A modified catalyst carrier material and a method for producing the same

Abstract

The application belongs to the technical field of catalyst carrier preparation, and particularly relates to a modified catalyst carrier material and a preparation method thereof. The preparation process comprises the following steps: (1) preparing an aluminum salt mixed solution containing hydroxypropyl-beta-cyclodextrin; (2) preparing a partial aluminate mixed solution containing a polyethylene polyamine small molecule compound; (3) adding the partial aluminate mixed solution into the aluminum salt mixed solution to obtain a precursor; and (4) obtaining the modified catalyst carrier material after reaction, post-treatment and calcination. A certain amount of polyethylene polyamine small molecule compound is added as a template assistant in the hydroxypropyl-beta-cyclodextrin template system. The unique properties of the hydroxypropyl-beta-cyclodextrin and the polyethylene polyamine small molecule compound are utilized to guide the aluminum salt and the partial aluminate to form a precursor with a porous channel structure, and finally an alumina carrier with a high specific surface area and a large pore size is obtained through calcination.

Description

Technical Field

[0001] This invention belongs to the field of catalyst support preparation technology, specifically relating to a modified catalyst support material and its preparation method. Background Technology

[0002] With the development of catalysis science and nanomaterials, more than 80% of chemical production processes now rely on catalysis. A catalyst is defined as "a chemical substance that can change the rate of a chemical reaction without altering its thermodynamic equilibrium position, and is not significantly consumed in the reaction." These substances can be metals, metal oxides, organic complexes, or enzymes. Therefore, to improve catalytic performance, modification of the catalyst itself is necessary, and nanomaterials, as active components or carriers, have become a hot research topic.

[0003] Porous materials play a crucial role in the adsorption, separation, and especially catalytic reactions of substances due to their advantages such as high specific surface area, ordered channels, continuously tunable pore size, and controllable microstructure. Porous alumina, with its high mechanical strength, large specific surface area, excellent thermal and chemical stability, unique channels, and ease of loading different metal species, has gradually attracted attention and is widely used in the field of catalysis, becoming the most commonly used catalyst support. Alumina loaded with noble metals such as gold, palladium, and platinum exhibits excellent catalytic activity in oxidation. However, numerous experiments have shown that the high dispersion and particle size of nano-metal particles on the support are prerequisites for high catalytic activity. To prepare highly active supported nano-metal catalysts, different types, sizes, and morphologies of catalyst supports are typically used to stabilize and disperse metal particles. Therefore, the current challenge remains the controllable preparation of alumina morphology and surface structure.

[0004] CN106268726A discloses a method for preparing high-purity alumina microsphere carriers. It improves and optimizes the spheroidizing process, using alumina with a particle size of less than 200 mesh as raw material. By adding a small amount of volatile additives during activation, and through improved processes such as seed ball manufacturing, sieving, pressing, ball lengthening, sieving, polishing, low-temperature drying, high-temperature drying, and calcination activation, high-purity alumina microspheres with high compressive strength are obtained. Compared with existing technologies, this invention has a pollution-free production process, and the final product contains high-purity alumina with no residual binder or additive components.

[0005] CN120618443A also discloses an alumina support with a defective surface and a dual-pore distribution, and its preparation method. The preparation method of the alumina support includes: preparing dimensionally distorted boehmite; mixing dimensionally distorted boehmite, boehmite A, and guar gum powder evenly, adding a binder and kneading to form a mixture, and then subjecting it to a second drying and a second calcination to obtain an alumina support precursor; the mass ratio of dimensionally distorted boehmite to boehmite A is 1:1-1:3; immersing the alumina support precursor in a second urea solution for a third hydrothermal treatment, and then subjecting it to filtration, washing, a third drying, and a third calcination to obtain an alumina support with a dual-pore distribution; this support has an open pore structure and a surface rich in defect structures, which can increase the number of active sites on the alumina support and facilitate the diffusion of macromolecular reactants into the interior of the alumina support. Although the above process improves the pore size and specific surface area of ​​the alumina support to a certain extent, its preparation process is complex and difficult to promote for industrial use. Summary of the Invention

[0006] To address the technical problems of complex and costly existing catalyst support preparation processes, this invention provides a modified catalyst support material and its preparation method. This method is simple, produces alumina supports with large specific surface area and pore size, and has low industrialization costs, meeting the current requirements of high efficiency, economy, and environmental protection.

