieve is more suitable.

[0056] Further preferably, the conditions of the second hydrothermal crystallization include: the temperature is 90-110°C, and the time is 20-50h.

[0057] Obviously, the design of the present application is not limited to this, and the present application further provides another method for preparing the hierarchical pore Y molecular sieve, which comprises the following steps:

[0058] (1) mixing a silicon source, an aluminum source, an alkali and water to obtain a mixture, and then performing static crystallization to obtain a crystallization liquid;

[0059] (2) diluting the crystallization liquid with water to a pH of 9-13 in the system, stirring at 70-90°C, and then performing solid-liquid separation to obtain a Y molecular sieve and a synthesis mother liquor;

[0060] (3) aging the synthesis mother liquor, and then mixing the Y molecular sieve with the synthesis mother liquor to perform hydrothermal crystallization.

[0061] In the preferred embodiment, in step (1), the molar ratio of the silicon source (calculated as SiO2), the aluminum source (calculated as Al2O3), the alkali source (calculated as the corresponding alkali metal oxide), and water is 10-18:0.9-1.3:3-6.5:150-240, and more preferably 10-14:0.9-1.1:3-5.5:150-200.

[0062] In a preferred embodiment, in step (1), the conditions of the static crystallization include: a temperature of 80-120℃, and a time of 2-5 days.

[0063] In a preferred embodiment, in step (2), the stirring time is 1-5h.

[0064] In a preferred embodiment, step (3) includes: aging the synthesis mother liquor, then mixing the Y molecular sieve with the aged synthesis mother liquor at a mass ratio of 10-25:100, and then performing hydrothermal crystallization.

[0065] In a preferred embodiment, in step (3), the conditions of the aging include: a temperature of 50-75℃, and a time of 2-5h.

[0066] In a preferred embodiment, in step (3), the conditions of the mixing include: a temperature of 60-90℃, and a time of 3-9h.

[0067] In a preferred embodiment, in step (3), the conditions of the hydrothermal crystallization include: a temperature of 90-110℃, and a time of 20-50h.

[0068] In the method, the liquid phase in the reaction liquid is first used as a pore-forming agent to utilize the alkalinity therein, and then the obtained synthesis mother liquor is mixed with the Y molecular sieve and subjected to hydrothermal crystallization to utilize the silicon and aluminum in the synthesis mother liquor, so that the substances in the synthesis mother liquor can be fully utilized, and the method has certain industrial application potential and can promote the green synthesis of molecular sieves.

[0069] The application further provides a hierarchical-pore Y molecular sieve prepared by the method.

[0070] The application further provides a catalyst, which uses the hierarchical-pore Y molecular sieve as a carrier. The application does not particularly limit the active component and the specific preparation method of the catalyst, for example, the active component can be Pt, and the preparation method can be an impregnation method.

[0071] In a specific embodiment, the catalyst is prepared by the following procedure: using the hierarchical-pore Y molecular sieve as a carrier, impregnating Pt by an equal-volume impregnation method, and then subjecting the impregnated catalyst to standing, drying and calcination to obtain the catalyst.

[0072] The application further provides the use of the catalyst in the field of heavy aromatic hydrocarbon lightening, in particular, the use of the catalyst in the conversion of heavy aromatic hydrocarbons. 10 + The application further provides the use of the catalyst in the field of heavy aromatic hydrocarbon lightening, in particular, the use of the catalyst in the conversion of heavy aromatic hydrocarbons.

[0073] The application will be described in detail below by way of examples, but the scope of protection of the application is not limited thereto. The experimental methods used in the following examples and comparative examples are conventional methods unless otherwise specified; the materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0074] In the following examples and comparative examples, the test method for the silicon-aluminum ratio (SiO2 / Al2O3) of the parent Y molecular sieve is X-ray fluorescence spectrometry (XRF).

[0075] In the following examples and comparative examples, room temperature refers to 25±2℃.

