Composite aluminum sol, its preparation method and application

Abstract

The present invention belongs to the technical field of the preparation of aluminosols, and particularly relates to a composite aluminosol and its preparation method and application. The composite aluminosol comprises the following raw materials in parts by weight: 20 parts to 30 parts of an aluminum source, 40 parts to 50 parts of silicon source microcapsules, 20 parts to 30 parts of cerium source microcapsules, 10 parts to 20 parts of a dispersant, and 600 parts to 850 parts of water; the shell material of the cerium source microcapsules is paraffin, and the shell material of the silicon source microcapsules is polymethyl methacrylate. The composite aluminosol provided by the present invention is formed by the composite hydrolysis of an aluminum source, a silicon source, and a cerium source to form a composite aluminosol, improving the stability of the aluminosol; the particle size of the composite aluminosol is uniform.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of aluminum sol, and particularly relates to a composite aluminum sol, a preparation method thereof and an application thereof. Background Art

[0002] Aluminum sol is a colloidal solution in which the dispersed phase is extremely fine aluminum hydroxide (Al(OH)3) or alumina (Al2O3) particles. Aluminum sol has many unique properties, such as a high specific surface area, good adhesion and film-forming properties, and thus has a wide range of applications in many fields such as catalysis, ceramics, papermaking, and textiles.

[0003] The preparation of aluminum sol usually involves the hydrolysis reaction of aluminum salts (such as aluminum chloride, aluminum sulfate or aluminum nitrate), or the hydrolysis and polycondensation process of aluminum alkoxides (such as aluminum isopropoxide). However, the traditional preparation method of aluminum sol has disadvantages such as uncontrollable particle size and poor repeatability. To solve this problem, in the prior art, an organic aluminum source is dissolved in an alcohol solvent, and then hydrolysis and other steps are carried out to obtain aluminum sol. Although this method controls the particle size of aluminum sol to a certain extent, since the rate of aluminum released by the organic aluminum source decreases with the decrease in concentration, and the molecules of the organic aluminum source are relatively large, the particle size of the prepared aluminum sol is not uniform enough. In addition, the yield and product purity of the preparation of the organic aluminum source not only affect the preparation of aluminum sol, but also increase the cost of preparing the organic aluminum source. Summary of the Invention

[0004] To solve the above problems, the present invention provides a composite aluminum sol, a preparation method thereof and an application thereof. The composite aluminum sol has high stability and mechanical strength. The composite aluminum sol prepared by the preparation method has uniform particle size and stable properties.

[0005] The present invention is achieved by the following technical solutions:

[0006] In the first aspect, the present invention provides a composite aluminum sol, comprising the following raw materials in parts by weight:

[0007] 20 parts to 30 parts of an aluminum source, 40 parts to 50 parts of a silicon source microcapsule, 20 parts to 30 parts of a cerium source microcapsule, 10 parts to 20 parts of a dispersant and 600 parts to 850 parts of water;

[0008] The shell material of the cerium source microcapsule is paraffin wax, and the shell material of the silicon source microcapsule is polymethyl methacrylate.

[0009] In the second aspect, the present invention provides a preparation method of the composite aluminum sol provided by the present invention, comprising the following steps:

[0010] Under stirring conditions, the mixed solution is subjected to hydrolysis treatment to obtain a hydrolysis product; the mixed solution includes an aluminum source, a silicon source microcapsule, a cerium source microcapsule, a dispersant and water;

[0011] Obtain the precipitate of the hydrolysis product, and then wash and age it to obtain a composite aluminum sol.

[0012] In some possible implementation manners, the rotation speed of the stirring condition is 10 rpm to 30 rpm.