[0007] Based on the above objectives, this invention provides a method for preparing a modified catalyst support material, comprising the following steps:

[0008] A method for preparing a modified catalyst support material includes the following steps:

[0009] (1) While stirring, dissolve and disperse the aluminum salt in deionized water to obtain an aluminum salt solution, and then add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution;

[0010] (2) While stirring, dissolve and disperse the aluminate in deionized water to obtain an aluminate solution. Then, add a polyethylene polyamine small molecule compound to the aluminate solution to obtain a mixed aluminate solution. The polyethylene polyamine small molecule compound has more than 2 nitrogen atoms. The mass ratio of the polyethylene polyamine small molecule compound to hydroxypropyl-β-cyclodextrin is (0.05-0.2):1.

[0011] (3) While stirring, add the aluminate mixture solution dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and adjust the pH of the precursor mixture solution to be greater than 7;

[0012] (4) After the addition is complete, continue stirring for a period of time, and then heat up to react; after post-processing and calcining the product, the modified catalyst support material is obtained.

[0013] This invention selects hydroxypropyl-β-cyclodextrin as a template agent for alumina. Hydroxypropyl-β-cyclodextrin has a higher number of hydroxyl groups than α-cyclodextrin, and it contains hydroxypropyl groups, which not only endows the cyclodextrin with a branched structure but also improves its solubility, giving it a cyclic structure with an internal lipophilic and an external hydrophilic nature. Compared to the commonly used linear polyethylene glycol and polyvinyl alcohol surfactants in alumina preparation, it is more conducive to forming a loose porous structure, improving the porosity and pore size of the alumina support. In previous work (CN118788318A), the inventors used hydroxypropyl-β-cyclodextrin as a template agent and surfactant to prepare porous alumina supports. However, the alumina supports prepared by this process had a small specific surface area and limited improvement in pore size. Although the inventors later improved the specific surface area of ​​the alumina support by adding organic polymers such as polyvinyl alcohol as template agents, polyvinyl alcohol has poor solubility. It usually requires heating to completely dissolve in water, making the solution preparation process cumbersome and time-consuming. Furthermore, the solution is prone to gel formation after cooling, which affects the uniformity of subsequent use.

[0014] Therefore, this invention adds a certain amount of polyethylene polyamine small molecule compound as a template agent to the hydroxypropyl-β-cyclodextrin template system. Utilizing the unique properties of both hydroxypropyl-β-cyclodextrin and the polyethylene polyamine small molecule compound as template agents, a precursor with a hierarchical porous structure is guided to form from aluminum salts and aluminates through a synergistic template effect. Finally, after calcination, a high specific surface area and large pore size alumina support is obtained. The hydroxypropyl-β-cyclodextrin molecule itself is a truncated pyramidal hollow macrocyclic molecule, and its hydroxypropyl substituent enhances its water solubility and compatibility with inorganic substances. During the formation of the aluminum precursor, the hydroxypropyl-β-cyclodextrin molecule is encapsulated or adsorbed between the growing particles. Its large volume physically occupies space, preventing the compact packing of particles. After the hydroxypropyl-β-cyclodextrin is removed, large-sized cavities are left in the positions it previously occupied, thus forming large pores. Although hydroxypropyl-β-cyclodextrin is not a traditional surfactant, its amphiphilic structure (hydrophilic outer wall and relatively hydrophobic inner cavity) allows it to interact with inorganic species to some extent. It can act as a soft template to guide the deposition of aluminum precursors around its exterior, forming a pore that "replicates" its external structure.

