Hierarchical pore y-zeolite and method for preparing the same

Abstract

The application relates to the field of nano-catalytic materials, and discloses a hierarchical pore Y-type molecular sieve and a preparation method thereof.The total pore volume of the molecular sieve is 0.3-0.45 cm 3 / g; wherein the total volume of mesopores with a pore size of 3-50 nm in the molecular sieve is 0.12-0.35 cm 3 / g; and the relative crystallinity of the molecular sieve is 65-100%. The molecular sieve provided by the application uses low-cost soluble starch as a template, effectively improves the mesopore volume, and maintains the relative crystallinity of the molecular sieve.

Description

Technical Field

[0001] This invention relates to the field of nanocatalytic materials, specifically to a hierarchical porous Y-type molecular sieve and its preparation method. Background Technology

[0002] Petroleum products are widely used in industry, agriculture, and national defense, and the petroleum refining industry plays a vital role in national economic and social development. Catalytic cracking (FCC), as the core process for the lightening of heavy oil, is currently the most important secondary processing step in the petroleum refining industry, and its success largely depends on the selection of catalysts. Among these, Y-zeolite, as the main active component of the most commonly used FCC catalyst, has attracted much attention. However, the narrow pores of traditional microporous Y-zeolite restrict the diffusion of macromolecular reactants and products, and reduce the accessibility of active sites. Furthermore, the excessive residence time of macromolecules within the pores leads to over-cracking and coking, thereby accelerating the deactivation of the zeolite. The construction of hierarchical pores can effectively solve these problems of Y-zeolite, improving reactant conversion, target product selectivity, and catalyst lifetime. Therefore, the research and development of hierarchical porous Y-zeolite catalytic materials is of great significance for further improving the efficiency of catalytic cracking reactions.

[0003] Currently, existing methods for preparing hierarchical porous molecular sieves include "top-down" and "bottom-up" methods. The "top-down" method essentially introduces a mesoporous structure through post-processing methods such as desilication or dealumination. While relatively simple to operate, it suffers from poor experimental reproducibility. Furthermore, the removal of framework atoms can damage the molecular sieve's framework structure, affecting its relative crystallinity and framework silica-to-alumina ratio. The "bottom-up" method mainly includes hard template methods, soft template methods, and template-free methods. Template-free methods are emerging but not yet mature, offering limited pore size adjustment and controllability. Commonly used soft templates are generally amphiphilic macromolecules, often including surfactants, water-soluble cationic polymers, and organosilane reagents. Carbon templates are the most common type of hard template, including carbon black, carbon nanoparticles, carbon nanotubes, and ordered mesoporous carbon. Template methods can maintain a good crystal structure of the molecular sieve, preparing hierarchical porous molecular sieves with good catalytic performance. However, templates are generally expensive, and post-processing is complex, with removal causing environmental pollution. Therefore, it is urgent to develop a simple, economical, and environmentally friendly method for preparing multi-level porous Y-type molecular sieves that can effectively increase mesopore volume, maintain its relative crystallinity, and is also feasible. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of high template cost, complex post-processing, low pore size adjustment, and easy influence on the crystallinity of molecular sieves in the existing technology. This invention provides a multi-level porous Y-type molecular sieve and its preparation method. The multi-level porous Y-type molecular sieve uses low-cost soluble starch as a template, which not only effectively increases the mesopore volume, but also maintains the relative crystallinity of the molecular sieve.

[0005] To achieve the above objectives, a first aspect of the present invention provides a multi-level porous Y-type molecular sieve, wherein the total pore volume of the molecular sieve is 0.3-0.45 cm³. 3 / g; wherein the molecular sieve has a total volume of mesopores with a pore size of 3-50nm and a total volume of 0.12-0.35cm³. 3 / g; the relative crystallinity of the molecular sieve is 65-100%.

[0006] A second aspect of the present invention provides a method for preparing a hierarchical porous Y-type molecular sieve, wherein the preparation method includes the following steps:

[0007] S1. In the presence of the first solvent, aluminum source and silicon source are mixed under alkaline conditions to carry out the first reaction to obtain a precursor mixture;

[0008] S2. The precursor mixture and water-soluble starch are mixed to carry out a second reaction to obtain a mixture after the second reaction; the seed crystal directing agent is mixed with the mixture after the second reaction to carry out crystallization; wherein the time of the second reaction is less than or equal to 15 hours;

[0009] S3. The solid product obtained by crystallization is washed and dried;

[0010] S4. Calcine the solid obtained in S3.

[0011] A third aspect of the present invention provides a multi-level porous Y-type molecular sieve prepared by the preparation method provided by the present invention.

[0012] The beneficial effects of the present invention through the above technical solution include:

[0013] This invention utilizes soluble starch—a green, low-cost, and abundant polysaccharide biomass—as a template to prepare hierarchical porous Y-molecule sieves using a green and economical template agent. Compared with traditional Y-molecule sieves, this invention effectively increases the mesopore volume of the hierarchical porous Y-molecule sieve, while maintaining a high relative crystallinity. Furthermore, the prepared hierarchical porous Y-molecule sieve exhibits a uniform particle size distribution, which is of great significance for the technological development and promotion of green synthesis of hierarchical porous molecular sieves.

