Aluminum sol with high aluminum-chlorine ratio and preparation method thereof

Abstract

The invention provides aluminum sol with a high aluminum-chlorine ratio and a preparation method of the aluminum sol, and belongs to the field of aluminum sol. The method comprises the following steps: mixing aluminum chloride, organic acid and deionized water to obtain a mixed acid solution; adding metal aluminum into the mixed acid solution, stirring, heating, condensing and refluxing, so that the metal aluminum is subjected to hydrolysis reaction under the conditions of first set temperature and first set time to obtain precursor liquid; cooling the precursor liquid to a second set temperature, so that the precursor liquid is subjected to a condensation polymerization reaction at the second set temperature for a second set time to obtain a mixed sol liquid; and filtering and separating the mixed sol solution to remove large-particle impurities so as to obtain the alumina sol. The aluminum-chlorine ratio of the aluminum sol is increased through incremental replacement of aluminum salt by metal aluminum, inhibition of Cl <-> combination by high-temperature hydrolysis, organic acid complexation regulation and low-temperature condensation polymerization of a stable structure.

Description

Technical Field

[0001] This application relates to the technical field of aluminosol, and particularly to an aluminosol with a high aluminum-chlorine ratio and a preparation method thereof. Background Art

[0002] Aluminosol is an inorganic polymer compound with high temperature resistance and good adhesion, and is widely used as a binder for fluid catalytic cracking (FCC) catalysts.

[0003] Currently, the common preparation methods of aluminosol include: metal aluminum method, organic alcohol salt hydrolysis method, powder dispersion method, etc. Among them, the metal aluminum method of preparing aluminosol by using metal aluminum and hydrochloric acid is the main production method in industry. The above methods can all prepare aluminosol for FCC catalysts, but the aluminum-chlorine ratio of the prepared aluminosol is relatively low, the pH value of the sol is 2-4, showing strong acidity, and the corrosion of the product is very strong. Generally, the molar ratio of Al:Cl is 1.0-1.5. Due to the high chlorine content, a large amount of HCl gas will overflow during the spray drying and forming process of the catalyst, thus corroding the equipment and causing environmental pollution; moreover, the formed HCl gas will damage the structure of the molecular sieve in the catalyst, significantly reducing the activity of the catalyst. Summary of the Invention

[0004] This application provides an aluminosol with a high aluminum-chlorine ratio and a preparation method thereof to solve the following technical problem: how to increase the aluminum-chlorine ratio of aluminosol.

[0005] In the first aspect, an embodiment of this application provides a preparation method of an aluminosol with a high aluminum-chlorine ratio, and the method includes:

[0006] Mix aluminum chloride, organic acid and deionized water to obtain a mixed acid solution;

[0007] Add metal aluminum to the mixed acid solution, stir and heat for condensation reflux, so that the metal aluminum undergoes a hydrolysis reaction under the conditions of a first set temperature and a first set time to obtain a precursor solution;

[0008] Cool the precursor solution to a second set temperature, so that the precursor solution undergoes a polycondensation reaction at the second set temperature for a second set time to obtain a mixed sol solution; and

[0009] Filter and separate the mixed sol solution to remove large particle impurities to obtain alumina sol.

[0010] Optionally, the first set temperature is 80°C - 100°C.

[0011] Optionally, the first set time is 10h - 15h.

[0012] Optionally, the second set temperature is 50°C - 70°C.

[0013] Optionally, the second set time is 2 h to 6 h.

[0014] Optionally, in the mixed acid solution, the molar ratio of Al 3+ to the organic acid is 1:(2 - 6).

[0015] Optionally, the organic acid includes one or more of glacial acetic acid, lactic acid, and formic acid.

[0016] Optionally, the molar ratio of metallic aluminum to aluminum chloride is (8 - 12):1.

[0017] Optionally, the metallic aluminum includes one or more of aluminum sheets, aluminum grains, and aluminum powders.

[0018] In a second aspect, the present application provides an alumina sol prepared by the method according to any one of the embodiments in the first aspect. The alumina sol satisfies the following properties: the average particle size of the colloidal particles is 200 nm to 300 nm, the pH value is 4.0 to 5.0, the aluminum-chlorine molar ratio is 2 to 4, and the solid content based on Al2O3 is 20 wt% to 30 wt%.

