阅读说明：本技术 一种介-微多级孔结构y型沸石分子筛的制备方法 (Preparation method of mesoporous-microporous Y-type zeolite molecular sieve ) 是由 袁程远 张海涛 谭争国 刘超伟 孙雪芹 曹庚振 慕彦君 潘志爽 段宏昌 郑云锋 于 2019-03-12 设计创作，主要内容包括：本发明提供了一种具有介-微多级孔结构的Y型沸石分子筛的制备方法,属于沸石分子筛制备技术领域,该方法过程包括：将NaY沸石分子筛、铵盐和水混合,经搅拌、过滤和洗涤后得到铵型Y型沸石分子筛；将铵型Y型沸石分子筛、含硼化合物和水混合搅拌,然后过滤、洗涤,最后经高温水热处理,即得介-微多级孔结构的Y型沸石分子筛。相对于传统Y型沸石分子筛,本发明提供的介-微多级孔结构Y型沸石分子筛具有丰富的介孔孔道结构,并且其制备方法过程简单、环境友好、成本低廉。(The invention provides a preparation method of a Y-type zeolite molecular sieve with a meso-micro hierarchical pore structure, belonging to the technical field of zeolite molecular sieve preparation, and the method comprises the following steps: mixing the NaY zeolite molecular sieve, ammonium salt and water, and stirring, filtering and washing to obtain an ammonium Y-type zeolite molecular sieve; mixing and stirring the ammonium Y-type zeolite molecular sieve, the boron-containing compound and water, then filtering, washing and finally carrying out high-temperature hydrothermal treatment to obtain the Y-type zeolite molecular sieve with the mesoporous-micro hierarchical pore structure. Compared with the traditional Y-type zeolite molecular sieve, the Y-type zeolite molecular sieve with the mesoporous-micro hierarchical pore structure provided by the invention has a rich mesoporous pore channel structure, and the preparation method has the advantages of simple process, environmental friendliness and low cost.)

1. A preparation method of a mesoporous-microporous structure Y-type zeolite molecular sieve is characterized by comprising the following steps:

(1) exchanging the NaY molecular sieve with ammonium ions: mixing and pulping the required ammonium salt, the NaY molecular sieve and deionized water according to the mass ratio of the ammonium salt to the NaY molecular sieve to the deionized water of 0.1-1:1:5-50, adjusting the pH value of a system to be 2-6 by using dilute hydrochloric acid, continuously stirring at the temperature of 50-95 ℃ for ion exchange for 0.5-5 hours, and then filtering and washing;

(2) and (2) mixing and pulping the required boron-containing compound, the molecular sieve obtained in the step (1) and deionized water according to the mass ratio of the boron-containing compound to the deionized water of 0.01-0.1:1:5-50 in terms of elemental boron, continuously stirring at the temperature of 30-95 ℃ for ion exchange for 0.5-3 hours, filtering, washing, and roasting the obtained filter cake at the temperature of 400-800 ℃ for 1-4 hours under the condition of 100% of water vapor to obtain the Y-type zeolite molecular sieve with the meso-micro hierarchical pore structure.

2. The preparation method of claim 1, wherein in the step (1), the mass ratio of the ammonium salt to the NaY molecular sieve to the deionized water is 0.15-0.5:1: 10-30.

3. The process according to claim 1, wherein in the step (1), the pH of the system is adjusted to 3 to 5 with dilute hydrochloric acid, and then ion exchange is carried out at 60 to 90 ℃ for 1 to 3 hours with continuous stirring.

4. The method according to claim 1, wherein in the step (1), the ammonium salt is a water-soluble ammonium salt.

5. The method according to claim 4, wherein the ammonium salt is selected from one or more of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium oxalate, ammonium citrate and ammonium phosphate.

6. The preparation method according to claim 1, wherein in the step (2), the mass ratio of the boron-containing compound to the molecular sieve obtained in the step (1) to the deionized water is 0.015-0.05:1:10-30 calculated as elemental boron.

