A kind of high specific surface area aluminum oxide and preparation method thereof

Abstract

The present invention belongs to the technical field of inorganic material preparation, and particularly relates to a high specific surface area alumina and a preparation method thereof. The alumina preparation method comprises the following steps: (1) preparing an aluminum salt solution and adding a long-chain hydrocarbon quaternary ammonium salt thereto; (2) preparing a metaaluminate solution and adding polyethylene glycol thereto; (3) adding the solution obtained in step (2) dropwise to the solution obtained in step (1) to obtain a final solution, and adjusting the pH of the final solution to be alkaline; (4) heating for reaction, and obtaining the high specific surface area alumina through post-treatment. By using a long-chain hydrocarbon quaternary ammonium salt as a main template and modifier and adding a small amount of polyethylene glycol, the technical problems of low specific surface area and small pore size of the alumina material prepared with the long-chain hydrocarbon quaternary ammonium salt are solved, and an alumina product with a high specific surface area is prepared, which has the advantages of low energy consumption and good economic efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic material preparation, and particularly relates to a high specific surface area aluminum oxide and a preparation method thereof. Background Art

[0002] The support is a crucial component of a catalyst, increasing its surface area, improving heat resistance and mechanical strength, and sometimes serving as a co-catalyst or promoter. Commonly used support materials include alumina, zirconium dioxide, titanium dioxide, silicon dioxide, molecular sieves, and composite oxides. Numerous methods exist for preparing supports, including sol-gel, coprecipitation, and mechanical methods.

[0003] Alumina has become the most widely used catalyst or catalyst support in the chemical industry due to its excellent mechanical strength, high thermal and chemical stability, adjustable surface acidity and alkalinity, and diverse crystalline phases. With the advancement of research, it has been recognized that for supported catalysts, the support's pore structure (specific surface area, pore volume, etc.) not only significantly influences the distribution of the loaded active components but is also closely related to the catalyst's activity, selectivity, and lifespan. Alumina supports with superior structures, with their large specific surface area, can support more active components, thereby enhancing reaction activity. Their large pore volume provides space for carbon deposits, metals, and other substances, while their large pore diameters prevent clogging and catalyst deactivation.

[0004] Among industrial catalyst carriers, alumina is the most widely used. Alumina is inexpensive and can be tailored to the desired crystal phase, surface area, and pore size distribution by varying the preparation conditions. Alumina, as a catalyst carrier, exhibits high-temperature resistance and oxidation resistance, making it widely used both domestically and internationally as a carrier for various catalysts, including automotive exhaust catalysts, petroleum refining catalysts, and hydrogenation and hydrodesulfurization catalysts. Alumina pores can generally be divided into three types: pores between microparticles, pores between primary particles, and pores formed during the molding of the alumina product. The interparticle spaces are the source of alumina pores, and the size and shape of the pores depend entirely on the particle size, shape, and stacking method. With the increasing application and development of alumina, catalysts prepared using high-specific surface area alumina carriers have shown higher activity, selectivity, and conversion rates than those prepared using low-specific surface area carriers. Therefore, the development of high-specific surface area alumina carriers is a future development direction.

[0005] Chinese invention patent application publication number CN117142503A provides a method for preparing composite activated alumina powder. This method uses a specific template to in-situ prepare aluminum hydroxide colloid, which is then calcined to produce composite activated alumina powder with a preferred pore size distribution. Chinese invention patent application publication number CN115445598A provides a method for preparing a modified α-alumina support. This method involves kneading, extrusion, drying, and calcination to produce a shaped alumina support with a high specific surface area. When using this modified alumina support to prepare a methane steam reforming catalyst, the catalyst exhibited higher methane conversion activity and better activity stability than commercial catalysts. A series of patents applied for by Shandong Gongquan Chemical Co., Ltd. (CN118045581A, CN118788318A, CN118807722A, and CN118929711A) also investigate the effects of different surfactants or templates on the performance of alumina catalyst supports. While this series of patents achieves a certain degree of improvement in the specific surface area of alumina and carrier performance, they all utilize various nonionic surfactants as modifiers to prepare the alumina carrier. This not only results in complex and costly processes, but also requires a complex washing process requiring large amounts of washing liquid to wash the alumina intermediates or products, resulting in high energy consumption and limited improvement in product performance. While cationic surfactants (such as various quaternary ammonium salts) have also been studied as templates in the alumina preparation process, simple quaternary ammonium salts suffer from technical limitations such as small pore size and low specific surface area. Summary of the Invention