[0014] The molecular sieve provided by this invention, compared to traditional NaY molecular sieves, optimizes the pore structure while maintaining a high relative crystallinity. The synthesis of hierarchical NaY molecular sieves mediated by soluble starch as a template is simple, green, and economical. The high relative crystallinity indicates that the molecular sieve maintains a relatively complete crystal structure without excessive loss of the framework species of traditional NaY molecular sieves, providing effective active sites for reactions such as catalytic cracking and isomerization. Simultaneously, the increased mesopore volume effectively overcomes diffusion limitations of substrate and product molecules, improving their transport efficiency and enhancing product molecule selectivity. Furthermore, the introduction of mesopores exposes more active sites, increasing their accessibility and optimizing substrate molecule conversion. Therefore, the molecular sieve provided by this invention is a product with great application potential.

[0015] In a preferred embodiment of the present invention, the increase in the total volume of mesopores with a pore size of 3-10 nm is significantly higher than the increase in the total volume of mesopores with a pore size of 10-50 nm, resulting in mesopores with a pore size concentrated in the 3-10 nm range. Attached Figure Description

[0016] Figure 1 These are XRD patterns of the multi-level porous NaY-1 prepared in Example 1 of the present invention and the NaY-13 prepared in Comparative Example 4 of the present invention.

[0017] Figure 2 The pore size diagrams are of the multi-level porous NaY-1 obtained in Example 1 of the present invention and the NaY-13 obtained in Comparative Example 4 of the present invention.

[0018] Figure 3 These are the XRD patterns of the multi-level porous NaY-2 prepared in Example 2 of the present invention and the NaY-13 prepared in Comparative Example 4 of the present invention.

[0019] Figure 4 The pore size diagrams are of the multi-level porous NaY-2 obtained in Example 2 of the present invention and the NaY-13 obtained in Comparative Example 4 of the present invention.

[0020] Figure 5 These are XRD patterns of the multi-level porous NaY-3 prepared in Example 3 of the present invention and the NaY-13 prepared in Comparative Example 4 of the present invention.

[0021] Figure 6 The images show the pore sizes of the multi-level porous NaY-3 prepared in Example 3 of this invention and the NaY-13 prepared in Comparative Example 4 of this invention. Detailed Implementation

[0022] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0023] The first aspect of this invention provides a multi-level porous Y-type molecular sieve, wherein the total pore volume of the molecular sieve is 0.3-0.45 cm³. 3 / g; wherein the molecular sieve has a total volume of mesopores with a pore size of 3-50nm and a total volume of 0.12-0.35cm³. 3 / g; the relative crystallinity of the molecular sieve is 65-100%.

[0024] According to the present invention, preferably, the total volume of mesopores with a pore size of 3-10 nm in the molecular sieve is 0.04-0.1 cm³. 3 / g, the total volume of mesopores with a pore size of 10-50nm is 0.08-0.25cm³. 3 / g.

[0025] Furthermore, in the molecular sieve, the total volume of mesopores with a pore size of 3-10 nm is 0.07-0.1 cm³. 3 / g, the total volume of mesopores with a pore size of 10-50nm is 0.16-0.25cm³. 3 / g.

[0026] Compared to traditional Y-type molecular sieves, the volume improvement of mesopores in both pore size ranges is significantly different; the volume improvement of mesopores with pore sizes of 3-10 nm is much higher than that of mesopores with pore sizes of 10-50 nm. This effectively improves the diffusion efficiency of larger substrate molecules without significantly negatively impacting the relative crystallinity of the molecular sieve.

[0027] In this invention, mesopores with a pore size of 3-10 nm include mesopores with a pore size of 10 nm, and mesopores with a pore size of 10-50 nm do not include mesopores with a pore size of 10 nm.

[0028] According to the present invention, preferably, the specific surface area of ​​the molecular sieve is 450-700 m². 2 / g.

[0029] According to the present invention, preferably, the relative crystallinity of the molecular sieve is 80-100%.

[0030] A second aspect of the present invention provides a method for preparing a hierarchical porous Y-type molecular sieve, wherein the preparation method includes the following steps:

[0031] S1. In the presence of the first solvent, aluminum source and silicon source are mixed under alkaline conditions to carry out the first reaction to obtain a precursor mixture;

[0032] S2. The precursor mixture and water-soluble starch are mixed to carry out a second reaction to obtain a mixture after the second reaction; the seed crystal directing agent is mixed with the mixture after the second reaction to carry out crystallization; wherein the time of the second reaction is less than or equal to 15 hours;

[0033] S3. The solid product obtained by crystallization is washed and dried;

[0034] S4. Calcine the solid obtained in S3.

[0035] In this invention, silicon and aluminum sources react to form an aluminosilicate precursor gel. The precursor gel is incorporated into the gel via a caramelization reaction through hydrogen bonding between the hydroxyl groups on starch and the Si-OH or Al-OH backbone, followed by crystallization. The resulting solid phase is centrifuged, washed until neutral, and dried. The dried material is then calcined to remove the template, yielding a hierarchical porous Y molecular sieve.

[0036] According to the present invention, preferably, in S1, the aluminum source is selected from water-soluble aluminum salts and / or water-soluble aluminates, more preferably from sodium aluminate and / or aluminum sulfate.

[0037] According to the present invention, preferably, the silicon source is a silicate, and more preferably sodium silicate.

[0038] According to the present invention, preferably, the first solvent is water.

[0039] According to the present invention, preferably, in S1, the amount of aluminum source is measured in molar amounts of Al2O3, and the amount of silicon source is measured in molar amounts of SiO2. When the first reaction is carried out, the amounts of aluminum source and silicon source are such that the molar ratio of Al2O3 to SiO2 is (1-20):(1-20).

[0040] Furthermore, when the aluminum source is sodium aluminate and aluminum sulfate, the amount of the aluminum source is calculated in terms of the molar amounts of Al2O3 and Na2O, and the amount of the silicon source is calculated in terms of the molar amounts of Na2O and SiO2. During the first reaction, the amounts of the aluminum source and the silicon source are such that the molar ratio of Al2O3, Na2O and SiO2 is (1-20):(1-20):(1-20).