[0019] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art:

[0020] The embodiments of the present application provide a method for preparing an aluminum sol with a high aluminum-chlorine ratio. The method includes: mixing aluminum chloride, an organic acid, and deionized water to obtain a mixed acid solution; adding metallic aluminum to the mixed acid solution, and performing stirring and heating under reflux condensation so that the metallic aluminum undergoes a hydrolysis reaction under the conditions of a first set temperature and a first set time to obtain a precursor solution; cooling the precursor solution to a second set temperature so that the precursor solution undergoes a polycondensation reaction at the second set temperature for a second set time to obtain a mixed sol solution; and filtering and separating the mixed sol solution to remove large particle impurities to obtain an alumina sol. First, by partially replacing aluminum salts with metallic aluminum, the introduction amount of chloride ions is reduced; second, by forming a chelate (such as [Al(CH3COO)3]) with the carboxyl group of the organic acid, the recombination of Al 3+ is inhibited, and the residual amount of Cl 3+ in the sol is reduced; third, by accelerating the hydrolysis of Al to generate Al - at high temperature, the contact time between Cl - (from AlCl3) and Al 3+ is shortened, and the hydrolysis by-products of AlCl3 (such as Al(OH)Cl2 - ) are reduced; fourth, by filtering and separating the mixed sol solution, large particle impurities are removed, and an alumina sol with a high aluminum-chlorine ratio is obtained. 3+ are reduced; fourth, by filtering and separating the mixed sol solution, large particle impurities are removed, and an alumina sol with a high aluminum-chlorine ratio is obtained. -) Formation; finally, Al-OH (from the hydrolysis of metallic aluminum) and the carboxyl group (-COOH) of the organic acid form an aluminum-oxygen network (-Al-O-Al-) through esterification condensation, and this process repels Cl - is embedded in the network structure, and Cl - exists in the liquid phase in a free state. Thus, by incrementally replacing aluminum salts with metallic aluminum, suppressing Cl - binding, regulating through organic acid complexation, and stabilizing the structure through low-temperature polycondensation, the aluminum-chlorine ratio of the aluminum sol is increased. Description of the Drawings

[0021] The drawings here are incorporated into the specification and form a part of this specification, showing embodiments consistent with this application, and are used together with the specification to explain the principles of this application.

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 is a schematic flow chart of a preparation method of an aluminum sol with a high aluminum-chlorine ratio provided by an embodiment of this application;

[0024] Figure 2 is a particle size distribution diagram of an alumina sol provided by Embodiment 1 of this application;

[0025] Figure 3 is a microstructural diagram of an alumina sol provided by Embodiment 1 of this application. Detailed Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are some but not all of the embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0027] Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0028] In addition, in the description of the specification of the present application, terms such as "including" and "comprising" mean "including but not limited to". In this text, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. The "parts representation method" such as weight parts and mass parts represents the proportional relationship between each component. In the proportional relationship involved in this text, the parameters that need to be described by proportion should be understood as the antecedents of the proportion formula in the order of description, and the proportional numbers should be understood as the consequents of the proportion formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportion formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0029] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present application can be obtained through market purchase or can be prepared by existing methods.

[0030] Figure 1 It is a schematic flow diagram of a preparation method of an aluminum sol with a high aluminum-chlorine ratio provided for the embodiments of the present application.

[0031] As Figure 1 shown, the present application provides a method for preparing an aluminum sol with a high aluminum-chlorine ratio, and the method includes:

[0032] S1. Mix aluminum chloride, organic acid and deionized water to obtain a mixed acid solution;

[0033] In some embodiments, the organic acid includes one or more of glacial acetic acid, lactic acid and formic acid.

[0034] Metal aluminum hydrolyzes to generate aluminum hydroxide (Al-OH), and the organic acid provides carboxyl (-COOH), and the two can undergo a polycondensation reaction to increase the solid content of the sol. At the same time, the carboxyl group of the organic acid (such as glacial acetic acid) forms a chelate (such as [Al(CH3COO)3]) with Al 3+ to inhibit the recombination of Al 3+ with Cl - , reducing the residual amount of Cl - in the sol. In addition, the organic acid acts as a proton source, accelerating the hydrolysis of metal aluminum and forming a high-molecular aluminum-oxygen chain (-Al-O-Al-) through a polycondensation reaction, reducing the possibility of Cl- embedding into the network.

