Near-neutral synthesis method of high-aluminum-content mesoporous aluminosilicate

Abstract

The invention discloses a near-neutral synthesis method of high-aluminum-content mesoporous aluminosilicate, which comprises the following steps: firstly, dissolving a template agent in deionized water, and fully stirring to obtain a uniform template agent solution; the preparation method comprises the following steps: uniformly mixing a silicon source with an inorganic salt, and uniformly mixing an aluminum source with a dilute sulfuric acid solution in deionized water to prepare a silicate solution and an aluminum salt solution; synchronously dripping the silicate solution and the aluminum salt solution into the template agent solution to form an aluminosilicate precursor; and performing crystallization, suction filtration, washing, drying and roasting treatment on the precursor to finally obtain the mesoporous aluminosilicate material. In the process of synthesizing the mesoporous aluminosilicate by using the inorganic salt under the near-neutral condition, anions and aluminum ions form a soluble complex (such as Al (HCO3) 2 +), hydrolytic precipitation of aluminum species in a neutral environment is effectively inhibited, and it is ensured that the aluminum element participates in the reaction in an active form; the efficient synthesis of the mesoporous aluminosilicate material with high aluminum content and high order degree is realized.

Description

A near-neutral synthesis method for high-alumina content mesoporous aluminosilicates Technical Field

[0001] This invention relates to the field of mesoporous aluminosilicate material synthesis technology, specifically to a near-neutral synthesis method for high-aluminum-content mesoporous aluminosilicates. Background Technology

[0002] Molecular sieves, due to their large specific surface area and regular, tunable pore structure, hold great promise in the transformation of macromolecules. However, their low Al introduction efficiency leads to low acidity and hydrothermal stability. The amorphous pore walls further restrict their hydrothermal stability, significantly limiting their application in harsh chemical processes, such as catalytic cracking (FCC). A one-step method is a simpler route for synthesizing Al-SBA-15; however, this method still suffers from limitations such as insufficient acid sites and poor textural properties (e.g., low specific surface area and pore volume). To address these issues, researchers both domestically and internationally have developed a neutral synthesis system that significantly improves aluminum introduction efficiency.

[0003] Lin et al. (Microporous and Mesoporous Materials, 2011, 142(2):526-534.) successfully synthesized Al-SBA-15 with high aluminum content by creating a weakly acidic environment through the hydrolysis of aluminum salts in a medium without the addition of inorganic acids. By changing synthesis parameters such as the Si / Al molar ratio, the P123 / Si molar ratio, and the aging temperature, the pore structure could be precisely controlled. A p6mm symmetrical hexagonal ordered structure was observed, and the structural order gradually increased as the Si / Al molar ratio in the gel decreased from 100 to 5. Aluminum species play an important role in the formation of mesoporous structures. Aluminum can be introduced into the mesoporous pore wall structure mainly in the form of tetrahedral coordination, and this method allows for the acquisition of materials with high order and hydrothermal stability. However, under weakly acidic conditions, the amount of aluminum introduced was less than half, indicating low aluminum introduction efficiency.

[0004] Jiang et al. (Microporous and Mesoporous Materials, 2011, 142(1):341–346) proposed a method for synthesizing Al-SBA-15 based on fluoride ion (NaF) regulation, successfully achieving controllable introduction of aluminum content and significant improvement in the hydrothermal stability of the material. In this strategy, F... -As a mineralizing agent, it effectively promotes the hydrolysis-condensation process of silicon-aluminum species, thereby enhancing the crosslinking degree of the framework. By adjusting the aluminum source feed ratio, the framework aluminum content can be precisely controlled within a certain range, thus achieving targeted regulation of the acid properties of the material. However, this method still has significant limitations: the reaction system always maintains a strongly acidic environment (pH=1.65), limiting its applicability under mild conditions; in addition, F - The introduction of this technology not only increases the difficulty and cost of wastewater treatment, but also brings certain environmental and operational risks.

[0005] Yu et al. (Journal of the American Chemical Society, 2018, 140(14):4770-4773) successfully prepared highly ordered SBA-15 and Fe-SBA-15 using ·OH radicals generated by Fenton's reagent under conditions without exogenous acid. With H + In comparison, ·OH exhibits superior depolymerization ability for TEOS, resulting in materials with higher specific surface area and iron induction efficiency. However, this method is not suitable for the synthesis of Al-SBA-15, mainly because aluminum species are difficult to effectively participate in Fenton-like reactions to generate ·OH, which is a key factor in promoting the hydrolysis and condensation of silicon sources under acid-free conditions.