[0006] The purpose of the present invention is to provide an alumina with a high specific surface area and a preparation method thereof. By using a long-chain hydrocarbon quaternary ammonium salt as a main template and modifier and adding a small amount of polyethylene glycol, the technical problems of low specific surface area and small pore size of the alumina material prepared by the long-chain hydrocarbon quaternary ammonium salt are solved, and an alumina product with a high specific surface area is prepared, which has the advantages of low energy consumption and good economy.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0009] (1) preparing an aluminum salt solution, adding a long-chain hydrocarbon quaternary ammonium salt thereto, and uniformly dispersing by ultrasonication; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt is (0.04-0.2):1;

[0010] (2) Prepare aluminate solution, add polyethylene glycol to it, and stir to disperse it evenly; the number average molecular weight of polyethylene glycol is 200-2000; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is (0.1-0.4):1; in order to promote the dissolution of polyethylene glycol, it can be heated appropriately to accelerate the dissolution rate.

[0011] By adding a long-chain alkyl quaternary ammonium salt and polyethylene glycol to the aluminum salt solution and metaaluminate solution, respectively, the dispersion of the crystals can be improved and agglomeration can be prevented. Since the aluminum ions in both the long-chain alkyl quaternary ammonium salt and the aluminum salt solution are positively charged, pre-adding the long-chain alkyl quaternary ammonium salt to the aluminum salt solution can further promote the dispersion of the micelles. Adding a nonionic surfactant (polyethylene glycol) to the metaaluminate solution not only maximizes the polyethylene glycol's templating function but also fully utilizes its dispersing function to promote the dispersion of the crystals.

[0012] If long-chain hydrocarbon quaternary ammonium salt is added to aluminate solution, or polyethylene glycol is added to aluminum salt solution, not only will the polyethylene glycol fail to function, but it will also easily cause the positively charged long-chain hydrocarbon quaternary ammonium salt to have a strong electrostatic interaction with the aluminate in advance, which is not conducive to the dispersion of the grains and affects the increase in the specific surface area of the alumina product.

[0013] The polyethylene glycol of suitable molecular weight has both taken into account good dissolution dispersibility on the basis of guaranteeing template effect, and can avoid the excessive molecular weight causing to interact with long-chain quaternary ammonium salt, affecting the dispersion of crystal grain or precipitation. Further, the polyethylene glycol molecular weight can be 300-1800, or 400-1500, or 600-1400, or any value between 800-1200.

[0014] (3) adding the solution obtained in step (2) dropwise to the solution obtained in step (1) to obtain a final solution, and adjusting the pH of the final solution to be alkaline;

[0015] The specific process of step (3) is as follows: first, heat the solution obtained in step (1) to 50-70°C, and then dropwise add the solution obtained in step (2) thereto while stirring; the stirring rate is 200-300 rpm; the dropping rate is 5-15 mL / min;

[0016] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment.

[0017] Depending on the surfactant template used, the commonly used synthesis methods for aluminum oxide can be divided into cationic template methods, anionic template methods, and nonionic template methods. Among them, nonionic surfactants (such as block copolymers) have the advantages of no ionization in water, good compatibility with other solutes, no influence from solution pH, and high operational stability. They are currently the most common templates for preparing high-specific surface area aluminum oxide. However, due to the generally large molecular weight of the polymer, poor solubility, and the relatively high price of many types of nonionic surfactants, they are not suitable for industrial production. Therefore, the present invention selects long-chain hydrocarbon quaternary ammonium salts as cationic templates. Alumina materials synthesized using long-chain hydrocarbon quaternary ammonium salts as templates have advantages such as regular mesopores, high order, and easily controllable pore size distribution and pore size.

[0018] However, the pore size formed by using a simple long-chain hydrocarbon quaternary ammonium salt as a template is relatively small, and the specific surface area is low. In actual production tests, the specific surface area of alumina prepared by using a long-chain hydrocarbon quaternary ammonium salt as a template in the aluminum salt-aluminate reaction system can only reach 200m 2 / g, and pore volume and pore diameter are lower.Therefore, the present invention has added a small amount of polyethylene glycol nonionic surfactant on the basis of long-chain alkyl quaternary ammonium salt template agent, to solve the problem that long-chain alkyl quaternary ammonium salt exists as cationic template agent.The pore diameter that polyethylene glycol nonionic surfactant synthesized is usually larger, and specific surface area is higher, and pore size can be regulated by changing the chain length of molecule.