[0041] According to the present invention, preferably, the amount of the first solvent is such that the weight ratio of the first solvent to SiO2 in the silicon source is (1-20):1.

[0042] According to the present invention, the first solvent can be added separately and mixed with the aluminum source and silicon source to carry out the first reaction, or the aluminum source and silicon source can be mixed separately in aqueous solution form, a portion of the first solvent is added together with the aluminum source and silicon source, and then an appropriate amount of the first solvent is added. According to a preferred embodiment of the present invention, sodium aluminate and aluminum sulfate are added in the form of sodium aluminate aqueous solution and aluminum sulfate aqueous solution, respectively, and sodium silicate is added in the form of water glass.

[0043] According to the present invention, preferably, the first reaction is carried out under conditions of pH 9-14.

[0044] According to the present invention, the aluminum source and the silicon source can be mixed with the first solvent, and then an alkaline solution can be added to adjust the pH value of the first reaction system. Alternatively, the alkaline solution can be added together with the aqueous solution of the aluminum source or the aqueous solution of the silicon source.

[0045] According to a preferred embodiment of the present invention, an alkaline sodium aluminate aqueous solution with a concentration of 3-8 mol / L and a pH value of 9-13 is first prepared, and then mixed with an aluminum sulfate aqueous solution with a concentration of 1-5 mol / L, water glass containing 200-270 g / L SiO2 and 60-90 g / L Na2O, and water in a volume ratio of (0.5-5):(2-6):(8-30):(4-12) to carry out a first reaction. The water glass is commercially available, for example, from the Catalyst Changling Branch of China Petroleum & Chemical Corporation.

[0046] According to a specific embodiment of the present invention, the preparation method of alkaline sodium aluminate aqueous solution includes: preparing 2-10 mol / L Al(OH)3 solution and 5-15 mol / L NaOH solution respectively, and then mixing them to obtain an alkaline sodium aluminate solution with a concentration of 3-8 mol / L and a pH value of 9-13.

[0047] According to the present invention, preferably, the temperature of the first reaction is 60-85°C and the time is 0.5-3h.

[0048] According to the present invention, preferably, the first reaction is carried out in an oil bath.

[0049] According to the present invention, preferably, during the second reaction, the amount of water-soluble starch used is such that the weight ratio of SiO2 in the silicon source to water-soluble starch is (1-15):1.

[0050] The present invention does not particularly limit the source of water-soluble starch. For example, the water-soluble starch may be potato starch, corn starch, wheat starch, cassava starch, etc.

[0051] According to the present invention, preferably, the temperature of the second reaction is 60-85°C and the time is 3-12h.

[0052] According to the present invention, preferably, in S2, the method for preparing the seed crystal directing agent includes: mixing sodium aluminate and sodium silicate under alkaline conditions in the presence of a second solvent to carry out a third reaction, followed by aging.

[0053] According to the present invention, preferably, the amount of sodium aluminate is based on the total molar amount of Al2O3 and Na2O, and the amount of sodium silicate is based on the total molar amount of Na2O and SiO2. When carrying out the third reaction, the amounts of sodium aluminate and sodium silicate are such that the molar ratio of Al2O3, Na2O and SiO2 is (1-30):(1-30):(1-30).

[0054] According to the present invention, preferably, the amount of the second solvent is such that the weight ratio of the second solvent to SiO2 in sodium silicate is (50-80):1.

[0055] According to the present invention, preferably, the second solvent is water.

[0056] According to the present invention, the second solvent can be added separately and mixed with sodium aluminate and sodium silicate to carry out the third reaction, or sodium aluminate and sodium silicate can be mixed separately in aqueous solution form, a portion of the second solvent is added together with sodium aluminate and sodium silicate, and then an appropriate amount of the second solvent is added later. According to a preferred embodiment of the present invention, sodium aluminate and sodium silicate are added in the form of an aqueous solution of sodium aluminate and water glass, respectively.

[0057] According to the present invention, preferably, the third reaction is carried out under conditions of pH 9-11.

[0058] According to the present invention, sodium aluminate and sodium silicate can be mixed with a second solvent, and then an alkaline solution can be added to adjust the pH value of the third reaction system. Alternatively, the alkaline solution can be added together with the sodium aluminate aqueous solution or water glass.

[0059] According to a specific embodiment of the present invention, the preparation method of the seed crystal directing agent includes: mixing an alkaline sodium aluminate aqueous solution containing 230-300 g / L Na2O and 30-60 g / L Al2O3 with a pH value of 9-14, water, and water glass containing 200-270 g / L SiO2 and 60-90 g / L Na2O in a volume ratio of (3-15):(0.01-1):(5-30) for a third reaction. The alkaline sodium aluminate aqueous solution containing 230-300 g / L Na2O and 30-60 g / L Al2O3 with a pH value of 9-14, and the water glass containing 200-270 g / L SiO2 and 60-90 g / L Na2O, are commercially available, for example, from the Catalyst Changling Branch of China Petroleum & Chemical Corporation.

[0060] According to the present invention, preferably, the temperature of the third reaction is 15-25°C and the time is 15-120 min.

[0061] According to the present invention, preferably, the aging temperature is 20-40°C and the time is 10-24h.

[0062] According to the present invention, preferably, in S2, the amount of the seed crystal directing agent is 5-30 wt%, based on the total weight of the second post-reaction mixture.