[0013] In some possible implementation manners, the hydrolysis treatment step includes:

[0014] Adjust and maintain the pH value of the mixed solution at 8.5 to 11.5, and heat the mixed solution to 60°C to 70°C at a heating rate of 10°C / min to 30°C / min and perform a first heat preservation to obtain a first sol;

[0015] Adjust and maintain the pH value of the first sol at 6 to 8, and heat the first sol from 60°C to 70°C to 110°C to 130°C at a heating rate of 8°C / min to 10°C / min and perform a second heat preservation to obtain a second sol;

[0016] Adjust and maintain the pH value of the second sol at 7 to 8, and heat the second sol from 110°C to 130°C to 150°C at a heating rate of 5°C / min to 8°C / min and perform a third heat preservation to obtain a hydrolysis product.

[0017] In some possible implementation manners, preparing the silicon source microcapsule includes the following steps: under the stirring condition with a rotation speed of 30 rpm to 50 rpm, mix the silicon source suspension and the polymethyl methacrylate solution and then perform a first spray drying to obtain the silicon source microcapsule;

[0018] Wherein, the silicon source suspension contains a silicon source and ethanol; the polymethyl methacrylate solution contains polymethyl methacrylate and acetone.

[0019] In some possible implementation manners, the temperature of the first spray drying is 60°C to 80°C.

[0020] In some possible implementation manners, preparing the cerium source microcapsule includes the following steps: under the stirring condition with a rotation speed of 30 rpm to 50 rpm, mix the cerium source suspension and the molten paraffin and then perform a second spray drying to obtain the cerium source microcapsule;

[0021] Wherein, the cerium source suspension contains a cerium source and ethanol.

[0022] In some possible implementation manners, the temperature of the second spray drying is 30°C to 40°C.

[0023] In some possible implementation manners, preparing the mixed solution includes the following steps: mixing an aluminum source, a silicon source microcapsule, a cerium source microcapsule, a dispersant, and water and stirring to obtain the mixed solution.

[0024] In a third aspect, the present invention provides an application of the composite aluminum sol provided by the present invention in the fields of catalysis, ceramics, papermaking, or textiles.

[0025] The composite aluminum sol provided by the present invention and its preparation method have at least the following beneficial technical effects compared with the prior art:

[0026] (1) For the composite aluminum sol provided by the present invention, the composite aluminum sol formed by the composite hydrolysis of an aluminum source, a silicon source, and a cerium source improves the stability of the aluminum sol.

[0027] (2) For the composite aluminum sol provided by the present invention, the particle size is uniform and the property is stable.

[0028] (3) For the preparation method of the composite aluminum sol provided by the present invention, the silicon source and the cerium source are uniformly dispersed in water in the form of microcapsules, and then under the stirring condition, segmented hydrolysis is carried out, so as to achieve the purpose of controlling the hydrolysis rate of the mixed solution, and further prepare a composite aluminum sol with a uniform particle size and stable properties. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present drawings or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following described drawings are only some embodiments of the present drawings. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0030] Figure 1 It is a TEM diagram of a composite aluminum sol provided in Embodiment 1 of the present invention;

[0031] Figure 2 It is a TEM diagram of a composite aluminum sol provided in Embodiment 2 of the present invention;

[0032] Figure 3 It is a TEM diagram of a composite aluminum sol provided in Embodiment 3 of the present invention;

[0033] Figure 4 It is a TEM diagram of a composite aluminum sol provided in Comparative Example 1 of the present invention;

[0034] Figure 5 It is a TEM diagram of a composite aluminum sol provided in Comparative Example 2 of the present invention;

[0035] Figure 6 It is a TEM diagram of a composite aluminum sol provided in Comparative Example 3 of the present invention.

[0036] The realization, functional features and advantages of this attached drawing will be further described with reference to the embodiments and the attached drawings. Specific Embodiments

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be described and explained below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0038] Obviously, the following description is only some examples or embodiments of the present invention. For those of ordinary skill in the art, the present invention can also be applied to other similar scenarios without making creative efforts. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present invention, some designs, manufacturing or production changes based on the technical content disclosed in the present invention are only conventional technical means and should not be understood as the content disclosed in the present invention being insufficient.

[0039] However, there will be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present invention and is not intended to limit the subject matter recited in the claims.