[0019] In a specific embodiment of the present invention, the aluminum salt in step (1) is at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate; and the concentration of the aluminum salt solution is 10-40 g / L.

[0020] In a specific embodiment of the present invention, the ultrasonic power in step (1) is 100-300W; the long-chain hydrocarbon quaternary ammonium salt is at least one of dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, and octadecyltrimethylammonium chloride. By combining the long-chain hydrocarbon quaternary ammonium salt with polyethylene glycol, the prepared alumina material not only has a large specific surface area, but also has a large pore size and a regular pore structure, which can allow large molecules and groups to pass through smoothly and significantly reduce the internal diffusion resistance during the reaction process, making it an ideal catalyst carrier. The mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt is (0.04-0.2):1; specifically, the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt can be 0.06:1, 0.08:1, 0.1:1, 0.12:1, 0.15:1, 0.18:1, and other specific values. By controlling the amount of the long-chain hydrocarbon quaternary ammonium salt within a suitable range, smaller crystals can be formed and the phenomenon of pore collapse during the calcination process after the template is removed can be avoided.

[0021] In a specific embodiment of the present invention, the aluminate in step (2) is at least one of sodium aluminate or potassium aluminate; and the concentration of the aluminate solution is 5-25 g / L.

[0022] In a specific embodiment of the present invention, the mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is (0.5-1):1; and the stirring rate of step (2) is 300-600 rpm.

[0023] In a specific embodiment of the present invention, the pH value in step (3) is 7.5-10. The method for adjusting the pH is not particularly limited, and the pH can be adjusted by adding an acid or a base. Specifically, an acidic substance selected from hydrochloric acid, sulfuric acid, or nitric acid, or an alkaline substance selected from sodium hydroxide, potassium hydroxide, or ammonia water is used for adjustment.

[0024] In a specific embodiment of the present invention, the heating reaction temperature in step (4) is 75-95°C, and the reaction time is 1-3 hours. The reaction apparatus is not particularly limited and can be carried out in a reactor.

[0025] In a specific embodiment of the present invention, the post-treatment in step (4) comprises filtration, washing, drying, and calcination. The long-chain alkyl quaternary ammonium salt combined with polyethylene glycol as a template can participate in the precipitation or hydrolysis of components during the synthesis process, which is conducive to the synthesis of a porous material with a large specific surface area.

[0026] In a specific embodiment of the present invention, the drying in step (4) is carried out by oven drying; the calcination temperature is 550-650° C., and the calcination time is 5-6 h.

[0027] On the other hand, the present invention also provides a high specific surface area alumina obtained by the above preparation method, which has the characteristics of large pore volume and large surface area, simple preparation process, and can be used as an industrial catalyst carrier.

[0028] Beneficial effects:

[0029] The present invention uses a long-chain hydrocarbon quaternary ammonium salt as a template, resulting in a synthesized alumina material with advantages such as regular mesopores, high order, and easily controllable pore size distribution and pore size. Polyethylene glycol nonionic surfactants typically produce larger pore sizes, and the pore size can be adjusted by varying the molecular chain length.

[0030] The simultaneous addition of long-chain hydrocarbon quaternary ammonium salts and polyethylene glycol, two cationic and non-ionic surfactants, can fully utilize the advantages of both: the long-chain hydrocarbon quaternary ammonium salt cationic surfactant easily combines with the aluminum source during the hydrolysis process, and the polyethylene glycol non-ionic surfactant contributes to the formation of pores during the precipitation and drying processes, thereby preparing an alumina product with a high surface area and pore volume, solving the technical problem of low specific surface area caused by the sole use of long-chain hydrocarbon quaternary ammonium salts. DETAILED DESCRIPTION

[0031] The examples are provided to better illustrate the present invention, but are not intended to limit the present invention to the examples. Therefore, non-essential improvements and adjustments to the embodiments made by those skilled in the art based on the above-mentioned invention still fall within the scope of protection of the present invention.