[0035] In some embodiments, in the mixed acid solution, the molar ratio of Al 3+ to the organic acid is 1:(2-6).

[0036] The carboxyl group (-COOH) of the organic acid forms a stable complex (such as [Al(CH3COO)3]) with Al 3+ to inhibit the combination of Al 3+ with Cl - to generate the by-product AlCl3, reducing the Cl - residue, thereby increasing the aluminum-chlorine ratio. At the same time, the organic acid provides a weak acidic environment (pH≈3-4), which not only promotes the hydrolysis of metal aluminum (Al→Al 3+ ), but also avoids strong acid corrosion of equipment or causing violent reactions. If the molar ratio of Al 3+ to the organic acid is less than 1:2: the organic acid is insufficient, and Al 3+ is not fully complexed, and it is easy to form a precipitate of Al(OH)Cl2 - . If the molar ratio of Al 3+ to the organic acid is higher than 1:6, the excessive organic acid results in too high viscosity of the sol, poor fluidity, and may introduce too much H + , inhibiting the polycondensation reaction. Exemplarily, the molar ratio of Al 3+ to the organic acid can be 1:2, 1:3, 1:4, 1:5, 1:6, etc.

[0037] S2. Add metallic aluminum to the mixed acid solution, stir and heat under reflux to cause the metallic aluminum to undergo a hydrolysis reaction at a first set temperature and for a first set time to obtain a precursor solution;

[0038] In some embodiments, the first set temperature is 80°C to 100°C.

[0039] In some embodiments, the first set time is 10 h to 15 h.

[0040] Define the hydrolysis reaction under high-temperature reaction conditions (80°C to 100°C, 10 h to 15 h). High temperature accelerates the dissolution of metallic aluminum and shortens the Cl - exposure time, reducing the complexation of Al 3+ with Cl - . At the same time, it can ensure that all the metallic aluminum is dissolved, avoiding the influence of unreacted aluminum residues on subsequent polycondensation. If the temperature is higher than 100°C, the reaction of metallic aluminum is violent, posing a safety hazard and wasting energy. If the reaction temperature is lower than 80°C, the reaction time will be too long and not all the metallic aluminum can be dissolved. Exemplarily, the reaction temperature of the hydrolysis reaction can be 80°C, 85°C, 90°C, 95°C, 100°C, etc., and the reaction time can be 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, etc.

[0041] In some embodiments, the metallic aluminum includes one or more of aluminum sheets, aluminum grains, and aluminum powders.

[0042] In some embodiments, the molar ratio of the metallic aluminum to the aluminum chloride is (8 to 12):1.

[0043] Define the molar ratio of metallic aluminum to aluminum chloride as (8 to 12):1. Metallic aluminum undergoes hydrolysis to generate Al 3+ (Reaction formula: 2Al + 6H + →2Al 3+ + 3H2↑), significantly increasing the total amount of Al 3+ and diluting the Cl - concentration. At the same time, after the metallic aluminum is dissolved, it generates Al(OH)3 colloid, which forms a three-dimensional network structure through polycondensation reaction, increasing the solid content of the aluminum sol. If the molar ratio of metallic aluminum to aluminum chloride is higher than 12:1, the reaction time will be too long and the formed sol will be unstable; if the molar ratio of metallic aluminum to aluminum chloride is lower than 8:1, the solid content of the sol will be low, reducing the aluminum-chlorine ratio. Exemplarily, the molar ratio of metallic aluminum to aluminum chloride can be 8:1, 9:1, 10:1, 11:1, 12:1, etc.

[0044] S3. Cool the precursor solution to a second set temperature to cause the precursor solution to undergo a polycondensation reaction at the second set temperature for a second set time to obtain a mixed sol solution; and

[0045] In some embodiments, the second set temperature is 50°C to 70°C.

[0046] In some embodiments, the second set time is 2 h to 6 h.