7. The method according to claim 1, wherein in the step (2), the ion exchange time is 1 to 2 hours and the continuous stirring temperature is 60 to 90 ℃.

8. The preparation method according to claim 1, wherein in the step (2), the calcination temperature of the filter cake is 500-700 ℃.

9. The production method according to claim 1, wherein in the step (2), the boron-containing compound is a water-soluble inorganic boron-containing compound.

10. The method according to claim 9, wherein the boron-containing compound is one or more selected from boric acid, ammonium borate and ammonium fluoroborate.

Technical Field

The invention relates to a preparation method of a Y-type zeolite molecular sieve, in particular to a preparation method of a Y-type zeolite molecular sieve with a meso-micro hierarchical pore structure.

Background

The Fluid Catalytic Cracking (FCC) technology is an important means for secondary processing of heavy oil in the world today due to its characteristics of low investment, strong raw material adaptability and simple operation, and the catalytic cracking catalyst plays a key role. With the increasing exhaustion of high-quality light crude oil resources and the improvement of delayed coking production energy in the world, in order to increase benefits, refineries blend a large proportion of inferior crude oil such as residual oil, coking wax oil, deasphalted oil and the like in a catalytic cracking unit, thereby seriously affecting the stable operation of the catalytic cracking unit and the distribution of cracked products, and further providing higher requirements for the performance of catalytic cracking catalysts.

The Si/Al ratio of the Y-type molecular sieve is generally between 1.5 and 3, the Y-type molecular sieve belongs to a faujasite type (FAU) molecular sieve, and the Y-type molecular sieve has a three-dimensional twelve-membered ring channel structure and a diameter of about 0.74 nm. Due to the unique pore channel structure, suitable acidity and thermal stability of the Y-type molecular sieve, the Y-type molecular sieve is widely applied to the petrochemical industry and plays an irreplaceable role in a Fluid Catalytic Cracking (FCC) reaction. However, the relatively narrow pore channel structure of the Y-type zeolite molecular sieve causes that heavy oil molecules with larger diameters are difficult to enter the pore channels with pore diameters of about 0.74nm, and in addition, the smaller pore diameters also increase the mass transfer resistance of reactants and products, so that reaction products cannot be diffused and deposited on the surface of the catalyst in time to form carbon deposition, and the catalytic activity is reduced. Thus, the smaller pore size limits the use of microporous zeolites in reactions involving macromolecules.

Mesoporous materials, for example, have a greater pore size advantage than conventional zeolite molecular sieves. Allowing molecules of larger diameter to enter the pore channels can catalyze reactions involving macromolecules. On the other hand, the larger aperture reduces the mass transfer resistance, which is beneficial to the diffusion of reactants and products. However, the acidity and hydrothermal stability of mesoporous molecular sieves are poor due to their amorphous pore wall structure, especially much lower than that of microporous zeolites, and these factors limit their use in catalysis.

In order to overcome the limitations of microporous zeolite and mesoporous molecular sieve, many researchers are dedicated to find a new material combining the advantages of microporous zeolite material and mesoporous material, which has high hydrothermal stability and high acid strength, and contains larger pore diameter, so that the advantages of the microporous zeolite material and the mesoporous material are complementary, and the new material can be widely applied to the field of catalysis. The mesoporous templating agent Cetyl Trimethyl Ammonium Bromide (CTAB) is added to the coagulation solution of the synthetic MFI zeolite containing Tetrapropylammonium (TPA), it is expected that CTAB can direct the formation of the mesoporous structure, while the microporous templating agent TPA can direct the formation of micropores on the mesoporous walls, thereby forming the composite molecular sieve having the micro-mesoporous structure. In practice, however, the two templates compete with each other to form a mixture of mesoporous and microporous materials. In 2008, researchers prepared three-dimensional ordered mesoporous carbon hard templates with adjustable pore diameters, and successfully synthesized ordered nano single crystals and generated intercrystalline mesopores by using the hard templates. In 2011, researchers creatively synthesized a series of bifunctional quaternary ammonium salt surfactants, which can simultaneously guide the generation of mesopores and micropores. These research results have realized the pore structure of hierarchical pore molecular sieve, the material not only contains mesopores, but also has crystallized pore wall structure, but these methods are too high in synthetic cost, complicated in preparation step, etc., unfavorable for the commercial process.