[0006] Liu et al. (Inorganic Chemistry, 2022, 61(30): 11820-11829; Industrial & Engineering Chemistry Research, 2023, 62(47): 20251-20258); Al-SBA-15 was synthesized under neutral conditions using sodium persulfate (SPS) as the hydroxyl radical source. This strategy avoids the inherent competition between iron and aluminum in the Fenton process, thus overcoming the problem of low aluminum introduction efficiency in the ·OH initiation system. The ·OH generated by SPS decomposition effectively promotes the hydrolysis and condensation of silicon source, while the neutral synthesis conditions significantly improve the introduction efficiency of aluminum species. The obtained material achieves a higher aluminum introduction amount in the pore wall, exhibits better hydrothermal stability, and the aluminum content and acidity can be flexibly controlled by adjusting the amount of SPS. However, the material synthesized by this method shows a decrease in specific surface area, pore volume, and mesoporous order, failing to fully reach the level of traditional methods.

[0007] In the study by Du et al. (Microporous and Mesoporous Materials, 2008, 112(1):225-234), SBA-15 with high hydrothermal stability and a hexagonal ordered mesoporous structure was successfully synthesized by introducing ammonium carbonate under neutral conditions, and the polymerization of silica by carbonate ions was confirmed. However, the method of using carbonate ions to guide the introduction of aluminum to synthesize Al-SBA-15 has not yet been verified.

[0008] Despite much work done on the synthesis of high-Al-content mesoporous aluminosilicates, the synthesis of aluminosilicates with high aluminum content, strong acidity, and regular mesoporous structure under neutral conditions still faces many challenges. Summary of the Invention

[0009] The present invention aims to solve the problem of synthesizing highly ordered Al-SBA-15 by introducing aluminum under neutral conditions.

[0010] This invention solves the above-mentioned technical problems by adding sodium bicarbonate under neutral conditions to synthesize mesoporous aluminosilicates with high aluminum content and high mesoporous order. The anions emitted from the ionization of inorganic salts exert multiple complex effects: firstly, HCO3-... - It forms soluble complexes with aluminum ions (such as Al(HCO3)). 2+ This effectively inhibits the hydrolysis and precipitation of aluminum species in a neutral environment, ensuring that aluminum participates in the reaction in its active form; secondly, the anions generate H+ through ionization equilibrium. + The process of hydrolysis-condensation of silicon source is mildly promoted, which accelerates the formation of silicon-oxygen network. In addition, in a near-neutral environment (pH > isoelectric point of silicon ≈ 2), the surface of silicon dioxide framework is negatively charged, while aluminum-inorganic salt complex carries positive charge. The electrostatic attraction between the two significantly enhances the enrichment and anchoring of aluminum species near the framework, thereby greatly improving the efficiency of aluminum introduction.

[0011] A near-neutral synthesis method for high-alumina content mesoporous aluminosilicates includes the following steps: (1) Preparation of template agent solution: The template agent is mixed with deionized water at a weight ratio of 1:1-10; the mixture is stirred at 10-100℃ for 5-15h to prepare a template agent solution; (2) Preparation of silicate solution: The silicon source and inorganic salt are added to deionized water and stirred at 10℃-80℃ for 1h-10h to obtain a silicate solution, n(SiO2):n(inorganic salt):n(H2O)=1:0.001-3:20-200; (3) Preparation of aluminum salt solution: The aluminum salt, 6M sulfuric acid solution and deionized water are mixed with deionized water. Mix water and stir to dissolve for 1-10 h at 10-80℃ to obtain aluminum salt solution, n(Al2O3):n(H2SO4):n(H2O)=1:0.001-3:5-100; (4) Mix the raw materials in a water bath at 20-70℃, add the solution obtained in step (2) and step (3) dropwise to the template agent solution, keep the pH at 4-10, assemble in a water bath at 10℃-70℃ for 4-48 h, then put the solid product and mother liquor into the reaction vessel, crystallize at 80-150℃ for 12-72 h, and finally filter, wash to neutral, dry and calcin to obtain mesoporous aluminosilicate product.

