A method for synthesizing thick-walled mesoporous molecular sieves with the assistance of carboxylic acid copolymers.

Abstract

This invention relates to a method for the synthesis of thick-walled mesoporous molecular sieves assisted by carboxylic acid copolymers, belonging to the field of mesoporous molecular sieve synthesis technology. The preparation method first prepares a precursor containing primary and secondary structural units of a Y-type molecular sieve, and then adds a carboxylic acid copolymer to obtain the final product. Beneficial effects: This invention uses a composite template agent of carboxylic acid copolymer and nonionic surfactant to assemble the above-mentioned precursor. Utilizing the electrostatic repulsion and steric hindrance effect of the carboxylic acid copolymer, the cell parameters of the mesoporous molecular sieve are significantly improved, thus obtaining a mesoporous molecular sieve with large pore wall thickness.

Description

Technical Field

[0001] This invention belongs to the field of mesoporous molecular sieve synthesis, and particularly relates to a method for synthesizing thick-walled mesoporous molecular sieves with the assistance of carboxylic acid copolymers. Background Technology

[0002] Mesoporous molecular sieves, due to their large specific surface area and regular, tunable pore structure, were considered promising for the conversion of heavy oil macromolecules from their inception. However, the amorphous pore walls result in poor hydrothermal stability, greatly limiting their application in harsh chemical processes. Therefore, increasing the pore wall thickness of mesoporous molecular sieves to improve their stability is of great significance.

[0003] Kresge (Nature, 1992, 359(6397):710-712) reported a method for synthesizing thick-walled mesoporous molecular sieves by calcining a template agent with a liquid crystal structure formed by silicates. The synthesized samples exhibit mesoporous order, and their pore size can be adjusted by adding different template agents or changing the reaction conditions. This method uses a liquid crystal structure formed by template agent micelles as a template, and silicate species polymerize around the block copolymer micelles to form pore walls, thereby forming a mesoporous molecular sieve.

[0004] Sangchoom (Journal of Materials Chemistry, 2012, 22(36): 18872-18878) synthesized pure silica MCM-41 samples using fumed silica, CTAB, tetramethylammonium hydroxide (TMAOH), and water as raw materials. The effect of high-temperature synthesis on the structural order and stability was investigated. Increasing the crystallization temperature led to an increase in pore size and a decrease in long-range order, but also resulted in thicker pore walls. The molecular sieve sample synthesized at 190℃ exhibited thicker pore walls, and... Hole wall thickness at 150℃ In comparison, the wall thickness of the molecular sieve sample increased. This is significantly higher than previously reported.

[0005] Cyril (Microporous and Mesoporous Materials, 2018, 271:196-202) synthesized SBA-15 via a sol-gel method. The effect of chloride ions on the structure and surface properties of SBA-15 was explored by varying the HCl concentration, aiming to adjust the surface density of active hydroxyl groups suitable for subsequent derivatization. Results showed that during the sol-gel preparation of SBA-15, increasing the HCl concentration from 0 to 2.0 M doubled the surface silanol coverage, while slightly widening the mesopore size from 4.2 nm to 4.9 nm. However, the smaller cell parameters are unfavorable for large molecules or large-scale transport of macromolecules.

[0006] Yuan et al. (Langmuir, 2008, 24(9): 5038-5043) studied mesoporous silica using P123 and perfluorooctanoic acid (PFOA) as co-templates in an acid-catalyzed sol-gel process. The results showed that by increasing the molar ratio of PFOA / P123 as the co-template, a structural transformation from a rod-like two-dimensional hexagonal mesostructure to one with sharp edges could be achieved, and the wall thickness of the silica was significantly increased.