[0040] If there is no special description, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0041] The following is a detailed description of an embodiment of the present invention, a composite aluminum sol and its preparation method.

[0042] The first aspect of the embodiment of the present invention provides a composite aluminum sol, comprising raw materials in the following parts by weight:

[0043] 20 parts to 30 parts of aluminum source, 40 parts to 50 parts of silicon source microcapsules, 20 parts to 30 parts of cerium source microcapsules, 10 parts to 20 parts of dispersant and 600 parts to 850 parts of water;

[0044] The shell material of the cerium source microcapsules is paraffin, and the shell material of the silicon source microcapsules is polymethyl methacrylate.

[0045] The composite aluminosilicate sol provided by the embodiment of the present invention is formed by the composite hydrolysis of an aluminum source, a silicon source, and a cerium source, making the composite aluminosilicate sol have high stability. The silicon source microcapsules and the cerium source microcapsules use shell materials with different melting points. When preparing the composite aluminosilicate sol, the silicon source and the cerium source can be slowly released, so that the silicon source and the cerium source carry out composite hydrolysis reactions at different temperatures and time periods, which can not only effectively control the hydrolysis conditions, but also control the hydrolysis rate, and finally prepare a composite aluminosilicate sol with uniform particle size and stable properties.

[0046] In some embodiments, the melting point of the paraffin wax is 50°C to 60°C.

[0047] In some embodiments, the melting point of polymethyl methacrylate (PMMA) is 100°C to 120°C.

[0048] In some embodiments, the aluminum source includes at least one of aluminum chloride, aluminum nitrate, and aluminum sulfate.

[0049] In some embodiments, the silicon source includes at least one of sodium silicate and potassium silicate.

[0050] In some embodiments, the cerium source includes at least one of cerium chloride, cerium nitrate, and cerium sulfate.

[0051] In some embodiments, the dispersant includes at least one of sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS).

[0052] The second aspect of the embodiment of the present invention provides a preparation method of the composite aluminosilicate sol provided by the embodiment of the present invention, including the following steps:

[0053] S10. Under stirring conditions, the mixed solution is subjected to hydrolysis treatment to obtain a hydrolysis product; the mixed solution includes an aluminum source, silicon source microcapsules, cerium source microcapsules, a dispersant, and water.

[0054] S20. The precipitate of the hydrolysis product is obtained by centrifugal separation, and then washed and aged to obtain the composite aluminosilicate sol.

[0055] The preparation method of the composite aluminosilicate sol provided by the embodiment of the present invention uniformly disperses the silicon source and the cerium source in water in the form of microcapsules, and then under stirring conditions, the reaction system is gradually heated, so that the shell materials of the cerium source microcapsules and the silicon source microcapsules are gradually dissolved to release the cerium source and the silicon source therein and hydrolyze, realizing the gradual hydrolysis of the aluminum source, the silicon source, and the cerium source, thereby effectively controlling the hydrolysis rate, and further preparing a composite aluminosilicate sol with uniform particle size and stable properties.

[0056] In some embodiments, in the above step S10, the stirring speed is 10 rpm to 30 rpm.

[0057] In some embodiments, in the above step S10, preparing the silicon source microcapsules includes the following steps:

[0058] S102. Under the stirring condition of a rotation speed of 30 rpm to 50 rpm, mix the silicon source suspension and the polymethyl methacrylate solution and then perform the first spray drying to obtain the silicon source microcapsules;

[0059] Among them, the silicon source suspension contains a silicon source and ethanol; the polymethyl methacrylate solution contains polymethyl methacrylate and acetone.

[0060] In the above steps of preparing the silicon source microcapsules, the silicon source as the core material is respectively made into a silicon source suspension, the polymethyl methacrylate as the shell material is made into a solution, and then the suspension and the solution are mixed and spray dried, so that the silicon source microcapsules can be prepared at room temperature, and the obtained silicon source microcapsules have uniform particle sizes.