[0063] In order to make the seed crystal guide agent and the second post-reaction mixture more uniformly mixed and thus better crystallize, in S2, the mixing method includes: stirring the seed crystal guide agent and the second post-reaction mixture at room temperature for 0.5-4 hours.

[0064] According to the present invention, preferably, the crystallization temperature is 90-110°C and the time is 24-60h.

[0065] According to the present invention, preferably, in S3, the washing conditions are such that the pH value of the washed material is 7.2-8.2.

[0066] According to a preferred embodiment of the present invention, the washing is performed by centrifugal washing, which includes: centrifuging the crystallized solid product at a speed of 5000-10000 rpm for 3-15 minutes until the pH value reaches 7.2-8.2.

[0067] According to the present invention, the drying can be carried out in a vacuum drying oven, preferably at a temperature of 50-100°C for a time of 10-24 hours.

[0068] According to the present invention, preferably, in S4, the calcination temperature is 500-650°C and the time is 5-20h.

[0069] A third aspect of the present invention provides a multi-level porous Y-type molecular sieve prepared by the preparation method provided by the present invention.

[0070] The present invention will be described in detail below through embodiments and comparative examples. Unless otherwise specified, the embodiments and comparative examples below are all conventional methods; the materials used are commercially available unless otherwise specified.

[0071] The highly alkaline sodium aluminate solution was provided by the Catalyst Changling Branch of China Petroleum & Chemical Corporation, with a pH of 12; the Na2O content was 276.6 g / L and the Al2O3 content was 40.3 g / L.

[0072] The water glass was supplied by the Catalyst Changling Branch of China Petroleum & Chemical Corporation, with a SiO2 content of 258.4 g / L and a Na2O content of 82.67 g / L.

[0073] The following examples illustrate the preparation of hierarchical porous Y-type molecular sieves.

[0074] Example 1

[0075] S1. Add 0.1 mL of deionized water to 7.7 mL of highly alkaline sodium aluminate solution. While stirring, add 10.2 mL of water glass dropwise (the amounts of highly alkaline sodium aluminate solution and water glass are such that the molar ratio of Al2O3, Na2O, and SiO2 is 1:16:15; the pH of the resulting mixture is 10; the total amount of water used makes the weight ratio of water to SiO2 in the water glass 64:1 (the total amount of water includes the added deionized water, the water contained in the highly alkaline sodium aluminate solution, and the water contained in the water glass). Continue stirring at 20°C for 30 min. Aging at 30°C for 18 h yields the seed crystal directing agent.

[0076] A 5.8 mol / L Al(OH)3 solution and a 7.8 mol / L NaOH solution were prepared separately and mixed and stirred until the solution was clear and transparent, yielding 1.45 mL of a 6.3 mol / L low-alkalinity sodium aluminate solution with a pH of 11. Under an oil bath at 80°C, the low-alkalinity sodium aluminate solution, a 3.77 mol / L Al2(SO4)3 solution, 10.67 mL of water glass, and 6.3 mL of water were mixed and stirred for 1.5 h to obtain a precursor mixture with a pH of 10. The amounts of low-alkalinity sodium aluminate solution, Al2(SO4)3 solution, and water glass were such that the molar ratio of Al2O3, Na2O, and SiO2 was 1:3:8; the total amount of water was such that the weight ratio of water to SiO2 in the water glass was 7.4:1 (the total amount of water includes the added deionized water, the water contained in the low-alkalinity sodium aluminate solution, the water contained in the Al2(SO4)3 solution, and the water contained in the water glass).

[0077] S2. Under 80℃ oil bath conditions, soluble starch was added to the precursor mixture and stirred for 12 hours. The amount of soluble starch was such that the weight ratio of SiO2 to soluble starch was 3:1. At room temperature, based on the total weight of the soluble starch and precursor mixture, 9 wt% of seed crystal directing agent was added and stirred for 1 hour, followed by hydrothermal crystallization at 100℃ for 48 hours.

[0078] S3. The solid material obtained after boiling was centrifuged and washed at 6000 rpm for 8 min, and washed multiple times until the pH value was 7.8. It was then dried in a vacuum drying oven at 60℃ for 18 h to obtain a solid white powder.

[0079] S4. The obtained powder was calcined at 600℃ for 10h to obtain hierarchical porous molecular sieve NaY-1.

[0080] The soluble starch mentioned above is corn starch.

[0081] Example 2

[0082] S1. Add 0.35 mL of deionized water to 10.1 mL of highly alkaline sodium aluminate solution. While stirring, add 15.87 mL of water glass dropwise (the amounts of highly alkaline sodium aluminate solution and water glass are such that the molar ratio of Al2O3, Na2O, and SiO2 is 1:5:1; the pH of the resulting mixture is 10.5; the total amount of water used makes the weight ratio of water to SiO2 in the water glass 76:1 (the total amount of water includes the added deionized water, the water contained in the highly alkaline sodium aluminate solution, and the water contained in the water glass). Continue stirring at 23°C for 45 min. Aging at 35°C for 15 h yields the seed crystal directing agent.

[0083] A 7.9 mol / L Al(OH)3 solution and a 14.6 mol / L NaOH solution were prepared separately and mixed and stirred until the solution was clear and transparent, yielding 2.45 mL of a 4.5 mol / L low-alkalinity sodium aluminate solution with a pH of 11.7. The low-alkalinity sodium aluminate solution, a 4.32 mol / L Al2(SO4)3 solution, 20.96 mL of water glass, and 10.5 mL of water were mixed and stirred for 1 h in a 60℃ oil bath to obtain a precursor mixture with a pH of 11.3. The amounts of low-alkalinity sodium aluminate solution, Al2(SO4)3 solution, and water glass used resulted in a molar ratio of Al2O3, Na2O, and SiO2 of 3:8:17; the total amount of water used resulted in a weight ratio of water to SiO2 in water glass of 10.1:1 (the total amount of water used includes the added deionized water, the water contained in the low-alkalinity sodium aluminate solution, the water contained in the Al2(SO4)3 solution, and the water contained in the water glass).