[0007] Jomekian (Journal of Porous Materials, 2012, 19: 979-988) synthesized a novel mesoporous MCM-41 using tetraethyl orthosilicate as the silica source, 1-hexadecylamine as the template agent, and 1,3,5-trimethylbenzene as the organic auxiliary agent. Compared with the maximum wall thickness of 1.8 nm of mesoporous MCM-41 prepared by conventional methods, the wall thickness of the molecular sieve sample obtained by solvent extraction to remove the template agent in this study is [missing information]. And the diameter of the channel is

[0008] An et al. (Chinese Journal of the Chinese Ceramic Society, 2019, 47(04): 473-479) synthesized MC-SBA-16 mesoporous molecular sieve by adding MC to F127 solution using conventional methods, with F127 as a template agent and methylcellulose (MC) as a co-templating agent. They then used this sieve as a support to prepare a Ni-based catalyst. The prepared catalyst was applied to a hydrogenation reaction for catalytic testing and compared with Ni-containing SBA-16. The results showed that the addition of MC effectively dispersed the molecules, thus altering some structural properties of the product, such as increasing the specific surface area and pore size. However, the block copolymer F127 had a relatively small molecular weight, making it difficult to ensure that the micelles formed during assembly were uniformly and neatly arranged and dispersed, resulting in smaller cell parameters for the synthesized SBA-16.

[0009] Precursor assembly technology introduces the primary and secondary structural units of microporous molecular sieves into the pore walls of mesoporous molecular sieves, thereby increasing the wall thickness of the molecular sieves and improving their hydrothermal stability.

[0010] Luo et al. (Journal of Chemical Research in Chinese Universities, 2007(05):801-805) prepared highly ordered mesoporous aluminosilicate molecular sieve MSAMS-4 by placing calcined SBA-15 in a diluent of β-zeolite precursor and glycerol for two high-temperature crystallization processes. Characterization using XRD and TEM showed that the microstructural units of the microporous molecular sieve were introduced into the pore walls of the mesoporous molecular sieve, and the pore wall thickness of the obtained aluminosilicate molecular sieve MSAMS-4 increased by 1.0 nm.

[0011] Laha et al. (Microporous and mesoporous materials, 2010, 133(1-3):82-90) used tetraethylammonium hydroxide (TEAOH) as a template agent. Under alkaline conditions, using HS-40 silica sol and aluminum hydroxide nonahydrate as silicon and aluminum sources, they mixed and crystallized the mixture to obtain a sol precursor containing β-zeolite structural units. Then, under the action of mesoporous template agents lauryl alcohol polyoxyethylene ether and CTAB, they self-assembled to synthesize Al-MCM-48-BEA molecular sieves. XRD results showed that Al-MCM-48-BEA maintained good mesoporous order after treatment in boiling water for 120 h and in steam at 700℃ for 4 h. Due to the presence of β-zeolite structures in Al-MCM-48-BEA, the mesoporous pore walls of the sample became thicker.

[0012] Li (Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013, 107: 218-226) investigated the introduction of Y-type molecular sieves as precursors into the formation of MCM-41 molecular sieves. The study found that when the Y-type precursor was mixed with hexadecyltrimethylammonium bromide (CTAB), the precursor containing secondary building blocks of the Y-type molecular sieve promoted the formation of metastable mesoporous structures. Conversely, low-polymerization aluminosilicates and well-crystallized molecular sieve crystals could not assemble with CTAB in this stage. The results indicate that the high anionic charge density and appropriate multicoordination number of the secondary building blocks of the molecular sieve promote the formation of mesoporous walls. The cell parameter a0 is 4.4 nm, and the wall thickness is 1.9 nm.

[0013] Mi et al. (Industrial & Engineering Chemistry Research, 2017, 56, 25, 7224–7228) synthesized mesoporous molecular sieves by introducing the ionic surfactant sodium dodecyl sulfate (SDS) into copolymers at extremely low concentrations. Their molecular sieve samples had a cell parameter a0 of 11.47 nm and a pore wall thickness of 5.27 nm. The study found that even at low concentrations of P123, the strong interaction between the hydrophobic chains of SDS and the polypropylene oxide (PPO) units of P123 led to the formation of mixed micelles. The self-aggregation of SDS molecules induced the formation of mixed micelles, the core of which consisted of SDS micelles with PPO units and poly(ethylene oxide) (PEO) units. The introduction of ionic surfactants improved the wall thickness and stability of the mesoporous molecular sieves.

[0014] Although the precursor assembly method significantly improves the wall thickness and stability of mesoporous molecular sieves, the stability of this process still needs further improvement. This is primarily due to the relatively low pore wall thickness of mesoporous molecular sieves. Therefore, increasing the pore wall thickness of mesoporous molecular sieves synthesized using the precursor assembly method has significant theoretical and practical value.

