CN112758952B - High-silica-alumina-ratio Y molecular sieve with hierarchical pore structure and preparation method thereof - Google Patents
High-silica-alumina-ratio Y molecular sieve with hierarchical pore structure and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a high-silica-alumina ratio Y molecular sieve with a hierarchical pore structure and a preparation method thereof. The preparation method comprises the following steps: carrying out liquid-phase isomorphous substitution on the Y molecular sieve at the temperature of 30-100 ℃ in a solution containing a boron source, and filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve; and introducing dry gas saturated by the gas-phase isomorphous substituting agent into the dried boron-containing heteroatom Y molecular sieve, reacting for 0.1-48 hours at 120-800 ℃, stopping introducing the dry gas saturated by the gas-phase isomorphous substituting agent after the reaction is finished, purging for 0.5-12 hours by using the dry gas, and cooling to room temperature to obtain the high-silicon-aluminum-ratio Y molecular sieve with the multistage pore structure. The Y molecular sieve with high silicon-aluminum ratio provided by the invention has the advantages of relative crystallinity of more than 90%, silicon-aluminum ratio of more than 10, simple preparation process, low production cost and industrial application prospect. The method has small damage to the framework of the molecular sieve, and the prepared Y molecular sieve has high silicon-aluminum ratio and abundant hierarchical pore structure; and the production cost is low.
Description
Technical Field
The invention belongs to the field of molecular sieve materials and preparation thereof, and particularly relates to a high-silica-alumina-ratio Y molecular sieve with a hierarchical pore structure and a preparation method thereof.
Background
The Y molecular sieve has excellent pore structure and proper surface acidity, and is widely applied in the fields of adsorption, separation, catalysis and the like. Along with the increasing weight change of raw oil, the accessibility of an active center of an oil refining catalyst is improved, and the improvement of the catalytic conversion capability of the oil refining catalyst on macromolecules becomes the key point of petrochemical catalyst development. With the continuous development of new synthesis processes of molecular sieve materials, the hierarchical pore molecular sieve becomes the key point for the research and development of novel petrochemical catalytic materials. The hierarchical pore Y molecular sieve has advantages in two aspects due to the mesoporous or macroporous structure: on one hand, the mass transfer of macromolecular substances is facilitated, the accessibility of catalytic active centers is improved, and the utilization rate of heavy oil is improved; on the other hand, the abundant and unobstructed multi-stage pore structure weakens the influence of pore channel blockage caused by carbon deposition or coking, and prolongs the one-way service life of the catalyst. Therefore, compared with the traditional Y-type molecular sieve, the multi-stage hole Y molecular sieve has more excellent catalytic performance.
The framework of the Y molecular sieve is composed of silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron, and the silicon-aluminum ratio (SiO) of the framework 2 /Al 2 O 3 ) Affecting the thermal stability, hydrothermal stability and acidity of the Y molecular sieve. The Y molecular sieve with higher silicon-aluminum ratio has better thermal stability and hydrothermal stability, the framework structure of the molecular sieve is not easily damaged in the catalytic reaction process and the regeneration process, and better catalytic stability and regeneration performance are shown.
The Y molecular sieve with high silicon-aluminum ratio can be obtained by a direct synthesis method and a post-treatment modification method.
In the direct synthesis method, the high silica-alumina ratio Y molecular sieve can be obtained by the steps of adjusting the feeding proportion, adding the template agent and adjusting the process.
In the preparation of the Y molecular sieve with high silica-alumina ratio by adjusting the raw material ratio, the method is more representative: patent CN104118885B discloses a method for synthesizing NaY zeolite with high silica-alumina ratio, which can synthesize NaY zeolite with high silica-alumina ratio in a shorter crystallization time by adjusting raw material ratio and preparation process conditions without using a template agent.
In the preparation of the Y molecular sieve with high silica-alumina ratio by adding the template agent, the method is more representative: the patent CN104692413B discloses a method for preparing a NaY molecular sieve with a high silicon-aluminum ratio and a product thereof, the method uses a non-volatile short-chain alkyl imidazole ionic liquid as a template agent, and the obtained high-silicon Y molecular sieve has high crystallinity and the silicon-aluminum ratio is more than 6; patent CN100390059C discloses a method for synthesizing faujasite with high silica-alumina ratio, which adopts a suitable template agent, and adopts a hydrothermal crystallization method to directly synthesize the faujasite with high silica-alumina ratio under the condition of less sodium dosage, and the method has the characteristics of short crystallization time and less alkali dosage.