[0047] The polycondensation reaction is limited to low-temperature reaction conditions (50 - 70°C, 2 - 6 h). Al-OH (from the hydrolysis of metallic aluminum) and organic acid -COOH form an aluminum-oxygen network (-Al-O-Al-) through esterification condensation (Al-OH + HOOC-R → Al-OOCR + H2O), improving the stability of the sol. Meanwhile, the excess water is slowly evaporated at low temperature, increasing the solid content of the sol while avoiding the over-fast growth of colloidal particles (the colloidal particle size is controlled within 200 nm to 300 nm). If the reaction temperature is higher than 70°C, the growth rate of colloidal particles will increase, destroying the stability of the sol and ultimately resulting in precipitation. If the reaction temperature is lower than 50°C, the reaction time will be relatively long. Exemplarily, the reaction temperatures of the polycondensation reaction are 50°C, 55°C, 60°C, 65°C, 70°C, etc., and the reaction times are 2 h, 3 h, 4 h, 5 h, 6 h, etc.

[0048] S4. Filter and separate the mixed sol liquid to remove large particle impurities, obtaining an alumina sol.

[0049] Based on a general inventive concept, the present application provides an alumina sol prepared by the method described in any one of the above embodiments. The alumina sol satisfies the following properties: the average size of colloidal particles is 200 nm to 300 nm, the pH value is 4.0 to 5.0, the aluminum-chlorine molar ratio is 2 to 4, and the solid content calculated as Al2O3 is 20 wt% to 30 wt%.

[0050] Thus, through the incremental hydrolysis of metallic aluminum, organic acid complexation regulation, and staged temperature control reaction in the embodiments of the present application, precise control of the aluminum-chlorine ratio, solid content, and colloidal particle size is achieved. By replacing part of the aluminum salt with metallic aluminum, the introduction of Cl- is reduced, and the aluminum-chlorine ratio is increased to 2 to 4. By rapid dissolution at high temperature + polycondensation at low temperature, the reaction efficiency and sol stability are balanced. By considering the industrial production requirements and end-application performance with a high solid content (20% - 30%) and weak acidity (pH 4 - 5). This technology is applicable to high-end fields such as lithium battery separator coatings and FCC catalyst carriers, and is significantly superior to traditional aluminum sol processes. Exemplarily, the average size of colloidal particles can be 200 nm, 220 nm, 240 nm, 260 nm, 280 nm, 300 nm, etc., the pH value can be 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, etc., the aluminum-chlorine molar ratio can be 2, 2.5, 3, 3.5, 4, etc., and the solid content calculated as Al2O3 can be 20 wt%, 22 wt%, 24 wt%, 26 wt%, 28 wt%, 30 wt%, etc.

[0051] The alumina sol is realized based on the above preparation method of the alumina sol. For the specific steps of the preparation method of the alumina sol, reference can be made to the above embodiments. Since the alumina sol adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated here one by one.

[0052] In summary, a high-aluminum-chlorine-ratio aluminum sol and its preparation method provided by the embodiments of the present application have the following advantages:

[0053] (1) The aluminum-chlorine ratio is significantly increased: Through the incremental hydrolysis of metallic aluminum and the complexation regulation of organic acids, the present application has successfully increased the aluminum-chlorine ratio of the aluminum sol to 2 - 4, which is much higher than that of traditional processes. This increase not only reduces the residual chlorine ions and the potential harm to subsequent applications (such as lithium battery separator coatings, FCC catalyst carriers, etc.), but also enhances the chemical stability and application performance of the sol.

[0054] (2) The solid content is efficiently increased: The present application has achieved an efficient increase in the solid content of the aluminum sol to 20wt% - 30wt% by precisely controlling the reaction conditions and the raw material ratio. A high solid content means that more alumina components are contained in the sol under the same volume, thus improving its efficiency and durability in practical applications.

[0055] (3) The colloidal particle size is precisely controlled: Through the staged temperature-controlled reaction, the present application has successfully controlled the colloidal particle size of the aluminum sol within the range of 200nm - 300nm. The colloidal particles within this size range not only have excellent dispersibility and stability, but also can better meet the requirements for the microstructure of materials in high-end fields.