[0015] Chinese patent application CN104591200A discloses a method for preparing SBA-15 mesoporous molecular sieves with significantly increased lattice spacing and pore wall thickness, belonging to the field of inorganic porous material preparation technology. This method uses polymer P123 as the main template agent and another enol polymer as an auxiliary template agent. Under hydrothermal conditions, through a copolymerization-hydrolysis reaction, SBA-15 mesoporous molecular sieves with significantly increased lattice spacing and pore wall thickness are prepared, improving thermal and hydrothermal stability and greatly increasing its application potential as a large-pore-size, large-specific-surface-area, especially as a thick-pore-walled support material in many fields such as energy, chemical engineering, environmental protection, and biotechnology. However, this patent does not disclose the use of carboxylic acid copolymers to prepare mesoporous molecular sieves. Summary of the Invention

[0016] The technical problem to be solved by this invention is how to solve the problem that the existing mesoporous molecular sieves have low pore wall thickness, which leads to poor stability of the mesoporous molecular sieves.

[0017] The present invention solves the above-mentioned technical problems through the following technical means:

[0018] The first aspect of this invention provides a method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers, comprising the following steps:

[0019] (1) Preparation of Y-type precursor:

[0020] Aluminum source, Na2O, silicon source and water are stirred and mixed to obtain Y-type precursor solution;

[0021] (2) Synthesis of mesoporous molecular sieves using carboxylic acid copolymer-assisted block nonionic surfactants:

[0022] The nonionic surfactant was dissolved in water, and then the carboxylic acid copolymer was added. After stirring, the Y-type precursor solution was added dropwise. After the addition was complete, the mixture was assembled and then transferred to a polytetrafluoroethylene reactor for crystallization. After filtration, washing, drying, and calcination, the mesoporous molecular sieve product was obtained.

[0023] Beneficial effects: This invention uses a combination of carboxylic acid copolymers and nonionic surfactants to assemble the precursor of Y-type molecular sieves. By utilizing the electrostatic repulsion and steric hindrance effect of the carboxylic acid copolymers, the cell parameters of the mesoporous molecular sieves are greatly improved, thereby obtaining mesoporous molecular sieves with larger pore wall thickness.

[0024] Preferably, the stirring in step (1) specifically involves stirring at 40-100℃ for 5-15 hours.

[0025] Preferably, in step (1), the molar ratio of aluminum source, Na2O, silicon source and water is 1:10-20:10-20:200-400.

[0026] Preferably, in step (1), the aluminum source is selected from one or more of aluminum sulfate octahydrate (Al2(SO4)3·18H2O), aluminum nitrate (Al(NO3)3), sodium aluminate (NaAlO2), aluminum chloride (AlCl3), and aluminum isopropoxide (AIP).

[0027] Preferably, in step (1), the silicon source is selected from one or more of tetraethyl orthosilicate (TEOS), sodium orthosilicate (Na4SiO4), water glass, silicon powder, and silica sol.

[0028] Preferably, the nonionic surfactant in step (2) is selected from polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO). 20 PPO 70 PEO 20 (P123), Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO) 80 PPO 30 PEO 80 (F68), Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO) 106 PPO 70 PEO 106 (F127), Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO) 43 PPO 14 PEO 43One or more of (F38) block copolymers.

[0029] Preferably, the carboxylic acid copolymer in step (2) is selected from one of methacrylic acid copolymer (AMPS), phosphoryl carboxylic acid copolymer (POCA), maleic acid-acrylic acid copolymer (AAMA), and acrylic acid-itaconic acid copolymer (IA-Co-AA).

[0030] Preferably, the mass ratio of the carboxylic acid copolymer and the nonionic surfactant in step (2) is 1:50-300.

[0031] Preferably, in step (2), the mass ratio of the carboxylic acid copolymer to water is 1:10-100.

[0032] Preferably, the crystallization temperature in step (2) is 80-150℃ and the crystallization time is 1-4 days.

[0033] Preferably, the roasting conditions in step (2) are: temperature 400-800℃, 4-8h.

[0034] A second aspect of the present invention provides a mesoporous molecular sieve prepared using the above method.