In the preparation of the Y molecular sieve with high silica-alumina ratio by modulation process steps, the method is more representative: patent CN101254929B discloses a preparation method of a NaY molecular sieve with high silica-alumina ratio, which comprises the steps of firstly preparing high-alkalinity silica-alumina gel obtained by uniformly mixing a conventional guiding agent, a silicon source, an aluminum source and water, then heating and crystallizing the high-alkalinity silica-alumina gel for a period of time, adding low-alkalinity silica-alumina gel, uniformly stirring, and heating to crystallize to obtain the NaY molecular sieve with high silica-alumina ratio; the patent CN100404418C and the patent CN100443407C adopt a first step of dynamic crystallization and a second step of static crystallization to obtain the NaY molecular sieve with high silicon-aluminum ratio and small crystal grain, the relative crystallinity of which is more than 80 percent; patent CN103896303B discloses a method for directly synthesizing a high silica alumina ratio superfine NaY molecular sieve, which adopts dynamic crystallization without template agent and additive, and goes through at least three sections of temperature programming to control the crystallization process, the average grain size of the obtained NaY molecular sieve is between 100-500 nm, and the silica-alumina ratio of the framework is higher than 6.5.
In the post-treatment modification method, the Y molecular sieve with high silica-alumina ratio can be obtained through acid treatment modification, hydrothermal roasting treatment and gas-solid phase modification.
The Y molecular sieve with high silica-alumina ratio can be obtained by acid treatment modification or hydrothermal roasting treatment, but the framework structure of the molecular sieve is damaged, the relative crystallinity is obviously reduced, and the stability and the acidity of the Y molecular sieve are greatly influenced. Patent CN103539151B of Shenbao Jian et al discloses a preparation method of Y-type zeolite with rich secondary pores and high silica-alumina ratio.
A representative method for obtaining the Y molecular sieve with high silica-alumina ratio through gas-solid phase modification comprises the following steps: in patent CN102553630B, naY/matrix is prepared by in-situ crystallization, and then the Y-type zeolite catalytic cracking catalyst with high silica-alumina ratio and small crystal grain is prepared by adopting gas phase ultra-stabilization treatment, and the catalyst has high activity and hydrothermal stability and good selectivity of target products.
At present, the research results show that: the ratio of silicon to aluminum of the Y molecular sieve directly synthesized by adjusting the feeding ratio is less than 6.0, and the ratio of silicon to aluminum of the molecular sieve still needs to be improved by subsequent modification treatment; although the silicon-aluminum ratio of the Y molecular sieve prepared by adopting the template method can reach more than 6.0, the used template is expensive, the production cost is increased, and in addition, the relative crystallinity of the molecular sieve is influenced by the removal of the template, and the environment is polluted; the process conditions for preparing the high-silicon Y molecular sieve by using fractional crystallization or dynamic crystallization are harsh, the production process is relatively complex, and the single-kettle yield is low. The preparation of the high-silicon Y molecular sieve by adopting acid treatment or hydrothermal roasting treatment is a method generally applied in industry, but multiple times of exchange, hydrothermal roasting and acid treatment are needed, the process steps are complex, the production cost is high, the framework structure of the molecular sieve is easy to damage in the modification process, the relative crystallinity is obviously reduced, the stability of the molecular sieve is influenced, and meanwhile, non-framework aluminum generated in the post-treatment process influences the surface acidity of the Y molecular sieve, so that the catalytic activity of the molecular sieve is influenced.
In conclusion, the analysis of the industrial production and the technical method reported in the literature shows that: the existing technical method for preparing the Y molecular sieve with high silica-alumina ratio has high production cost, complex process and low yield, and the obtained molecular sieve has low relative crystallinity and the silica-alumina ratio of the molecular sieve is not high enough.
Disclosure of Invention
Based on the problems of high production cost, complex process, low yield, low relative crystallinity of the obtained molecular sieve and low silica-alumina ratio of the molecular sieve in the prior art, the invention aims to provide the Y molecular sieve with high silica-alumina ratio and the preparation method thereof, wherein the Y molecular sieve has the advantages of cheap and easily obtained raw materials, simple process, low production cost and multistage pore structure on the basis of improving the silica-alumina ratio.