[0084] S2. Under 60℃ oil bath conditions, soluble starch was added to the precursor mixture and stirred for 10 h. The amount of soluble starch was such that the weight ratio of SiO2 to soluble starch was 1.5:1. At room temperature, based on the total weight of the soluble starch and precursor mixture, 16 wt% of seed crystal directing agent was added and stirred for 2.5 h. Hydrothermal crystallization was then carried out at 110℃ for 36 h.

[0085] S3. The solid phase obtained after boiling is centrifuged and washed at 9000 rpm for 4 min, and washed multiple times until the pH value is 8. It is then dried in a vacuum drying oven at 80℃ for 15 h to obtain a solid white powder.

[0086] S4. The obtained powder was calcined at 600℃ for 8 hours to obtain hierarchical porous molecular sieve NaY-2.

[0087] The soluble starch mentioned above is potato starch.

[0088] Example 3

[0089] S1. Add 0.15 mL of deionized water to 13.9 mL of highly alkaline sodium aluminate solution. While stirring, add 20.11 mL of water glass dropwise (the amounts of highly alkaline sodium aluminate solution and water glass are such that the molar ratio of Al2O3, Na2O, and SiO2 is 1:13:17; the pH of the resulting mixture is 10.6; the total amount of water used makes the weight ratio of water to SiO2 in the water glass 71:1 (the total amount of water includes the added deionized water, the water contained in the highly alkaline sodium aluminate solution, and the water contained in the water glass). Continue stirring at 25 °C for 80 min. Aging at 30 °C for 24 h yields the seed crystal guiding agent.

[0090] A 4.3 mol / L Al(OH)3 solution and a 10.4 mol / L NaOH solution were prepared separately and mixed and stirred until the solution was clear and transparent, yielding 1.33 mL of a low-alkalinity sodium aluminate solution with a concentration of 6.96 mol / L and a pH of 11.8. The low-alkalinity sodium aluminate solution, a 0.9 mol / L Al2(SO4)3 solution, 25.6 mL of water glass, and 12.3 mL of water were mixed and stirred for 3 h in a 70℃ oil bath to obtain a precursor mixture with a pH of 11. The amounts of low-alkalinity sodium aluminate solution, Al2(SO4)3 solution, and water glass used resulted in a molar ratio of Al2O3, Na2O, and SiO2 of 2:11:32; the total amount of water used resulted in a weight ratio of water to SiO2 in water glass of 8.9:1 (the total amount of water used includes the added deionized water, the water contained in the low-alkalinity sodium aluminate solution, the water contained in the Al2(SO4)3 solution, and the water contained in the water glass).

[0091] S2. Under 70℃ oil bath conditions, soluble starch was added to the precursor mixture and stirred for 8 hours. The amount of soluble starch was such that the weight ratio of SiO2 to soluble starch was 12:1. At room temperature, based on the total weight of the soluble starch and precursor mixture, 7 wt% of seed crystal directing agent was added and stirred for 0.8 hours. Hydrothermal crystallization was then carried out at 98℃ for 44 hours.

[0092] S3. The solid phase obtained after boiling was centrifuged and washed at 8000 rpm for 5 min, and washed multiple times until the pH value was 7.6. It was then dried in a vacuum drying oven at 85℃ for 12 h to obtain a solid white powder.

[0093] S4. The obtained powder was calcined at 550℃ for 13 hours to obtain hierarchical porous molecular sieve NaY-3.

[0094] The soluble starch mentioned above is tapioca starch.

[0095] Example 4

[0096] Molecular sieves were prepared according to the method of Example 1, except that the amounts of aluminum and silicon sources were different when preparing the precursor mixture. Specifically, in S1, the amounts of "low-alkalinity sodium aluminate solution, Al2(SO4)3 solution, and water glass such that the molar ratio of Al2O3, Na2O, and SiO2 is 1:21:10" were replaced with "the amounts of low-alkalinity sodium aluminate solution, Al2(SO4)3 solution, and water glass such that the molar ratio of Al2O3, Na2O, and SiO2 is 1:3:8". This yielded hierarchical porous molecular sieve NaY-4.

[0097] Example 5

[0098] Molecular sieves were prepared according to the method of Example 1, except that the amount of soluble starch used in the reaction of the soluble starch with the precursor mixture was different. Specifically, in S2, the phrase "the amount of soluble starch is such that the weight ratio of SiO2 to soluble starch is 15.5:1" was replaced with "the amount of soluble starch is such that the weight ratio of SiO2 to soluble starch is 3:1". This yielded a hierarchical porous molecular sieve, NaY-5.

[0099] Example 6

[0100] Molecular sieves were prepared according to the method in Example 1, except that the aging temperature was different when preparing the seed crystal directing agent. Specifically, in S1, "aging at 42°C for 18 hours to obtain the seed crystal directing agent" was replaced with "aging at 30°C for 18 hours to obtain the seed crystal directing agent". A hierarchical porous molecular sieve, NaY-6, was obtained.

[0101] Example 7

[0102] Molecular sieves were prepared according to the method of Example 1, except that the conditions for preparing the precursor mixture and the reaction conditions of the soluble starch and the precursor mixture were different. Specifically, in S1 and S2, "under 55°C oil bath conditions" was replaced with "under 80°C oil bath conditions". Hierarchical porous molecular sieve NaY-7 was obtained.

