A method for continuously preparing high-purity organic aluminum alkoxide

Abstract

This invention belongs to the field of catalyst support material preparation technology, specifically relating to a continuous method for preparing high-purity organic aluminum alkoxides. The method includes: adding a molecular sieve to an organic alcohol, allowing it to stand to obtain a dehydrated organic alcohol; subsequently adding a portion of the dehydrated organic alcohol to an aluminum source, followed by the continuous addition of the remaining dehydrated organic alcohol to the aluminum source; after reaction, aluminum alkoxides are obtained; the obtained aluminum alkoxides are then filtered sequentially using a titanium rod and a ceramic membrane to obtain high-purity organic aluminum alkoxides. This invention employs a self-catalytic process, requiring no external catalyst, and can be carried out under normal pressure. Combined with molecular sieve dehydration and staged filtration, it can obtain high-purity, high-yield organic aluminum alkoxides. Furthermore, this method enables continuous industrial production, solving the problems of impurity introduction, harsh reaction conditions, low production efficiency, difficult filtration, and high cost in the preparation of organic aluminum alkoxides in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of catalyst support material preparation technology, specifically relating to a method for the continuous preparation of high-purity organic aluminum alkoxides. Background Technology

[0002] Existing aluminum alkoxide preparation processes typically use organic alcohols and metallic aluminum in the form of aluminum beans, rods, or ingots as raw materials, reacting them with catalysts such as mercury, mercuric chloride, anhydrous aluminum chloride, and iodine to produce aluminum alkoxides. If a fixed bed is not used, this process easily yields black, crude organic aluminum alkoxides. In addition, the raw material metallic aluminum itself contains impurities such as iron and silicon, making subsequent filtration of the material difficult. Therefore, the crude aluminum alkoxides need to be purified and refined through methods such as vacuum distillation, filtration, and magnetic separation-assisted filtration.

[0003] The hydrolysis process of organic aluminum alkoxides has problems such as harsh reaction conditions, excessively fast reaction rate, and the need to use HgCl2 heavy metal catalyst. In addition, the above-mentioned hydrolysis process requires the addition of catalyst to initiate the reaction, but the addition of catalyst will introduce additional impurities, and the introduced impurities are difficult to completely remove, affecting the purity of the product.

[0004] The production of organic aluminum alkoxides is mostly carried out in atmospheric pressure reactors and is often an intermittent process, resulting in low production efficiency and a longer production cycle.

[0005] CN119735487A provides a method for preparing high-purity aluminum alkoxy. The method involves circulating organic alcohol vapors, where metallic aluminum and alcohol react directly in a first reaction apparatus to prepare aluminum alkoxy, thus addressing safety concerns related to the use of mercury salt catalysts and excessively fast reaction rates. Then, in a second reaction apparatus, micron-sized unreacted aluminum particles are treated with an alumina catalyst supported on glycine, thereby improving reaction conversion and product purity. This technology is a batch reaction.

[0006] CN115872838A discloses a continuous method for preparing high-purity aluminum isopropoxide. The method includes: loading elemental metal into a fixed-bed reactor; rinsing the reactor bed with an isopropanol solution containing an initiator; continuously injecting isopropanol into the fixed-bed reactor under pressure and heating to carry out the reaction; collecting the reaction product; and drying after vacuum distillation to obtain high-purity aluminum isopropoxide. This method, through continuous preparation of high-purity aluminum isopropoxide, effectively improves upon the low production efficiency of batch reaction processes. However, this process requires reaction in a fixed-bed reactor under high pressure, resulting in high production costs and significant safety risks.

[0007] CN120887780A provides a method for producing stable liquid aluminum isopropoxide. The method includes: reacting an aluminum source with its surface oxide film removed and deeply dehydrated isopropanol in an inert gas atmosphere at 60-80°C with 0.1-0.5% anhydrous aluminum trichloride catalyst for 3-5 hours to obtain initial liquid aluminum isopropoxide; then adding a composite solvent in a certain proportion; and filtering the mixture through a 0.1 μm precision filter to obtain stable liquid aluminum isopropoxide, achieving a shelf life of 6-12 months. However, this method requires not only the addition of a catalyst but also maintenance under a nitrogen atmosphere, resulting in high production costs.