[0076] Example 1

[0077] (1) 37.10 g of sodium hydroxide was added to 230.40 g of deionized water, and after stirring until uniform, 31.50 g of sodium aluminate was added, and stirring was continued until the solution was clear. 400.00 g of silica sol (the content of SiO2 in the silica sol was 30 wt%) was added, and the molar ratio of the materials was SiO2:Al2O3:Na2O:H2O = 12:1:4:170. After stirring at room temperature for 24 h, a gel-like mixture was obtained. The mixture was statically crystallized at 100℃ for 5 days to obtain a crystallization liquid;

[0078] (2) The crystallization liquid was filtered to obtain a synthesis mother liquor and a solid. The solid was washed with deionized water until neutral, and then transferred to an oven and dried at 100℃ for 12 h to obtain a parent Y molecular sieve (SiO2 / Al2O3 = 5.2);

[0079] (3) Part of the synthesis mother liquor was diluted to pH = 13 to obtain a first synthesis mother liquor. The first synthesis mother liquor was stirred with the parent Y molecular sieve in a water bath at 80℃ for 1 h, and the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor was 20:100. After the water bath, the solid phase and the first liquid phase were obtained by filtration. The solid phase was immediately washed with distilled water until neutral, and then placed in a 100℃ oven for drying for 12 h to obtain a first solid phase;

[0080] (4) Part of the synthesis mother liquor was aged at 70℃ for 3 h to obtain a second synthesis mother liquor, which was then mixed with the above first solid phase and stirred for another 3 h to obtain a mixed system. The mass ratio of the first solid phase to the second synthesis mother liquor was 20:100. The mixed system was subjected to first hydrothermal crystallization (temperature 100℃, time 24 h, static crystallization method) to obtain a hierarchical pore molecular sieve MY-1.

[0081] Example 2

[0082] The method described in Example 1 was implemented, except that in step (3), the time of water bath stirring was 2h, and finally the hierarchical porous molecular sieve MY-2 was prepared.

[0083] Example 3

[0084] The method described in Example 1 was implemented, except that in step (3), the time of water bath stirring was 3h, and finally the hierarchical porous molecular sieve MY-3 was prepared.

[0085] Example 4

[0086] The method described in Example 1 was implemented, except that in step (3), the time of water bath stirring was 4h, and finally the hierarchical porous molecular sieve MY-4 was prepared.

[0087] Example 5

[0088] The method described in Example 1 was implemented, except that in step (3), the time of water bath stirring was 5h, and finally the hierarchical porous molecular sieve MY-5 was prepared.

[0089] Example 6

[0090] The method described in Example 2 was implemented, except that in step (3), part of the synthesis mother liquor was diluted to pH = 11 to obtain a first synthesis mother liquor; and finally the hierarchical porous molecular sieve MY-6 was prepared.

[0091] Example 7

[0092] The method described in Example 2 was implemented, except that in step (3), part of the synthesis mother liquor was diluted to pH = 9 to obtain a first synthesis mother liquor; and finally the hierarchical porous molecular sieve MY-7 was prepared.

[0093] Example 8

[0094] The method described in Example 2 was implemented, except that the prepared hierarchical porous molecular sieve MY-2 was returned to step (3), and finally the hierarchical porous molecular sieve MY-8 was prepared.

[0095] Specifically, the following steps are included:

[0096] (1) 37.10 g of sodium hydroxide was added to 230.40 g of deionized water, after stirring to uniform, 31.50 g of sodium aluminate was added, and stirring was continued until the solution was clear, 400.00 g of silica sol (the content of SiO2 in the silica sol was 30 wt%) was added, wherein the molar ratio of each material was SiO2:Al2O3:Na2O:H2O = 12:1:4:170, and a gel-like mixture was obtained after stirring at room temperature for 24 h, and the mixture was statically crystallized at 100°C for 5 days to obtain a crystallization liquid;

[0097] (2) The crystallization liquid was filtered to obtain a synthesis mother liquor and a solid, and the solid was washed with deionized water until neutral, then transferred to an oven and dried at 100°C for 12 h to obtain a parent Y molecular sieve (SiO2 / Al2O3 = 5.2);

[0098] (3) Part of the synthesis mother liquor was diluted to pH = 13 to obtain a first synthesis mother liquor, and the first synthesis mother liquor was stirred with the parent Y molecular sieve in a 80°C water bath for 2 h, wherein the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor was 20:100, and after the water bath was completed, the solid phase obtained was immediately washed with distilled water until neutral, and then placed in a 100°C oven for drying for 12 h to obtain a first solid phase;