The method comprises the steps of firstly carrying out liquid-phase isomorphous substitution on a Y molecular sieve to obtain a boron-containing heteroatom Y molecular sieve, and then carrying out gas-phase boron removal, silicon supplement and aluminum removal on the boron-containing heteroatom Y molecular sieve, namely substituting boron and partial aluminum in the molecular sieve with silicon to finally obtain the Y molecular sieve with high silicon-aluminum ratio. The technical scheme is as follows:
a preparation method of a high-silica-alumina-ratio Y molecular sieve with a hierarchical pore structure is characterized by comprising the following steps: the process comprises the following steps:
(1) Liquid phase isomorphous substitution of Y molecular sieve: carrying out liquid-phase isomorphous substitution on the Y molecular sieve in a solution containing a boron source, wherein the mass ratio of the solution containing the boron source to the Y molecular sieve is (1-100): 1, treating at 30-100 ℃ for 0.1-48 hours, and filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve;
(2) Gas phase isomorphous substitution of boron-containing heteroatom Y molecular sieves: treating the boron-containing heteroatom Y molecular sieve at 100-700 ℃ for 0.1-48 hours, wherein the water content of the obtained dried boron-containing heteroatom Y molecular sieve is lower than 2wt.%; cooling the dried boron-containing heteroatom Y molecular sieve to 80-600 ℃; under the drying condition, introducing dry gas saturated by gas-phase isomorphous substituting agent into the dried boron-containing heteroatom Y molecular sieve, and reacting at the temperature of 120-800 ℃ for 0.1-48 hours; after the reaction is finished, stopping introducing dry gas saturated by the gas-phase isomorphous substituting agent, purging for 0.5-12 hours by using the dry gas, and cooling to room temperature to obtain the high-silica-alumina-ratio Y molecular sieve with the hierarchical pore structure;
the boron source is one or more of fluoroboric acid, ammonium fluoroborate, lithium fluoroborate, sodium fluoroborate and potassium fluoroborate.
In the preparation method according to the invention, the Y molecular sieve preferably comprises NaY molecular sieve and NH 4 One or more of Y molecular sieve, HY molecular sieve or REY molecular sieveWith SiO 2 And Al 2 O 3 The molar ratio of (3.0 to 6.0) is preferably 1.
In the production method according to the present invention, the concentration of the solution containing a boron source is preferably 0.01 to 5mol/L;
in the preparation method of the invention, in the liquid-phase isomorphous substitution process of the Y molecular sieve, the mass ratio of the solution containing the boron source to the Y molecular sieve is preferably (1-50): the treatment temperature is preferably 40 to 95 ℃ and the treatment time is preferably 0.5 to 24 hours.
In the gas-phase isomorphous substitution of the boron-containing heteroatom Y molecular sieve in the preparation method according to the present invention, the drying temperature of the heteroatom Y molecular sieve is preferably 200 to 650 ℃, the drying time is preferably 0.5 to 24 hours, the water content of the boron-containing heteroatom Y molecular sieve after drying is preferably less than 1wt.%, and the temperature is preferably reduced to 120 to 400 ℃.
In the preparation method, the gas-phase isomorphous substituting agent is one or more of dichlorosilane, trichlorosilane and tetrachlorosilane.
In the preparation method, the reaction temperature after the dry gas saturated by the gas-phase isomorphous substituting agent is introduced into the dried boron-containing heteroatom Y molecular sieve is preferably 150-650 ℃, the reaction time is preferably 0.5-12 hours, and the time for purging by the dry gas after the reaction is finished is preferably 1-6 hours. Wherein, the preferable drying gas is one or more of drying air, drying helium, drying nitrogen and drying argon.
The preparation method provided by the invention adopts fluoroboric acid and fluoroborate as boron sources for the first time, and obtains the boron-containing heteroatom Y molecular sieve by a liquid-phase isomorphous substitution method. Compared with the existing molecular sieve modification method, in the preparation method provided by the invention, fluoroboric acid or fluoroborate in an aqueous solution is hydrolyzed to generate borate ions and fluoride ions, wherein the borate ions interact with framework aluminum in the molecular sieve, boron replaces aluminum in the framework to enter the framework of the molecular sieve to form framework boron, the framework structure of the molecular sieve is not damaged, and the crystallinity of the molecular sieve is kept; the fluorine ions have an etching effect on the molecular sieve framework, namely, under relatively mild reaction conditions, fluorine can etch the pore canal, so that the Y molecular sieve has an abundant hierarchical pore structure, and in addition, the formed hierarchical pore enables the pore canal of the molecular sieve to be more unobstructed, thereby reducing the diffusion limitation on gas phase isomorphous substituting agents in the subsequent gas phase isomorphous substituting process.