[0015] In this system, polyethylenepolyamine small molecule compounds play a role in structural regulation and stabilization. They can form hydrogen bonds with numerous hydroxyl groups on the hydroxypropyl-β-cyclodextrin molecule, helping to maintain small crystallite sizes. Simultaneously, as organic bases with multidentate ligands, polyethylenepolyamine small molecule compounds facilitate the slow and uniform co-precipitation of aluminum salts and aluminates, promoting the formation of porous alumina structures. Furthermore, the nitrogen atoms in the polyethylenepolyamine small molecule compounds possess lone pairs of electrons, enabling strong complexation with aluminum ions to form stable, soluble complexes, promoting the uniform and orderly formation of precursors and contributing to a more stable framework and more developed pores. Additionally, as small linear molecules, polyethylenepolyamine small molecule compounds can fill the smaller gaps in the precursor, contributing smaller mesopores and forming a pore gradation with the macropores generated by hydroxypropyl-β-cyclodextrin, further optimizing the pore structure. However, the amount of polyethylenepolyamine small molecule compounds should not be excessive; otherwise, excessive cross-linking with hydroxypropyl-β-cyclodextrin through hydrogen bonding can lead to the formation of stacked structures, which is detrimental to increasing the specific surface area of ​​the alumina support.

[0016] Furthermore, in step (1), the aluminum salt is one or more of aluminum nitrate, aluminum chloride, aluminum bromide, and aluminum sulfate.

[0017] Furthermore, the aluminum salt concentration in the aluminum salt solution is 8-15 g / L; the mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is (0.15-0.25):1. Specifically, the mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.15:1, 0.18:1, 0.2:1, or 0.25:1.

[0018] Furthermore, in step (2), the aluminate is one or more of sodium aluminate or potassium aluminate; the mass ratio of aluminate to aluminum salt is (0.5-1):1; and the aluminate concentration in the aluminate solution is 5-10 g / L. Specifically, the aluminate concentration in the aluminate solution can be 5 g / L, 6 g / L, 7 g / L, 8 g / L, 9 g / L, or 10 g / L.

[0019] Furthermore, in step (2), the polyethylene polyamine small molecule compound is one or more of diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, heptaethyleneoctamine, octaethylenenonamine, nonaethylenedecamine, and decaethyleneundecamine. The nitrogen atoms in the polyethylene polyamine small molecule compound have lone pairs of electrons, which can strongly complex with aluminum ions, promoting the formation of a uniform precursor structure. In particular, polyethylene polyamine small molecule compounds with different numbers of nitrogen atoms can be used in combination. Polyethylene polyamine small molecule compounds with different chain lengths and nitrogen atom numbers can promote the formation of interparticle pores and increase the specific surface area of ​​alumina. For example, diethylenetriamine and triethylenetetramine, or diethylenetriamine and tetraethylenepentamine, can be used in combination. Furthermore, diethylenetriamine and tetraethylenepentamine can be selected, and the amount of each is not particularly limited. Specifically, the molar ratio of diethylenetriamine to tetraethylenepentamine can be (0.2-4):1; further, it can be (1.5-3):1.

[0020] Furthermore, during the dropwise addition process in step (3), the aluminum salt mixture solution is heated to a temperature of 45-65℃; the dropwise acceleration rate is 5-15 mL / min. Specifically, the dropwise acceleration rate can be 5 mL / min, 8 mL / min, 10 mL / min, 12 mL / min or 15 mL / min.

[0021] Further, in step (3), the pH is adjusted to 8-10. The pH is adjusted by adding acidic substances such as hydrochloric acid, nitric acid, and acetic acid, or by using alkaline substances such as sodium hydroxide and ammonia.

[0022] Furthermore, the stirring time in step (4) is 0.4-1h.

[0023] Furthermore, in step (4), the temperature for heating the reaction is 70-90℃ and the reaction time is 1.5-3h; the post-treatment is filtration, washing and drying.

[0024] Furthermore, in step (4), the calcination temperature is 550-650℃ and the calcination time is 4-6h. A suitable calcination temperature can promote the improvement of the porous morphology of the alumina support and better increase the specific surface area of ​​the support.