[0099] (4) Part of the synthesis mother liquor was aged at 70°C for 3 h to obtain a second synthesis mother liquor, which was then mixed with the above-mentioned first solid phase and continued to stir for 3 h to obtain a mixed system; wherein the mass ratio of the first solid phase to the second synthesis mother liquor was 20:100; the mixed system was subjected to first hydrothermal crystallization (temperature was 100°C, time was 24 h, static crystallization method) to obtain a product (i.e. hierarchical pore molecular sieve MY-2);

[0100] (5) The above-mentioned hierarchical pore molecular sieve MY-2 was stirred with the above-mentioned first synthesis mother liquor in a 80°C water bath for 2 h, wherein the mass ratio of the hierarchical pore molecular sieve MY-2 to the first synthesis mother liquor was 20:100, and after the water bath was completed, the solid phase obtained was immediately washed with distilled water until neutral, and then placed in a 100°C oven for drying for 12 h to obtain a second solid phase;

[0101] (6) The above-mentioned second solid phase was stirred with the above-mentioned second synthesis mother liquor at 70°C for 3 h, wherein the mass ratio of the second solid phase to the second synthesis mother liquor was 20:100, and then subjected to second hydrothermal crystallization (temperature was 100°C, time was 24 h, static crystallization method) to obtain a hierarchical pore molecular sieve MY-8.

[0102] Example 9

[0103] The method is carried out according to the method described in Example 8, except that the prepared hierarchical porous molecular sieve MY-8 is returned to step (3), and finally the hierarchical porous molecular sieve MY-9 is prepared.

[0104] Specifically, the following steps are included:

[0105] (1) 37.10 g of sodium hydroxide was added to 230.40 g of deionized water, and after stirring uniformly, 31.50 g of sodium aluminate was added, and stirring was continued until the solution was clear, and 400.00 g of silica sol (the content of SiO2 in the silica sol was 30 wt%) was added, wherein the molar ratio of each material was SiO2:Al2O3:Na2O:H2O=12:1:4:170, and a gel-like mixture was obtained after stirring at room temperature for 24 h, and the mixture was statically crystallized at 100°C for 5 days to obtain a crystallization liquid;

[0106] (2) The crystallization liquid was filtered to obtain a synthesis mother liquor and a solid, and the solid was washed with deionized water until neutral, then transferred to an oven and dried at 100°C for 12 h to obtain a parent Y molecular sieve (SiO2 / Al2O3=5.2);

[0107] (3) Part of the synthesis mother liquor was diluted to pH=13 to obtain a first synthesis mother liquor, and the first synthesis mother liquor was stirred with the parent Y molecular sieve in a 80°C water bath for 2 h, wherein the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor was 20:100, and after the water bath was completed, filtration was performed, and the obtained solid phase was immediately washed with distilled water until neutral, and then placed in a 100°C oven for drying for 12 h to obtain a first solid phase;

[0108] (4) Part of the synthesis mother liquor was aged at 70°C for 3 h to obtain a second synthesis mother liquor, which was then mixed with the above-mentioned first solid phase and continued to stir for 3 h to obtain a mixed system; wherein the mass ratio of the first solid phase to the second synthesis mother liquor was 20:100; the mixed system was subjected to first hydrothermal crystallization (temperature was 100°C, time was 24 h, static crystallization method) to obtain a product (i.e. hierarchical porous molecular sieve MY-2);

[0109] (5) The above-mentioned hierarchical porous molecular sieve MY-2 was stirred with the above-mentioned first synthesis mother liquor in a 80°C water bath for 2 h, wherein the mass ratio of the hierarchical porous molecular sieve MY-2 to the first synthesis mother liquor was 20:100, and after the water bath was completed, filtration was performed, and the obtained solid phase was immediately washed with distilled water until neutral, and then placed in a 100°C oven for drying for 12 h to obtain a second solid phase;

[0110] (6) The above-mentioned second solid phase was stirred with the above-mentioned second synthesis mother liquor at 70°C for 3 h, and then subjected to second hydrothermal crystallization (temperature was 100°C, time was 24 h, static crystallization method) to obtain a hierarchical porous molecular sieve MY-8;

[0111] (7) The above multi-level pore molecular sieve MY-8 is stirred with the above first synthesis mother liquor in a water bath at 80°C for 2h, wherein the mass ratio of the multi-level pore molecular sieve MY-8 to the first synthesis mother liquor is 20:100, after the water bath is completed, filtration is performed, and the obtained solid phase is immediately washed with distilled water until neutral, and then placed in a 100°C oven for drying for 12h to obtain a third solid phase;

[0112] (8) The above third solid phase is stirred with the above second synthesis mother liquor at 70°C for 3h, wherein the mass ratio of the third solid phase to the second synthesis mother liquor is 20:100, and then a third hydrothermal crystallization is performed (temperature is 100°C, time is 24h, static crystallization method) to obtain the multi-level pore molecular sieve MY-9.

