Modified aluminum sol, and preparation method and application thereof

Abstract

This invention discloses a modified aluminum sol, its preparation method, and its application, belonging to the field of aluminum sol technology. The method includes the following steps: At room temperature, a 2 mol / L aluminum trichloride solution is prepared using crystalline aluminum chloride and distilled water. A 6 mol / L ammonia solution is added dropwise to the aluminum trichloride solution until the pH of the system reaches 7-8. The solution is filtered, and the filter cake is washed to obtain an intermediate product. Another 2 mol / L aluminum trichloride solution is prepared, and the intermediate product is added to it. After stirring for 10 minutes, the temperature is raised to 60°C for 50-60 minutes to obtain an aluminum sol. The aluminum sol is ultrasonically dispersed at room temperature for 15 minutes and then transferred to a reaction vessel. The reaction temperature is controlled at 60°C, and auxiliary components are added under stirring conditions. The reaction is maintained at this temperature for 3 hours to obtain the modified aluminum sol. This invention does not add highly corrosive hydrochloric acid during the preparation of the modified aluminum sol, making it safe and environmentally friendly. Furthermore, the introduction of auxiliary components improves the stability and adhesion of the aluminum sol.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum sol and specifically relates to a modified aluminum sol and a preparation method and application thereof. BACKGROUND

[0002] With the increasing degree of heavy and poor quality of catalytic cracking (FCC) feedstock oil, efficient conversion of heavy and poor quality feedstock oil has become one of the main trends of future oil refining development, which puts forward higher requirements for FCC catalysts. As an important component of the FCC catalyst, the binder has the following advantages: 1) enhancing the mechanical strength of the catalyst, strong resistance to metal pollution and high coke selectivity; 2) transferring the active substance of the reaction; 3) providing mesopores and macropores for the catalyst to improve the diffusion performance. Currently, commonly used binders include aluminum sol, peptized pseudo-boehmite, silica sol, silica-aluminum sol and phosphorus-aluminum sol, each of which has unique advantages and is widely used in various fields.

[0003] The widely used binder is a double aluminum-based binder, i.e. acidified pseudo-boehmite and aluminum sol. The aluminum sol binder is prepared by an aluminum-hydrochloric acid process, and has problems of unstable performance of the aluminum sol, poor storage stability and generation of hydrogen.

[0004] Therefore, it is necessary to provide a more high-quality aluminum sol and a preparation method thereof. SUMMARY

[0005] The purpose of the present application is to provide a modified aluminum sol and a preparation method and application thereof to solve the problems in the background art.

[0006] The purpose of the present application can be achieved by the following technical solutions.

[0007] A preparation method of a modified aluminum sol, comprising the following steps:

[0008] Step S1, at room temperature, crystalline aluminum chloride is added to distilled water to prepare a 2 mol / L aluminum chloride solution, ammonia water solution with a concentration of 6 mol / L is slowly added to the obtained aluminum chloride solution until the pH value of the system is 7-8, and amorphous aluminum hydroxide precipitate is prepared, and the filter cake is washed until the washing liquid does not contain Cl - , to obtain an intermediate product;

[0009] Step S2, a 2 mol / L aluminum chloride solution is prepared again in the manner of step S1, and the intermediate product is added thereto, stirred at a speed of 60-100 r / min for 10 min, and then heated to 60℃ for 50-60 min to obtain an aluminum sol;

[0010] Step S3, after the aluminum sol is ultrasonically dispersed at room temperature for 15 min, it is transferred to a reaction kettle, auxiliary components are added under the conditions of reaction temperature control at 60 DEG C and stirring, and the reaction is kept for 3 h to obtain a modified aluminum sol.

[0011] As a further scheme of the present application, the mass ratio of the aluminum chloride solution to the intermediate product in step S2 is 100:16-20.

[0012] As a further scheme of the present application, the ultrasonic dispersion power in step S3 is 50-120 W, and the amount of the auxiliary components is 10-20% of the mass of the aluminum sol.

[0013] As a further scheme of the present application, the auxiliary components are prepared by the following steps:

[0014] The siloxane monomer, anhydrous ethanol and deionized water are mixed, the hydrochloric acid solution is slowly added dropwise under stirring at 40-50 DEG C, the pH value is controlled to be 3-4, the reaction is kept for 4-6 h, after the reaction is completed, the solvent is removed by rotary evaporation, and drying treatment is performed to obtain the auxiliary components, which are hyperbranched polymers containing Schiff base structure, phenolic hydroxyl and silicon hydroxyl, i.e. the auxiliary components, by hydrolysis and polycondensation of the siloxane monomer.