[0008] Some researchers have proposed using aluminum chloride as a catalyst to activate the metal before the reaction, removing the oxide film on the aluminum surface and accelerating the reaction rate between aluminum and organic alcohols. This process avoids the use of heavy metal catalysts, but it suffers from problems such as excessively fast reaction rates and ineffective control of the reaction process, posing serious safety hazards in industrial-scale production. Furthermore, the raw material, aluminum, contains impurities such as silicon and iron, which traditional catalytic reactions easily generate nanoscale black colloidal impurities. These ultrafine impurities can easily penetrate the filter layer and clog the filter cake.

[0009] Therefore, there is an urgent need for a process that can produce organic aluminum alkoxides without introducing additional impurities, can be carried out under normal pressure, has high product purity, high production efficiency, low production cost, high safety, and can be continuously produced. Summary of the Invention

[0010] Based on the above technical background, the main objective of this invention is to provide a method for the continuous preparation of high-purity organic aluminum alkoxides, so as to overcome the shortcomings of the prior art.

[0011] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0012] This invention provides a method for the continuous preparation of high-purity organic aluminum alkoxides, the method comprising the following steps: Step 1: Add molecular sieves to organic alcohol, let stand, and obtain organic alcohol with water removed; Step 2: Add the organic alcohol obtained in step 1 to the aluminum source in portions. After the reaction, aluminum alkoxide is obtained. Step 3: Filter the aluminum alkoxide obtained in Step 2 using a titanium rod, followed by filtration using a ceramic membrane to obtain high-purity organic aluminum alkoxide.

[0013] The steps described above are described in detail below.

[0014] In step 1, the molecular sieve is selected from one or more of grade 3A, grade 4A, or grade 5A molecular sieves.

[0015] Preferably, the molecular sieve is a 3A grade molecular sieve.

[0016] 3A-grade molecular sieves are alkali metal aluminosilicate crystals with a pore size of 3 Å (1 Å = 0.1 nanometers), belonging to type A molecular sieves (corresponding to potassium-type A molecular sieves, KA). Their characteristic is that they only allow small molecules with a diameter ≤ 3 Å (such as water molecules, approximately 2.8 Å in diameter) to pass through, while repelling larger molecules (such as organic molecules like ethanol and methanol, whose diameters are > 3 Å). Therefore, the molecular sieve added in this invention is mainly used for the selective adsorption of moisture in gases or liquids, while avoiding the adsorption of target products.

[0017] 4A-grade molecular sieves, also known as sodium A-type molecular sieves, have a pore size of 4 Å and the chemical formula Na₂O·Al₂O₃·2SiO₂·4.5H₂O, with a silicon-to-aluminum ratio (SiO₂ / Al₂O₃) of approximately 2. They can adsorb water, methanol, ethanol, hydrogen sulfide, sulfur dioxide, carbon dioxide, chloromethane, bromomethane, ethane, acetylene, ethylene, propylene, ammonia, etc., but do not adsorb any molecules with a diameter greater than 4 Å (including propane). Their selective adsorption performance for water is higher than any other molecular sieve.

[0018] The molecular formula of 5A molecular sieve is 3 / 4CaO·1 / 4Na2O·Al2O3·2SiO2·9 / 2H2O. Its silicon-to-aluminum ratio is approximately 2, i.e., SiO2 / Al2O3≈2, and its effective pore size is approximately 5 Å. 5A molecular sieve is a calcium-type molecular sieve, capable of adsorbing any molecules smaller than its pore size, hence the name calcium molecular sieve. In addition to possessing the functions of 3A and 4A molecular sieves, 5A molecular sieve can also adsorb substances such as C3-C4 n-alkanes, chloroethane, bromoethane, and butanol.