[0113] Example 10

[0114] The implementation is performed according to the method described in Example 2, except that step (4): the first liquid phase obtained in step (3) is aged at 70°C for 3h to obtain a second synthesis mother liquor.

[0115] Specifically, the following steps are included:

[0116] (1) 37.10g of sodium hydroxide is added to 230.40g of deionized water, and after being stirred uniformly, 31.50g of sodium metaaluminate is added, and continues to be stirred until the solution is clear, and 400.00g of silica sol (the content of SiO2 in the silica sol is 30wt%) is added, wherein the molar ratio of each material is SiO2:Al2O3:Na2O:H2O = 12:1:4:170, and after being stirred at room temperature for 24h, a gel-like mixture is obtained, and the mixture is statically crystallized at 100°C for 5 days to obtain a crystallization liquid;

[0117] (2) The crystallization liquid is filtered to obtain a synthesis mother liquor and a solid, and after the solid is washed with deionized water until neutral, it is transferred to an oven and dried at 100°C for 12h to obtain a parent Y molecular sieve (SiO2 / Al2O3 = 5.2);

[0118] (3) Part of the synthesis mother liquor is diluted to pH = 13 to obtain a first synthesis mother liquor, and the first synthesis mother liquor is stirred with the parent Y molecular sieve in a water bath at 80°C for 2h, wherein the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor is 20:100, after the water bath is completed, filtration is performed to obtain a solid phase and a first liquid phase, the solid phase is immediately washed with distilled water until neutral, and then placed in a 100°C oven for drying for 12h to obtain a first solid phase;

[0119] (4) the first liquid phase obtained in step (3) is aged at 70 °C for 3 h to obtain a second synthesis mother liquor, which is then mixed with the first solid phase described above, and stirring is continued for 3 h to obtain a mixed system; wherein the mass ratio of the first solid phase to the second synthesis mother liquor is 20:100; the mixed system is subjected to first hydrothermal crystallization (temperature is 100 °C, time is 24 h, static crystallization method) to obtain hierarchical porous molecular sieve MY-10.

[0120] Example 11

[0121] (1) 44.48 g of sodium hydroxide is added to 437.75 g of deionized water, and after stirring uniformly, 37.77 g of sodium metaaluminate is added, and stirring is continued until the solution is clear, and 400.00 g of silica sol (in the silica sol, the content of SiO2 is 30 wt%) is added, wherein the molar ratio of each material is SiO2:Al2O3:NaOH:H2O = 10:1:4:200, and after stirring at room temperature for 24 h, a gel-like mixture is obtained, and the mixture is subjected to static crystallization at 110 °C for 4 d;

[0122] (2) the reaction liquid is filtered to obtain a synthesis mother liquor and a solid, and after the solid is washed to neutral with deionized water, it is transferred to an oven and dried at 100 °C for 12 h to obtain a parent Y molecular sieve (SiO2 / Al2O3 = 5.0);

[0123] (3) part of the synthesis mother liquor is diluted to pH = 13 to obtain a first synthesis mother liquor, and the first synthesis mother liquor is stirred with the parent Y molecular sieve in a water bath at 80 °C for 4 h, wherein the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor is 20:100, and after the water bath is completed, the solid phase is filtered and immediately washed to neutral with distilled water, and then placed in a 100 °C oven and dried for 12 h to obtain a first solid phase;

[0124] (4) part of the synthesis mother liquor is aged at 70 °C for 3 h to obtain a second synthesis mother liquor, which is then mixed with the first solid phase described above, and stirring is continued for 3 h to obtain a mixed system; wherein the mass ratio of the first solid phase to the second synthesis mother liquor is 20:100; the mixed system is subjected to static crystallization at 100 °C for 24 h to obtain hierarchical porous molecular sieve MY-11.