[0035] The advantages of this invention are:

[0036] 1. This invention uses a combination of carboxylic acid copolymers and nonionic surfactants to assemble the precursor of Y-type molecular sieves. By utilizing the electrostatic repulsion and steric hindrance effect of the carboxylic acid copolymers, the cell parameters of the mesoporous molecular sieves are significantly improved, thereby obtaining mesoporous molecular sieves with larger pore wall thickness.

[0037] 2. This invention uses carboxylic acid copolymers as auxiliary templates to synthesize mesoporous molecular sieves. For example, AAMA contains multiple -COOH bonds, which interact with the PEO segments in the block copolymer F68 to form complex micelles. The presence of multiple carboxyl groups increases the electrostatic repulsion of the micelles; moreover, it has significant steric hindrance, resulting in an increase in the cell parameters of the micelle samples. When the pore sizes are similar, the increase in cell parameters will significantly increase the pore wall thickness of the molecular sieve. Attached Figure Description

[0038] Figure 1 The image shows the XRD characterization results of the mesoporous molecular sieve prepared in Example 1. It can be seen that the product has a typical ordered two-dimensional mesoporous structure.

[0039] Figure 2 The BET characterization results of the mesoporous molecular sieve prepared in Example 1 show that the product has the hysteresis loop characteristic of mesoporous materials.

[0040] Figure 3The pore size distribution curve of the mesoporous molecular sieve prepared in Example 1 shows that the product has a mesoporous structure. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0043] Raw material sources: Aluminum sulfate and other raw materials are from Lanzhou Petrochemical Company of China National Petroleum Corporation, and are all industrial products; template agent is purchased from Jiangsu Haian Petrochemical Co., Ltd., and is an industrial product; tetraethyl orthosilicate and maleic acid-acrylic acid copolymer are commercially available reagents, industrial grade.

[0044] Analytical methods: Phase detection and confirmation were performed using a Shimadzu XRD-7000 X-ray crystal powder diffractometer. Instrument parameters: Cu-Ka rays, wavelength 0.1543 nm, tube voltage 40 kV, tube current 50 mA. Sample testing conditions: scanning angle 0.5°–5°, scanning speed 1° / min.

[0045] The adsorption-desorption isotherms of the samples were determined using an ASAP2020M fully automated adsorption instrument manufactured by Micromeritics, USA, at liquid nitrogen temperature. Nitrogen was used as the adsorbate. The specific surface area of ​​the samples was calculated based on the adsorption equilibrium isotherms between relative pressures of 0.05 and 0.25 using the Brunauer-Emmett-Teller (BET) equation. The t-plot model was used to distinguish between the internal and external surface areas of the samples. The pore volume and pore size distribution were determined using the static volumetric method, thereby calculating the pore structure parameters.

[0046] Example 1:

[0047] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0048] (1) Preparation of Y-type precursor 1:

[0049] Prepare the mixture by mixing Al2(SO4)3·18H2O:Na2O:SiO2:H2O = 1:18:15:320 at 98℃ for 8 hours.

[0050] (2) Synthesis of mesoporous molecular sieves:

[0051] At 35℃, 40g of nonionic surfactant F68 was dissolved in 600mL of deionized water, and then 0.6g of AAMA was added. The mixture was stirred for 0.5h until dissolved. Then, 350g of Y-type precursor 1 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 20h, then transferred to a polytetrafluoroethylene reactor and crystallized for 1 day. After filtration, washing, drying, and calcination at 550℃ for 6h, the mesoporous molecular sieve product was obtained.

[0052] Example 2:

[0053] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0054] (1) Preparation of Y-type precursor 1:

[0055] Prepare the mixture by mixing Al2(SO4)3·18H2O:Na2O:SiO2:H2O = 1:18:15:320 at 98℃ for 8 hours.

[0056] (2) Synthesis of mesoporous molecular sieves:

[0057] At 20℃, 20g of nonionic surfactant F38 was dissolved in 100mL of deionized water, and then 0.2g of POCA was added. The mixture was stirred for 0.5h until dissolved. Then, 50g of Y-type precursor 1 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 10h, then transferred to a polytetrafluoroethylene reactor and crystallized for 1 day. After filtration, washing, drying, and calcination at 400℃ for 4h, the mesoporous molecular sieve product was obtained.