[0061] In some embodiments, in the above step S102, preparing the silicon source suspension includes the following steps:

[0062] S1021. Stir and mix the silicon source and ethanol to obtain the silicon source suspension.

[0063] In some embodiments, in the above step S102, the mass-volume ratio of the silicon source to ethanol is 1 g:(1 ml to 5 ml).

[0064] In some embodiments, in the above step S102, preparing the polymethyl methacrylate solution includes the following steps:

[0065] S1022. Stir and mix the polymethyl methacrylate and acetone to obtain the polymethyl methacrylate solution.

[0066] In some embodiments, in the above step S102, the mass-volume ratio of the polymethyl methacrylate to acetone is 1 g:(10 ml to 20 ml).

[0067] In some embodiments, in the above step S102, the temperature of the first spray drying is 60 °C to 80 °C.

[0068] In some embodiments, in the above step S10, preparing the cerium source microcapsules includes the following steps:

[0069] S103. Under the stirring condition of a rotation speed of 30 rpm to 50 rpm, mix the cerium source suspension and the molten paraffin and then perform the second spray drying to obtain the cerium source microcapsules;

[0070] Among them, the cerium source suspension contains a cerium source and ethanol.

[0071] In some embodiments, in the above step S103, preparing the cerium source suspension includes the following steps:

[0072] S1031. Stir and mix the cerium source and ethanol to obtain a cerium source suspension.

[0073] In some embodiments, in the above step S103, the mass-to-volume ratio of the cerium source to ethanol is 1 g : (1 ml - 5 ml).

[0074] In some embodiments, in the above step S103, the temperature of the second spray drying is 30°C - 40°C.

[0075] In some embodiments, in the above step S10, preparing the mixed solution includes the following steps:

[0076] S104. Mix and stir the aluminum source, silicon source microcapsules, cerium source microcapsules, dispersant and water to obtain a mixed solution.

[0077] In some embodiments, in the above step S10, the hydrolysis treatment step includes:

[0078] S105. Adjust and maintain the pH value of the mixed solution at 8.5 - 11.5, and heat the mixed solution to 60°C - 70°C at a heating rate of 10°C / min - 30°C / min and perform the first heat preservation to obtain a first sol.

[0079] S106. Adjust and maintain the pH value of the first sol at 6 - 8, and heat the first sol from 60°C - 70°C to 110°C - 130°C at a heating rate of 8°C / min - 10°C / min and perform the second heat preservation to obtain a second sol.

[0080] S107. Adjust and maintain the pH value of the second sol at 7 - 8, and heat the second sol from 110°C - 130°C to 150°C at a heating rate of 5°C / min - 8°C / min and perform the third heat preservation to obtain a hydrolysis product.

[0081] In some embodiments, in the above step S105, the first heat preservation time is 0.5 h - 1.5 h.

[0082] In some embodiments, in the above step S106, the second heat preservation time is 2 h - 3 h.

[0083] In some embodiments, in the above step S107, the third heat preservation time is 6 h - 8 h.

[0084] In some embodiments, in the above step S105, the pH value of the mixed solution is adjusted and maintained using a sodium hydroxide solution or a potassium hydroxide solution.

[0085] In some embodiments, in the above step S106, the pH value of the first sol is adjusted and maintained using dilute hydrochloric acid or dilute sulfuric acid.

[0086] In some embodiments, in the above step S107 , dilute hydrochloric acid or sodium hydroxide solution is used to adjust and maintain the pH value of the second sol.

[0087] In some embodiments, in step S20, the rotation speed of the centrifugal separation is 3000 rpm to 5000 rpm. It should be noted that the rotation speed range shown in the embodiment of the present invention is only an example of the present invention, and the rotation speed of the centrifugal separation can be adjusted according to actual needs and is not limited to the range shown in the embodiment of the present invention.

[0088] In some embodiments, in the above step S20, washing includes the following steps:

[0089] S201. Disperse the precipitate in deionized water at a stirring speed of 20 rpm to 30 rpm, heat to 120°C to 130°C, continue stirring for 0.2h to 0.5h, and centrifuge to obtain a washed precipitate and a washing liquid.