[0019] The organic alcohol is selected from one or more of ethanol, isopropanol, sec-butanol, n-butanol, and isobutanol. The organic alcohol is an industrial-grade organic alcohol. In this invention, the organic alcohol is used as a reaction raw material to generate high-purity organoalcohol aluminum. Pretreatment of the organic alcohol to remove water can improve the purity and yield of the product after the reaction.

[0020] Preferably, the organic alcohol is n-butanol. Experiments have shown that n-butanol provides a suitable dehydration rate for pretreatment, and the reaction can proceed at a temperature of 120°C. Isopropanol has a slow dehydration rate, requiring the addition of a catalyst and increasing the need for subsequent impurity removal steps. sec-butanol has an excessively fast dehydration rate, resulting in low safety, while isobutanol has a slow dehydration rate and low reaction efficiency. In summary, using n-butanol as a raw material allows the generated aluminum n-butoxide to act as a catalyst for subsequent reactions, eliminating the need for additional catalysts and avoiding subsequent impurity removal steps. Furthermore, n-butanol offers a moderate dehydration rate, combining high reaction efficiency with production safety.

[0021] The amount of molecular sieve added is calculated as 20-30% of the mass of statically adsorbed water.

[0022] Preferably, the amount of molecular sieve added is calculated as 25% of the mass of statically adsorbed water.

[0023] The calculation method for the amount of molecular sieve added is as follows: first determine the water content of the organic alcohol. The water absorption capacity of the molecular sieve is 100 parts. The molecular sieve can adsorb 20 to 30 parts of water. Under the above conditions, the amount of molecular sieve added needs to be able to absorb 20 to 30% of the water content in the organic alcohol.

[0024] Add the molecular sieve to the organic alcohol and let it stand for 10 to 15 hours at a temperature of 20 to 27°C.

[0025] Preferably, the molecular sieve is added to the organic alcohol and left to stand for 12 hours at 25°C.

[0026] In step 2, the reaction is carried out in an atmospheric pressure reactor. The specific steps for adding the organic alcohol obtained in step 1 to the aluminum source in stages are as follows: First, a portion of the dehydrated organic alcohol is added to the aluminum source. The volume of the partially dehydrated organic alcohol added is 1 / 3 to 2 / 3 of the volume of the atmospheric pressure reactor. After the reaction is complete, the remaining dehydrated organic alcohol obtained in step 1 is continuously added to the aluminum source in the second stage.

[0027] Preferably, the volume of the partially dehydrated organic alcohol added is 1 / 2 of the volume of the atmospheric pressure reactor.

[0028] This invention utilizes a method of adding organic alcohol in stages. First, a certain amount of organic alcohol is added to the aluminum source. The organic alcohol aluminum (especially n-butoxide aluminum) generated by the reaction between the aluminum source and the organic alcohol can act as a catalyst to autocatalyze the subsequent addition of organic alcohol and aluminum source, which can significantly accelerate the subsequent autocatalytic reaction rate. After the reaction rate is improved, a continuous feeding method is adopted for the second stage, which can effectively improve production efficiency and product yield.

[0029] The molar ratio of the total amount of aluminum source and organic alcohol obtained in step 1 is 1:(3-4).

[0030] Preferably, the molar ratio of the total amount of aluminum source and organic alcohol obtained in step 1 is 1:3.5.

[0031] An aluminum source is added to an atmospheric pressure reactor in one go. Then, a portion of the dehydrated organic alcohol is added to the aluminum source. After reacting at atmospheric pressure and 120–130°C for 1–2 hours, the remaining dehydrated organic alcohol is added to the aluminum source a second time. An autocatalytic reaction is then carried out at atmospheric pressure and 120–130°C.

[0032] Preferably, the aluminum source is added into the atmospheric pressure reactor in one go, and then a portion of the dehydrated organic alcohol is added to the aluminum source. The reaction is carried out at atmospheric pressure and 120°C for 1.5 h. The remaining dehydrated organic alcohol is added to the aluminum source a second time, and the autocatalytic reaction is carried out at atmospheric pressure and 120°C.

