Method for preparing sheet-like phase pseudo-boehmite using coe-tyler vortex reaction

Abstract

The present invention relates to a method for preparing a plate-like pseudo-boehmite using a Couette-Taylor vortex flow. According to one embodiment, a method for preparing a plate-like pseudo-boehmite can be provided, in which a plate-like pseudo-boehmite is obtained by including the following processes: a) adding an organic acid to an aqueous solution in which an aluminum precursor is dispersed; and b) adding the product of the process a) to a Taylor reactor, wherein the pressure of the Taylor reactor is 1 to 100 bar. According to one embodiment of the present invention, the Taylor reactor using a Couette-Taylor flow has a more excellent stirring capacity compared to a conventional batch reactor, and the production efficiency of a plate-like pseudo-boehmite can be improved by controlling the Taylor reactor to a specific condition of high temperature-high pressure.

Description

Technical Field

[0001] This invention relates to a method for preparing lamellar boehmite using a Couette-Taylor eddy current reaction. Specifically, this invention relates to a method for preparing lamellar boehmite using a Couette-Taylor flow under high temperature and high pressure, wherein the lamellar boehmite is used to coat ceramics on one or both sides of a battery separator. Background Technology

[0002] A separator is a tiny thin film used in batteries for electric vehicles, mobile phones, laptops, etc., that prevents electrical contact between electrodes by blocking the contact between the positive and negative electrodes, thereby improving stability. Battery separators have pores of tens of nanometers in size, and ions pass through these pores to perform the battery's function.

[0003] Commonly used polyolefin-based separators exhibit severe thermal shrinkage at high temperatures and poor physical durability. Therefore, if a battery malfunctions, causing an increase in internal temperature, the separator is prone to deformation, and in severe cases, it may fail to adequately prevent contact between electrodes, potentially leading to a short circuit and subsequent explosion.

[0004] To address the stability issues mentioned above, a ceramic coated separator (CCS) has been developed that uses inorganic particles to form an inorganic particle layer on one or both sides of an existing polyolefin-based separator. The inorganic particles used in this separator include alumina, aluminum hydroxide, silica, barium oxide, titanium oxide, magnesium oxide, magnesium hydroxide, clay, glass powder, boehmite, or mixtures thereof.

[0005] The advantage of using batteries with separators containing inorganic particles, especially those with a pseudo-thin boehmite coating, is that the shedding of inorganic particles within the coating due to battery expansion and surface friction is significantly reduced, resulting in improved thermal stability. Furthermore, the weight of the coating can be reduced compared to the use of other inorganic particles such as alumina.

[0006] Pseudoboehmite can possess various phase forms. Needle-shaped pseudoboehmite with a main phase of linear (nanowire) or rod-like (nanorod) form is known to be obtained by growth under acidic conditions, while sheet-like pseudoboehmite with a main phase of platy form is known to be obtained by growth under alkaline conditions. However, when preparing pseudoboehmite to form a sheet-like phase under alkaline conditions, there is a problem of not being able to ensure a sufficiently thin thickness.

[0007] Previously, batch reactors were used as a method for synthesizing boehmite. However, due to equipment limitations and other issues, batch reactors cannot generate a high-temperature, high-pressure atmosphere, and a long reaction time of about 24 hours is usually required to ensure the formation of platy boehmite in a batch reactor, thus reducing production efficiency. Summary of the Invention

[0008] Technical problems to be solved

[0009] The primary objective of this invention is to improve the production efficiency of boehmite, and especially to improve the production efficiency of platy boehmite.

[0010] A second objective of this invention is to improve the production efficiency of flaky boehmite that can be produced in a thin layer under an acidic atmosphere.

[0011] Technical solution

[0012] As a method for achieving the above objectives, according to a specific embodiment of the present invention, a method for preparing platy boehmite can be provided, wherein the platy boehmite is obtained by comprising the following steps: a) adding an organic acid to an aqueous solution in which an aluminum precursor is dispersed; and b) adding the product of step a) to a Taylor reactor, wherein the pressure of the Taylor reactor is 1-100 bar.

[0013] According to one specific implementation, the temperature of the Taylor reactor can be 100-300°C.

[0014] According to one specific implementation, the reaction time of the Taylor reactor can be 1-20 hours.