[0090] S202. Repeat step S201 three or more times.

[0091] In the above washing step, after repeating step S201 three times, check whether there are free ions remaining. You can take a small amount of washing liquid and add the corresponding compound for detection. For example, the washing liquid may contain Cl - , then use AgNO3 solution for detection. If there is no precipitation, it means that Cl - Washed clean; the washing liquid may contain SO4 2- , then use Ba 2- Perform the test (if BaCl2 is used, Cl must be tested first - , then detect SO4 2- ).

[0092] In some embodiments, in the above step S20, aging includes the following steps:

[0093] S203. Disperse the solid product obtained by washing in deionized water to form a suspension.

[0094] S204. Adjust the pH value of the suspension to 7-7.5.

[0095] S205. Aging for 6 h to 12 h at a stirring speed of 20 rpm to 30 rpm and a temperature of 100° C. to 120° C.

[0096] The following is further described with reference to specific embodiments.

[0097] For the convenience of explanation, in the following examples and comparative examples, unless otherwise specified, the following parameters are adopted:

[0098] (1) Preparation of silicon source microcapsules:

[0099] ① Mix silicon source and ethanol at a mass - volume ratio of 1 g:2 ml by stirring to obtain a silicon source suspension.

[0100] ② Mix polymethyl methacrylate and acetone at a mass - volume ratio of 1 g:15 ml by stirring to obtain a silicon source suspension.

[0101] ③ Under the stirring condition of a rotation speed of 40 rpm, mix the silicon source suspension and the polymethyl methacrylate solution and then perform spray drying to obtain silicon source microcapsules; the temperature of spray drying is 80 °C.

[0102] (2) Preparation of cerium source microcapsules:

[0103] ① Mix cerium source and ethanol at a mass - volume ratio of 1 g:3 ml by stirring to obtain a cerium source suspension.

[0104] ② Under the stirring condition of a rotation speed of 30 rpm, mix the cerium source suspension and molten paraffin and then perform spray drying to obtain cerium source microcapsules; the temperature of spray drying is 40 °C.

[0105] (3) The rotation speed of the centrifugal separation involved is 4000 rpm.

[0106] (4) Adjust the pH value of the relevant reaction systems in the examples and comparative examples using dilute hydrochloric acid or sodium hydroxide solution.

[0107] (5) The washing steps are as follows:

[0108] ① Under the stirring condition of a rotation speed of 30 rpm, disperse the precipitate obtained by centrifugal separation in deionized water, then heat to 120 °C and continue stirring for 0.4 h, and then perform centrifugal separation to obtain a washed precipitate and a washing solution.

[0109] ② Repeat the above step ① more than three times until there are no free anions and cations remaining in the washing solution.

[0110] Example 1

[0111] Example 1 provides a composite aluminum sol, which is composed of the following raw materials in parts by weight:

[0112] 30 parts of aluminum chloride, 50 parts of sodium silicate microcapsules, 20 parts of cerium chloride microcapsules, 20 parts of sodium dodecyl sulfate (SDS) (dispersant) and 700 parts of water.

[0113] Among them, in the silicon source microcapsules, the shell material is polymethyl methacrylate with a melting point of 120 °C;

[0114] In the cerium source microcapsules, the shell material is paraffin with a melting point of 55 °C.

[0115] This embodiment also provides a method for preparing the composite aluminosol provided in this embodiment, and the steps are as follows:

[0116] E1. Under the stirring condition with a rotation speed of 20 rpm, the following hydrolysis treatment is carried out on the mixed solution:

[0117] E101. Adjust and maintain the pH value of the mixed solution at 9, heat the mixed solution to 65 °C at a heating rate of 20 °C / min and keep it warm for 1 h to obtain the first sol.

[0118] E102. Adjust and maintain the pH value of the first sol at 7, heat the first sol from 70 °C to 130 °C at a heating rate of 10 °C / min and keep it warm for 2 h to obtain the second sol.