[0012] Beneficial effects of this invention: In the process of synthesizing mesoporous aluminosilicates under near-neutral conditions using inorganic salts, the anions of this invention play a multiple complexing role: First, the anions form soluble complexes with aluminum ions (such as Al(HCO3)). 2+ This effectively inhibits the hydrolysis and precipitation of aluminum species in a neutral environment, ensuring that aluminum participates in the reaction in its active form; secondly, the anions generate H+ through ionization equilibrium. + The process of hydrolysis-condensation of the silicon source is mildly promoted, accelerating the formation of the silicon-oxygen network. Furthermore, in a near-neutral environment (pH > isoelectric point of silicon ≈ 2), the silica framework surface carries a negative charge, while the aluminum-anion complex carries a positive charge. The electrostatic attraction between them significantly enhances the enrichment and anchoring of aluminum species near the framework, thereby greatly improving the efficiency of aluminum introduction. Simultaneously, the establishment of anion buffer pairs effectively maintains the pH stability of the reaction system, avoiding acid-base fluctuations caused by reagent hydrolysis, and providing a continuously stable chemical environment for the orderly assembly of silicon, aluminum, and the template agent. The synergistic effect of these multiple mechanisms ultimately achieves the efficient synthesis of high-aluminum-content, highly ordered mesoporous aluminosilicates. Attached Figure Description

[0013] Figure 1 shows the XRD patterns of the mesoporous aluminosilicates prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention; Figure 2 shows the BET adsorption-desorption curves of the mesoporous aluminosilicates prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention; Figure 3 shows the pore size distribution curves of the mesoporous aluminosilicates prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 of the present invention. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0015] The experimental raw materials used in the following examples were sourced from: silicon source, aluminum source, etc., which were all industrial products from Lanzhou Petrochemical Company of China National Petroleum Corporation; the main components of water glass in the silicon source were: 27.8wt% SiO2, 63.2wt% H2O, and 8.98wt% Na2O; the main components of silica were: 90wt% SiO2 and 10wt% H2O; the main components of silica sol were: 20wt% SiO2 and 80wt% H2O; the main component of silica powder was: ≥99wt% SiO2; the main components of silicic acid were: 5wt% SiO2 and 95wt% H2O; the sulfuric acid solution was prepared using concentrated sulfuric acid solution (98wt%); the template agent (F68(PEO) 80 PPO 30 PEO 80 The molecular weight is 8350, F127 (PEO) 106 PPO 70 PEO 106 The molecular weight is 12600, P123(PEO) 20 PPO 70 PEO 20 Molecular weight 8600, F88 (PEO) 100 PPO 39 PEO 100 The molecular weight is 11400, P103 (PEO) 17 PPO 85 PEO 17 The molecular weight is 4950, P65 (PEO) 20 PPO 30 PEO 20 The molecular weight is 3400, L121 (PEO5PPO) 70PEO5 (molecular weight 4400) was purchased from Sigma-Aldrich Trading Co., Ltd., Jiangsu Jiasheng Chemical Technology Co., Ltd., etc. Concentrated sulfuric acid, inorganic salts or organoaluminum salts (sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, calcium bicarbonate, ammonium carbonate, aluminum sulfate, boehmite, aluminum chloride, aluminum citrate, aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum chloride or aluminum nitrate) were all commercially available analytical grade reagents from Xilong Scientific Co., Ltd.; other experimental materials and reagents, unless otherwise specified, were obtained commercially.

[0016] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0017] The Al-SBA-15 samples provided in the examples were tested using the following analytical instruments: 1. 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 30 mA. Sample testing conditions: scanning angle 5° to 40°, scanning speed 8° / min; 2. Adsorption-desorption isotherms of the samples were determined using an ASAP2020M fully automated adsorption analyzer manufactured by Micromeritics, USA, at liquid nitrogen temperature. Nitrogen gas was used as the adsorbate. The T-plot model was used to distinguish 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; 3. Elemental content was analyzed using an inductively coupled plasma atomic emission spectrometer (ICP-AES, Agilent 5800, USA). Infrared spectra were acquired using a Vertex 70V spectrometer. Thermogravimetric analysis was performed on a Hitachi STA7300 instrument under the following conditions: room temperature to 1200°C, argon atmosphere, and heating rate of 10°C / min.