The preparation method provided by the invention firstly utilizes silane as a gas-phase isomorphous substituent to carry out gas-phase boron removal, dealumination and silicon supplement on the boron-containing heteroatom molecular sieve. Compared with the existing gas phase dealuminization silicon supplementing method, the preparation method of the invention carries out gas phase dealuminization silicon supplementing on heteroatom boron introduced in liquid phase isomorphous substitution. The boron-containing heteroatom molecular sieve skeleton prepared by the invention contains boron, aluminum and silicon, and the boron and the aluminum belong to the same main group and different periodic elements, so the boron and the aluminum have the same coordination structure, but the electronegativity is obviously different. In addition, the bond energy of the B-O covalent bond formed by the framework boron and the framework oxygen is smaller than that of the Al-O covalent bond formed by the framework aluminum and the framework oxygen, so that the framework boron is weaker than the framework aluminum in the heteroatom molecular sieve and is easier to remove from the framework. In the gas-phase isomorphous substitution process of the boron-containing heteroatom molecular sieve, silane is preferably isomorphous substituted with framework boron with poor stability, and then isomorphous substituted with framework aluminum, namely in the gas-phase isomorphous substitution process, boron and partial aluminum in a Y molecular sieve framework are removed from the framework to form vacancies, and meanwhile, silicon in a gas-phase isomorphous substitution agent enters the vacancies of the molecular sieve, so that the substitution of the framework boron and the framework aluminum by the silicon is realized on the basis of the preservation of a crystal phase structure of the Y molecular sieve. Because the positions of boron and partial aluminum in the Y molecular sieve after gas-phase isomorphous substitution are substituted by silicon, the silicon-aluminum ratio of the molecular sieve is obviously improved. In the gas-phase isomorphous substitution process, only the gas-phase substitution agent, framework boron and framework aluminum are substituted, and the molecular sieve framework structure is kept complete and has relatively high relative crystallinity.
The preparation method provided by the invention combines the boron-containing heteroatom molecular sieve prepared by liquid-phase isomorphous substitution of the Y molecular sieve with a gas-phase isomorphous substitution technology, utilizes the instability of heteroatom boron in a molecular sieve framework, preferentially substitutes the heteroatom by a gas-phase isomorphous substitution agent, namely realizes the substitution of framework boron and framework aluminum by silicon on the basis of preserving the crystal phase structure of the Y molecular sieve, thereby greatly improving the framework silicon-aluminum ratio of the Y molecular sieve, reserving the complete molecular sieve framework structure, maintaining the high relative crystallinity of the molecular sieve and forming a rich multistage pore structure.
Compared with the prior art, the invention has the innovation points and advantages that:
1. the method has small damage to the framework of the molecular sieve, and the prepared Y molecular sieve has high silicon-aluminum ratio and abundant hierarchical pore structures.
2. The boron source used by the method is cheap and easy to obtain, and the production cost is reduced.
3. The method can adjust the multi-stage pore structure and the proportion of the Y molecular sieve by changing the process conditions of liquid-phase isomorphous substitution and gas-phase isomorphous substitution on the basis of ensuring the relative crystallinity of the Y molecular sieve, and the prepared Y molecular sieve with high silica-alumina ratio can keep the complete molecular sieve framework structure, maintain the high relative crystallinity and form rich multi-stage pore structures.
Detailed Description
The present invention is further illustrated by the following comparative examples and examples, without thereby limiting the scope of the invention.
In each example, XRD characterization of the synthesized product was performed to calculate the framework silicon to aluminum ratio (SiO) and relative crystallinity of each sample 2 /Al 2 O 3 ) The crystal packet parameter a of the molecular sieve is measured according to the RIPP145-90 standard method 0 Then according to the formula SiO 2 /Al 2 O 3 Molar ratio = (2.5935-a) 0 )/(a 0 -2.4212) × 2 calculated; the relative crystallinity is calculated by using NaY molecular sieve of southern Kai university as a standard sample.