[0058] Example 3:

[0059] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0060] (1) Preparation of Y-type precursor 2:

[0061] Prepare the mixture by mixing Al(NO3)3:Na2O:SiO2:H2O in a molar ratio of 1:20:20:400 and stirring at 40°C for 15 hours.

[0062] (2) Synthesis of mesoporous molecular sieves:

[0063] At 70℃, 40g of nonionic surfactant F127 was dissolved in 1000mL of deionized water, and then 2g of AMPS was added. The mixture was stirred for 2 hours until dissolved. Then, 500g of Y-type precursor 2 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 40 hours, then transferred to a polytetrafluoroethylene reactor and crystallized for 4 days. After filtration, washing, drying, and calcination at 800℃ for 8 hours, the mesoporous molecular sieve product was obtained.

[0064] Example 4:

[0065] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0066] (1) Preparation of Y-type precursor 3:

[0067] Prepare the mixture by mixing Al2(SO4)3·18H2O:Na2O:SiO2:H2O = 1:10:10:200 and stirring at 100℃ for 10 hours.

[0068] (2) Synthesis of mesoporous molecular sieves:

[0069] At 35℃, 100g of nonionic surfactant P123 was dissolved in 800mL of deionized water, and then 1g of AAMA was added. The mixture was stirred for 1 hour until dissolved. Then, 500g of Y-type precursor 3 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 30 hours, then transferred to a polytetrafluoroethylene reactor and crystallized for 2 days. After filtration, washing, drying, and calcination at 600℃ for 6 hours, the mesoporous molecular sieve product was obtained.

[0070] Example 5:

[0071] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0072] (1) Preparation of Y-type precursor 4:

[0073] molar ratio NaAlO2:Na2O:C8H 20 The mixture was prepared with O4Si:H2O = 1:15:15:300 and stirred at 80℃ for 8 hours.

[0074] (2) Synthesis of mesoporous molecular sieves:

[0075] At 50℃, 35g of nonionic surfactant F68 was dissolved in 500mL of deionized water. Then, 0.5g of IA-Co-AA was added and stirred for 0.5h until dissolved. 350g of Y-type precursor 4 solution was then added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 25h, then transferred to a polytetrafluoroethylene reactor for crystallization for 2d. After filtration, washing, drying, and calcination at 500℃ for 8h, the mesoporous molecular sieve product was obtained.

[0076] Example 6:

[0077] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0078] (1) Preparation of Y-type precursor 5:

[0079] Prepare the solution by mixing AIP:Na2O:SiO2:H2O in a molar ratio of 1:16:15:400 and stirring at 50°C for 10 hours.

[0080] (2) Synthesis of mesoporous molecular sieves:

[0081] At 35℃, 40g of nonionic surfactant F38 was dissolved in 600mL of deionized water, and then 1.5g of IA-Co-AA was added. The mixture was stirred for 0.5h and then for 2h until dissolved. Then, 200g of Y-type precursor 5 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 20h, then transferred to a polytetrafluoroethylene reactor for crystallization for 3 days. After filtration, washing, drying, and calcination at 550℃ for 4h, the mesoporous molecular sieve product was obtained.

[0082] Example 7:

[0083] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0084] (1) Preparation of Y-type precursor 6:

[0085] Prepare the mixture by mixing AlCl3:Na2O:Na4SiO4:H2O in a molar ratio of 1:19:20:350 and stirring at 35°C for 10 hours.

[0086] (2) Synthesis of mesoporous molecular sieves:

[0087] At 30℃, 50g of nonionic surfactant P123 was dissolved in 900mL of deionized water, and then 0.6g of POCA was added. The mixture was stirred for 1 hour until dissolved. Then, 300g of Y-type precursor 6 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 24 hours, then transferred to a polytetrafluoroethylene reactor and crystallized for 4 days. After filtration, washing, drying, and calcination at 700℃ for 5 hours, the mesoporous molecular sieve product was obtained.

[0088] Example 8:

[0089] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0090] (1) Preparation of Y-type precursor 3:

[0091] Prepare the mixture by mixing Al2(SO4)3·18H2O:Na2O:SiO2:H2O = 1:10:10:200 and stirring at 100℃ for 10 hours.