[0018] The following is a specific implementation method, Example 1: The template agent P123 is mixed with deionized water at a weight ratio of 1:10; the mixture is stirred at 40°C for 5 hours to prepare a template agent solution; water glass and sodium bicarbonate reagent are added to 100g of deionized water and stirred at 35°C for 4 hours to obtain a silicate solution; aluminum sulfate octadecylhydrate, 6M sulfuric acid solution and deionized water are mixed and stirred at 35°C for 4 hours to obtain an aluminum salt solution; under a 40°C water bath, the solutions obtained in steps (2) and (3) are added dropwise to the template agent solution, with a pH of about 6 and a rotation speed of 5mL / min, and assembled under a 40°C water bath for 24 hours. Then the solid product and mother liquor are loaded into the reaction vessel. All components: n(P123):n(Na2O):n(SiO2):n(Al2O3):n(CO3) 2-):n(H2O)=0.01:3.3:1:0.05:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0019] Figure 1 shows the XRD pattern of the mesoporous molecular sieve product prepared in this embodiment. It can be seen that the mesoporous molecular sieve product prepared in this embodiment has a typical ordered two-dimensional mesoporous structure. Figure 2 shows the BET adsorption-desorption curve and pore size distribution of the mesoporous molecular sieve product prepared in this embodiment. It can be seen that the mesoporous molecular sieve product prepared in this embodiment has the hysteresis loop unique to mesoporous materials.

[0020] Example 2: The difference between Example 2 and Example 1 is that the template agent in Example 2 is F68, which includes the following steps: mixing template agent F68 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(F68):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0021] Example 3: The difference between Example 3 and Example 1 is that the template agent in Example 3 is F127, which includes the following steps: mixing template agent F127 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(F127):n(Na2O):n(SiO2):n(Al2O3):n(CO3)2- ):n(H2O)=0.01:3.3:1:0.05:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0022] Example 4: The difference between Example 4 and Example 1 is that the silicon source in Example 4 is silicon powder, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding silicon powder and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0023] Example 5: The difference between Example 5 and Example 1 is that the silicon source in Example 5 is silica. It includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding silica and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0024] Example 6: The difference between Example 6 and Example 1 is that the silicon source in Example 6 is TEOS, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding TEOS and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0025] Example 7: The difference between Example 7 and Example 1 is that the silicon source in Example 7 is TMOS, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding TMOS and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0026] Example 8: The difference between Example 8 and Example 1 is that the aluminum source in Example 8 is aluminum nitrate, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum nitrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components are: (P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0027] Example 9: The difference between Example 9 and Example 1 is that the aluminum source in Example 9 is aluminum chloride, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum chloride, 6M sulfuric acid solution and deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0028] Example 10: The difference between Example 10 and Example 1 is that the aluminum source in Example 10 is aluminum citrate, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum citrate, 6M sulfuric acid solution and deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0029] Example 11: The difference between Example 11 and Example 1 is that the aluminum source in Example 11 is aluminum isopropoxide, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum isopropoxide, 6M sulfuric acid solution and deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0030] Example 12: The difference between Example 12 and Example 1 is that the inorganic salt in Example 12 is sodium carbonate. It includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium carbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0031] Example 13: The difference between Example 13 and Example 1 is that the inorganic salt in Example 13 is potassium bicarbonate. It includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and potassium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at 40°C in a water bath, with a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C in a water bath for 24 hours, and then loading the solid product and mother liquor into a reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0032] Example 14: The difference between Example 14 and Example 1 is that the inorganic salt in Example 14 is potassium carbonate. It includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and potassium carbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:4.15:0.05:1:0.85:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0033] Example 15: The difference between Example 15 and Example 1 is that the inorganic salt in Example 15 is calcium bicarbonate, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and calcium bicarbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.5:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0034] Example 16: The difference between Example 16 and Example 1 is that the inorganic salt in Example 16 is ammonium carbonate, which includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and ammonium carbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:0.25:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0035] Example 17: The difference between Example 17 and Example 1 is that the inorganic salt in Example 17 is lithium carbonate. It includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the above mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and lithium carbonate reagent to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution at a pH of around 6 and a rotation speed of 5mL / min, assembling at 40°C for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2O)=0.01:3.3:0.05:1:1:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0036] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that a larger amount of sulfuric acid solution was added to the materials in Comparative Example 1 to make the mother liquor acidic, while sodium bicarbonate was not added. It includes the following steps: Mixing template agent P123, H2SO4 solution, and deionized water; stirring the mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass to 100g of deionized water and stirring to dissolve at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadechydrate, sulfuric acid solution, and deionized water and stirring to dissolve at 35°C for 4 hours to obtain an aluminum salt. Solution; Under 40℃ water bath conditions, the solutions obtained in steps (2) and (3) are added dropwise to the template agent solution simultaneously, with a pH of about 6 and a rotation speed of 5 mL / min. The mixture is assembled for 24 h under 40℃ water bath conditions. Then, the solid product and mother liquor are loaded into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(H2O)=0.01:3.3:0.05:1:350; Crystallize at 100℃ for 48 h. Finally, after filtration, washing to neutrality, drying, and calcination, mesoporous aluminosilicate product is obtained.