[0033] The remaining organic alcohol used for dehydration removal is continuously added to the aluminum source at a flow rate of 0.6–1.2 m³ / s. 3 / h. The addition rate of organic alcohols needs to be determined based on temperature changes.

[0034] Preferably, the flow rate of the remaining dehydrated organic alcohol continuously added to the aluminum source is 0.9 m³. 3 / h.

[0035] The purity of the aluminum source is ≥99%, and the aluminum source is selected from one or more of aluminum briquettes, aluminum rods, or aluminum ingots.

[0036] The aluminum alkoxide generated in this step can act as a catalyst to autocatalyze the reaction between organic alcohols and aluminum sources, eliminating the need for additional catalysts and avoiding the introduction of other impurities into the reaction system.

[0037] In step 3, the titanium rod used in this invention, specifically referring to the titanium rod filter element, is a porous filter element made from industrial high-purity titanium powder as raw material through processes such as powder classification, cold isostatic pressing, and high-temperature high-vacuum sintering. It is the core component of the filtration equipment.

[0038] Titanium rod precision refers to the filtration precision of titanium rod filter elements, that is, the smallest impurity particle size that titanium rods can effectively trap, measured in micrometers (μm).

[0039] The titanium rod has a precision of 0.22–10 μm.

[0040] Preferably, the titanium rod has a precision of 0.5 to 5 μm, for example, the titanium rod has a precision of 1 μm.

[0041] The ceramic film has a precision of 0.5–2 nm.

[0042] Preferably, the ceramic film has a precision of 1 nm.

[0043] The precision of a ceramic membrane refers to the filtration precision of the ceramic membrane filter element, that is, the size of the smallest impurity particle that the ceramic membrane can effectively trap, measured in nanometers (nm). In this invention, the precision of the ceramic membrane is at the nanometer level, forming a graded filtration system with the micrometer-level precision of the titanium rod.

[0044] The high-purity organic aluminum alkoxide obtained by this invention has a purity ≥ 93.71%.

[0045] This invention employs an autocatalytic process in an atmospheric pressure reactor to achieve a continuous reaction between organic alcohols and metallic aluminum. No external catalyst is required; the autocatalysis is achieved solely through the generated organic aluminum alcohol. Combined with secondary staged filtration using titanium rods and ceramic membranes, high-purity organic aluminum alcohol products can be obtained. Experimental verification shows that the method produces aluminum n-butoxide with a purity ≥93.71% and a stable yield of 99% or higher. This method can be operated continuously. The method of this invention overcomes the shortcomings of existing methods, such as difficult filtration and impurity removal. It achieves high-purity, high-yield preparation without additional purification or high-pressure modifications, reducing equipment and overall production costs, and shortening the reaction induction period, thus breaking through the bottleneck of the incompatibility between reaction rate and purity.

[0046] The beneficial effects of this invention are as follows: (1) The method of the present invention first uses molecular sieves to remove water from the organic alcohol, then adds a portion of the dehydrated organic alcohol to the aluminum source for reaction, and then continuously adds the remaining dehydrated organic alcohol to the aluminum source for reaction. Finally, a two-stage filtration process using titanium rods and ceramic membranes is used to obtain high-purity, high-yield organic aluminum alcohol. This method does not require the addition of an additional catalyst during the preparation process. It relies on the organic aluminum alcohol generated by the reaction to achieve self-catalysis, effectively avoiding the introduction of additional impurities, eliminating the post-processing steps caused by the addition of an additional catalyst, significantly shortening the reaction process, improving reaction efficiency, and increasing product purity. It solves the shortcomings of the prior art, such as the need to introduce an additional catalyst, difficulty in removing impurities, low production efficiency, and low product purity.