[0015] As a further scheme of the present application, the amount ratio of the siloxane monomer, anhydrous ethanol and deionized water is 40 g:64-70 mL:6-10 mL, and the mass fraction of the hydrochloric acid solution is 37%.

[0016] As a further scheme of the present application, the siloxane monomer is prepared by the following steps:

[0017] The 3-aminopropyl triethoxysilane, anhydrous sodium sulfate and anhydrous ethanol are added to a reaction kettle, after stirring at 25 DEG C for 15 min under nitrogen protection, the o-hydroxybenzaldehyde is added dropwise while stirring, the dropping speed is 1 drop / s, after the dropping is completed, the temperature is raised to reflux under nitrogen atmosphere, and the reaction is kept for 3-5 h, after the reaction is completed, the sodium sulfate is removed by hot filtration, and the anhydrous ethanol is removed by distillation under reduced pressure from the filtrate to obtain the siloxane monomer;

[0018] The amount ratio of the 3-aminopropyl triethoxysilane, anhydrous sodium sulfate, anhydrous ethanol and o-hydroxybenzaldehyde is 2.7-3.3 g:2 g:50-80 mL:1.8 g, the anhydrous sodium sulfate is used as a drying agent, the 3-aminopropyl triethoxysilane and the o-hydroxybenzaldehyde are used as reaction substrates, the siloxane monomer containing Schiff base structure is obtained by condensation reaction of amino and aldehyde groups.

[0019] As a further scheme of the present application, a modified aluminum sol is prepared by the above preparation method.

[0020] As a further aspect of the present application, the use of a modified aluminum sol as a binder in a catalytic cracking catalyst.

[0021] Advantages of the present application:

[0022] 1、The present application uses crystalline aluminum chloride as aluminum source and ammonia as precipitant to prepare amorphous aluminum hydroxide, and then uses the solution of amorphous aluminum hydroxide and crystalline aluminum chloride to obtain sol. The solution of crystalline aluminum chloride has strong acidity and can replace hydrochloric acid to react with amorphous aluminum hydroxide. This preparation method avoids the use of highly corrosive hydrochloric acid solution, is friendly to production equipment, and has easy-to-obtain raw materials, mild reaction conditions, convenient operation, saves manpower and material resources, and reduces production cost.

[0023] 2、The present application introduces an auxiliary component into the aluminum sol system. The auxiliary component is a hyperbranched polymer, which has good solubility in the aluminum sol and contains a large number of cavities. The aluminum oxide particles in the aluminum sol can easily enter the cavities, so that the aluminum oxide particles are more uniformly dispersed, and the obtained aluminum sol is more stable.

[0024] 3、The present application introduces an auxiliary component into the aluminum sol system. The auxiliary component contains active silicon hydroxyl groups, which can react with the catalyst matrix (binder, molecular sieve) and the surface hydroxyl groups of the aluminum oxide particles, play a "bridge" role, and chemically connect the aluminum oxide particles to the surface of the catalyst matrix to improve the adhesion strength of the aluminum sol. In addition, the auxiliary component contains Schiff base structure and phenolic hydroxyl groups, which can coordinate with the metal materials in the catalyst to improve the adhesion strength of the aluminum sol and endow the catalyst with excellent wear resistance. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0026] Embodiment 1

[0027] An auxiliary component is prepared by the following steps:

[0028] 40g of siloxane monomer, 64mL of anhydrous ethanol and 6mL of deionized water are mixed, and a hydrochloric acid solution is slowly added under stirring at 40℃ until the pH value is controlled at 3. After reaction for 4h, the solvent is removed by rotary evaporation, and the auxiliary component is obtained after drying treatment. The mass fraction of the hydrochloric acid solution is 37%.

[0029] The siloxane monomer is prepared by the following steps:

[0030] 2.7 g of 3-aminopropyltriethoxysilane, 2 g of anhydrous sodium sulfate, and 50 mL of anhydrous ethanol were added to a reaction vessel. Under nitrogen protection, the mixture was stirred at 25 °C for 15 min. Then, 1.8 g of o-hydroxybenzaldehyde was added dropwise while stirring at a rate of 1 drop / second. After the addition was completed, the mixture was heated to reflux under nitrogen atmosphere for 3 h. After the reaction was completed, the sodium sulfate was removed by hot filtration, and the anhydrous ethanol was removed by vacuum distillation of the filtrate to obtain the siloxane monomer.