[0092] (2) Synthesis of mesoporous molecular sieves:

[0093] At 25℃, 20g of nonionic surfactant F127 was dissolved in 200mL of deionized water, and then 1.2g of AMPS was added. The mixture was stirred for 0.5h until dissolved. Then, 450g of Y-type precursor 3 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 40h, then transferred to a polytetrafluoroethylene reactor and crystallized for 3 days. After filtration, washing, drying, and calcination at 800℃ for 4h, the mesoporous molecular sieve product was obtained.

[0094] Example 9:

[0095] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0096] (1) Preparation of Y-type precursor 2:

[0097] Prepare the mixture by mixing Al(NO3)3:Na2O:SiO2:H2O in a molar ratio of 1:20:20:400 and stirring at 40°C for 15 hours.

[0098] (2) Synthesis of mesoporous molecular sieves:

[0099] At 45℃, 10g of nonionic surfactant F38 was dissolved in 100mL of deionized water, and then 0.8g of AAMA was added. The mixture was stirred for 1.2h until dissolved. Then, 150g of Y-type precursor 2 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 16h, then transferred to a polytetrafluoroethylene reactor and crystallized for 2d. After filtration, washing, drying, and calcination at 400℃ for 8h, the mesoporous molecular sieve product was obtained.

[0100] Example 10:

[0101] A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers includes the following steps:

[0102] (1) Preparation of Y-type precursor 5:

[0103] Prepare the solution by mixing AIP:Na2O:SiO2:H2O in a molar ratio of 1:16:15:400 and stirring at 50°C for 10 hours.

[0104] (2) Synthesis of mesoporous molecular sieves:

[0105] At 30℃, 50g of nonionic surfactant F68 was dissolved in 750mL of deionized water, and then 0.6g of IA-Co-AA was added. The mixture was stirred for 1 hour until dissolved. Then, 300g of Y-type precursor 5 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 16 hours, then transferred to a polytetrafluoroethylene reactor and crystallized for 2 days. After filtration, washing, drying, and calcination at 400℃ for 8 hours, the mesoporous molecular sieve product was obtained.

[0106] Comparative Example 1:

[0107] (1) Preparation of Y-type precursor 1:

[0108] Prepare the mixture by mixing Al2(SO4)3·18H2O:Na2O:SiO2:H2O = 1:18:15:320 at 98℃ for 8 hours.

[0109] (2) Synthesis of mesoporous molecular sieves:

[0110] At 35℃, 40g of nonionic surfactant F68 was dissolved in 600mL of deionized water and stirred for 0.5h. After dissolution, 350g of Y-type precursor 1 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 20h, then transferred to a polytetrafluoroethylene reactor and crystallized for 1 day. After filtration, washing, drying, and calcination at 550℃ for 6h, the mesoporous molecular sieve product was obtained.

[0111] Comparative Example 2:

[0112] (1) Preparation of Y-type precursor 1:

[0113] Prepare the mixture by mixing Al2(SO4)3·18H2O:Na2O:SiO2:H2O = 1:18:15:320 at 98℃ for 8 hours.

[0114] (2) Synthesis of mesoporous molecular sieves:

[0115] At 35℃, 40g of nonionic surfactant F68 was dissolved in 600mL of deionized water, and then 0.6g of sodium α-olefin sulfonate was added. The mixture was stirred for 0.5h until dissolved. Then, 350g of Y-type precursor 1 solution was added dropwise, while adjusting the pH of the solution with sulfuric acid. After the addition was complete, the mixture was assembled for 20h, then transferred to a polytetrafluoroethylene reactor and crystallized for 1 day. After filtration, washing, drying, and calcination at 550℃ for 6h, the mesoporous molecular sieve product was obtained.

[0116] Table 1 Physicochemical parameters of the samples

[0117]

[0118] Comparative Example 1 shows the relevant parameters of the sample without AAMA. As can be seen from the table, the sample has a larger 2θ angle, resulting in a smaller unit cell parameter and a pore wall thickness of 5.61 nm. Example 1 shows the relevant parameters of the sample with 0.6 g of AAMA added under the same conditions. It can be seen that after adding AAMA, the 2θ angle is larger, resulting in a larger unit cell parameter. AAMA contains multiple -COOH bonds, which interact with the PEO segment in F68 to form complex micelles. The presence of multiple carboxyl groups increases the electrostatic repulsion of the micelles; moreover, it has significant steric hindrance, leading to an increase in the unit cell parameter of the micelle sample. When the pore size is similar, an increase in the unit cell parameter will significantly increase the pore wall thickness of the molecular sieve.