[0047] (2) The present invention adopts an autocatalytic process in an atmospheric pressure reactor, which does not require any external catalyst. It relies solely on the organic aluminum alcohol generated during the reaction to achieve autocatalysis, thus eliminating the impurity pollution caused by the catalyst from the source. At the same time, in step 1, molecular sieves are used to pretreat the organic alcohol to remove water. The selected molecular sieve (preferably 3A grade molecular sieve) can selectively adsorb water without adsorbing organic alcohol, further reducing the impact of water on the purity of the reaction. Combined with the graded filtration of titanium rods and ceramic membranes (micron-level filtration of titanium rods + nano-level filtration of ceramic membranes), impurities such as iron and silicon in the raw material aluminum source and ultrafine colloidal impurities that may be generated during the reaction can be effectively intercepted, so that the purity of the final organic aluminum alcohol is ≥93.71%, which solves the problems of high pressure reaction, low safety, difficulty in removing impurities, and difficulty in filtration in the existing organic aluminum alcohol preparation process.

[0048] (3) The entire reaction process of this invention is carried out in an atmospheric pressure reactor, eliminating the need for high-pressure equipment modification and avoiding the safety hazards and equipment investment costs associated with high-pressure reactions. The reaction of this invention does not require inert gas protection, nor does it require additional activation treatment of the aluminum source; the reaction conditions are mild, simplifying the process steps and reducing operational difficulty and production costs. Simultaneously, the autocatalytic reaction can effectively control the reaction rate, avoiding the industrial scale-up safety risks caused by excessively fast reaction rates in traditional catalytic processes, thus improving the industrial applicability of the process. Furthermore, this invention uses n-butanol as a reactant, resulting in a low reaction temperature and significantly reducing reaction energy consumption.

[0049] (4) This invention breaks through the limitation of most existing processes being intermittent production. By first adding a portion of dehydrated organic alcohol and then continuously adding the remaining dehydrated organic alcohol, the continuous reaction between organic alcohol and aluminum source is achieved. Combined with the subsequent continuous graded filtration process, large-scale continuous production can be achieved, shortening the production cycle, improving production efficiency and product yield. The product yield is stable at over 98%, solving the problems of low production efficiency and unstable product yield caused by intermittent production.

[0050] (5) The process method described in this invention only includes three core steps: dehydration of organic alcohol, continuous reaction, and staged filtration. It does not require complex reaction devices and precision control equipment. The filtration process can achieve high-efficiency filtration by using titanium rods in combination with ceramic membranes. It does not require additional purification steps such as vacuum distillation and magnetic separation. It is easy to operate and can be easily realized for large-scale industrial production.

[0051] (6) This invention does not use heavy metal catalysts, produces no harmful pollutants, and has no additional waste emissions during the reaction process; the molecular sieve can be repeatedly recycled and reused, and the organic alcohol can be recycled to participate in the reaction, which reduces raw material loss and environmental pressure, and is in line with the development trend of green chemical industry. Attached Figure Description

[0052] Figure 1 A schematic flowchart of the process for preparing organic aluminum alkoxides according to the present invention is shown. Detailed Implementation

[0053] The present invention will now be described in detail, and its features and advantages will become clearer and more apparent from these descriptions.

[0054] Example The present invention is further illustrated below with specific examples. These embodiments are merely illustrative and not intended to limit the scope of the invention. All raw materials used in the embodiments of the present invention are commercially available.

[0055] Example 1 A continuous method for preparing high-purity organic aluminum alkoxides, such as Figure 1 As shown, the method includes the following steps: Step 1: Add 3A grade molecular sieve to n-butanol and let it stand at 25°C for 12 h to remove water from the organic alcohol, thus obtaining n-butanol with water removed.

[0056] Step 2: Add the aluminum source (aluminum briquettes with a purity ≥ 99%) to the atmospheric pressure reactor all at once. Add the n-butanol obtained in Step 1 to the aluminum source in portions. For the first addition, add a portion of the n-butanol from Step 1 (after removing moisture) to the aluminum source, initially adding 1 / 2 of the volume of the atmospheric pressure reactor. React at atmospheric pressure and 120℃ for 1.5 h. Then, continuously add the remaining n-butanol (after removing moisture) to the aluminum source in a second step. The flow rate of the remaining n-butanol added to the aluminum source is 0.9 m³ / h. 3 / h, aluminum source and n-butanol undergo autocatalytic reaction at atmospheric pressure and 120℃ until all remaining n-butanol is added. After the reaction, aluminum n-butoxide is obtained. The molar ratio of the total amount of aluminum source and organic alcohol obtained in step 1 is 1:3.5. An excess of organic alcohol can ensure the full progress of the reaction.