[0032] The terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. Unless the context clearly indicates a different meaning, expressions in the singular include expressions in the plural. As used herein, it should be understood that terms such as "include," "have," and "comprise" are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terms of the present invention are disclosed in the specification and are not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may exist or may be added.

[0033] Example 1

[0034] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0035] (1) preparing an aluminum salt solution, adding a long-chain hydrocarbon quaternary ammonium salt thereto, and uniformly dispersing the solution through ultrasonication; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt is 0.08:1; the aluminum salt is aluminum nitrate; the concentration of the aluminum salt solution is 16 g / L; the ultrasonic power is 200 W; the long-chain hydrocarbon quaternary ammonium salt is hexadecyltrimethylammonium bromide;

[0036] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 800; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.1:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 11 g / L; and the stirring rate is 400 rpm;

[0037] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.6:1;

[0038] (3) The solution obtained in step (1) was first heated to 50°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 8; the stirring rate was 250 rpm; the dropping rate was 7 mL / min;

[0039] (4) Heating reaction, and obtaining high specific surface area alumina through post-treatment; the heating reaction temperature is 75°C, and the reaction time is 3 hours; the post-treatment process includes filtration, washing, drying, and calcination; drying is carried out in an oven; the calcination temperature is 550°C, and the calcination time is 6 hours.

[0040] Example 2

[0041] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0042] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.15:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 20 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0043] (2) preparing a metaaluminate solution, adding polyethylene glycol thereto, and stirring to disperse uniformly; the number average molecular weight of the polyethylene glycol is 1200; the mass ratio of the polyethylene glycol to the long-chain hydrocarbon quaternary ammonium salt is 0.4:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 14 g / L; and the stirring rate is 400 rpm;

[0044] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.8:1;

[0045] (3) First, heat the solution obtained in step (1) to 70°C, then add the solution obtained in step (2) dropwise while stirring to obtain a final solution, and adjust the pH value of the final solution to 10; the stirring rate is 250 rpm; the dropwise addition rate is 12 mL / min;

[0046] (4) Heating reaction, and obtaining high specific surface area alumina through post-treatment; the heating reaction temperature is 95°C, and the reaction time is 1 hour; the post-treatment process includes filtration, washing, drying, and calcination; drying is carried out in an oven; the calcination temperature is 650°C, and the calcination time is 5 hours.

[0047] Example 3

[0048] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0049] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.04:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0050] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 1200; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0051] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0052] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0053] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0054] Example 4

[0055] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0056] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.15:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 17 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0057] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 1500; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.1:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 14 g / L; and the stirring rate is 400 rpm;

[0058] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.6:1;

[0059] (3) The solution obtained in step (1) was first heated to 70°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 10; the stirring rate was 250 rpm; the dropping rate was 7 mL / min;

[0060] (4) Heating reaction, and obtaining high specific surface area alumina through post-treatment; the heating reaction temperature is 75°C, and the reaction time is 1 hour; the post-treatment process includes filtration, washing, drying, and calcination; drying is carried out in an oven; the calcination temperature is 650°C, and the calcination time is 6 hours.

[0061] Example 5

[0062] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0063] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.2:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0064] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 1200; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0065] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0066] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0067] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0068] Example 6

[0069] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0070] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.09:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 17 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0071] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 1000; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0072] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.65:1;

[0073] (3) The solution obtained in step (1) was first heated to 56°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 8; the stirring rate was 250 rpm; the dropping rate was 8 mL / min;

[0074] (4) Heating reaction, and obtaining high specific surface area alumina through post-treatment; the heating reaction temperature is 78°C, and the reaction time is 2.4h; the post-treatment process includes filtration, washing, drying, and calcination; drying is carried out in an oven; the calcination temperature is 580°C, and the calcination time is 5.7h.

[0075] Example 7

[0076] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0077] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.12:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0078] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 200; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0079] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0080] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0081] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0082] Example 8

[0083] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0084] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.14:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 19 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0085] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 1500; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.3:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0086] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.75:1;

[0087] (3) The solution obtained in step (1) was first heated to 66°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 11 mL / min;

[0088] (4) Heating reaction, and obtaining high specific surface area alumina through post-treatment; the heating reaction temperature is 90°C, and the reaction time is 1.8h; the post-treatment process includes filtration, washing, drying, and calcination; drying is carried out in an oven; the calcination temperature is 620°C, and the calcination time is 5.2h.