Example 1
Liquid phase isomorphous substitution of Y molecular sieve: mixing 0.5mol/L fluoroboric acid solution with NaY molecular sieve according to the weight ratio of 10:1, stirring for 2 hours at 80 ℃, filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve.
Gas phase isomorphous substitution of boron containing heteroatom Y molecular sieves: weighing machine10g of boron-containing heteroatom Y molecular sieve, drying at 500 deg.C for 12 hr, cooling to 400 deg.C, and introducing SiCl 4 And (3) heating saturated dry nitrogen to 500 ℃, reacting for 4 hours, blowing the nitrogen for 2 hours by using the dry nitrogen after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S1 with high silicon-aluminum ratio and high relative crystallinity.
Example 2:
liquid phase isomorphous substitution of Y molecular sieve: mixing 0.5mol/L ammonium fluoroborate solution with NH 4 The Y molecular sieve is prepared according to the following steps of 10:1, stirring for 2 hours at 70 ℃, and filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve.
Gas phase isomorphous substitution of boron containing heteroatom Y molecular sieves: 10g of boron-containing heteroatom Y molecular sieve are weighed, dried at 600 ℃ for 12 hours, cooled to 350 ℃ and then charged with SiCl 4 And (3) heating saturated dry nitrogen to 550 ℃, reacting for 2 hours, blowing the reaction product for 2 hours by using the dry nitrogen after the reaction is finished, and cooling the reaction product to room temperature to obtain the Y molecular sieve S2 with high silicon-aluminum ratio and high relative crystallinity.
Example 3:
liquid phase isomorphous substitution of Y molecular sieve: mixing 0.3mol/L lithium fluoborate solution with HY molecular sieve according to the weight ratio of 8:1, stirring for 4 hours at 65 ℃, and filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve.
Gas phase isomorphous substitution of boron containing heteroatom Y molecular sieves: 10g of boron-containing heteroatom Y molecular sieve are weighed, dried at 550 ℃ for 12 hours, cooled to 350 ℃ and then SiCl is introduced 4 And (3) heating saturated dry nitrogen to 580 ℃, reacting for 2 hours, purging with dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S3 with high silica-alumina ratio and high relative crystallinity.
Example 4:
liquid phase isomorphous substitution of Y molecular sieve: mixing 0.8mol/L sodium fluoborate solution with a REY molecular sieve according to the weight ratio of 15:1, stirring for 3 hours at 75 ℃, filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve.
Gas phase isomorphous substitution of boron-containing heteroatom Y molecular sieves: 10g of boron-containing heteroatom Y molecular sieve are weighed, dried at 600 ℃ for 18 hours, cooled to 400 ℃ and then charged with SiCl 4 And (3) heating saturated dry nitrogen to 600 ℃, reacting for 5 hours, blowing the reaction product for 2 hours by using the dry nitrogen after the reaction is finished, and cooling the reaction product to room temperature to obtain the Y molecular sieve S4 with high silicon-aluminum ratio and high relative crystallinity.
Example 5:
liquid phase isomorphous substitution of Y molecular sieve: 1.0mol/L potassium fluoborate solution and NH 4 The molecular sieve Y is prepared according to the following weight ratio of 10:1, stirring for 2 hours at 80 ℃, filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve.
Gas phase isomorphous substitution of boron-containing heteroatom Y molecular sieves: 10g of boron-containing heteroatom Y molecular sieve are weighed, dried at 600 ℃ for 24 hours, cooled to 400 ℃ and then charged with SiCl 4 And (3) heating saturated dry nitrogen to 450 ℃, reacting for 6 hours, blowing the nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S5 with high relative crystallinity and high silica-alumina ratio.
Example 6:
liquid phase isomorphous substitution of Y molecular sieve: mixing 2.0mol/L ammonium fluoborate solution with NaY molecular sieve according to the ratio of 20:1, stirring for 4 hours at 80 ℃, filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve.
Gas phase isomorphous substitution of boron containing heteroatom Y molecular sieves: 10g of boron-containing heteroatom Y molecular sieve are weighed, dried at 600 ℃ for 12 hours, cooled to 350 ℃ and then SiCl is introduced 4 And (3) heating saturated dry nitrogen to 600 ℃, reacting for 1 hour, blowing with the dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S6 with high silicon-aluminum ratio and high relative crystallinity.