[0031] Example 2

[0032] An auxiliary component is prepared by the following steps:

[0033] 40g of siloxane monomer, 70mL of anhydrous ethanol and 10mL of deionized water were mixed and stirred at 50℃. Hydrochloric acid solution was slowly added dropwise while controlling the pH value to 4. The reaction was kept at this temperature for 6h. After the reaction was completed, the solvent was removed by rotary evaporation and dried to obtain the auxiliary component. The mass fraction of the hydrochloric acid solution was 37%.

[0034] The siloxane monomer is prepared by the following steps:

[0035] 3.3 g of 3-aminopropyltriethoxysilane, 2 g of anhydrous sodium sulfate, and 80 mL of anhydrous ethanol were added to a reaction vessel. Under nitrogen protection, the mixture was stirred at 25 °C for 15 min. Then, 1.8 g of o-hydroxybenzaldehyde was added dropwise while stirring at a rate of 1 drop / second. After the addition was completed, the mixture was heated to reflux under nitrogen atmosphere for 5 h. After the reaction was completed, the sodium sulfate was removed by hot filtration, and the anhydrous ethanol was removed by vacuum distillation of the filtrate to obtain the siloxane monomer.

[0036] Comparative Example 1

[0037] This comparative example provides an auxiliary composition. Compared with Example 1, the siloxane monomer in Example 1 is replaced with 3-aminopropyltriethoxysilane, and the remaining raw materials and preparation process are the same as in Example 1.

[0038] Example 3

[0039] A method for preparing modified aluminum sol includes the following steps:

[0040] Step S1: At room temperature, crystalline aluminum chloride is added to distilled water to prepare a 2 mol / L aluminum trichloride solution. A 6 mol / L ammonia solution is slowly added dropwise to the resulting aluminum trichloride solution until the pH of the system reaches 7, preparing an amorphous aluminum hydroxide precipitate. The precipitate is filtered, and the filter cake is washed until the washing liquid is free of Cl. - To obtain intermediate products;

[0041] Step S2: Prepare a 2 mol / L aluminum chloride solution again according to the method in step S1, add the intermediate product to it, stir at 60 r / min for 10 min, then heat to 60℃ for 50 min to gel, and obtain aluminum sol. The mass ratio of aluminum chloride solution to intermediate product is 100:16.

[0042] Step S3: After ultrasonically dispersing the aluminum sol at room temperature for 15 min, transfer it to a reaction vessel, control the reaction temperature at 60°C, add the auxiliary component of Example 1 under stirring, and keep the reaction at this temperature for 3 h to obtain the modified aluminum sol. The ultrasonic dispersion power is 50 W, and the amount of auxiliary component is 10% of the mass of the aluminum sol.

[0043] Example 4

[0044] A method for preparing modified aluminum sol includes the following steps:

[0045] Step S1: At room temperature, crystalline aluminum chloride is added to distilled water to prepare a 2 mol / L aluminum trichloride solution. A 6 mol / L ammonia solution is slowly added dropwise to the resulting aluminum trichloride solution until the pH of the system reaches 8, preparing an amorphous aluminum hydroxide precipitate. The precipitate is filtered, and the filter cake is washed until the washing liquid is free of Cl. - To obtain intermediate products;

[0046] Step S2: Prepare a 2 mol / L aluminum chloride solution again according to the method in step S1, add the intermediate product to it, stir at 80 r / min for 10 min, then heat to 60℃ for 55 min to gel, and obtain aluminum sol. The mass ratio of aluminum chloride solution to intermediate product is 100:18.

[0047] Step S3: After ultrasonically dispersing the aluminum sol at room temperature for 15 min, transfer it to a reaction vessel, control the reaction temperature at 60°C, add the auxiliary component of Example 2 under stirring, and keep the reaction at this temperature for 3 h to obtain the modified aluminum sol. The ultrasonic dispersion power is 100 W, and the amount of auxiliary component is 15% of the mass of the aluminum sol.

[0048] Example 5

[0049] A method for preparing modified aluminum sol includes the following steps:

[0050] Step S1: At room temperature, crystalline aluminum chloride is added to distilled water to prepare a 2 mol / L aluminum trichloride solution. A 6 mol / L ammonia solution is slowly added dropwise to the resulting aluminum trichloride solution until the pH of the system reaches 8, preparing an amorphous aluminum hydroxide precipitate. The precipitate is filtered, and the filter cake is washed until the washing liquid is free of Cl. - To obtain intermediate products;

[0051] Step S2: Prepare a 2 mol / L aluminum chloride solution again according to the method in step S1, add the intermediate product to it, stir at 100 r / min for 10 min, then heat to 60℃ for 60 min to gel, and obtain aluminum sol. The mass ratio of aluminum chloride solution to intermediate product is 100:20.