[0037] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that sodium bicarbonate is not added to the materials in Comparative Example 1. It includes the following steps: mixing template agent P123 with deionized water at a weight ratio of 1:10; stirring the mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass to 100g of deionized water and stirring at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadechydrate, a small amount of 6M sulfuric acid solution, and deionized water and stirring at 35°C for 4 hours to obtain an aluminum salt solution; and then dissolving the solution in a 40°C water bath. Under the conditions, the solutions obtained in steps (2) and (3) were added dropwise to the template agent solution simultaneously. The pH was around 9, the rotation speed was 5 mL / min, and the mixture was assembled in a water bath at 40℃ for 24 h. Then, the solid product and the mother liquor were loaded into the reaction vessel. All components were: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(H2O)=0.01:3.3:0.05:1:350. The mixture was crystallized at 100℃ for 48 h. Finally, the product was obtained by filtration, washing until neutral, drying, and calcination.

[0038] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that Comparative Example 1 adds more sulfuric acid solution to the material to make the mother liquor acidic. It includes the following steps: mixing template agent P123 with deionized water, stirring the mixture at 40°C for 5 hours to prepare a template agent solution; adding water glass and sodium bicarbonate reagent to 100g of deionized water, stirring and dissolving at 35°C for 4 hours to obtain a silicate solution; mixing aluminum sulfate octadecylhydrate, 6M sulfuric acid solution with deionized water, stirring and dissolving at 35°C for 4 hours to obtain an aluminum salt solution; simultaneously adding the solutions obtained in steps (2) and (3) dropwise to the template agent solution under 40°C water bath conditions, with a pH of about 3 and a rotation speed of 5mL / min, assembling under 40°C water bath conditions for 24 hours, and then loading the solid product and mother liquor into the reaction vessel. All components: n(P123):n(Na2O):n(Al2O3):n(SiO2):n(CO3) 2- ):n(H2SO4):n(H2O)=0.01:3.3:0.05:1:1:0.7:350; crystallized at 100℃ for 48h, and finally obtained mesoporous aluminosilicate product by filtration, washing to neutrality, drying and calcination.

[0039] The adsorption-desorption isotherms of the samples were determined using an ASAP2020M fully automated adsorption instrument manufactured by Micromeritics, USA, at liquid nitrogen temperature, with nitrogen as the adsorbate.

[0040] The specific surface area of ​​the sample was calculated using the Brunauer-Emmett-Teller (BET) equation based on the adsorption equilibrium isotherm between relative pressures of 0.05 and 0.25. The t-plot model was used to distinguish between the internal and external surface areas of the sample. The pore volume and pore size distribution were determined using the static volumetric method, thereby calculating the pore structure parameters.