At present, a catalytic cracking catalyst mainly comprises a Y-type molecular sieve and a matrix component, wherein the Y-type molecular sieve is used as a main active component of the catalytic cracking catalyst and has a decisive effect on the catalytic cracking performance of the catalyst. Because heavy oil molecules have the characteristics of large molecular size and easy coke generation, the heavy oil catalytic cracking catalyst is required to have suitable surface acidity and larger specific surface and pore volume so as to be beneficial to mass transfer and diffusion of heavy oil macromolecules.

The Y-type molecular sieve belongs to a microporous zeolite molecular sieve, and the aperture of the Y-type molecular sieve is less than 2nm, so that the Y-type molecular sieve serving as an active component is difficult to meet the requirement of the current heavy oil catalytic cracking reaction. Aiming at the problem, a solution for preparing the Y-type molecular sieve with the meso-micro hierarchical pore structure is provided. Compared with the traditional Y-type molecular sieve, the Y-type molecular sieve with the meso-micro hierarchical pore structure not only has good surface acidity, but also has higher specific surface and pore volume, so that the Y-type molecular sieve becomes a research hotspot in the field of current catalytic cracking.

Jacobsen et al (Journal of the American Chemical Society,200,122(29): 7116-.

Xiao et al (Colloids and Surfaces A: physical and engineering characteristics, 2008,318:269-274) use cationic polymer poly (diallyldimethylammonium chloride) as an organic template, and synthesize the mesoporous NaX molecular sieve with the mesoporous size of 4nm-50nm under the combined action of faujasite precursors. Xiao and MeO porous Materials,2010,131:58-67) respectively use tetraethylammonium radical and tetrapropylammonium radical small cations and organic cationic polymers with the Mesoporous size of polymers poly diallyl dimethyl ammonium chloride and dimethyl diallyl ammonium chloride acrylamide copolymer (PDD-AM) as template agents to synthesize Mesoporous Beta and ZSM-5 molecular sieves with the Mesoporous size of 5nm-40 nm. In the process, the hydrophilic cationic polymer is easily dissolved in a synthesis system and effectively interacts with a negatively charged silicon source to crystallize and form the molecular sieve.

Zhu et al (Zhu H.B., et al, The Journal of Physical Chemistry C,112: 17257-.

CN102259889A discloses a method for synthesizing Y-type mesoporous zeolite, which takes water glass as a silicon source, aluminum sulfate and sodium aluminate as aluminum sources, and a macromolecular sieve surfactant N, N-diethyl-N-hexadecyl-N- (3-methoxylsilylpropane) ammonium iodide as a template agent, and synthesizes the mesoporous Y-type zeolite molecular sieve by a traditional hydrothermal method.

CN101108736A discloses a preparation method of a Y-type molecular sieve with micropores and mesopores, which comprises the steps of mixing and crystallizing an alkali source, an aluminum source, a silicon source and water, adjusting the pH value of the system with dilute acid, adding a surfactant for further crystallization, and finally filtering, drying and roasting to obtain the Y-type molecular sieve.

CN201110182984.6 discloses a method for synthesizing Y-type mesoporous zeolite, which takes water glass as a silicon source, aluminum sulfate and sodium aluminate as aluminum sources, and a macromolecular surfactant N, N-diethyl-N-hexadecyl-N- (3-methoxylsilylpropane) ammonium iodide as a template agent, and synthesizes the Y-type mesoporous zeolite by a traditional hydrothermal method. The synthetic method is simple, and the synthesized Y zeolite material has a large number of mesoporous structures while having a traditional molecular sieve microporous structure, so that the Y zeolite material has wide application prospects as a catalyst and a carrier thereof in the heavy oil refining industry and the synthesis industry of macromolecular fine chemicals.