[0119] E103. Adjust and maintain the pH value of the second sol at 7, heat the second sol from 130 °C to 150 °C at a heating rate of 8 °C / min and keep it warm for 7 h to obtain the hydrolysis product.

[0120] E2. Washing and aging:

[0121] E201. Centrifuge to separate the precipitate of the hydrolysis product and wash it to obtain the solid product.

[0122] E202. Disperse the solid product in deionized water to form a suspension.

[0123] E203. Adjust the pH value of the suspension to 7 - 7.5.

[0124] E204. Age for 12 h at a stirring speed of 30 rpm and a temperature of 100 °C to obtain the composite aluminosol.

[0125] Example 2

[0126] Example 2 provides a composite aluminosol, which is composed of the following raw materials in parts by weight:

[0127] 20 parts of aluminum nitrate, 40 parts of sodium silicate microcapsules, 24 parts of cerium nitrate microcapsules, 10 parts of sodium dodecyl sulfate (SDS) (dispersant) and 600 parts of water.

[0128] Among them, in the silicon source microcapsules, the shell material is polymethyl methacrylate with a melting point of 100 °C;

[0129] In the cerium source microcapsules, the shell material is paraffin with a melting point of 50 °C.

[0130] This embodiment also provides a method for preparing the composite aluminosol provided in this embodiment, and the steps are basically the same as those in Example 1, except that:

[0131] The content of step E1 is as follows:

[0132] E1. Under the stirring condition of 10 rpm, the mixed solution is subjected to the following hydrolysis treatment:

[0133] E101. Adjust and maintain the pH value of the mixed solution at 10, heat the mixed solution to 60 °C at a heating rate of 10 °C / min and keep it warm for 1.5 h to obtain the first sol.

[0134] E102. Adjust and maintain the pH value of the first sol at 8, heat the first sol from 60 °C to 110 °C at a heating rate of 8 °C / min and keep it warm for 3 h to obtain the second sol.

[0135] E103. Adjust and maintain the pH value of the second sol at 7, heat the second sol from 110 °C to 150 °C at a heating rate of 5 °C / min and keep it warm for 8 h to obtain the hydrolysis product.

[0136] Example 3

[0137] Example 3 provides a composite aluminum sol, which is composed of the following raw materials in parts by weight:

[0138] 25 parts of aluminum nitrate, 45 parts of potassium silicate microcapsules, 30 parts of cerium nitrate microcapsules, 15 parts of sodium dodecyl sulfate (SDS) (dispersant) and 850 parts of water.

[0139] Among them, in the potassium silicate microcapsules, the shell material is polymethyl methacrylate with a melting point of 110 °C;

[0140] In the cerium nitrate microcapsules, the shell material is paraffin with a melting point of 60 °C.

[0141] This example also provides a preparation method of the composite aluminum sol provided in this example. The steps are basically the same as those in Example 1, except that:

[0142] The content of step E1 is as follows:

[0143] E1. Under the stirring condition of 30 rpm, the mixed solution is subjected to the following hydrolysis treatment:

[0144] E101. Adjust and maintain the pH value of the mixed solution at 11, heat the mixed solution to 70 °C at a heating rate of 30 °C / min and keep it warm for 0.5 h to obtain the first sol.

[0145] E102. Adjust and maintain the pH value of the first sol at 6, heat the first sol from 70 °C to 120 °C at a heating rate of 10 °C / min and keep it warm for 2.5 h to obtain the second sol.

[0146] E103. Adjust and maintain the pH value of the second sol at 8, heat the second sol from 120 °C to 150 °C at a heating rate of 7 °C / min and keep it warm for 6 h to obtain the hydrolysis product.

[0147] Comparative Example 1

[0148] Comparative Example 1 provides a composite aluminum sol, which is composed of the following raw materials in parts by weight:

[0149] 30 parts of aluminum chloride, 50 parts of sodium silicate, 20 parts of cerium chloride and 700 parts of water.