[0015] According to one specific implementation, the stirring speed of the Taylor reactor can be 100-800 rpm.

[0016] According to one specific embodiment, the aluminum precursor may comprise one or a mixture of aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum halide, aluminum sulfide, aluminum hydroxide, aluminum oxide, aluminum hydroxyoxide, and aluminum alkoxide. The aluminum halide may be AlCl3 or AlF3. The aluminum alkoxide may be Al(Oi-Pr)3.

[0017] According to one specific embodiment, the aqueous solution containing the aluminum precursor can be prepared by dispersing the aluminum precursor in distilled water and then distilling it.

[0018] According to one specific embodiment, the organic acid may include one or a mixture of acetic acid, propionic acid, butyric acid, lactic acid, oxalic acid, malic acid, tartaric acid, and citric acid.

[0019] According to one specific implementation, the pH of the product of step a) can be 2 to 6.

[0020] According to one specific implementation, the Taylor reactor can be a continuous Taylor reactor, and the product of step a) can be added to the Taylor reactor at a rate of 0.1-10 ml / min.

[0021] According to one specific implementation, the Taylor reactor can be a batch Taylor reactor, and the product of step a) can be added at a rate of more than 80% of the total volume of the Taylor reactor.

[0022] In addition, as another method for achieving the above objectives, according to a specific embodiment of the present invention, a plate-like boehmite can be provided, wherein the plate-like boehmite has a major axis of 1-200 nm, a minor axis of 1-200 nm, and a thickness of 1-10 nm.

[0023] According to one specific implementation, the ratio of major diameter to minor diameter can be less than 5.0.

[0024] According to one specific embodiment, the lamellar boehmite can be prepared by including the following steps: a) adding an organic acid to an aqueous solution in which an aluminum precursor is dispersed; and b) adding the product of step a) into a Taylor reactor at a pressure of 1-100 bar.

[0025] According to one specific implementation, the temperature of the Taylor reactor can be 100-300°C.

[0026] Furthermore, as another method for achieving the above-mentioned objective, according to a specific embodiment of the present invention, a platy boehmite-like solution can be provided, wherein, by weight%, the platy boehmite-like solution comprises 0.1-30% by weight of the platy boehmite-like solution of the above-described specific embodiment, more than 0% by weight and less than 5% by weight of organic acid, and the balance being solvent.

[0027] Furthermore, as another method for achieving the above objectives, according to a specific embodiment of the present invention, a diaphragm may be provided having a coating on one or both sides, the coating comprising the sheet-like boehmite of the above specific embodiment.

[0028] Furthermore, as another method for achieving the above objectives, according to a specific embodiment of the present invention, an electrochemical device can be provided, the electrochemical device comprising the diaphragm of the above specific embodiment.

[0029] Beneficial effects

[0030] According to one specific embodiment of the present invention, the Taylor reactor utilizing the Coetzee-Taylor flow has superior stirring capability compared to existing batch reactors, and the production efficiency of platy boehmite can be improved by controlling the Taylor reactor under specific high-temperature and high-pressure conditions.

[0031] Existing batch reactors have difficulty establishing high-pressure conditions without a separate pressurizer, and the reaction pressure deviates significantly from the initial pressure. However, the Taylor reactor according to a specific embodiment of the present invention easily establishes high-pressure conditions and has a small deviation from the initial pressure, thus having the advantage of facilitating mass production.

[0032] When using existing batch reactors, there is a problem that it is difficult to adjust the reaction conditions during the reaction process after the reactants are added. However, according to a specific embodiment of the present invention, the Taylor reactor can easily adjust the reaction conditions during the reaction process, thereby providing real-time feedback on the reaction process, and thus has significant industrial advantages.

[0033] According to a specific embodiment of the present invention, a continuous Taylor reactor can be used to prepare large quantities of platy boehmite, thus providing significant industrial advantages.

[0034] According to one specific embodiment of the present invention, the production efficiency of thin-film diatomite with a thin layer of platy phase can be improved under an acidic atmosphere. Attached Figure Description

[0035] Figure 1 This is a diagram of a Taylor reactor according to a specific embodiment of the present invention.

[0036] Figure 2 This is a transmission electron microscope (TEM) image of the pseudoboehmite from Example 1.

[0037] Figure 3 This is a TEM image of the pseudoboehmite from Example 2.