CN200910056811.2 discloses a method for synthesizing mesoporous zeolite, which mainly solves the problems of the prior art that the preparation of mesoporous zeolite needs expensive or difficultly obtained materials as mesoporous templates, the synthesis process is complex and the cost is highAnd (5) problems are solved. The invention mixes silicon source, aluminum source, alkali metal, organic amine structure directing agent SDA, macromolecule mesoporous template agent R and water, the mole ratio of the silicon source, aluminum source, alkali metal, organic amine structure directing agent SDA and water in the mixture is: SiO 2₂/Al₂O₃＝20～200，SiO₂/Na₂O＝10～100，H₂O/SiO₂＝5～300，SDA/SiO₂00.1-0.5, a polymer mesoporous template and SiO₂In a weight ratio of R/SiO₂0.05-3; crystallizing the mixture at 140-170 ℃ for 2-10 days to obtain a crystallized product, and washing, drying and roasting the crystallized product to obtain the mesoporous zeolite; wherein the polymer mesoporous template agent R is selected from at least one of polyvinyl alcohol, polyvinyl formal or polyvinyl butyral, and the technical scheme can better solve the problem and can be used in the industrial production of mesoporous zeolite.

CN10321400A discloses a mesoporous Y-type zeolite molecular sieve and a preparation method thereof, which firstly prepares a Y-type zeolite guiding agent, and then guides and synthesizes the mesoporous Y-type zeolite molecular sieve by using amphiphilic organosilicon N, N-dimethyl-N- [3- (trimethoxysilane) propyl ] octadecyl ammonium chloride as a mesoporous template agent.

CN103172082A discloses a preparation method of a mesoporous-containing Y-type molecular sieve, which comprises the following steps: firstly, preparing a sodium type Y-shaped molecular sieve; secondly, preparing an ammonium Y-type molecular sieve; thirdly, treating the organic acid aqueous solution; fourthly, NaOH treatment; fifthly, treating ammonium nitrate aqueous solution.

CN104760973A discloses a Y-type molecular sieve with ultrahigh mesoporous content and a preparation method thereof. The method comprises the following steps: pretreating the Y-type zeolite at the temperature of 300-600 ℃ for 1-5 h; cooling to 200-600 ℃; in an anhydrous drying environment, introducing dry gas saturated by the dealuminizing and silicon supplementing agent into the pretreated Y-type zeolite, and reacting for 0.5-7h to obtain a crude product; or in an anhydrous drying environment, raising the temperature to 250-700 ℃ at a constant speed, introducing dry gas saturated by the dealumination silicon-supplementing agent into the pretreated Y-type zeolite, and reacting for 0.5-7h to obtain a crude product; carrying out acid treatment on the crude product; and (4) carrying out alkali treatment on the crude product after the acid treatment to obtain the Y-type molecular sieve.

CN106927477A discloses a preparation method of a mesoporous Y-type molecular sieve, which is characterized in that the method comprises the steps of treating the Y-type molecular sieve in a mixed solution of glycerol and cellulose at 150-220 ℃ for 0.5-5 h, contacting the treated Y-type molecular sieve with an inorganic guiding agent at normal temperature and normal pressure for 0.5-2 h, placing the mixture in a closed reaction kettle at 80-120 ℃ for 2-20 h, and recovering the obtained product.

CN106809857A discloses a method for synthesizing an ordered macroporous-mesoporous-microporous hierarchical pore Y-type silicon-aluminum molecular sieve, which comprises the following steps: 1) preparing Y-type silicon-aluminum molecular sieve nanocrystals, 2) preparing macroporous template polymer microspheres, and 3) preparing a precursor composite material: mixing Y-type silicon-aluminum molecular sieve nanocrystals with macroporous template polymer microspheres and dispersing the mixture in water to form a suspension, adding an organic carbon source and a strong oxidizing acid into the suspension, performing ultrasonic evaporation and self-assembly to obtain a mixed solution, and then performing carbonization and solidification treatment on the mixed solution to obtain a precursor composite material; 4) and removing the macroporous template and the carbon material in the precursor composite material through high-temperature calcination to obtain the ordered macroporous-mesoporous-microporous hierarchical-pore Y-type silicon-aluminum molecular sieve.