[0025] Beneficial effects:

[0026] This invention adds a certain amount of polyethylene polyamine small molecule compound as a template agent to a hydroxypropyl-β-cyclodextrin template system. Utilizing the unique properties of both hydroxypropyl-β-cyclodextrin and the polyethylene polyamine small molecule compound as template agents, a precursor with a hierarchical porous structure is formed by guiding aluminum salts and aluminates to form a synergistic template effect through calcination. Finally, a high specific surface area and large pore size alumina support is obtained. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0030] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0031] Unless otherwise specified, the preparation processes and raw materials of the following examples and comparative examples are the same.

[0032] Performance testing: The specific surface area, pore size, and pore volume of the modified catalyst support materials prepared in the following examples and comparative examples were tested using the BET method.

[0033] Example 1

[0034] A method for preparing a modified catalyst support material includes the following steps:

[0035] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 8 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.15:1.

[0036] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylene polyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylene polyamine small molecule compound was triethylenetetramine. The mass ratio of the polyethylene polyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.2:1. The mass ratio of aluminate to aluminum salt was 0.6:1. The aluminate concentration in the aluminate solution was 6 g / L.

[0037] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 8; during the dropwise addition process, the aluminum salt mixture solution was heated to 45℃; the dropwise acceleration rate was 7mL / min;

[0038] (4) After the addition is complete, continue stirring for 0.4 h, then raise the temperature to 70℃ and react for 3 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 550℃ and the calcination time is 6 h. The specific surface area of ​​this support material is tested to be 292 m². 2 / g, pore size 16.3nm, pore volume 1.31cm³ 3 / g.

[0039] Example 2

[0040] A method for preparing a modified catalyst support material includes the following steps:

[0041] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 15 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.25:1.

[0042] (2) Sodium aluminate is dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylene polyamine small molecule compound is added to the aluminate solution to obtain a mixed aluminate solution. The polyethylene polyamine small molecule compound is tetraethylenepentamine. The mass ratio of the polyethylene polyamine small molecule compound to hydroxypropyl-β-cyclodextrin is 0.05:1. The mass ratio of aluminate to aluminum salt is 0.8:1. The aluminate concentration in the aluminate solution is 10 g / L.

[0043] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 10; during the dropwise addition process, the aluminum salt mixture solution was heated to 65℃; the dropwise acceleration rate was 14mL / min.

[0044] (4) After the addition is complete, continue stirring for 1 hour, then raise the temperature to 85℃ and react for 1.5 hours; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 600℃ and the calcination time is 4 hours. The specific surface area of ​​this support material is measured to be 316 m². 2 / g, pore size 16.8nm, pore volume 1.37cm³ 3 / g.

[0045] Example 3

[0046] A method for preparing a modified catalyst support material includes the following steps:

[0047] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then, add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 11 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.2:1.

[0048] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was diethylenetriamine. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.14:1. The mass ratio of aluminate to aluminum salt was 0.7:1. The aluminate concentration in the aluminate solution was 8 g / L.

[0049] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 55℃; the dropwise acceleration rate was 10mL / min.

[0050] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 2.4 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 580℃ and the calcination time is 5 h. The specific surface area of ​​this support material is tested to be 306 m². 2 / g, pore size 17.1nm, pore volume 1.33cm³ 3 / g.

[0051] Example 4

[0052] A method for preparing a modified catalyst support material includes the following steps:

[0053] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then, add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 9 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.17:1.

[0054] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylene polyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylene polyamine small molecule compound was triethylenetetramine. The mass ratio of the polyethylene polyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.18:1. The mass ratio of aluminate to aluminum salt was 0.62:1. The aluminate concentration in the aluminate solution was 10 g / L.

[0055] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 8; during the dropwise addition process, the aluminum salt mixture solution was heated to 63℃; the dropwise acceleration rate was 8 mL / min;

[0056] (4) After the addition is complete, continue stirring for 0.5 h, then raise the temperature to 72℃ and react for 1.6 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 560℃ and the calcination time is 4.2 h. The specific surface area of ​​this support material is measured to be 297 m². 2 / g, pore size 16.7nm, pore volume 1.32cm³ 3 / g.