[0125] Example 12

[0126] According to the method described in Example 4, the difference is that the solid-liquid separation in step (2) is not required (i.e. the parent Y molecular sieve after synthesis does not need to be separated from the synthesis mother liquor), and the specific steps are as follows:

[0127] (1) 37.10 g of sodium hydroxide was added into 230.40 g of deionized water, after stirring uniformly, 31.50 g of sodium metaaluminate was added, and stirring was continued until the solution was clear, and 400.00 g of silica sol (the content of SiO2 in the silica sol was 30 wt%) was added, wherein the molar ratio of each material was SiO2:Al2O3:NaOH:H2O = 12:1:4:170, and a gel-like mixture was obtained after stirring at room temperature for 24 h, and the mixture was statically crystallized at 100 °C for 5 days to obtain a reaction liquid;

[0128] (2) The reaction liquid was diluted with water to pH = 13, and stirred in a water bath at 80 °C for 4 h, and then solid-liquid separation was performed to obtain Y molecular sieve and a synthesis mother liquor;

[0129] (3) The synthesis mother liquor was aged at 70 °C for 3 h, and the Y molecular sieve was mixed with the aged synthesis mother liquor at a mass ratio of 20:100, and stirring was continued for 3 h to obtain a mixed system; the mixed system was statically crystallized at 100 °C for 24 h to obtain a hierarchical pore molecular sieve MY-12.

[0130] Comparative Example 1

[0131] The method described in Example 4 was implemented, except that step (4) was not performed, and the first solid phase obtained in step (3) was a molecular sieve, which was denoted as molecular sieve DY-1.

[0132] Comparative Example 2

[0133] The method described in Example 4 was implemented, except that water was not added for dilution in step (3), and finally a molecular sieve DY-2 was prepared.

[0134] Comparative Example 3

[0135] The method described in Example 4 was implemented, except that the synthesis mother liquor was not aged in step (4), and finally a molecular sieve DY-3 was prepared.

[0136] Comparative Example 4

[0137] The parent Y molecular sieve prepared in step (2) of Example 4 was denoted as molecular sieve DY-4.

[0138] Test Example 1

[0139] The molecular sieves prepared in the examples and comparative examples were tested for physical properties (specific surface area, pore volume, and crystallinity, etc.), and the test results are shown in Table 1 below, where S BET represents the specific surface area; S micro represents the micropore specific surface area; S ext represents the external specific surface area; V total represents the total pore volume (P / P0 = 0.98); Vmicro V represents the micropore volume; meso Represents the volume of mesopores.

[0140] Table 1

[0141]

[0142] As shown in Table 1, the hierarchical porous Y molecular sieves prepared in Examples 1-12 have abundant mesopores and micropores, and high crystallinity. Meanwhile, as shown in Examples 1-5, under the same pH conditions, the number of mesopores does not continuously increase with the extension of water bath stirring time; this is determined by the total alkali content of the system.

[0143] Test Example 2

[0144] Using the molecular sieves prepared in the examples and comparative examples as carriers, 3% Pt was impregnated by the equal volume impregnation method. The impregnated catalyst was left to stand at room temperature for 6 hours, then transferred to an oven at 120°C for 5 hours to dry, and finally calcined at 500°C for 5 hours to obtain the catalyst.

[0145] The catalyst was tableted, crushed, and sieved to obtain particles of 20–40 mesh. 8g of catalyst was loaded into a fixed-bed reactor, and hydrogen was introduced to reduce the catalyst at 500℃ for 3 hours, followed by cooling to 350℃. Subsequently, C… 10 + Using heavy aromatics as feedstock, space velocity 1 h⁻¹ -1 The pressure was 5 MPa, the hydrogen-to-oil volume ratio was 1000, and the conversion rate was calculated. The results are shown in Table 2 below.

[0146] Table 2

[0147]

[0148]

[0149] As shown in Table 2, the catalysts prepared using the molecular sieves obtained in Examples 1-12 of this invention exhibit high conversion rates (above 80%) for heavy aromatics. Meanwhile, the catalyst prepared using the molecular sieve in Example 8 demonstrates the best catalytic performance. This is likely because the sample underwent two alkali treatments and recrystallization processes, resulting in the most suitable mesoporous content, which is beneficial for larger C2 volumes. 10 + Diffusion of raw materials.