[0056] (4) The weak acidic environment is optimized: The present application utilizes the weak acidic environment provided by organic acids, which not only promotes the hydrolysis reaction of metallic aluminum, but also avoids the corrosion of strong acids to equipment and the occurrence of violent reactions. This optimization not only improves the safety of production, but also reduces the equipment maintenance cost.

[0057] (5) The raw materials are easily available and the cost is controllable: The raw materials adopted in the present application (such as aluminum chloride, organic acids, metallic aluminum, etc.) are all commonly used industrial raw materials, which are easy to obtain and the cost is controllable. This reduces the production cost and improves the market competitiveness of the product.

[0058] (6) There is great potential for industrial production: The method proposed in the present application has the potential for industrial production. By precisely controlling the reaction conditions and the raw material ratio, large-scale and stable production of the aluminum sol can be achieved. In addition, this method is also applicable to various forms of metallic aluminum (such as aluminum sheets, aluminum grains, aluminum powders, etc.), further broadening the raw material sources and the flexibility of production.

[0059] (7) Wide range of application fields: Since the aluminum sol prepared in this application has excellent properties (such as high aluminum-chlorine ratio, high solid content, precisely controlled colloid particle size, etc.), it is applicable to a variety of high-end fields. For example, in the coating of lithium-ion battery separators, a high aluminum-chlorine ratio and low chloride ion residue can improve the performance and safety of the battery; in the FCC catalyst support, a high solid content and stable microstructure can improve the activity and stability of the catalyst.

[0060] The following will further elaborate on this application in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate this application and not to limit the scope of this application. For the experimental methods without specific conditions noted in the following embodiments, they are usually determined according to industry standards. If there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0061] Example 1

[0062] This example provides a method for preparing an aluminum oxide sol with a high aluminum-chlorine ratio, including the following steps:

[0063] S1: Add 360 g of deionized water to a 1 L three-necked round-bottom flask, and successively add 6 g of formic acid, 5 g of acetic acid, and 25 g of aluminum chloride under the condition of 90 °C condensation reflux. After stirring for 30 min, a mixed acid solution is formed.

[0064] S2: Add 27 g of aluminum powder to the mixed solution obtained in step (1) at one time. After stirring and reacting for 10 h, then lower the water bath temperature to 60 °C, turn off the condensation reflux device, and continue to react for 3 h. After the reaction is completed, an aluminum oxide sol is obtained.

[0065] S3: Filter and separate the sol obtained in step (2) to remove large particle impurities, and obtain a transparent aluminum oxide sol with a high aluminum-chlorine ratio.

[0066] The average particle size of the colloid is 221 nm, the pH value is 4.35, the aluminum-chlorine molar ratio is 3.6, and the solid content is 21 wt% (calculated based on Al2O3).

[0067] Figure 2 It is the particle size distribution diagram of the aluminum oxide sol provided in Example 1 of this application;

[0068] As can be seen from Figure 2 the average particle size of the sol is 221 nm, and the distribution is relatively concentrated;

[0069] Figure 3 It is the microscopic structure diagram of the aluminum oxide sol provided in Example 1 of this application;

[0070] As can be seen from Figure 3 the core size of the colloid is about 50 nm, showing a granular shape, enabling the sol to maintain a high solid content.

[0071] Example 2

[0072] This example provides a method for preparing alumina sol with a high aluminum-chlorine ratio, and the steps are as follows:

[0073] S1: Add 360 g of deionized water to a 1 L three-necked round-bottom flask. Under the condition of condensation reflux at 80 °C, add 8 g of formic acid, 7 g of acetic acid, and 23 g of aluminum chloride in sequence. After stirring for 30 min, a mixed acid solution is formed.

[0074] S2: Add 27 g of aluminum pellets to the mixed solution obtained in step (1) at one time. After stirring and reacting for 15 h, then lower the water bath temperature to 50 °C, turn off the condensation reflux device, and continue to react for 5 h. After the reaction is completed, alumina sol is obtained.

[0075] S3: Filter and separate the sol obtained in step (2) to remove large particle impurities, and obtain a transparent alumina sol with a high aluminum-chlorine ratio.