[0057] Example 5

[0058] A method for preparing a modified catalyst support material includes the following steps:

[0059] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then, add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 11 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.2:1.

[0060] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was tetraethylenepentamine. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.14:1. The mass ratio of aluminate to aluminum salt was 0.7:1. The aluminate concentration in the aluminate solution was 8 g / L.

[0061] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 55℃; the dropwise acceleration rate was 10mL / min.

[0062] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 2.4 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 580℃ and the calcination time is 5 h. The specific surface area of ​​this support material is tested to be 302 m². 2 / g, pore size 17.3nm, pore volume 1.34cm³ 3 / g.

[0063] Example 6

[0064] A method for preparing a modified catalyst support material includes the following steps:

[0065] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 10 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.18:1.

[0066] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was a mixture of diethylenetriamine and triethylenetetramine in a molar ratio of 0.2:1. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.1:1. The mass ratio of aluminate to aluminum salt was 0.66:1. The aluminate concentration in the aluminate solution was 7 g / L.

[0067] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 8; during the dropwise addition process, the aluminum salt mixture solution was heated to 48℃; the dropwise acceleration rate was 9 mL / min;

[0068] (4) After the addition is complete, continue stirring for 0.6 h, then raise the temperature to 75℃ and react for 2.5 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 570℃ and the calcination time is 5.5 h. The specific surface area of ​​this support material is tested to be 314 m². 2 / g, pore size 17.8nm, pore volume 1.40cm³ 3 / g.

[0069] Example 7

[0070] A method for preparing a modified catalyst support material includes the following steps:

[0071] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then, add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 11 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.2:1.

[0072] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was a mixture of diethylenetriamine and tetraethylenepentamine in a molar ratio of 1:2.5. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.14:1. The mass ratio of aluminate to aluminum salt was 0.7:1. The aluminate concentration in the aluminate solution was 8 g / L.

[0073] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 55℃; the dropwise acceleration rate was 10mL / min.

[0074] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 2.4 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 580℃ and the calcination time is 5 h. The specific surface area of ​​this support material is tested to be 311 m². 2 / g, pore size 17.5nm, pore volume 1.35cm³ 3 / g.

[0075] Example 8

[0076] A method for preparing a modified catalyst support material includes the following steps:

[0077] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 13 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.23:1.

[0078] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was a mixture of diethylenetriamine and triethylenetetramine in a molar ratio of 1.2:1. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.16:1. The mass ratio of aluminate to aluminum salt was 0.75:1. The aluminate concentration in the aluminate solution was 9 g / L.

[0079] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 10; during the dropwise addition process, the aluminum salt mixture solution was heated to 60℃; the dropwise acceleration rate was 13mL / min.

[0080] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 1.8 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 590℃ and the calcination time is 4.7 h. The specific surface area of ​​this support material is measured to be 307 m². 2 / g, pore size 17.9nm, pore volume 1.43cm³ 3 / g.

[0081] Example 9

[0082] A method for preparing a modified catalyst support material includes the following steps:

[0083] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 10 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.21:1.

[0084] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylene polyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylene polyamine small molecule compound was triethylenetetramine. The mass ratio of the polyethylene polyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.12:1. The mass ratio of aluminate to aluminum salt was 0.68:1. The aluminate concentration in the aluminate solution was 8.5 g / L.

[0085] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 57°C; the dropwise acceleration rate was 9 mL / min.

[0086] (4) After the addition is complete, continue stirring for 0.7 h, then raise the temperature to 78℃ and react for 2.2 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 570℃ and the calcination time is 5.2 h. The specific surface area of ​​this support material is tested to be 295 m². 2 / g, pore size 17.5nm, pore volume 1.38cm³ 3 / g.

[0087] Example 10

[0088] A method for preparing a modified catalyst support material includes the following steps:

[0089] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then, add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 11 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.2:1.