[0052] Step S3: After ultrasonically dispersing the aluminum sol at room temperature for 15 min, transfer it to a reaction vessel, control the reaction temperature at 60°C, add the auxiliary component of Example 2 under stirring, and keep the reaction at this temperature for 3 h to obtain the modified aluminum sol. The ultrasonic dispersion power is 120 W, and the amount of auxiliary component is 20% of the mass of the aluminum sol.

[0053] Comparative Example 2

[0054] A method for preparing modified aluminum sol, compared with Example 3, is described in which the auxiliary component in Example 3 is replaced with the substance in Comparative Example 1, and the remaining raw materials and preparation process are the same as in Example 3.

[0055] Comparative Example 3

[0056] A method for preparing modified aluminum sol, compared with Example 3, removes the auxiliary components in Example 3, while the remaining raw materials and preparation process are the same as in Example 3.

[0057] The performance stability of the aluminum sols obtained in Examples 3-5 and Comparative Examples 2-3 was tested. The specific operation was as follows: each group of aluminum sols was left to stand at room temperature for 100 hours. During the experimental period, it was observed whether precipitation occurred. If precipitation occurred, it was confirmed that the colloid was unstable. The structure is shown in Table 1.

[0058] 1115g of kaolin and 2756g of deionized water were mixed evenly. Then, 250g of REY molecular sieve, 859g of USY molecular sieve, and 300g of REHY molecular sieve were added and stirred for 1 hour. 1160g of the modified aluminum sol obtained in Example 3 was added, mixed evenly, spray-dried, and calcined at 500℃ for 1 hour to obtain the catalyst. The above operation was repeated, except that the modified aluminum sol was changed to the modified aluminum sol obtained in Example 4, Example 5, Comparative Example 2, and Comparative Example 3, respectively, to obtain the corresponding catalysts. The catalyst performance was tested, and the test items are as follows:

[0059] I. Wear resistance test: The air lift method in Q / SYLS0518-2002 was used for testing. Each group of catalysts of equal mass was placed in a fixed device and polished under constant airflow for 5 hours. The average wear percentage of the last four hours, excluding the first hour, was called the wear index of the catalyst, in % per hour. The test results are shown in Table 3.

[0060] II. Evaluation of microreaction activity (MA): The catalyst was pretreated at 800℃ and 100% steam for 17h using the ASTM-D3970 method. Dagang light diesel oil was used as the feedstock. The reaction temperature was 460℃, the oil inlet time was 70s, and the catalyst loading was 2.5g. The yield of gasoline after the reaction was analyzed by gas chromatography GC7890. The test results are shown in Table 3.

[0061] III. Catalytic Cracking Reaction Selectivity Evaluation: The catalytic cracking reaction selectivity evaluation was conducted in a small-scale fixed fluidized bed (FFB) unit. The catalyst was pretreated at 800℃ and 100% steam for 10 hours. The properties of the feedstock oil are shown in Table 2. The reaction temperature was 500℃, and the space velocity was 12–15 h⁻¹. -1 The agent-to-oil ratio was 5, the conversion rate = gasoline yield + liquefied petroleum gas yield + dry gas yield + coke yield, and the coke selectivity = coke yield / conversion rate. The test results are shown in Table 4.

[0062] Table 1. Stability of modified aluminum sol

[0063] Item Example 3 Example 4 Example 5 Comparative Example 2 Comparative Example 3 Stability No precipitation No precipitation No precipitation No precipitation Precipitation

[0064] Table 1 above shows the test results of the modified aluminum sol obtained from the examples and comparative examples. The comparison shows that the sol systems obtained from Examples 3-5 and Comparative Example 2 are stable. The reason is that Examples 3-5 and Comparative Example 2 introduced auxiliary components into the aluminum sol system. These auxiliary components are hyperbranched polymers, which have good solubility in aluminum sol and contain a large number of cavity structures. The alumina particles of the aluminum sol can easily enter the cavities, making the alumina particles more uniformly dispersed and the resulting aluminum sol state more stable. Comparative Example 3 did not introduce auxiliary components, and its stability was poor.

[0065] Table 2 Properties of Crude Oil

[0066]

[0067]

[0068] Table 2 above shows the physicochemical data of the feedstock oil used in the catalyst performance tests of Dagang light diesel oil, namely the examples and comparative examples.