[0119] Comparative Example 2 shows the relevant parameters of the sample after adding sodium α-alkenylsulfonate. Sodium α-alkenylsulfonate contains a hydrophilic group -SO3H, which interacts with the hydrophobic groups of the block copolymer, dispersing the composite micelles in the solution. This promotes the assembly of inorganic species with the composite micelles, improving the orderliness of the molecular sieve sample. This is similar to adding AAMA. However, the significant steric hindrance effect of AAMA itself increases the cell parameters of the molecular sieve sample, thereby increasing the pore wall thickness of the molecular sieve without affecting the pore size.

[0120] Figure 1 The image shows the XRD characterization results of the mesoporous molecular sieve prepared in Example 1. As can be seen from the image, the product has a typical ordered two-dimensional mesoporous structure.

[0121] Figure 2 The figure shows the BET characterization results of the mesoporous molecular sieve prepared in Example 1. It can be seen from the figure that the product has the hysteresis loop unique to mesoporous materials.

[0122] Figure 3 The graph shows the pore size distribution of the mesoporous molecular sieve prepared in Example 1. As can be seen from the graph, the product has a mesoporous structure.

[0123] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing highly stable mesoporous molecular sieves with the assistance of carboxylic acid copolymers, characterized in that, Includes the following steps: (1) Preparation of Y-type precursor: Aluminum source, Na2O, silicon source and water are stirred and mixed to obtain Y-type precursor solution; (2) Synthesis of mesoporous molecular sieves using carboxylic acid copolymer-assisted block nonionic surfactants: The nonionic surfactant was dissolved in water, and then the carboxylic acid copolymer was added and stirred. After it was dissolved, the Y-type precursor solution was added dropwise. After the addition was completed, the mixture was assembled and then transferred to a polytetrafluoroethylene reactor for crystallization. After filtration, washing, drying and calcination, the mesoporous molecular sieve product was obtained. The nonionic surfactant is selected from polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO). 20 PPO 70 PEO 20 Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO) 80 PPO 30 PEO 80 Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO) 106 PPO 70 PEO 106 Polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO) 43 PPO 14 PEO 43 One or more of the following; The carboxylic acid copolymer is selected from one of the following: methacrylic acid copolymer, phosphoryl carboxylic acid copolymer, maleic acid-acrylic acid copolymer, and acrylic acid-itaconic acid copolymer; The mass ratio of the carboxylic acid copolymer to the nonionic surfactant is 1:50-300.

2. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, In step (1), the molar ratio of aluminum source, Na2O, silicon source and water is 1: 10-20: 10-20: 200-400; the stirring in step (1) is specifically: stirring at 40-100 °C for 5-15 h.

3. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, In step (1), the aluminum source is selected from one or more of aluminum sulfate octadechydrate, aluminum nitrate, sodium aluminate, aluminum chloride, and aluminum isopropoxide; in step (1), the silicon source is selected from one or more of tetraethyl orthosilicate, sodium orthosilicate, water glass, silicon powder, and silica sol.

4. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, In step (2), the nonionic surfactant is polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO). 20 PPO 70 PEO 20 .

5. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, The carboxylic acid copolymer in step (2) is a methacrylic acid copolymer.

6. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, In step (2), the mass ratio of the carboxylic acid copolymer to water is 1:10-100.

7. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, The crystallization temperature in step (2) is 80-150 ℃, and the crystallization time is 1-4 days.

8. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 1, characterized in that, The calcination conditions in step (2) are: temperature 400-800 °C, 4-8 h.

9. The method for synthesizing highly stable mesoporous molecular sieves with carboxylic acid copolymer assistance according to claim 8, characterized in that, The calcination conditions in step (2) are: 550°C for 6 hours.

10. The mesoporous molecular sieve prepared by the method according to any one of claims 1-9.

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