[0076] The average particle size of the colloid is 252 nm, the pH value is 4.09, the aluminum-chlorine molar ratio is 3.9, and the solid content is 26 wt% (calculated based on Al2O3).

[0077] Example 3

[0078] This example provides a method for preparing alumina sol with a high aluminum-chlorine ratio, and the steps are as follows:

[0079] S1: Add 360 g of deionized water to a 1 L three-necked round-bottom flask. Under the condition of condensation reflux at 80 °C, add 18 g of formic acid, 16 g of acetic acid, and 30 g of aluminum chloride in sequence. After stirring for 30 min, a mixed acid solution is formed.

[0080] S2: Add 27 g of aluminum powder to the mixed solution obtained in step (1) at one time. After stirring and reacting for 15 h, then lower the water bath temperature to 70 °C, turn off the condensation reflux device, and continue to react for 6 h. After the reaction is completed, alumina sol is obtained.

[0081] S3: Filter and separate the sol obtained in step (2) to remove large particle impurities, and obtain a transparent alumina sol with a high aluminum-chlorine ratio.

[0082] The average particle size of the colloid is 289 nm, the pH value is 4.50, the aluminum-chlorine molar ratio is 3.1, and the solid content is 28 wt% (calculated based on Al2O3).

[0083] Example 4

[0084] This example provides a method for preparing alumina sol with a high aluminum-chlorine ratio, and the steps are as follows:

[0085] S1: Add 360 g of deionized water into a 1-L three-necked round-bottom flask. Sequentially add 20 g of formic acid, 17 g of acetic acid, and 27 g of aluminum chloride under the condition of reflux condensation at 85 °C. After stirring for 30 min, a mixed acid solution is formed.

[0086] S2: Add 27 g of aluminum sheets into the mixed solution obtained in step (1) at one time. After stirring and reacting for 13 h, then lower the water bath temperature to 65 °C, turn off the reflux condensation device, and continue to react for 3 h. After the reaction is completed, an alumina sol is obtained.

[0087] S3: Filter and separate the sol described in step (2) to remove large particle impurities, and a transparent alumina sol with a high aluminum-chlorine ratio is obtained.

[0088] The average size of the colloidal particles is 235 nm, the pH value is 4.10, the aluminum-chlorine molar ratio is 4.2, and the solid content is 25 wt% (calculated based on Al2O3).

[0089] Example 5

[0090] This example provides a method for preparing an alumina sol with a high aluminum-chlorine ratio, including the following steps:

[0091] S1: Add 360 g of deionized water into a 1-L three-necked round-bottom flask. Sequentially add 17 g of formic acid, 14 g of acetic acid, and 21 g of aluminum chloride under the condition of reflux condensation at 95 °C. After stirring for 30 min, a mixed acid solution is formed.

[0092] S2: Add 27 g of aluminum powder into the mixed solution obtained in step (1) at one time. After stirring and reacting for 12 h, then lower the water bath temperature to 55 °C, turn off the reflux condensation device, and continue to react for 6 h. After the reaction is completed, an alumina sol is obtained.

[0093] S3: Filter and separate the sol described in step (2) to remove large particle impurities, and a transparent alumina sol with a high aluminum-chlorine ratio is obtained.

[0094] The average size of the colloidal particles is 235 nm, the pH value is 4.10, the aluminum-chlorine molar ratio is 4.2, and the solid content is 23 wt% (calculated based on Al2O3).

[0095] Comparative Example 1

[0096] This comparative example provides a method for preparing an alumina sol with a high aluminum-chlorine ratio, including the following steps:

[0097] S1: Add 360 g of deionized water into a 1-L three-necked round-bottom flask. Sequentially add 5 g of formic acid, 4 g of acetic acid, and 70 g of aluminum chloride under the condition of reflux condensation at 80 °C. After stirring for 30 min, a mixed acid solution is formed.

[0098] S2: Add 27 g of aluminum powder to the mixed solution obtained in step (1) at one time. After stirring and reacting for 12 h, then lower the water bath temperature to 70 °C, turn off the condensation reflux device, and continue reacting for 2 h. After the reaction is completed, an alumina sol is obtained.

