阅读说明：本技术 一种具有多级孔结构的高硅铝比y分子筛及其制备方法 (High-silica-alumina-ratio Y molecular sieve with hierarchical pore structure and preparation method thereof ) 是由 王凌涛 臧甲忠 刘冠锋 于海斌 洪美花 邱宇 王银斌 洪鲁伟 宋万仓 季超 石芳 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种具有多级孔结构的高硅铝比Y分子筛及其制备方法。本发明制备方法包括：在含有硼源的溶液30～100℃下对Y分子筛进行液相同晶取代,反应结束后将产物经过滤、洗涤、干燥,得到含硼的杂原子Y分子筛；向干燥后的含硼的杂原子Y分子筛中通入被气相同晶取代剂饱和的干燥气体,在120～800℃下反应0.1～48小时,反应结束后,停止通入被气相同晶取代剂饱和的干燥气体,用干燥气体吹扫0.5～12小时,降至室温,得到具有多级孔结构的高硅铝比Y分子筛。本发明提供的高硅铝比Y分子筛的相对结晶度大于90％,硅铝比大于10,制备工艺简单,生产成本低,具有工业应用前景。本发明方法对分子筛骨架破坏小,制备得到的Y分子筛的硅铝比高,且具有丰富的多级孔结构；还具有生产成本低。(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 hierarchical pore structure. The high-silicon-aluminum-ratio Y molecular sieve provided by the invention has the advantages that the relative crystallinity is more than 90%, the silicon-aluminum ratio is more than 10, the preparation process is simple, the production cost is low, and the industrial application prospect is realized. The method has small damage to the framework of the molecular sieve, and the prepared Y molecular sieve has high silicon-aluminum ratio and rich hierarchical pore structure; and the production cost is low.)

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 a 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 dried boron-containing heteroatom Y molecular sieve is lower than 2 wt.%; cooling the dried boron-containing heteroatom Y molecular sieve to 80-600 ℃; under the drying condition, introducing a drying gas saturated by a gas-phase isomorphous substituent into the dried boron-containing heteroatom Y molecular sieve, and reacting at the temperature of 120-800 ℃ for 0.1-48 hours; and after the reaction is finished, stopping introducing the 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.

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 NH₄One or more of Y molecular sieve, HY molecular sieve or REY molecular sieve, and SiO₂And Al₂O₃The molar ratio of silicon to aluminum is 3.0-6.0: 1.

3. 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 boron source is one or more of fluoboric acid, ammonium fluoborate, lithium fluoborate, sodium fluoborate and potassium fluoborate.

4. The method for preparing the high silica alumina ratio Y molecular sieve with the hierarchical pore structure according to claim 3, wherein the method comprises the following steps: the concentration of the solution containing the boron source is 0.01-5 mol/L.

5. The preparation method of the Y molecular sieve with the hierarchical pore structure and the high silica-alumina ratio as claimed in claim 1, wherein in the liquid-phase isomorphous substitution process of the Y molecular sieve, the mass ratio of a solution containing a boron source to the Y molecular sieve is (1-50): 1, the treatment temperature is 40-95 ℃, and the treatment time is 0.5-24 hours.

6. 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 boron-containing heteroatom Y molecular sieve, the drying temperature of the heteroatom Y molecular sieve is 200-650 ℃, the drying time is 0.5-24 hours, the water content of the dried boron-containing heteroatom Y molecular sieve is less than 1 wt.%, and the temperature is reduced to 120-400 ℃.

7. The method for preparing the high silica-alumina ratio Y molecular sieve with the hierarchical pore structure as set forth in claim 1, wherein the gas phase isomorphous substituting agent is one or more of dichlorosilane, trichlorosilane and tetrachlorosilane.

8. 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 the reaction temperature of the dried boron-containing heteroatom Y molecular sieve after introducing the dry gas saturated by the gas-phase isomorphous substituent is 150-650 ℃, the reaction time is 0.5-12 hours, and the time of purging by the dry gas after the reaction is finished is 1-6 hours.

9. The method for preparing the high silica-alumina ratio Y molecular sieve with the hierarchical pore structure of claim 8, wherein the dry gas is one or more of dry air, dry helium, dry nitrogen and dry argon.

10. A high silica-alumina ratio Y molecular sieve having a hierarchical pore structure prepared according to the method of any one of claims 1-9.

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 to 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 pore 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 framework₂/Al₂O₃) 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 short crystallization time by adjusting the raw material ratio and the 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: patent CN104692413B discloses a method for preparing NaY molecular sieve with high silica-alumina ratio and a product thereof, the method uses nonvolatilizable short-chain alkyl imidazole ionic liquid as a template agent, and the obtained high-silica Y molecular sieve has high crystallinity and the silica-alumina 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 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 a 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 the 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 a high silica alumina ratio small crystal grain NaY molecular sieve with the relative crystallinity of more than 80 percent; the patent CN103896303B discloses a method for directly synthesizing a high silica-alumina ratio superfine NaY molecular sieve, which adopts dynamic crystallization without a template agent and an additive, and undergoes at least three stages of temperature programming control crystallization processes, the average grain size of the obtained NaY molecular sieve is between 100 and 500nm, and the framework silica-alumina ratio 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 sword et al discloses a preparation method of Y-type zeolite with rich secondary pores and high silica-alumina ratio, which comprises the steps of firstly synthesizing Fe-Y molecular sieve, and then respectively carrying out ammonium exchange and hydrothermal roasting treatment twice, wherein the obtained Y-type zeolite has higher silica-alumina ratio and more rich secondary pores.