[0090] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was a mixture of diethylenetriamine and tetraethylenepentamine in a molar ratio of 2.5:1. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.14:1. The mass ratio of aluminate to aluminum salt was 0.7:1. The aluminate concentration in the aluminate solution was 8 g / L.

[0091] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 55℃; the dropwise acceleration rate was 10mL / min.

[0092] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 2.4 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 580℃ and the calcination time is 5 h. The specific surface area of ​​this support material is tested to be 315 m². 2 / g, pore size 18.3nm, pore volume 1.42cm³ 3 / g.

[0093] Comparative Example 1

[0094] A method for preparing a modified catalyst support material includes the following steps:

[0095] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then add β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 11 g / L. The mass ratio of β-cyclodextrin to aluminum salt is 0.2:1.

[0096] (2) Sodium aluminate is dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound is added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound is a mixture of diethylenetriamine and tetraethylenepentamine in a molar ratio of 2.5:1. The mass ratio of the polyethylenepolyamine small molecule compound to β-cyclodextrin is 0.14:1. The mass ratio of aluminate to aluminum salt is 0.7:1. The aluminate concentration in the aluminate solution is 8 g / L.

[0097] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 55℃; the dropwise acceleration rate was 10mL / min.

[0098] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 2.4 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 580℃ and the calcination time is 5 h. The specific surface area of ​​this support material is measured to be 232 m². 2 / g, pore size 12.3nm, pore volume 0.95cm³ 3 / g.

[0099] Comparative Example 2

[0100] A method for preparing a modified catalyst support material includes the following steps:

[0101] (1) While stirring, dissolve and disperse aluminum nitrate in deionized water to obtain an aluminum salt solution. Then, add hydroxypropyl-β-cyclodextrin to the aluminum salt solution to obtain a mixed aluminum salt solution. The concentration of aluminum salt in the aluminum salt solution is 11 g / L. The mass ratio of hydroxypropyl-β-cyclodextrin to aluminum salt is 0.2:1.

[0102] (2) Sodium aluminate was dissolved and dispersed in deionized water while stirring to obtain an aluminate solution. Then, a polyethylenepolyamine small molecule compound was added to the aluminate solution to obtain a mixed aluminate solution. The polyethylenepolyamine small molecule compound was a mixture of diethylenetriamine and tetraethylenepentamine in a molar ratio of 2.5:1. The mass ratio of the polyethylenepolyamine small molecule compound to hydroxypropyl-β-cyclodextrin was 0.4:1. The mass ratio of aluminate to aluminum salt was 0.7:1. The aluminate concentration in the aluminate solution was 8 g / L.

[0103] (3) While stirring, the aluminate mixture solution was added dropwise to the aluminum salt mixture solution to obtain the precursor mixture solution, and the pH of the precursor mixture solution was adjusted to 9; during the dropwise addition process, the aluminum salt mixture solution was heated to 55℃; the dropwise acceleration rate was 10mL / min.

[0104] (4) After the addition is complete, continue stirring for 0.8 h, then raise the temperature to 80℃ and react for 2.4 h; filter, wash, dry, and calcine the product to obtain the modified catalyst support material; the calcination temperature is 580℃ and the calcination time is 5 h. The specific surface area of ​​this support material is tested to be 255 m². 2 / g, pore size 14.6nm, pore volume 1.04cm³ 3 / g.

[0105] As can be seen from the above examples and comparative examples, this invention adds a certain amount of polyethylene polyamine small molecule compound as a template agent to the hydroxypropyl-β-cyclodextrin template system. Utilizing the unique properties of both hydroxypropyl-β-cyclodextrin and the polyethylene polyamine small molecule compound as template agents, a precursor with a hierarchical porous structure is guided to form from aluminum salts and aluminates through a synergistic template effect. Finally, after calcination, a high specific surface area and large pore size alumina support is obtained. The hydroxypropyl-β-cyclodextrin molecule itself is a truncated pyramidal hollow macrocyclic molecule, and its hydroxypropyl substituent enhances its water solubility and compatibility with inorganic substances. During the formation of the aluminum precursor, the hydroxypropyl-β-cyclodextrin molecule is encapsulated or adsorbed between the growing particles. Its large volume physically occupies space, preventing the compact packing of particles. After the hydroxypropyl-β-cyclodextrin is removed, large-sized cavities are left in the positions it previously occupied, thus forming large pores. Although hydroxypropyl-β-cyclodextrin is not a traditional surfactant, its amphiphilic structure (hydrophilic outer wall and relatively hydrophobic inner cavity) allows it to interact with inorganic materials to some extent. It can act as a soft template to guide the deposition of aluminum precursors around its exterior, forming a channel that "replicates" its external structure.