[0057] Step 3: First, filter the aluminum n-butoxide using a titanium rod with a precision of 1 μm, and then filter it using a ceramic membrane with a precision of 1 nm. After two stages of filtration, high-purity aluminum n-butoxide is obtained.

[0058] The purity, conversion rate, and yield of the aluminum n-butoxide product obtained by this method are shown in Table 1.

[0059] Example 2 A continuous method for preparing high-purity organic aluminum alkoxides, such as Figure 1 As shown, the method includes the following steps: Step 1: Add 3A grade molecular sieve to n-butanol and let it stand at 20°C for 15 h to remove water from the organic alcohol, thus obtaining n-butanol with water removed.

[0060] Step 2: Add the aluminum source (aluminum brittle with a purity ≥ 99%) to the atmospheric pressure reactor all at once. Add the n-butanol obtained in Step 1 to the aluminum source in portions. For the first addition, add a portion of the n-butanol from Step 1 (after removing moisture) to the aluminum source, initially adding 1 / 3 of the volume of the atmospheric pressure reactor. React at atmospheric pressure and 125°C for 1 hour. Then, continuously add the remaining n-butanol (after removing moisture) to the aluminum source in a second step. The flow rate of the remaining n-butanol added to the aluminum source is 0.6 m³ / h. 3 / h, aluminum source and n-butanol undergo autocatalytic reaction at atmospheric pressure and 125℃ until all remaining n-butanol is added. After the reaction, aluminum n-butoxide is obtained. The molar ratio of the total amount of aluminum source and organic alcohol obtained in step 1 is 1:3.5. An excess of organic alcohol can ensure the full progress of the reaction.

[0061] Step 3: First, filter the aluminum n-butoxide using a titanium rod with a precision of 0.22 μm, and then filter it using a ceramic membrane with a precision of 0.5 nm. After two stages of filtration, high-purity aluminum n-butoxide is obtained.

[0062] The purity, conversion rate, and yield of the aluminum n-butoxide product obtained by this method are shown in Table 1.

[0063] Example 3 A continuous method for preparing high-purity organic aluminum alkoxides, such as Figure 1 As shown, the method includes the following steps: Step 1: Add 3A grade molecular sieve to n-butanol and let it stand at 27°C for 10 h to remove water from the organic alcohol, thus obtaining n-butanol with water removed.

[0064] Step 2: Add the aluminum source (aluminum brittle with a purity ≥ 99%) to the atmospheric pressure reactor all at once. Add the n-butanol obtained in Step 1 to the aluminum source in portions. For the first addition, add a portion of the n-butanol from Step 1 (after removing moisture) to the aluminum source, initially adding 2 / 3 of the volume of the atmospheric pressure reactor. React at atmospheric pressure and 130℃ for 2 hours. Then, continuously add the remaining n-butanol (after removing moisture) to the aluminum source in a second step. The flow rate of the remaining n-butanol added to the aluminum source is 1.2 m³ / h. 3 / h, aluminum source and n-butanol undergo autocatalytic reaction at atmospheric pressure and 130℃ until all remaining n-butanol is added. After the reaction, aluminum n-butoxide is obtained. The molar ratio of the total amount of aluminum source and organic alcohol obtained in step 1 is 1:3.5. An excess of organic alcohol can ensure the full progress of the reaction.

[0065] Step 3: First, filter the aluminum n-butoxide using a titanium rod with a precision of 10 μm, and then filter it using a ceramic membrane with a precision of 2 nm. After two stages of filtration, high-purity aluminum n-butoxide is obtained.

[0066] The purity, conversion rate, and yield of the aluminum n-butoxide product obtained by this method are shown in Table 1.