CN106927479A discloses a method for preparing a mesoporous Y-type molecular sieve, which is characterized by comprising the following steps: (1) mixing a silicon source, an aluminum source and water, and then aging to obtain a crystallization directing agent; (2) firstly, mixing a crystallization guiding agent and a silicon source, then adding an aluminum source and water to prepare reactive silicon-aluminum sol, and crystallizing the reactive silicon-aluminum sol to obtain a crystallization liquid I, wherein in the reactive silicon-aluminum sol, the addition amount of the crystallization guiding agent accounts for 0.5-5% of the total mass of the reactive silicon-aluminum sol; (3) adding polyacrylamide into the crystallization liquid I, continuing crystallization and recovering the product.

CN201410604975.5 discloses a preparation method and application of a titanium-containing mesoporous Y-type molecular sieve with catalytic oxidation activity, which relates to a preparation method and application of a titanium-containing mesoporous molecular sieve. The invention aims to solve the problem that the mesoporous Y-type molecular sieve prepared by the existing method is poor in oxidation desulfurization effect. The method comprises the following steps: firstly, calcining a mesoporous Y-type molecular sieve; secondly, mixing the mixture with an organic titanium source, performing ultrasonic dispersion, and drying; thirdly, calcining at high temperature to obtain the catalyst.

CN201511020128.5 discloses a method for preparing a mesoporous Y-type molecular sieve, which is characterized by comprising the following steps: (1) mixing a silicon source, an aluminum source and water, and then aging to obtain a crystallization directing agent; (2) firstly, mixing a crystallization guiding agent and a silicon source, then adding an aluminum source and water to prepare reactive silicon-aluminum sol, and crystallizing the reactive silicon-aluminum sol to obtain a crystallization liquid I, wherein in the reactive silicon-aluminum sol, the addition amount of the crystallization guiding agent accounts for 0.5-5% of the total mass of the reactive silicon-aluminum sol; (3) adding polyacrylamide into the crystallization liquid I, continuing crystallization and recovering the product. The product obtained by the method has the pore size distribution centralized at 1.5-3 nm, and the logarithmic coordinate value dV/dlogD of the pore volume/pore size of the peak top with the pore size of 1.5-3 nm in the BJH desorption peak is more than 1 cc/g.

CN201511018119.2 discloses a preparation method of a mesoporous Y-type molecular sieve, which is characterized in that the method comprises the steps of treating the Y-type molecular sieve in a mixed solution of glycerol and cellulose at 150-220 ℃ for 0.5-5 h, contacting the treated Y-type molecular sieve with an inorganic guiding agent at normal temperature and normal pressure for 0.5-2 h, placing the mixture in a closed reaction kettle at 80-120 ℃ for 2-20 h, and recovering the obtained product; wherein the mass ratio of the Y-type molecular sieve to the glycerol to the cellulose is 1: (1-20): (0.01-3), wherein the mass ratio of the Y-type molecular sieve to the inorganic guiding agent is 1: (0.1-10). In the mesoporous Y-type molecular sieve obtained by the method, the volume of mesopores can reach 40-60% of the total pore volume.