[0103] Example 8

[0104] Molecular sieves were prepared according to the method in Example 1, except that the calcination temperature of the solid white powder was different. Specifically, in S4, "calcining the obtained powder at 400°C for 10 hours" was replaced with "calcining the obtained powder at 600°C for 10 hours". This yielded a hierarchical porous molecular sieve, NaY-8.

[0105] Example 9

[0106] Molecular sieves were prepared according to the method of Example 1, except that the amount of water used in preparing the precursor mixture was different. Specifically, in S1, the mixture of "low-alkalinity sodium aluminate solution, 3.77 mol / L Al2(SO4)3 solution, 10.67 mL water glass, and 15 mL water was stirred for 1.5 h; the total amount of water was such that the weight ratio of water to SiO2 in the water glass was 21:1" was used instead of "mixing low-alkalinity sodium aluminate solution, 3.77 mol / L Al2(SO4)3 solution, 10.67 mL water glass, and 6.3 mL water for 1.5 h; the total amount of water was such that the weight ratio of water to SiO2 in the water glass was 7.4:1". This yielded hierarchical porous molecular sieve NaY-9.

[0107] Comparative Example 1

[0108] Molecular sieves were prepared according to the method in Example 1, except that the stirring time after adding soluble starch to the precursor mixture was different. Specifically, in S2, "adding soluble starch to the precursor mixture and stirring for 16 hours in an oil bath at 80°C" was replaced with "adding soluble starch to the precursor mixture and stirring for 12 hours in an oil bath at 80°C". This yielded a hierarchical porous molecular sieve, NaY-10.

[0109] Comparative Example 2

[0110] Molecular sieves were prepared according to the method of Example 1, except that the order of addition was changed when preparing the precursor mixture; the seed crystal directing agent, silicon source, and aluminum source were added to the system simultaneously. Specifically, in S1, "mixing and stirring 9 wt% seed crystal directing agent, low-alkalinity sodium aluminate solution, 3.77 mol / L Al2(SO4)3 solution, 10.67 mL water glass, and 6.3 mL water for 1.5 h in an oil bath at 80°C" was replaced with "mixing and stirring 9 wt% seed crystal directing agent, low-alkalinity sodium aluminate solution, 3.77 mol / L Al2(SO4)3 solution, 10.67 mL water glass, and 6.3 mL water for 1.5 h in an oil bath at 80°C"; and no seed crystal directing agent was added in S2. Molecular sieve NaY-11 was obtained.

[0111] Comparative Example 3

[0112] Molecular sieves were prepared according to the method in Example 1, except that when preparing the precursor mixture, seed crystal directing agent, silicon source, aluminum source, and soluble starch were added to the system simultaneously. Specifically, in S1, "9 wt% seed crystal directing agent, low-alkalinity sodium aluminate solution, 3.77 mol / L Al2(SO4)3 solution, 10.67 mL water glass, 6.3 mL water, and soluble starch were mixed and stirred for 12 h under 80°C oil bath conditions, with the amount of soluble starch such that the weight ratio of SiO2 to soluble starch was 3:1" was used instead of "9 wt% seed crystal directing agent, low-alkalinity sodium aluminate solution, 3.77 mol / L Al2(SO4)3 solution, 10.67 mL water glass, and 6.3 mL water were mixed and stirred for 1.5 h under 80°C oil bath conditions," and in S2, seed crystal directing agent and soluble starch were not added. Molecular sieve NaY-12 was obtained.

[0113] Comparative Example 4

[0114] Molecular sieves were prepared according to the method of Example 1, except that no template agent (soluble starch) was added. Specifically, S2 was carried out at room temperature, based on the total weight of the precursor mixture, with the addition of 9 wt% seed crystal directing agent and stirring for 1 h, followed by hydrothermal crystallization at 100°C for 48 h. Molecular sieve NaY-13 was obtained.

[0115] Comparative Example 5

[0116] Molecular sieves were prepared according to the method of Example 1, except that glucose was used as a template agent. Specifically, in S2, "add glucose to the precursor mixture and continue stirring for 12 hours, with the amount of glucose such that the weight ratio of SiO2 to soluble starch is 3:1" was replaced with "add soluble starch to the precursor mixture and continue stirring for 12 hours, with the amount of soluble starch such that the weight ratio of SiO2 to soluble starch is 3:1". Molecular sieve NaY-14 was obtained.

[0117] Test case

[0118] The crystallinity of the molecular sieves was determined using a multi-functional XRD diffractometer, and the specific surface area and pore size distribution of the molecular sieves were determined using an ASAP 2460 surface area-pore size analyzer. The relative crystallinity, total pore volume, and total mesopore volume of the molecular sieves obtained from each embodiment and comparative example, after fitting calculations, are shown in Table 1.

[0119] Figure 1 To obtain the XRD patterns of the prepared hierarchical porous NaY-1 and conventional NaY (NaY-13), by... Figure 1It can be seen that the peak intensity of hierarchical NaY-1 molecular sieve is slightly higher than that of NaY-13 molecular sieve. However, the relative crystallinity of NaY-1 molecular sieve and NaY-13 molecular sieve obtained by fitting calculation is not much different. The relative crystallinity of NaY-1 molecular sieve is 98%.