The method for obtaining the high-silica-alumina-ratio Y molecular sieve through gas-solid phase modification is representative: 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 grains 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 silicon-aluminum ratio of the Y molecular sieve directly synthesized by adjusting the feeding ratio is less than 6.0, and the subsequent modification treatment is still needed to improve the silicon-aluminum ratio of the molecular sieve; 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 utilizing fractional crystallization or dynamic crystallization are harsh, the production process is relatively complex, and the yield of a single kettle 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 and low yield in the prior art, low relative crystallinity of the obtained molecular sieve and low silicon-aluminum ratio of the molecular sieve, the invention aims to provide the Y molecular sieve with high silicon-aluminum 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 a multistage pore structure on the basis of improving the silicon-aluminum 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 a 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 dried boron-containing heteroatom Y molecular sieve is lower than 2 wt.%; cooling the dried boron-containing heteroatom Y molecular sieve to 80-600 ℃; under the drying condition, introducing a drying gas saturated by a gas-phase isomorphous substituent 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 fluoboric acid, ammonium fluoborate, lithium fluoborate, sodium fluoborate and potassium fluoborate.

In the preparation method according to the invention, the Y molecular sieve preferably comprises NaY molecular sieve and NH₄One or more of Y molecular sieve, HY molecular sieve or REY molecular sieve, and SiO₂And Al₂O₃The molar ratio of (3.0-6.0) to (1) is preferred.

In the preparation method, the concentration of the solution containing the boron source is preferably 0.01-5 mol/L;

in the preparation method, 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): 1, the treatment temperature is preferably 40-95 ℃, and the treatment time is preferably 0.5-24 hours.

In the preparation method, in the gas-phase isomorphous substitution of the boron-containing heteroatom Y molecular sieve, the drying temperature of the heteroatom Y molecular sieve is preferably 200-650 ℃, the drying time is preferably 0.5-24 hours, the water content of the dried boron-containing heteroatom Y molecular sieve is preferably lower than 1 wt.%, and the temperature is preferably reduced to 120-400 ℃.

In the preparation method, the gas-phase isomorphous substituent is one or more of dichlorosilane, trichlorosilane and tetrachlorosilane.

According to the preparation method, the reaction temperature of the dried boron-containing heteroatom Y molecular sieve after the dry gas saturated by the gas-phase isomorphous substituent is introduced is preferably 150-650 ℃, the reaction time is preferably 0.5-12 hours, and the time of 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 and enters 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 boron removal and silicon supplementing on heteroatom boron introduced in liquid-phase isomorphous substitution. The boron-containing heteroatom molecular sieve prepared by the invention contains boron, aluminum and silicon, and because the boron and the aluminum belong to the same main group and different periodic elements, 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 is substituted with framework boron and framework aluminum, the framework structure of the molecular sieve is kept complete, and the molecular sieve 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, but the scope of the invention which can be practiced is not limited thereby.

In each example, XRD characterization of the synthesized product was performed to calculate the framework silicon-aluminum ratio (SiO) and relative crystallinity of each sample₂/Al₂O₃) The crystal packet parameter a of the molecular sieve is measured according to the RIPP145-90 standard method₀Then according to the formula SiO₂/Al₂O₃(2.5935-a)₀)/(a₀-2.4212) × 2 calculation; 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: 10g of boron-containing heteroatom Y molecular sieve are weighed, dried at 500 ℃ for 12 hours, cooled to 400 ℃ and then SiCl is introduced₄And (3) heating saturated dry nitrogen to 500 ℃, reacting for 4 hours, purging with dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S1 with high silica-alumina ratio and high relative crystallinity.

Example 2:

liquid phase isomorphous substitution of Y molecular sieve: 0.5mol/L ammonium fluoroborate solution and NH₄The molecular sieve Y is prepared according to the following weight ratio of 10: 1, stirring for 2 hours at 70 ℃, 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 introduced₄And (3) heating saturated dry nitrogen to 550 ℃, 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 S2 with high silica-alumina 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 ℃, 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 introduced₄And (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 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 SiCl is introduced₄And (3) heating saturated dry nitrogen to 600 ℃, reacting for 5 hours, purging with dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S4 with high silica-alumina ratio and high relative crystallinity.

Example 5:

liquid phase isomorphous substitution of Y molecular sieve: 1.0mol/L potassium fluoborate solution and NH₄The 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 SiCl is introduced₄Saturated dry nitrogen, heating to 450 ℃, reacting for 6 hours, purging with dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecule with high silicon-aluminum ratio and high relative crystallinityScreen S5.

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 introduced₄And (3) heating saturated dry nitrogen to 600 ℃, reacting for 1 hour, purging with dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve S6 with high silica-alumina ratio and high relative crystallinity.

Comparative example:

gas phase isomorphous substitution of NaY molecular sieve: weighing 10g NaY molecular sieve, drying at 500 deg.C for 12 hr, cooling to 400 deg.C, and introducing SiCl₄And (3) heating saturated dry nitrogen to 500 ℃, reacting for 4 hours, purging with dry nitrogen for 2 hours after the reaction is finished, and cooling to room temperature to obtain the Y molecular sieve D1 with high silica-alumina ratio and high relative crystallinity.

Table 1 shows the specific surface area and pore volume results of the samples obtained in examples 1 to 6 and comparative examples.

TABLE 1