CN201310121037.5 discloses a mesoporous Y-type zeolite molecular sieve and a preparation method thereof, firstly preparing a Y-type zeolite guiding agent, and then guiding the synthesis of the mesoporous Y-type zeolite molecular sieve by using amphiphilic organosilane N, N-dimethyl-N- [3- (trimethoxysilane) propyl ] octadecyl ammonium chloride (TPOAC) as a mesoporous template. The siloxane group at the end of the organosilane is firstly hydrolyzed into a silicon hydroxyl group, the silicon hydroxyl group is connected to the framework on the surface of the zeolite through a chemical bond, and the other alkyl end participates in pore expansion after polymerization. The method provided by the invention can synthesize the mesoporous zeolite by utilizing a one-step hydrothermal process, has simple preparation process, easy operation and low cost, has good connectivity between mesopores and micropores, and is beneficial to the diffusion of macromolecules. The mesoporous zeolite molecular sieve prepared by the invention has mesopores and micropores, avoids the defect of a single pore structure, and has wide application prospect in the field of catalysis, particularly in reactions related to macromolecules and limited by diffusion.

CN201410083417.9 discloses a preparation method of a mesoporous Y-type molecular sieve. The method firstly synthesizes a structure directing agent of the Y-type molecular sieve, and the composition of the directing agent is (1-32) Na₂O∶Al₂O₃∶(10-40)SiO₂∶(200-500)H₂O, adopting a seed crystal method to replace an organic template agent to synthesize the molecular sieve, wherein the gel has the composition of (1-100) Na₂O∶Al₂O₃∶(1-100)SiO₂∶(20-800)H₂O, the addition amount of the seed crystal is SiO in the gel system₂1-15% of the mass, and synthesizing the mesoporous Y-type molecular sieve by hydrothermal crystallization under an alkaline condition. The catalyst prepared by the molecular sieve shows good catalytic performance for catalytic cracking of heavy oil, does not use an organic template, omits a subsequent calcining process, and greatly reduces the synthesis cost of the mesoporous Y-type molecular sieve while ensuring higher synthesis efficiency of the molecular sieve.

CN201511020266.3 discloses a preparation method of a mesoporous Y-type molecular sieve, which is characterized in that the Y-type molecular sieve and glycerol are mixed for treatment for 0.5-5 h at 150-220 ℃, the obtained glycerol treatment mixed liquor is mixed with an inorganic guiding agent, a quaternary ammonium compound, ethanol and cellulose for 0.5-2 h at 30-80 ℃, then the mixture is placed in a closed reaction kettle for treatment for 2-20 h at 80-120 ℃, and a product is recovered to obtain the mesoporous Y-type molecular sieve; wherein the mass ratio of the Y-type molecular sieve to the glycerol is 1: (2-15), wherein the mass ratio of the Y-type molecular sieve to the inorganic guiding agent, the quaternary ammonium compound, the ethanol and the cellulose is 1: (0.1-10): (0.02-1): (0.1-10): (0.005-1).

CN201310121037.5 discloses a mesoporous Y-type zeolite molecular sieve and a preparation method thereof, firstly preparing a Y-type zeolite guiding agent, and then guiding the synthesis of the mesoporous Y-type zeolite molecular sieve by using amphiphilic organosilane N, N-dimethyl-N- [3- (trimethoxysilane) propyl ] octadecyl ammonium chloride (TPOAC) as a mesoporous template. The siloxane group at the end of the organosilane is firstly hydrolyzed into a silicon hydroxyl group, the silicon hydroxyl group is connected to the framework on the surface of the zeolite through a chemical bond, and the other alkyl end participates in pore expansion after polymerization. The method provided by the invention can synthesize the mesoporous zeolite by utilizing a one-step hydrothermal process, has simple preparation process, easy operation and low cost, has good connectivity between mesopores and micropores, and is beneficial to the diffusion of macromolecules. The mesoporous zeolite molecular sieve prepared by the invention has mesopores and micropores, avoids the defect of a single pore structure, and has wide application prospect in the field of catalysis, particularly in reactions related to macromolecules and limited by diffusion.