[0067] Example 4 Aluminum n-butoxide was prepared in a manner similar to that in Example 1, except that the 3A grade molecular sieve was replaced with a 4A grade molecular sieve. In step 1, the 4A grade molecular sieve was added to n-butanol and allowed to stand at 27°C for 10 h to remove water from the organic alcohol, thus obtaining n-butanol with water removed.

[0068] Example 5 Aluminum n-butoxide was prepared in a manner similar to that in Example 1, except that the 3A grade molecular sieve was replaced with a 5A grade molecular sieve. In step 1, the 5A grade molecular sieve was added to n-butanol and allowed to stand at 27°C for 10 h to remove water from the organic alcohol, thus obtaining n-butanol with water removed.

[0069] Example 6 Aluminum alkoxide was prepared in a manner similar to that in Example 1, except that n-butanol was replaced with isobutanol to obtain aluminum isobutanol.

[0070] Comparative Example Comparative Example 1 Aluminum n-butoxide was prepared in a manner similar to that in Example 1, except that step 1 was omitted, the water in the n-butanol was not removed, and the n-butanol was directly subjected to steps 2 and 3 in sequence.

[0071] Comparative Example 2 Aluminum n-butoxide was prepared in a manner similar to that in Example 1, except that in step 1, grade 3A molecular sieve was added to n-butanol and allowed to stand at 25°C for 8 hours to remove water from the organic alcohol, thus obtaining dehydrated n-butanol.

[0072] Comparative Example 3 Aluminum n-butoxide was prepared in a manner similar to that in Example 1, except that in step 2, the aluminum source (aluminum brittle with a purity ≥ 99%) and dehydrated n-butanol were simultaneously and continuously added to the atmospheric pressure reactor at a flow rate of 1.7 m³ / s. 3 The aluminum source is continuously added to the atmospheric pressure reactor at a flow rate of 1.8 m³ / h. 3 / h, aluminum source and n-butanol undergo an autocatalytic reaction in an atmospheric pressure reactor. The autocatalytic reaction continues at atmospheric pressure and 120℃ until all aluminum source and n-butanol are added. After the reaction, aluminum n-butoxide is obtained.

[0073] Comparative Example 4 The preparation of aluminum n-butoxide was carried out in a manner similar to that in Example 1, except that in step 3, aluminum n-butoxide was filtered using a ceramic membrane with a precision of 2 nm, and high-purity aluminum n-butoxide was obtained after filtration.

[0074] Experimental Example Results of Yield, Purity and Conversion Tests in Example 1 The yield and purity of the above embodiments were tested, and the specific testing process is as follows: Yield = Output / Input; The specific test procedure for purity is as follows: Weigh about 10g (G2) of the sample, accurate to 0.0001g, place it in a 500mL beaker, add 300mL of water, and steam it in a water bath until there is no alcohol odor (about 2h). Then add 100mL of water, filter it with quantitative filter paper, and wash it with hot water until neutral. Place the residue in a porcelain crucible of known weight, dry it, and ignite it at 950℃±5℃ for 2.5h. Weigh it (G1).

[0075] Result calculation: The percentage of aluminum content (X) in aluminum n-butoxide is calculated using the following formula (1).

[0076] Equation (1); In formula (1): G1 - Weight of the precipitate after ignition, in grams (g). G2 - The weight of the sample, in grams (g). M Al - Molar mass of aluminum, in grams per mole (g / mol), (M=26.982) M-molar mass of alumina, in grams per mole (g / mol), (M=101.961). The content of aluminum n-butoxide in the sample = X M 正丁醇铝 / M Al Equation (2); In formula (2): M 正丁醇铝 - Molar mass of aluminum n-butoxide, in grams per mole (g / mol) (M=246.32).

[0077] Note: After submitting the aluminum n-butoxide sample, it should be weighed promptly to avoid inaccurate sample weight due to the volatilization of n-butanol.

[0078] The yield, purity, and conversion rate of the aluminum alkoxides obtained in Examples 1-6 and Comparative Examples 1-4 were tested respectively, and the test results are shown in Table 1.