[0120] Figure 2 The pore size diagrams of the prepared hierarchical porous NaY-1 molecular sieve and the traditional NaY (NaY-13) molecular sieve are shown. Figure 2 It can be seen that in NaY-13 molecular sieve, the volume of mesopores with a pore size of 3-10 nm accounts for 22.1% of the total mesopore volume, and the volume of mesopores with a pore size of 10-50 nm accounts for 77.9% of the total mesopore volume. In NaY-1 molecular sieve, the volume of mesopores with a pore size of 3-10 nm accounts for 21% of the total mesopore volume, which is 30.24 times higher than that of NaY-13 molecular sieve; the volume of mesopores with a pore size of 10-50 nm accounts for 75.6% of the total mesopore volume, which is 2.25 times higher than that of NaY-13 molecular sieve. Relatively speaking, the increase in the volume of mesopores with a pore size of 3-10 nm far exceeds the increase in the volume of mesopores with a pore size of 10-50 nm.

[0121] Figure 3 The XRD patterns of the prepared hierarchical porous NaY-2 molecular sieve and the traditional NaY (NaY-13) molecular sieve are shown below. Figure 3 It can be seen that the peak intensity of hierarchical NaY-2 molecular sieve is slightly higher than that of NaY-13 molecular sieve. However, the relative crystallinity of NaY-2 molecular sieve obtained by fitting calculation is slightly lower than that of NaY-13 molecular sieve, with a relative crystallinity of 92%.

[0122] Figure 4 The pore size diagrams of the prepared hierarchical porous NaY-2 molecular sieve and the traditional NaY (NaY-13) molecular sieve are shown. Figure 4 It can be seen that in NaY-13 molecular sieve, the volume of mesopores with a pore size of 3-10 nm accounts for 22.1% of the total mesopore volume, and the volume of mesopores with a pore size of 10-50 nm accounts for 77.9% of the total mesopore volume. In NaY-2 molecular sieve, the volume of mesopores with a pore size of 3-10 nm accounts for 24.4% of the total mesopore volume, which is 13.83 times higher than that of NaY-13 molecular sieve; the volume of mesopores with a pore size of 10-50 nm accounts for 75.6% of the total mesopore volume, which is 0.36 times higher than that of NaY-13. Relatively speaking, the increase in the volume of mesopores with a pore size of 3-10 nm far exceeds the increase in the volume of mesopores with a pore size of 10-50 nm.

[0123] Figure 5 The XRD patterns of the prepared hierarchical porous NaY-3 molecular sieve and the traditional NaY (NaY-13) molecular sieve are shown by... Figure 5It can be seen that the peak intensity of hierarchical NaY-3 molecular sieve is slightly higher than that of NaY-13 molecular sieve. However, the relative crystallinity of NaY-3 molecular sieve obtained by fitting calculation is slightly lower than that of NaY-13 molecular sieve, with a relative crystallinity of 89%.

[0124] Figure 6 The pore size diagrams of the prepared hierarchical porous NaY-3 molecular sieve and the traditional NaY (NaY-13) molecular sieve are shown. Figure 6 It can be seen that in NaY-13 molecular sieve, the volume of mesopores with a pore size of 3-10 nm accounts for 22.1% of the total mesopore volume, while the volume of mesopores with a pore size of 10-50 nm accounts for 77.9% of the total mesopore volume. In NaY-3 molecular sieve, the volume of mesopores with a pore size of 3-10 nm also accounts for 22.1% of the total mesopore volume, but this is 34.77 times higher than that of NaY-13 molecular sieve; the volume of mesopores with a pore size of 10-50 nm accounts for 77.9% of the total mesopore volume, which is 2.71 times higher than that of NaY-13 molecular sieve. Relatively speaking, the increase in the volume of mesopores with a pore size of 3-10 nm far exceeds the increase in the volume of mesopores with a pore size of 10-50 nm.

[0125] Table 1

[0126]

[0127]

[0128] As can be seen from the data in Table 1, the molecular sieves provided by the present invention prepared in Examples 1-9 have high relative crystallinity, high specific surface area, high total pore volume, and high mesopore volume. Comparative Example 1 extended the stirring time after adding soluble starch to the precursor mixture; Comparative Examples 2 and 3 both changed the feeding sequence when preparing the precursor mixture, resulting in molecular sieves with very low relative crystallinity or forming amorphous structures. Comparative Example 4 was a traditional molecular sieve without the addition of a template agent; although its relative crystallinity was as high as 100%, its mesopore volume was significantly reduced compared to Examples 1-9. Comparative Example 5 used glucose as a template agent; compared to Examples 1-9, not only was the relative crystallinity reduced, but the mesopore volume was also significantly reduced. This demonstrates that, compared to the traditional molecular sieve NaY-13, the molecular sieve prepared by the method of the present invention not only maintains a high relative crystallinity but also effectively improves the mesopore volume of the molecular sieve.

[0129] Furthermore, Example 4 changed the amounts of aluminum and silicon sources used in preparing the precursor mixture; Example 5 changed the amount of soluble starch; Example 6 changed the aging temperature used in preparing the seed crystal directing agent; compared with Example 1, both the relative crystallinity and mesopore volume decreased; Example 7 changed the temperature used in preparing the precursor mixture and in the reaction between the soluble starch and the precursor mixture; Example 8 changed the calcination temperature of the crystallized solid; compared with Example 1, although the relative crystallinity did not decrease significantly, the mesopore volume decreased; Example 9 changed the amount of water used in preparing the precursor mixture; compared with Example 1, both the relative crystallinity and mesopore volume decreased. This demonstrates that when the amounts of aluminum and silicon sources used in preparing the precursor mixture, the amount of soluble starch used, the aging temperature used in preparing the seed crystal directing agent, the temperature used in preparing the precursor mixture and in the reaction between the soluble starch and the precursor mixture, the calcination temperature of the crystallized solid, and the amount of water used in preparing the precursor mixture meet the preferred conditions, the relative crystallinity and mesopore volume of the obtained molecular sieve can be further improved. Examples 1-3 that meet the preferred conditions not only enable Y molecular sieves to maintain a high relative crystallinity (80-100%), but also significantly increase the volume of mesopores in the molecular sieves. Among them, the volume increase of mesopores with a pore size of 3-10 nm is the most significant, which is much higher than the volume increase of mesopores with a pore size of 10-50 nm.