CN201410083417.9 discloses a preparation method of a mesoporous Y-type molecular sieve. The method firstly synthesizes a structure directing agent of the Y-type molecular sieve, and the composition of the directing agent is (1-32) Na₂O：Al₂O₃：(10-40)SiO₂：(200-500)H₂O, adopting a seed crystal method to replace an organic template agent to synthesize the molecular sieve, wherein the gel has the composition of (1-100) Na₂O：Al₂O₃：(1-100)SiO₂：(20-800)H₂O, the addition amount of the seed crystal is SiO in the gel system₂1-15% of the mass, and synthesizing the mesoporous Y-type molecular sieve by hydrothermal crystallization under an alkaline condition. The catalyst prepared by the molecular sieve shows good catalytic performance for catalytic cracking of heavy oil, does not use an organic template, omits a subsequent calcining process, and greatly reduces the synthesis cost of the mesoporous Y-type molecular sieve while ensuring higher synthesis efficiency of the molecular sieve.

Although some progress has been made in the current research on the preparation of the mesoporous-microporous structure Y-type zeolite molecular sieve, some technical defects still exist. By adopting an in-situ synthesis mode, an organic template is often required to be introduced into a Y-type molecular sieve synthesis system, and the template is removed by subsequent roasting, so that a mesoporous pore channel structure is generated. However, most of the template agents used in the prior art are high in cost, so that the material cost is greatly increased, and the synthesis process is complicated; although the post-modification method can avoid the use of an organic template, the existing post-modification method usually needs to adopt an acid or alkali suction filtration method, which not only easily causes the damage of the molecular sieve, but also can generate a large amount of acid and alkali waste liquid. Therefore, the development of a preparation process method of the mesoporous-microporous Y-type zeolite molecular sieve with simple process, low cost and environment-friendly structure becomes a very challenging research work at present.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a method for preparing a Y-type molecular sieve having a meso-micro hierarchical pore structure, which has the characteristics of simple process, low cost and environmental friendliness.

The preparation method of the mesoporous-microporous structure Y-type zeolite molecular sieve comprises the following steps:

(1) exchanging the NaY molecular sieve with ammonium ions: mixing the required ammonium salt, the NaY molecular sieve and deionized water according to the mass ratio of the ammonium salt to the NaY molecular sieve to the deionized water of 0.1-1:1:5-50, preferably 0.15-0.5:1:10-30, pulping, adjusting the pH value of the system to 2-6, preferably 3-5, by using dilute hydrochloric acid, then carrying out ion exchange for 0.5-5 hours, preferably 1-3 hours at the temperature of 50-95 ℃, preferably 60-90 ℃ by continuously stirring, and then filtering and washing.

(2) And (2) mixing the required boron-containing compound, the molecular sieve obtained in the step (1) and deionized water according to the mass ratio of the boron-containing compound to the molecular sieve to the deionized water of 0.01-0.1:1:5-50, preferably 0.015-0.05:1:10-30, pulping, continuously stirring at the temperature of 30-95 ℃, preferably 60-90 ℃, performing ion exchange for 0.5-3 hours, preferably 1-2 hours, filtering, washing, and roasting the obtained filter cake for 1-4 hours at the temperature of 400-800 ℃, preferably 500-700 ℃ and 100% steam to obtain the Y-type zeolite molecular sieve with the meso-micro hierarchical pore structure.

In the method provided by the invention, the ammonium salt in the step (1) can be selected from water-soluble ammonium salts, such as one or more of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium oxalate, ammonium citrate and ammonium phosphate.

In the method provided by the invention, the boron-containing compound in the step (2) can be selected from water-soluble inorganic boron-containing compounds, such as one or more of boric acid, ammonium borate and ammonium fluoroborate.

The preparation method of the Y-type zeolite molecular sieve with the meso-micro hierarchical pore structure comprises the steps of firstly preparing the ammonium Y-type zeolite molecular sieve by using NaY zeolite molecular sieve ammonium ion exchange, then modifying the ammonium Y-type zeolite molecular sieve by using an ion exchange method, and finally carrying out appropriate framework dealumination on the Y-type zeolite molecular sieve by using the dealumination effect of an acid boron element under a high-temperature hydrothermal environment through a high-temperature hydrothermal treatment process, so that a rich secondary mesoporous structure is generated in the structure of the Y-type zeolite molecular sieve while high crystallinity of the Y-type molecular sieve is kept, and the specific surface and pore volume of the Y-type molecular sieve are obviously improved. When the molecular sieve is modified by the boron element, the secondary pore structure is generated and the deep damage to the structure of the molecular sieve is avoided by controlling the mass ratio of the boron element to the molecular sieve.