Comparative example:
gas phase isomorphous substitution of NaY molecular sieve: weighing 10g of NaY molecular sieve, drying at 500 ℃ for 12 hours, cooling to 400 ℃, and introducing SiCl 4 Saturation ofHeating the reaction solution to 500 ℃, reacting for 4 hours, blowing the reaction solution for 2 hours by using dry nitrogen after the reaction is finished, and cooling the reaction solution to room temperature to obtain the Y molecular sieve D1 with high silica-alumina ratio and high relative crystallinity.
Table 1 shows the results of the specific surface area and pore volume of the samples obtained in examples 1 to 6 and comparative example.
TABLE 1
Claims (6)
1. A preparation method of a high-silica-alumina-ratio Y molecular sieve with a hierarchical pore structure is characterized by comprising the following steps: the process comprises the following steps:
(1) Liquid phase isomorphous substitution of Y molecular sieve: carrying out liquid-phase isomorphous substitution on the Y molecular sieve in a solution containing a boron source, wherein the mass ratio of the solution containing the boron source to the Y molecular sieve is (1-100): 1, treating at 30-100 ℃ for 0.1-48 hours, and filtering, washing and drying a product after the reaction is finished to obtain the boron-containing heteroatom Y molecular sieve;
(2) Gas phase isomorphous substitution of boron containing heteroatom Y molecular sieves: treating the boron-containing heteroatom Y molecular sieve at 100-700 ℃ for 0.1-48 hours to obtain a dried boron-containing heteroatom Y molecular sieve with the water content of less than 2wt.%, and cooling the dried boron-containing heteroatom Y molecular sieve to 80-600 ℃; under the drying condition, introducing dry gas saturated by a gas-phase isomorphous substituting agent into the dried boron-containing heteroatom Y molecular sieve, and reacting at the temperature of 120 to 800 ℃ for 0.1 to 48 hours; after the reaction is finished, stopping introducing dry gas saturated by the gas-phase isomorphous substituting agent, purging for 0.5 to 12 hours by using the dry gas, and cooling to room temperature to obtain the high-silica-alumina-ratio Y molecular sieve with the hierarchical pore structure; the boron source is one or more of fluoroboric acid, ammonium fluoroborate, lithium fluoroborate, sodium fluoroborate and potassium fluoroborate, and the concentration of the solution containing the boron source is 0.01-5 mol/L; the gas-phase isomorphous substituting agent is one or more of dichlorosilane, trichlorosilane and tetrachlorosilane.
2. The method for preparing the high silica alumina ratio Y molecular sieve with the hierarchical pore structure according to claim 1, wherein the method comprises the following steps: the Y molecular sieve comprises NaY molecular sieve and NH 4 One or more of Y molecular sieve, HY molecular sieve or REY molecular sieve, and SiO 2 And Al 2 O 3 The molar ratio of silicon to aluminum is 3.0 to 6.0) to 1.
3. The method for preparing the Y molecular sieve with the high silica-alumina ratio and the hierarchical pore structure according to claim 1, wherein in the liquid-phase isomorphous substitution of the Y molecular sieve, the mass ratio of a solution containing a boron source to the Y molecular sieve is (1 to 50): 1, the processing temperature is 40 to 95 ℃, and the processing time is 0.5 to 24 hours.
4. The method for preparing the Y molecular sieve with the hierarchical pore structure and the high silica alumina ratio as claimed in claim 1, wherein in the gas phase isomorphous substitution of the Y molecular sieve containing boron and heteroatom, the drying temperature of the Y molecular sieve containing heteroatom is 200 to 650 ℃, the drying time is 0.5 to 24 hours, the water content of the Y molecular sieve containing boron and heteroatom after drying is lower than 1wt.%, and the temperature is reduced to 120 to 400 ℃.
5. The method for preparing the Y molecular sieve with the high silica-alumina ratio and the hierarchical pore structure according to claim 1, wherein the reaction temperature of the dried boron-containing heteroatom Y molecular sieve after the dry gas saturated with the gas-phase isomorphous substituting agent is 150 to 650 ℃, the reaction time is 0.5 to 12 hours, and the time of purging with the dry gas after the reaction is finished is 1 to 6 hours.
6. The method for preparing the Y molecular sieve with the high silica-alumina ratio and the hierarchical pore structure according to claim 5, wherein the dry gas is one or more of dry air, dry helium, dry nitrogen and dry argon.
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