[0150] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a hierarchical-pore Y molecular sieve, characterized in that, The method comprises the following steps: (1) mixing a silicon source, an aluminum source, an alkali and water to obtain a mixture, and subjecting the mixture to static crystallization to obtain a crystallization liquid; (2) subjecting the crystallization liquid to solid-liquid separation to obtain a parent Y molecular sieve and a synthesis mother liquor; (3) diluting part of the synthesis mother liquor with water to a pH of 9-13 to obtain a first synthesis mother liquor, and stirring the first synthesis mother liquor with the parent Y molecular sieve at 70-90°C, and subjecting the mixture to solid-liquid separation to obtain a first solid phase and a first liquid phase; (4) subjecting part of the synthesis mother liquor and / or the first liquid phase to aging to obtain a second synthesis mother liquor, and mixing the second synthesis mother liquor with the first solid phase and subjecting the mixture to first hydrothermal crystallization.

2. The method of claim 1, wherein, In step (1), the molar ratio of the silicon source (calculated as SiO2), the aluminum source (calculated as Al2O3), the alkali (calculated as the corresponding alkali metal oxide) and water is 10-18:0.9-1.3:3-6.5:150-240.

3. The method of claim 2, wherein, In step (1), the static crystallization is performed at a temperature of 80-120°C for 2-5 days.

4. The method of claim 2, wherein, In step (2), the parent Y molecular sieve has a SiO2 / Al2O3 ratio of greater than 5.

5. The method of claim 1, wherein, In step (3), the mass ratio of the parent Y molecular sieve to the first synthesis mother liquor is 10-25:

100.

6. The method of claim 5, wherein, In step (3), the stirring is performed for 1-5 h.

7. The method of claim 5, wherein, In step (4), the aging is performed at a temperature of 50-75°C for 2-5 h.

8. The method of claim 5, wherein, In step (4), the mixing is performed at a temperature of 60-90°C for 3-9 h.

9. The method of claim 5, wherein, In step (4), the first hydrothermal crystallization is performed at a temperature of 90-110°C for 20-50 h.

10. The method of claim 1, wherein, The method further comprises: stirring the product obtained from the first hydrothermal crystallization with the first synthesis mother liquor at 70-90°C, and subjecting the mixture to solid-liquid separation to obtain a second solid phase; mixing the second solid phase with the second synthesis mother liquor and subjecting the mixture to second hydrothermal crystallization.

11. A method for preparing a hierarchical pore Y molecular sieve, characterized in that, The method comprises the following steps: (1) mixing a silicon source, an aluminum source, an alkali and water to obtain a mixture, and subjecting the mixture to static crystallization to obtain a crystallization liquid; (2) diluting the crystallization liquid with water to a pH of 9-13 in the system, stirring at 70-90°C, and then subjecting the mixture to solid-liquid separation to obtain a Y molecular sieve and a synthesis mother liquor; (3) subjecting the synthesis mother liquor to aging, and then mixing the aged synthesis mother liquor with the Y molecular sieve and subjecting the mixture to hydrothermal crystallization.

12. The method of claim 11, wherein, In step (1), the molar ratio of the silicon source (calculated as SiO2), the aluminum source (calculated as Al2O3), the alkali (calculated as the corresponding alkali metal oxide) and water is 10-18:0.9-1.3:3-6.5:150-240.

13. The method of claim 11, wherein, In step (1), the static crystallization is performed at a temperature of 80-120°C for 2-5 days.

14. The method according to any one of claims 11-13, characterized in that, In step (3), the aging is performed at a temperature of 50-75°C for 2-5 h.

15. The method of claim 14, wherein, In step (3), the mixing is performed at a temperature of 60-90°C for 3-9 h.

16. The method of claim 14, wherein, In step (3), the hydrothermal crystallization conditions include a temperature of 90-110°C and a time of 20-50 hours.

17. A hierarchical-pore Y molecular sieve prepared by the method of any one of claims 1-16.

18. A catalyst characterized by, The catalyst uses the hierarchical-pore Y molecular sieve of claim 17 as a carrier.

19. Use of the catalyst of claim 18 in the field of heavy aromatic hydrocarbon lightening.

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