Compared with the prior art, the technology provided by the invention has the following advantages: (1) a template agent is not needed in the preparation process, so that the material cost is reduced, and the preparation process is simplified; (2) the boron element is used for post-modification, and an acid and alkali extraction process does not exist in the process, so that the damage to the molecular sieve structure is reduced, acid and alkali waste liquid is not generated, and the damage to the environment is reduced.

In conclusion, compared with the prior art, the technology of the invention has the characteristics of simple process, low cost and environmental friendliness, thereby having better application prospect.

Detailed Description

The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and the experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.

The preparation method of the mesoporous-microporous structure Y-type zeolite molecular sieve comprises the following steps:

(1) exchanging the NaY molecular sieve with ammonium ions: mixing the required ammonium salt, the NaY molecular sieve and deionized water according to the mass ratio of the ammonium salt to the NaY molecular sieve to the deionized water of 0.1-1:1:5-50, preferably 0.15-0.5:1:10-30, pulping, adjusting the pH value of the system to 2-6, preferably 3-5, by using dilute hydrochloric acid, then carrying out ion exchange for 0.5-5 hours, preferably 1-3 hours at the temperature of 50-95 ℃, preferably 60-90 ℃ by continuously stirring, and then filtering and washing.

(2) And (2) mixing the required boron-containing compound, the molecular sieve obtained in the step (1) and deionized water according to the mass ratio of the boron-containing compound to the molecular sieve to the deionized water of 0.01-0.1:1:5-50, preferably 0.015-0.05:1:10-30, pulping, continuously stirring at the temperature of 30-95 ℃, preferably 60-90 ℃, performing ion exchange for 0.5-3 hours, preferably 1-2 hours, filtering, washing, and roasting the obtained filter cake for 1-4 hours at the temperature of 400-800 ℃, preferably 500-700 ℃ and 100% steam to obtain the Y-type zeolite molecular sieve with the meso-micro hierarchical pore structure.

In the method provided by the invention, the ammonium salt in the step (1) can be selected from water-soluble ammonium salts, such as one or more of ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium oxalate, ammonium citrate and ammonium phosphate.

In the method provided by the invention, the boron-containing compound in the step (2) can be selected from water-soluble inorganic boron-containing compounds, such as one or more of boric acid, ammonium borate and ammonium fluoroborate.

Raw material sources and specifications:

NaY molecular sieve, available from catalyst works of landification, inc; ammonium chloride, ammonium nitrate, ammonium sulfate, boric acid, ammonium borate and ammonium fluoroborate are all commercially available reagents, and were analytically pure.

Characterization of the samples:

the relative crystallinity analysis of the samples was carried out on an X-ray diffractometer model D/max-2200PC manufactured by Rigaku corporation, Japan, under the experimental conditions: tube voltage 40kV, tube current 40mA, copper target. The relative crystallinity was determined according to SH/T0340-92 (Standard compilation for chemical industry, published by Chinese standards, 2000 th edition) standard methods.

Determination of the specific surface and pore volume parameters of the samples N, model ASAP3000, manufactured by Micromeritics, USA₂The adsorption-desorption is carried out on an instrument. The total specific surface area and the total pore volume of the zeolite molecular sieve were measured from the adsorption isotherm of the sample according to the RIPP151-90 standard method (analytical method for petrochemical industry, scientific Press, 1990 edition), and then the zeolite fraction was measured from the adsorption isotherm according to the T-plot methodThe volume of the micropore of the sub-sieve and the specific surface of the micropore are obtained, and the mesoporous volume and the specific surface are obtained by subtracting the micro-pore from the micro-pore.