[0038] Figure 4 This is a TEM image of the pseudoboehmite from Comparative Example 1.

[0039] Figure 5 This is a TEM image of the pseudoboehmite from Comparative Example 2.

[0040] Figure 6 This is a TEM image of the pseudoboehmite from Comparative Example 3.

[0041] Figure 7 This is a TEM image of the pseudoboehmite from Comparative Example 4.

[0042] Figure 8 This is a TEM image of the pseudoboehmite from Comparative Example 5.

[0043] Figure 9 This is a TEM image of the pseudoboehmite from Comparative Example 6.

[0044] Figure 10 This is a TEM image of the pseudoboehmite from Comparative Example 7.

[0045] Figure 11 This is a TEM image of the pseudoboehmite from Comparative Example 8.

[0046] Explanation of reference numerals in the attached figures

[0047] 100: Gel slurry storage container

[0048] 200: Pressure Pump

[0049] 300: Taylor Reactor

[0050] 400: Pressure regulating device

[0051] 500: Storage container Detailed Implementation

[0052] The advantages and features of the invention, as well as the methods of implementing them, can be clearly understood by referring to the accompanying drawings and detailed description of specific embodiments. However, the invention is not limited to the specific embodiments disclosed below, but is implemented through various embodiments that differ from each other. These specific embodiments are provided merely to fully disclose the invention and to fully describe its scope to those skilled in the art, and the invention is defined only by the scope of the claims. Specific embodiments of the invention are described in detail below with reference to the accompanying drawings. Unrelated to the drawings, the same reference numerals denote the same constituent elements, and "and / or" includes each of the mentioned items and all combinations of more than one item.

[0053] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) are to be used as they are commonly understood by one of ordinary skill in the art to which this invention pertains. Throughout this specification, unless specifically stated otherwise to the contrary, the description of a part as "comprising" or "including" a constituent element means that other constituent elements may also be included, rather than excluding other constituent elements. Furthermore, unless otherwise specified, the singular form also includes the plural form.

[0054] In this specification, when describing a layer, film, region, plate, or other part as being "on" or "on top of" another part, this includes not only cases where it is "directly" "on" another part, but also cases where there are other parts in between.

[0055] In this specification, "Taylor reactor" refers to all types of reactors capable of producing couette-Taylor vortex or couette-Taylor flow. A Taylor reactor may be, for example, a commonly used Taylor reactor, but is not limited to this.

[0056] When platy boehmite is used in the coating of battery CCS, the detachment of coating particles due to battery expansion and surface friction is significantly improved compared to existing conventional inorganic particles. In other words, when platy boehmite is used as the main component of the battery CCS coating, the thermal stability of the battery is further improved, and the weight of the coating can be reduced by replacing relatively heavy inorganic particles such as alumina. To date, no technology has been developed to produce platy boehmite with high efficiency.

[0057] To address these issues, the inventors, through repeated research, discovered that controlling the Taylor reactor under specific conditions to produce boehmite can improve the production efficiency of platy boehmite. According to a specific embodiment of the invention, platy boehmite can be obtained by comprising the following steps: a) adding an organic acid to an aqueous solution containing an aluminum precursor; and b) adding the product of step a) to the Taylor reactor. Each step is described in detail below.

[0058] According to one specific implementation, a) an organic acid can be added to an aqueous solution in which the aluminum precursor is dispersed.

[0059] According to one specific embodiment, an aqueous solution containing a dispersed aluminum precursor can be prepared by dispersing the aluminum precursor in distilled water followed by distillation. According to this embodiment, the distillation process can remove condensation reaction byproducts from the aluminum precursor aqueous solution. Distillation can be performed under reduced pressure, for example at 100-900 mbar, 200-800 mbar, or 300-700 mbar. The temperature of the aqueous solution can be, for example, 50-100°C, specifically 60-97°C, and more specifically 70-95°C.

[0060] According to a specific embodiment, the aluminum precursor can be any aluminum-containing substance and is not particularly limited. The aluminum precursor may comprise one or a mixture of aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum halide, aluminum sulfide, aluminum hydroxide, aluminum oxide, aluminum hydroxyaluminate, and aluminum alkoxide, or for example, one or a mixture of Al2O3, Al(OH)3, Al2(SO4)3, AlCl3, Al(Oi-Pr)3, Al(NO3)3, and AlF3, but is not limited thereto.