[0099] S3: Filter and separate the sol described in step (2) to remove large particle impurities, and obtain a transparent alumina sol with a low aluminum-chlorine ratio.

[0100] The average particle size of the colloidal particles is 264 nm, the pH value is 2.85, the molar ratio of aluminum to chlorine is 1.5, and the solid content is 22 wt% (calculated based on Al2O3).

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing an alumina sol with a high aluminum-chlorine ratio, including the following steps:

[0103] S1: Add 360 g of deionized water to a 1 L three-necked round-bottom flask. Under the condition of 90 °C condensation reflux, add 10 g of formic acid, 8 g of acetic acid, and 23 g of aluminum chloride in sequence. After stirring for 30 min, a mixed acid solution is formed.

[0104] S2: Add 27 g of aluminum flakes to the mixed solution obtained in step (1) at one time. After stirring and reacting for 10 h, then lower the water bath temperature to 80 °C, turn off the condensation reflux device, and continue reacting for 6 h. After the reaction is completed, a white precipitate appears, and no alumina sol is obtained.

[0105] In addition, one or more technical solutions in the embodiments of the present application at least further have the following technical effects or advantages:

[0106] In the embodiments of the present application, the preparation method of the alumina sol is simple, the raw materials are simple and easy to obtain, and it is easy to industrialize production.

[0107] In the embodiments of the present application, the preparation method of the alumina sol first uses a high-temperature reaction to promote the rapid dissolution of metallic aluminum, and then uses a low-temperature reaction to evaporate excess water, causing it to undergo a polycondensation reaction to increase the solid content, solving the problem that it is difficult to form an aluminum sol due to insufficient acidity.

[0108] In the embodiments of the present application, the alumina sol is uniform and transparent, has a high pH, and weak acidity, solving the problem of strong corrosion of the existing alumina sol.

[0109] In the embodiments of the present application, the problems that the existing alumina sol has a low aluminum-chlorine ratio, corrodes equipment due to high chlorine content, and causes environmental pollution are solved. At the same time, the problem that the HCl gas volatilized from the low aluminum-chlorine ratio aluminum sol destroys the molecular sieve structure in the catalyst and reduces the catalyst activity is solved.

[0110] In the embodiments of the present application, the alumina sol has a high aluminum-chlorine ratio and is suitable for use as a binder in the preparation of FCC catalysts.

[0111] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing an aluminum sol with a high aluminum-chlorine ratio, the method comprising: Mixing aluminum chloride, an organic acid, and deionized water to obtain a mixed acid solution; Adding metallic aluminum to the mixed acid solution, and stirring and heating for condensation reflux to enable the metallic aluminum to undergo a hydrolysis reaction under the conditions of a first set temperature and a first set time to obtain a precursor liquid; Cooling the precursor liquid to a second set temperature to enable the precursor liquid to undergo a polycondensation reaction at the second set temperature for a second set time to obtain a mixed sol solution; And Filtering and separating the mixed sol solution to remove large particle impurities to obtain an alumina sol.

2. The method according to claim 1, wherein The first set temperature is 80°C to 100°C.

3. The method according to claim 1, wherein The first set time is 10 h to 15 h.

4. The method according to claim 1, wherein The second set temperature is 50°C to 70°C.

5. The method according to claim 1, wherein The second set time is 2 h to 6 h.

6. The method according to claim 1, wherein In the mixed acid solution, the molar ratio of Al 3+ to the organic acid is 1:(2 - 6).

7. The method according to claim 6, characterized in that, The organic acid includes one or more of glacial acetic acid, lactic acid, and formic acid.

8. The method according to claim 1, wherein The molar ratio of the metallic aluminum to the aluminum chloride is (8 to 12):

1.

9. The method according to claim 8, wherein The metallic aluminum includes one or more of aluminum sheets, aluminum grains, and aluminum powder.

10. An alumina sol prepared by the method according to any one of claims 1 to 9, the alumina sol having the following properties: an average particle size of the colloidal particles is 200 nm to 300 nm, a pH value is 4.0 to 5.0, an aluminum-chlorine molar ratio is 2 to 4, and a solid content calculated as Al2O3 is 20 wt% to 30 wt%.

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