[0130] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A multi-level porous Y-type molecular sieve, characterized in that, The molecular sieve has a total pore volume of 0.3-0.45 cm³. 3 / g; wherein the molecular sieve has a total volume of mesopores with a pore size of 3-50nm and a total volume of 0.12-0.35cm³. 3 / g; the relative crystallinity of the molecular sieve is 65-100%; the total volume of mesopores with a pore size of 3-10 nm in the molecular sieve is 0.04-0.1 cm³. 3 / g; the total volume of mesopores with a pore size of 10-50 nm is 0.08-0.25 cm³. 3 / g.

2. The molecular sieve according to claim 1, characterized in that, In the molecular sieve, the total volume of mesopores with a pore size of 3-10 nm is 0.07-0.1 cm³. 3 / g; the total volume of mesopores with a pore size of 10-50 nm is 0.16-0.25 cm³. 3 / g.

3. The molecular sieve according to claim 1, characterized in that, The specific surface area of ​​the molecular sieve is 450-700 m². 2 / g.

4. The molecular sieve according to claim 1, characterized in that, The relative crystallinity of the molecular sieve is 80-100%.

5. A method for preparing a hierarchical porous Y-type molecular sieve according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: S1. In the presence of the first solvent, aluminum source and silicon source are mixed under alkaline conditions to carry out the first reaction to obtain a precursor mixture; S2. The precursor mixture and water-soluble starch are mixed to carry out a second reaction to obtain a mixture after the second reaction; the seed crystal directing agent is mixed with the mixture after the second reaction to carry out crystallization; wherein the time of the second reaction is less than or equal to 15 hours; S3. The solid product obtained by crystallization is washed and dried; S4. Calcine the solid obtained in S3.

6. The preparation method according to claim 5, characterized in that, In S1, the aluminum source is selected from water-soluble aluminum salts and / or water-soluble aluminates.

7. The preparation method according to claim 6, characterized in that, In S1, the aluminum source is selected from sodium aluminate and / or aluminum sulfate.

8. The preparation method according to claim 5, characterized in that, The silicon source is silicate.

9. The preparation method according to claim 8, characterized in that, The silicon source is sodium silicate.

10. The preparation method according to claim 5, characterized in that, The first solvent is water.

11. The preparation method according to claim 5, characterized in that, In S1, the amount of aluminum source is measured in molar amounts of Al2O3, and the amount of silicon source is measured in molar amounts of SiO2. During the first reaction, the amounts of aluminum source and silicon source are such that the molar ratio of Al2O3 to SiO2 is (1-20):(1-20).

12. The preparation method according to claim 11, characterized in that, The amount of the first solvent used is such that the weight ratio of the first solvent to SiO2 in the silicon source is (1-20):

1.

13. The preparation method according to claim 5, characterized in that, The first reaction was carried out at a pH of 9-14.

14. The preparation method according to claim 5, characterized in that, The temperature of the first reaction is 60-85℃, and the time is 0.5-3h.

15. The preparation method according to claim 5, characterized in that, During the second reaction, the amount of water-soluble starch used is such that the weight ratio of SiO2 to water-soluble starch in the silicon source is (1-15):

1.

16. The preparation method according to claim 5, characterized in that, The second reaction is carried out at a temperature of 60-85℃ for 3-12 hours.

17. The preparation method according to claim 5, characterized in that, In S2, the preparation method of the seed crystal directing agent includes: mixing sodium aluminate and sodium silicate under alkaline conditions in the presence of a second solvent to carry out a third reaction, followed by aging.

18. The preparation method according to claim 17, characterized in that, The amount of sodium aluminate is based on the total molar amount of Al2O3 and Na2O, and the amount of sodium silicate is based on the total molar amount of Na2O and SiO2. When carrying out the third reaction, the amount of sodium aluminate and sodium silicate is such that the molar ratio of Al2O3, Na2O and SiO2 is (1-30):(1-30):(1-30).

19. The preparation method according to claim 18, characterized in that, The amount of the second solvent used is such that the weight ratio of the second solvent to SiO2 in sodium silicate is (50-80):

1.

20. The preparation method according to claim 19, characterized in that, The second solvent is water.

21. The preparation method according to claim 17, characterized in that, The third reaction was carried out at a pH of 9-11.

22. The preparation method according to claim 17, characterized in that, The temperature of the third reaction is 15-25℃, and the time is 15-120 min.

23. The preparation method according to claim 17, characterized in that, The aging temperature is 20-40℃, and the time is 10-24h.

24. The preparation method according to any one of claims 5-23, characterized in that, In S2, the amount of the seed crystal directing agent is 5-30 wt%, based on the total weight of the mixture after the second reaction.

25. The preparation method according to claim 5, characterized in that, The crystallization temperature is 90-110℃ and the time is 24-60h.

26. The preparation method according to claim 5, characterized in that, In S3, the washing conditions result in a pH value of 7.2-8.2 for the washed material.

27. The preparation method according to claim 5, characterized in that, The drying temperature is 50-100℃, and the time is 10-24h.

28. The preparation method according to claim 5, characterized in that, In S4, the calcination temperature is 500-650℃ and the time is 5-20h.

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