[0061] Considering the removal of condensation reaction byproducts during the aforementioned distillation process, the aluminum precursor can be, for example, aluminum alkoxide. Aluminum alkoxide is characterized by higher hydrolytic reactivity and easier removal of byproducts. Aluminum alkoxide can be, for example, an aluminum alkoxide having alkoxy groups having 2 to 5 carbon atoms, and may include one or a mixture of aluminum triethanolamine, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, etc.

[0062] The purpose of adding an organic acid according to a specific embodiment is to adjust the pH to prepare pseudoboehmite, and all organic acids that achieve the above purpose can be used. The organic acid may, for example, include one or a mixture of acetic acid, propionic acid, butyric acid, lactic acid, oxalic acid, malic acid, tartaric acid, and citric acid.

[0063] The product of step a) can be, for example, an aluminum gel solution. The pH of the product of step a) can be, for example, 2 to 6 or 3 to 5. According to the specific embodiment, by using the acidic product of step a) with added organic acid, a thin, lamellar boehmite-like material can be prepared under acidic conditions. The thickness can be, for example, 1-10 nm, 1-5 nm, or 1-2 nm.

[0064] According to one specific implementation, b) the product of step a) can be added to the Taylor reactor.

[0065] A Taylor reactor according to one specific embodiment can be any type of reactor that generates a Couette-Taylor vortex or a Couette-Taylor flow. A Taylor reactor according to one specific embodiment may include: a production chamber having an inner space; a heater that divides the inner space of the production chamber into multiple spaces and controls the temperature of the divided spaces; an inner cylinder disposed in each of the divided spaces and rotated by a motor; a pressure device that controls the pressure of the production chamber; and a pressure pump that supplies reactants to the production chamber. Hereinafter, to aid in understanding the invention, the invention is described using the Taylor reactor and its structure illustrated above, but it should be noted that the invention is not limited thereto.

[0066] According to one embodiment, the product of step a) can be stored in a separate storage container before being supplied to the Taylor reactor. According to another embodiment, the product of step a) can be supplied to the production chamber using a pressure pump located on one side of the Taylor reactor. The pressure pump can be used to achieve the above objectives, and its structure is not particularly limited, but it can be, for example, one or a combination of a High Performance Liquid Chromatography (HPLC) pump, a rotary pump, a syringe pump, a tubing pump, a diaphragm pump, a solenoid pump, a high-pressure piston pump, and a high-pressure plunger pump.

[0067] According to another specific embodiment, by utilizing a pressurizing pump located on one side of the Taylor reactor while simultaneously providing a pressure regulating device on the other side, the product of step a) can be supplied to the production chamber more efficiently. The pressure regulating device can be, for example, one or a combination of a back pressure regulator (BPR), a pressure regulating ball valve, a needle valve, or the like. According to one specific embodiment, a separate storage container for storing the product can be located at the rear end of the pressure regulating device.

[0068] The Taylor reactor according to this specific embodiment utilizes a Couette-Taylor flow, thus providing superior stirring capabilities compared to existing batch reactors, and creating a high-temperature, high-pressure atmosphere within the reactor, thereby improving the production efficiency of platy boehmite.

[0069] According to one specific embodiment, the temperature of the Taylor reactor can be 100-300°C. When the temperature of the Taylor reactor is below 100°C, crystal growth cannot proceed normally, and therefore the proportion of amorphous phase, needle phase, or rod phase that does not form the crystal itself may increase. On the other hand, when the temperature of the Taylor reactor exceeds 300°C, crystal overgrowth occurs, making it difficult to ensure a thin layer of platy boehmite, and the time or cost required to obtain boehmite at room temperature may be excessive. To further improve the above effects, the temperature of the Taylor reactor can be, for example, 150-250°C or 170-200°C.

[0070] According to one specific embodiment, the pressure of the Taylor reactor can be 1-100 bar. When the pressure of the Taylor reactor is less than 1 bar, crystal growth cannot proceed normally, and therefore the proportion of amorphous phases, needle-like phases, or rod-like phases that do not form the crystal itself may increase. On the other hand, due to the limitations of continuous process equipment, it is difficult to control the pressure of the Taylor reactor to exceed 100 bar. To further improve the above effects, the pressure of the Taylor reactor can be, for example, 5-40 bar, 5-30 bar, 10-40 bar, 10-30 bar, 20-40 bar, or 20-30 bar.