[0041] Table 1. Physical parameters of each comparative example and embodiment: total specific surface area / m² 2 ·g -1 Mesoporous specific surface area / m 2 ·g -1 Pore ​​volume / m 3 ·g -1Si / Al ratio (ICP) Comparative Example 1: 393.43, 86.20, 435, 0.3; Comparative Example 2: 527.74, 89.30, 423, 5.2; Comparative Example 3: 635.74, 25.30, 434, 3.2; Example 1: 823.68, 01.30, 621, 0.3; Example 2: 774.37, 30.60, 581, 2.4; Example 3: 769.37, 23.30, 57; Example 4: 754.67, 13.80, 55; Example 5: 746.86, 25.20, 54; Example 6: 739.56, 72.30, 51; Example 7: 7 30.6652.10.48 Example 8 726.7648.80.47 Example 9 725.3641.70.46 Example 10 714.9635.90.44 Example 11 710.7648.50.48 Example 12 704.1641.60.51 Example 13 698.6635.40.47 Example 14 691.5628.90.46 Example 15 684.2621.80.48 Example 16 673.3617.80.44 Example 17 661.9609.30.49 As shown in Table 1, compared with Comparative Example 1, Example 1 has a sharper 100-plane diffraction peak, exhibiting better mesoporous order, while its specific surface area (823.6 m²·g) is also higher. -1 The concentration of sodium bicarbonate in the control group was significantly greater than that in the control group (393.4 m²·g) synthesized under acidic conditions without the addition of sodium bicarbonate (Comparative Example 1). -1 ICP testing results showed that the Si / Al ratio in Example 1 was 10.3, significantly lower than the 50.3 in Comparative Example 1, indicating a higher aluminum loading in Example 1. This demonstrates that acidic conditions can only yield Al-SBA-15 with a lower aluminum loading, and acidic conditions are unfavorable for aluminum introduction. The specific surface area of ​​Comparative Example 2, without the addition of sodium bicarbonate under neutral conditions, was only 527.7 m²·g. -1 This indicates that Al-SBA-15 synthesized under neutral conditions without the addition of sodium bicarbonate has an extremely low specific surface area and poor mesoporous order. Furthermore, the Si / Al ratio of Example 1 (10.3) is lower than that of Comparative Example 2 (35.2), further confirming its higher aluminum loading. In addition, compared to Comparative Example 3, Example 1 has a higher specific surface area (823.6 m²·g⁻¹). -1 vs. 635.7m²·g -1It also shows significant advantages in terms of aluminum content, and its Si / Al ratio (10.3) is lower than that of Comparative Example 3 (43.2), indicating a higher aluminum loading. During the synthesis process, a large number of bubbles are generated because bicarbonate reacts with acid to produce carbon dioxide, rendering the carbonate ions ineffective. This results in the synthesized Al-SBA-15 lacking a high specific surface area and mesoporous order. Therefore, it can be concluded that Al-SBA-15 with significantly increased aluminum content can be synthesized under neutral conditions by adding sodium bicarbonate, demonstrating excellent development potential.

[0042] 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 near-neutral synthesis method for high-alumina content mesoporous aluminosilicates, characterized in that, Includes the following steps: S1. Dissolve the template agent in deionized water and stir thoroughly in a water bath to obtain a homogeneous template agent solution. S2. Mix and stir the silicon source, inorganic salt, and deionized water in a water bath to obtain a silicate solution. S3. Mix the aluminum salt, sulfuric acid solution, and deionized water and stir to dissolve to obtain an aluminum salt solution. S4. Under water bath conditions, simultaneously add the silicate solution and aluminum salt solution dropwise to the template agent solution, maintain the pH at a certain condition, assemble under water bath conditions, then load the solid product and mother liquor into a reaction vessel for crystallization, and finally filter, wash until neutral, dry, and calcine to obtain a mesoporous aluminosilicate product.

2. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, The template agent in step S1 includes triblock copolymer F68:PEO 80 PPO 30 PEO 80 F127: PEO 106 PPO 70 PEO 106 P123: PEO 20 PPO 70 PEO 20 F88: PEO 100 PPO 39 PEO 100 P103: PEO 17 PPO 85 PEO 17 P65: PEO 20 PPO 30 PEO 20 L121: PEO5PPO 70 PEO5.

3. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, In step S1, the water bath temperature is between 10-80 ℃.

4. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, The silicon source in step S2 includes one or more of tetraethyl orthosilicate, silica sol, silicon powder, silicic acid, silica, and water glass.

5. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, The inorganic salts in step S2 include one or a mixture of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, lithium carbonate, calcium bicarbonate, and ammonium carbonate.

6. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, The aluminum source in step S3 includes one or a mixture of aluminum sulfate, boehmite, aluminum chloride, aluminum citrate, aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum chloride, or aluminum nitrate.

7. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, The concentration of sulfuric acid in step S3 is 0.5M-10M.

8. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, In step S4, the molar ratio of the substances n(Al2O3): n(Na2O): n(SiO2): n(H2O): n(template agent): n(inorganic salt) = 1: 10-30: 10-40: 100-500: 0.1-5: 1-100.

9. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, The synthesis conditions in step S4 are as follows: under water bath conditions of 20-70 ℃, silicate solution and aluminum salt solution are added dropwise to the template agent solution, the pH is maintained at 4-10, and the mixture is assembled under water bath conditions of 10-70 ℃ for 4-72 h. Then, the solid product and mother liquor are loaded into the reaction vessel and crystallized at 80-150 ℃ for 12-72 h.

10. The near-neutral synthesis method of high-alumina content mesoporous aluminosilicates according to claim 1, characterized in that, In step S4, the dropping rates of the two solutions are between 1 and 120 mL / min, and the dropping rates of the two solutions are not necessarily the same.

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