[0150] This comparative example also provides a preparation method of the composite aluminum sol provided by this comparative example, and the steps are as follows:

[0151] D1-1. Mix aluminum chloride, sodium silicate, cerium chloride and water to obtain a mixed solution.

[0152] D1-2. Under the stirring condition of 20 rpm, adjust and maintain the pH value of the mixed solution at 8, and hydrolyze the mixed solution at a constant temperature of 100 °C until no precipitation occurs to obtain a hydrolysis product.

[0153] D1-3. Centrifuge to separate the precipitate of the hydrolysis product and wash it to obtain a solid product.

[0154] D1-4. Disperse the solid product in deionized water to form a suspension.

[0155] D1-5. Adjust the pH value of the suspension to 7 - 7.5.

[0156] D1-6. Age for 12 h at a stirring speed of 30 rpm and a temperature of 100 °C to obtain a composite aluminum sol.

[0157] Comparative Example 2

[0158] Comparative Example 2 provides a preparation method of the composite aluminum sol provided by Comparative Example 1, and the steps are as follows:

[0159] D2-1. Under the conditions of stirring at 20 rpm and constant temperature of 100 °C, adjust and maintain the pH value of the reaction system at 8. After adding aluminum chloride to water and hydrolyzing, then add cerium chloride for hydrolysis, and finally add aluminum silicate for hydrolysis until no precipitation occurs to obtain a hydrolysis product.

[0160] D2-2. Centrifuge to separate the precipitate of the hydrolysis product and wash it to obtain a solid product.

[0161] D2-3. Disperse the solid product in deionized water to form a suspension.

[0162] D2-4. Adjust the pH value of the suspension to 7 - 7.5.

[0163] D2-5. Age for 12 h at a stirring speed of 30 rpm and a temperature of 100 °C to obtain a composite aluminum sol.

[0164] Comparative Example 3

[0165] Comparative Example 3 provides a preparation method of the composite aluminum sol provided in Example 1. The steps are basically the same as those in Example 1, except that:

[0166] The content of step E1 is as follows:

[0167] E1. Under the stirring condition with a rotation speed of 20 rpm, the mixed solution was heated to 150 °C at a heating rate of 30 °C / min and kept warm for 8 h to obtain a hydrolysis product.

[0168] To verify the progressiveness of the composite aluminum sol and its preparation method in the embodiments of the present invention, a transmission electron microscope was used to observe the composite aluminum sols provided in the examples and comparative examples. The TEM images are as Figures 1 to 6 shown. After the composite aluminum sols provided in the examples and comparative examples were post-treated to obtain molecular sieve catalysts, the microactivity of the molecular sieve catalysts was experimentally detected. The results are shown in Table 1 below.

[0169] Among them, the steps for post-treating the composite aluminum sols provided in the examples and comparative examples are as follows: The composite aluminum sol was dried at 90 °C, then calcined in a helium atmosphere at 600 °C for 6 h, and ground to obtain a molecular sieve catalyst with an average particle size of 60 μm.

[0170] The experimental conditions for the microactivity of the molecular sieve are:

[0171] The reaction temperature is 480 °C, the catalyst-oil ratio is 3.2, the weight hourly space velocity is 16 -1 , the catalyst loading is 5.0 g, the oil feed amount is 1.56 g, the oil feed time is 70 s, and the feedstock oil is Dagang light diesel.

[0172] .

[0173] From the attached Figures 1 to 6 of the specification and the data in Table 1 above, at least the following conclusions can be obtained:

[0174] (1) As can be seen from the attached Figures 1 to 6 of the specification, the particle size of the composite aluminum sol provided in the embodiments of the present invention is uniform and mostly nano-particles, indicating that the silica source microcapsules and cerium source microcapsules in the embodiments of the present invention use shell materials with different melting points. When preparing the composite aluminum sol, the silica source and cerium source can be slowly released, so that the silica source and cerium source can carry out a composite hydrolysis reaction at different temperatures and time periods, which can not only effectively control the hydrolysis conditions, but also control the hydrolysis rate, and finally prepare a composite aluminum sol with uniform particle size and stable properties.