[0106] Specifically, compared to Example 10, Comparative Example 1 used β-cyclodextrin instead of hydroxypropyl-β-cyclodextrin, resulting in a significant reduction in both specific surface area and pore size. This indicates that the amphiphilic structure of hydroxypropyl-β-cyclodextrin can act as a soft template, guiding the deposition of aluminum precursors around its exterior, promoting the formation of pore structures, and increasing the specific surface area of ​​the alumina support material. In Comparative Example 2, the excessive amount of polyethylenepolyamine small molecule compound caused excessive cross-linking between its nitrogen-containing groups and the hydroxyl groups on hydroxypropyl-β-cyclodextrin due to hydrogen bonding, which was detrimental to the dispersion of the precursor, leading to the formation of a stacked structure and a decrease in the specific surface area of ​​the support material after calcination.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a modified catalyst support material, characterized by, The method comprises the following steps: (1) dissolving and dispersing aluminum salt in deionized water to obtain an aluminum salt solution, and then adding hydroxypropyl-beta-cyclodextrin to the aluminum salt solution to obtain an aluminum salt mixed solution; (2) dissolving and dispersing met aluminite in deionized water to obtain a met aluminite solution, and then adding a polyethylene polyamine small molecule compound to the met aluminite solution to obtain a met aluminite mixed solution; the mass ratio of the polyethylene polyamine small molecule compound to the hydroxypropyl-beta-cyclodextrin is (0.05-0.2):1; the polyethylene polyamine small molecule compound is one or more of diethylene triamine, triethylene tetramine, tetraethylene pentamine, pentaethylene hexamine, hexaethylene heptamine, heptaethylene octamine, octaethylene nonamine, nonaethylene decamine, and decaethylene undecamine; (3) adding the met aluminite mixed solution to the aluminum salt mixed solution dropwise to obtain a precursor mixed solution, and adjusting the pH of the precursor mixed solution to be greater than 7; (4) after the dropwise addition is completed, continuing to stir for a period of time, and then performing a temperature rising reaction; after the product is post-treated and calcined, a modified catalyst carrier material is obtained.

2. The method of preparing a modified catalyst support material according to claim 1, wherein In step (1), the mass ratio of the hydroxypropyl-beta-cyclodextrin to the aluminum salt is (0.15-0.25):

1.

3. The method of preparing a modified catalyst support material according to claim 1, wherein the support material is a porous support material. In step (2), the mass ratio of the met aluminite to the aluminum salt is (0.5-1):

1.

4. The method of preparing a modified catalyst support material according to claim 1, wherein the support material is a porous support material. In the dropwise addition process in step (3), the aluminum salt mixed solution is heated, and the heating temperature is 45-65 DEG C.

5. The method of preparing a modified catalyst support material according to claim 1, wherein the support material is a porous support material. In step (4), the stirring time is 0.4-1 h.

6. The method of making a modified catalyst support material according to claim 1, wherein, In step (4), the temperature rising reaction temperature is 70-90 DEG C, and the temperature rising reaction time is 1.5-3 h.

7. The method of making a modified catalyst support material according to claim 1, wherein, In step (4), the post-treatment is a filtration, washing, and drying process.

8. The method of making a modified catalyst support material according to claim 1, wherein, In step (4), the calcination temperature is 550-650 DEG C, and the calcination time is 4-6 h.

9. A modified catalyst support material, characterized by, The modified catalyst carrier material is prepared by the method in any one of claims 1-8.