[0079] Table 1

[0080] As can be seen from Table 1, the purity of the aluminum alkoxides obtained in Examples 1 to 6 is all higher than 93.5%, and the yield is all higher than 98%. The above results show that the aluminum alkoxides obtained by the preparation method described in this invention have the beneficial effects of high purity and high yield.

[0081] Compared to Example 1, Comparative Example 1 did not remove water from n-butanol. The results showed that the purity of the aluminum alkoxide prepared in Comparative Example 1 was lower than that in Example 1. These results indicate that removing water from n-butanol helps to improve the purity of aluminum alkoxide.

[0082] Compared with Example 1, Comparative Example 2 changed the standing time during the removal of water from n-butanol. The results showed that the purity of aluminum alkoxide obtained by Comparative Example 2 was lower than that of Example 1. The above results indicate that the standing time of n-butanol in the molecular sieve affects the removal of water from n-butanol by the molecular sieve, thereby affecting the purity of the obtained product. Only when the standing time is sufficient to remove water from n-butanol can the purity of the product be improved.

[0083] Compared to Example 1, Comparative Example 3 involved the simultaneous and continuous addition of n-butanol and an aluminum source. The results showed that the purity of the aluminum alkoxide product obtained in Comparative Example 3 was significantly lower than that in Example 1. These results indicate that the method of adding the organic alcohol and aluminum source has a significant impact on the purity of the final aluminum alkoxide product. Adding the aluminum source in one step and the organic alcohol in two separate steps, with the second addition being continuous, is more conducive to improving the purity of the aluminum alkoxide product.

[0084] Compared to Example 1, Comparative Example 4 only used a ceramic membrane for filtration, and the purity of the product in Comparative Example 4 was lower than that in Example 1. These results indicate that a two-stage filtration method, first using a titanium rod and then a ceramic membrane, is beneficial for improving the purity of the aluminum alkoxide product.

[0085] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A method for continuously producing high purity organoaluminum alkoxide, characterized by, The method includes the following steps: Step 1: Add molecular sieves to organic alcohol, let stand, and obtain organic alcohol with water removed; Step 2: Add the organic alcohol obtained in step 1 to the aluminum source in portions. After the reaction, aluminum alkoxide is obtained. Step 3: Filter the aluminum alkoxide obtained in Step 2 using a titanium rod, followed by filtration using a ceramic membrane to obtain high-purity organic aluminum alkoxide.

2. The method of claim 1, wherein, In step 1, The molecular sieve is selected from one or more of the following: grade 3A molecular sieve, grade 4A molecular sieve, or grade 5A molecular sieve.

3. The method of claim 1, wherein, In step 1, The organic alcohol is selected from one or more of ethanol, isopropanol, sec-butanol, n-butanol and isobutanol.

4. The method of claim 1, wherein, In step 1, Add the molecular sieve to the organic alcohol and let it stand for 10 to 15 hours at a temperature of 20 to 27°C.

5. The method of claim 1, wherein, In step 2, The reaction is carried out in an atmospheric pressure reactor. The volume of the organic alcohol added in the first step is 1 / 3 to 2 / 3 of the volume of the atmospheric pressure reactor. The remaining organic alcohol after removing moisture is continuously added to the aluminum source in the second step. The molar ratio of the total amount of aluminum source and organic alcohol obtained in step 1 is 1:(3-4).

6. The method of claim 5, wherein, In step 2, The first step involves adding a portion of the dehydrated organic alcohol to the aluminum source and reacting it at atmospheric pressure and 120–130°C for 1–2 hours. Then, the remaining dehydrated organic alcohol is continuously added to the aluminum source for a second step, and the autocatalytic reaction is carried out at atmospheric pressure and 120–130°C.

7. The method of claim 6, wherein, In step 2, The remaining organic alcohol used for dehydration removal is continuously added to the aluminum source at a flow rate of 0.6–1.2 m³ / s. 3 / h.

8. The method of claim 1, wherein, In step 3, The titanium rod has a precision of 0.22–10 μm.

9. The method of claim 1, wherein, In step 3, The ceramic film has a precision of 0.5–2 nm.

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