[0175] (2)It can be seen from the comparison of the micro-reactivity of Examples 1 to 3 and Comparative Examples 1 to 3 that the zeolite molecular sieve prepared from the composite aluminum sol of the examples of the present invention has a very high micro-reactivity, which improves the raw material conversion rate and the light product yield, and reduces the unit usage amount of the catalyst, etc.

[0176] It should be noted that the present invention is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same composition and the same effect as the technical idea within the technical solution scope of the present invention are included in the technical scope of the present invention. In addition, within the scope not departing from the gist of the present invention, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways constructed by combining some constituent elements in the embodiments are also included in the scope of the present invention.

Claims

1. A preparation method of a composite aluminum sol, characterized in that, It includes the following steps: Under stirring conditions, subject the mixed solution to hydrolysis treatment to obtain a hydrolysis product; The mixed solution includes an aluminum source, a silicon source microcapsule, a cerium source microcapsule, a dispersant, and water; Obtain the precipitate of the hydrolysis product, and then wash and age it to obtain a composite aluminum sol; The hydrolysis treatment step includes: Adjust and maintain the pH value of the mixed solution at 8.5 - 11.5, heat the mixed solution to 60°C - 70°C at a heating rate of 10°C / min - 30°C / min and perform the first heat preservation to obtain a first sol; Adjust and maintain the pH value of the first sol at 6 - 8, heat the first sol from 60°C - 70°C to 110°C - 130°C at a heating rate of 8°C / min - 10°C / min and perform the second heat preservation to obtain a second sol; Adjust and maintain the pH value of the second sol at 7 - 8, heat the second sol from 110°C - 130°C to 150°C at a heating rate of 5°C / min - 8°C / min and perform the third heat preservation to obtain a hydrolysis product; The composite aluminum sol includes the following raw materials in parts by weight: 20 - 30 parts of aluminum source, 40 - 50 parts of silicon source microcapsule, 20 - 30 parts of cerium source microcapsule, 10 - 20 parts of dispersant, and 600 - 850 parts of water; The shell material of the cerium source microcapsule is paraffin, and the shell material of the silicon source microcapsule is polymethyl methacrylate.

2. The preparation method of the composite aluminum sol according to claim 1, characterized in that, The rotation speed of the stirring conditions is 10 rpm - 30 rpm.

3. The preparation method of the composite aluminum sol according to claim 1, wherein Preparing the silicon source microcapsule includes the following steps: Under stirring conditions with a rotation speed of 30 rpm - 50 rpm, mix the silicon source suspension and the polymethyl methacrylate solution and then perform the first spray drying to obtain the silicon source microcapsule; wherein, the silicon source suspension contains a silicon source and ethanol; the polymethyl methacrylate solution contains polymethyl methacrylate and acetone.

4. The preparation method of the composite aluminum sol according to claim 3, characterized in that, The temperature of the first spray drying is 60°C - 80°C.

5. The preparation method of the composite aluminum sol according to claim 1, wherein Preparing the cerium source microcapsule includes the following steps: Under stirring conditions with a rotation speed of 30 rpm - 50 rpm, mix the cerium source suspension and molten paraffin and then perform the second spray drying to obtain the cerium source microcapsule; wherein, the cerium source suspension contains a cerium source and ethanol.

6. The preparation method of the composite aluminum sol according to claim 5, characterized in that, The temperature of the second spray drying is 30°C - 40°C.

7. The preparation method of the composite aluminum sol according to claim 1, wherein Preparing the mixed solution includes the following steps: Mix and stir the aluminum source, the silicon source microcapsule, the cerium source microcapsule, the dispersant, and water to obtain a mixed solution.

8. A composite aluminum sol prepared by the preparation method according to any one of claims 1 - 7.

9. An application of the composite aluminum sol according to claim 8 in the fields of catalysis, ceramics, papermaking, or textiles.

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