[0069] Table 3. Catalyst chlorine content, wear resistance, and microreaction activity (MA)

[0070] Item Example 3 Example 4 Example 5 Comparative Example 2 Comparative Example 3 Wear index (wt%) 1.3 1.1 0.7 1.5 2.1 Micro-reactivity (wt%) 60 62 65 59 58

[0071] Table 2 above shows the performance test results of the catalysts obtained in the examples and comparative examples. The wear index of the catalysts obtained in Examples 3-5 was 0.7-1.3%, while the wear index of the comparative examples was 1.5-2.1%. It can be seen from the comparison that the catalysts obtained in the examples have better wear resistance. The reason is that the present invention introduces an auxiliary component into the alumina sol system. This auxiliary component contains active silanol groups, which can react with the catalyst matrix (bonding, molecular sieve) and the hydroxyl groups on the surface of alumina particles to improve the bonding strength of the alumina sol. In addition, this auxiliary component contains Schiff base structure and phenolic hydroxyl groups, which can coordinate with the metal materials in the catalyst to improve the bonding strength of the alumina sol and give the catalyst excellent wear resistance. No auxiliary component was added in Comparative Example 3. Although an auxiliary component was added in Comparative Example 2, the auxiliary component did not contain Schiff base, phenolic hydroxyl groups and other structures. Therefore, the wear resistance of the prepared catalyst was lower than that of Examples 3-5.

[0072] Table 4 Selectivity of Catalytic Cracking

[0073] Item Example 3 Example 4 Example 5 Comparative Example 2 Comparative Example 3 Conversion / % 85.83 85.94 86.21 85.44 85.36 Coke selectivity / % 7.13 6.59 6.52 7.8 8.1

[0074] Table 4 above shows the performance test results of the catalysts obtained in the examples and comparative examples. As can be seen from the comparative examples, the catalysts prepared in Examples 3-5 have higher catalytic effects. In summary, the binder prepared by modifying aluminum sol in this invention meets the performance requirements of the binder required for catalytic cracking catalysts.

[0075] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing modified aluminum sol, characterized in that, Includes the following steps: Step S1: At room temperature, prepare a 2 mol / L aluminum chloride solution using crystalline aluminum chloride and distilled water. Add ammonia dropwise to the aluminum chloride solution until the pH of the system is 7-8. Filter the solution and wash the filter cake to obtain the intermediate product. Step S2: Prepare a 2 mol / L aluminum trichloride solution again, add the intermediate product to it, stir for 10 min, and then heat to 60℃ for 50-60 min to obtain aluminum sol; Step S3: After ultrasonically dispersing the aluminum sol at room temperature for 15 min, transfer it to a reaction vessel, control the reaction temperature at 60℃, add auxiliary components under stirring, and keep the reaction at this temperature for 3 h to obtain modified aluminum sol; The auxiliary components are prepared through the following steps: Mix siloxane monomer, anhydrous ethanol and deionized water, stir well at 40-50℃, slowly add hydrochloric acid solution, control the pH value to 3-4, keep the reaction at the temperature for 4-6 hours to obtain auxiliary components; Siloxane monomers are prepared by the following steps: 3-Aminopropyltriethoxysilane, anhydrous sodium sulfate, and anhydrous ethanol were added to a reaction vessel. Under nitrogen protection, the mixture was stirred at 25°C for 15 min. Then, o-hydroxybenzaldehyde was added dropwise while stirring. After the addition was completed, the mixture was heated to reflux under nitrogen atmosphere for 3-5 h. After the reaction was completed, the sodium sulfate was removed by hot filtration. The anhydrous ethanol was removed by vacuum distillation of the filtrate to obtain the siloxane monomer.

2. The method for preparing a modified aluminum sol according to claim 1, characterized in that, In step S2, the mass ratio of aluminum trichloride solution to intermediate product is 100:16-20.

3. The method for preparing a modified aluminum sol according to claim 1, characterized in that, In step S3, the amount of auxiliary components used is 10-20% of the mass of aluminum sol.

4. The method for preparing a modified aluminum sol according to claim 1, characterized in that, The ratio of siloxane monomer, anhydrous ethanol and deionized water is 40g: 64-70mL: 6-10mL, and the hydrochloric acid solution has a mass fraction of 37%.

5. The method for preparing a modified aluminum sol according to claim 1, characterized in that, The ratio of 3-aminopropyltriethoxysilane, anhydrous sodium sulfate, anhydrous ethanol and o-hydroxybenzaldehyde is 2.7-3.3g:2g:50-80mL:1.8g.

6. A modified aluminum sol, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

7. An application of the modified aluminum sol according to claim 6, characterized in that, It is used in the preparation of catalytic cracking catalysts.

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