[0089] Example 9

[0090] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0091] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.12:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0092] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 2000; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0093] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0094] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0095] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0096] Example 10

[0097] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0098] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.13:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0099] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 800; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.25:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12.5 g / L; and the stirring rate is 400 rpm;

[0100] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.72:1;

[0101] (3) The solution obtained in step (1) was first heated to 64°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 8.5; the stirring rate was 250 rpm; the dropping rate was 8 mL / min;

[0102] (4) Heating reaction, and obtaining high specific surface area alumina through post-treatment; the heating reaction temperature is 87°C, and the reaction time is 1.4h; the post-treatment process includes filtration, washing, drying, and calcination; drying is carried out in an oven; the calcination temperature is 580°C, and the calcination time is 5.8h.

[0103] Example 11

[0104] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0105] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.12:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0106] (2) Prepare a metaaluminate solution, add polyethylene glycol thereto, and stir to disperse uniformly; the number average molecular weight of polyethylene glycol is 1200; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0107] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0108] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0109] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0110] Comparative Example 1

[0111] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0112] (1) Prepare an aluminum salt solution, add polyethylene glycol thereto, and disperse uniformly by ultrasonication; the number average molecular weight of polyethylene glycol is 1200; the mass ratio of polyethylene glycol to long-chain hydrocarbon quaternary ammonium salt is 0.2:1; the aluminum salt is aluminum nitrate; the concentration of the aluminum salt solution is 18 g / L; and the ultrasonic power is 200 W;

[0113] (2) preparing a metaaluminate solution, adding a long-chain hydrocarbon quaternary ammonium salt thereto, and stirring and dispersing the solution uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt is 0.12:1; the long-chain hydrocarbon quaternary ammonium salt is hexadecyltrimethylammonium bromide; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0114] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0115] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0116] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0117] Comparative Example 2

[0118] A method for preparing high specific surface area aluminum oxide comprises the following steps:

[0119] (1) An aluminum salt solution was prepared, and a long-chain hydrocarbon quaternary ammonium salt was added thereto, and ultrasonic dispersion was performed uniformly; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt was 0.12:1; the aluminum salt was aluminum nitrate; the concentration of the aluminum salt solution was 18 g / L; the ultrasonic power was 200 W; the long-chain hydrocarbon quaternary ammonium salt was hexadecyltrimethylammonium bromide;

[0120] (2) preparing a metaaluminate solution, adding polyethylene glycol thereto, and stirring to disperse uniformly; the number average molecular weight of the polyethylene glycol is 1200; the mass ratio of the polyethylene glycol to the long-chain hydrocarbon quaternary ammonium salt is 1:1; the metaaluminate is sodium metaaluminate; the concentration of the metaaluminate solution is 12 g / L; and the stirring rate is 400 rpm;

[0121] The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is 0.7:1;

[0122] (3) The solution obtained in step (1) was first heated to 61°C, and then the solution obtained in step (2) was added dropwise while stirring to obtain a final solution, and the pH value of the final solution was adjusted to 9; the stirring rate was 250 rpm; the dropping rate was 9 mL / min;

[0123] (4) Heat the reaction and obtain high specific surface area alumina through post-treatment; the heating reaction temperature is 84°C and the reaction time is 2 hours; the post-treatment process includes filtration, washing, drying and calcination; drying is carried out in an oven; the calcination temperature is 600°C and the calcination time is 5.5 hours.

[0124] The specific surface area (m2) of the high specific surface area alumina prepared in Examples 1 to 11 and Comparative Examples 1 and 2 was measured by gas adsorption method (BET). 2 / g), pore size (nm) and pore volume (cm 3 / g) and other properties, as shown in Table 1 and Table 2.

[0125] Table 1 Properties of high specific surface area alumina prepared in Examples 1 to 7

[0126]

[0127] Table 2 Properties of high specific surface area alumina prepared in Examples 8-11 and Comparative Examples 1-2

[0128]

[0129] As can be seen from Table 1 and Table 2, the present invention adopts long-chain alkyl quaternary ammonium salt as main template agent and properties-correcting agent, by adding a small amount of polyethylene glycol auxiliary surfactant, solved the technical problem that the aluminum oxide material specific surface area prepared by long-chain alkyl quaternary ammonium salt is low, the pore size is little, prepares the aluminum oxide product with high specific surface area.Long-chain alkyl quaternary ammonium salt has mesopore regularity as the aluminum oxide material synthesized by template agent, and orderliness is high, and pore size distribution and pore size are easy to control.The pore size that polyethylene glycol nonionic surfactant synthesizes is usually larger, and pore size can be regulated by changing the molecular chain length.Add long-chain alkyl quaternary ammonium salt and polyethylene glycol two kinds of cations and nonionic surfactants simultaneously, can give full play to the two advantages: the long-chain alkyl quaternary ammonium salt cation surfactant is easily combined with the aluminum source in the hydrolysis process, and the polyethylene glycol nonionic surfactant then helps the formation in hole in precipitation and drying process, thereby prepares the aluminum oxide product with high surface area and pore volume, solved the technical problem that the specific surface area that simply uses long-chain alkyl quaternary ammonium salt to cause is low.

[0130] Compared with Example 11, Comparative Example 1 joins long-chain alkyl quaternary ammonium salt to metaaluminate solution, and polyethylene glycol joins in the aluminum salt solution, and not only polyethylene glycol cannot play a role, and easily causes positively charged long-chain alkyl quaternary ammonium salt and metaaluminate to have strong electrostatic interaction, is unfavorable for the dispersion of crystal grain, affects the raising of aluminum oxide product specific surface area.Comparative Example 2 shows that because polyethylene glycol belongs to polymeric surfactant, its own consumption can strongly affect long-chain alkyl quaternary ammonium salt effect. Although polyethylene glycol has template effect, in this reaction system, its Main Function is to contribute to the formation in hole in precipitation and drying process, thereby prepares the aluminum oxide product with high surface area and pore volume; When polyethylene glycol consumption is too much, can affect the formation of micelle, is unfavorable for the raising of aluminum oxide product performance.

[0131] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing high specific surface area alumina, characterized in that: The following steps are involved: (1) preparing an aluminum salt solution, adding a long-chain hydrocarbon quaternary ammonium salt thereto, and uniformly dispersing by ultrasonication; the mass ratio of the long-chain hydrocarbon quaternary ammonium salt to the aluminum salt is (0.04-0.2):1; (2) preparing a metaaluminate solution, adding polyethylene glycol thereto, and stirring to disperse uniformly; the number average molecular weight of the polyethylene glycol is 200-2000; the mass ratio of the polyethylene glycol to the long-chain hydrocarbon quaternary ammonium salt is (0.1-0.4):1; (3) adding the solution obtained in step (2) dropwise to the solution obtained in step (1) to obtain a final solution, and adjusting the pH of the final solution to be alkaline; (4) heating reaction and obtaining high specific surface area alumina through post-treatment; The heating reaction temperature is 75-95° C., and the reaction time is 1-3 hours; the post-treatment includes filtering, washing, drying, and calcining processes.

2. The method for preparing a high specific surface area aluminum oxide according to claim 1, wherein: In step (1), the aluminum salt is at least one of aluminum nitrate, aluminum chloride, and aluminum sulfate; and the concentration of the aluminum salt solution is 10-40 g / L.

3. The method for preparing a high specific surface area aluminum oxide according to claim 1, wherein: The ultrasonic power in step (1) is 100-300W; the long-chain hydrocarbon quaternary ammonium salt is at least one of dodecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, and octadecyltrimethylammonium chloride.

4. The method for preparing alumina with high specific surface area according to claim 1, wherein: In step (2), the aluminate is at least one of sodium aluminate or potassium aluminate; and the concentration of the aluminate solution is 5-25 g / L.

5. The method for preparing alumina with high specific surface area according to claim 1, wherein: The mass ratio of the metaaluminate in step (2) to the aluminum salt in step (1) is (0.5-1):1; the stirring rate in step (2) is 300-600 rpm.

6. The method for preparing alumina with high specific surface area according to claim 1, wherein: The pH value in step (3) is 7.5-10.

7. The method for preparing alumina with high specific surface area according to claim 1, wherein: The drying in step (4) is carried out in an oven; the calcination temperature is 550-650° C., and the calcination time is 5-6 hours.

8. A high specific surface area alumina, characterized in that: The aluminum oxide is prepared by the method for preparing a high specific surface area aluminum oxide according to any one of claims 1 to 7.

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