[0071] According to one specific embodiment, a high-temperature-high-pressure atmosphere is created by controlling the temperature and pressure of the Taylor reactor within the aforementioned range, and when boehmite is grown under this atmosphere, the reaction time required to ensure the platy phase of boehmite can be significantly reduced. The reaction time required to ensure the platy phase of boehmite can be, for example, 1-20 hours, specifically 3-10 hours, and more specifically 5-7 hours. To ensure the platy phase of boehmite using existing batch reactors without separate additional equipment or instruments would require a long time of approximately 24 hours or more. However, according to one specific embodiment, the reaction time required to ensure the platy phase is significantly reduced, for example, to approximately 6 hours. Therefore, compared to the past, the production efficiency of platy phase boehmite can be increased by approximately four times.

[0072] According to a specific implementation, for a high-temperature-high-pressure atmosphere, when the pressure of the Taylor reactor is controlled to be above 5 bar, the temperature of the Taylor reactor is preferably above 180°C. In this case, the pressure and temperature of the Taylor reactor can be, for example, 5-40 bar and 180-300°C, 5-40 bar and 180-250°C, or 5-40 bar and 180-200°C.

[0073] According to another specific implementation, for a high-temperature-high-pressure atmosphere, when the pressure of the Taylor reactor is controlled to be above 10 bar, the temperature of the Taylor reactor is preferably above 170°C. In this case, the pressure and temperature of the Taylor reactor can be, for example, 10-40 bar and 170-300°C, 10-40 bar and 170-250°C, or 10-40 bar and 170-200°C.

[0074] According to one specific implementation, the stirring speed of the Taylor reactor can be 100-800 rpm, 200-700 rpm, or 300-600 rpm. To ensure further improved stirring capacity, the stirring speed of the Taylor reactor can be, for example, above 100 rpm. Considering equipment limitations and cost, the stirring speed of the Taylor reactor is preferably below 800 rpm.

[0075] According to a specific implementation plan, the Taylor reactor can be operated continuously or intermittently.

[0076] In a continuous Taylor reactor according to a specific embodiment, the product of step a) can be added from one side, and the product obtained through the reaction can be obtained from the other side. The product of step a) can be added to the Taylor reactor at a rate of 0.1-10 ml / min. Considering the residence time of the reactants in the reactor, the addition rate can be, for example, 0.5-5 ml / min or 1-3 ml / min. For the residence time of the product of step a) added to the continuous Taylor reactor, in order to ensure the platy phase similar to boehmite, the residence time can be, for example, 1-20 hours, or, considering production efficiency, 3-10 hours, or, further considering production efficiency, 5-7 hours.

[0077] In a batch Taylor reactor according to a specific embodiment, the product of step a) can be added from one side, and the product of step a) added can be more than 80% of the total volume of the Taylor reactor. The reaction time of the product of step a) added to the batch Taylor reactor can be, for example, 1-20 hours, or, considering production efficiency, 3-10 hours, or, further considering production efficiency, 5-7 hours.

[0078] According to one specific embodiment of the present invention, in order to mass-produce pseudoboehmite, the Taylor reactor can be operated under continuous conditions.

[0079] To aid understanding, use Figure 1 A Taylor reactor according to a specific implementation scheme is described. Figure 1 This is a diagram of a Taylor reactor. When the Taylor reactor is configured as a batch reactor, it is possible to... Figure 1Excluding the pressure regulating device 400 from the device diagram, if the Taylor reactor is set as a continuous reactor, it can be configured to include... Figure 1 All structures are shown in the diagram. In the batch process, the reaction takes place under pressure in the Taylor reactor 300, thus eliminating the need for an additional pressure regulating device 400. On the other hand, in the continuous process, to prevent a decrease in the internal pressure of the Taylor reactor 300 and to continuously discharge the product, a pressure regulating device 400 for adjusting the pressure is further provided at the rear end of the reactor.

[0080] Reference Figure 1 According to one specific embodiment of the batch Taylor reactor, stirred reactants (aluminum gel) are pumped at a constant rate from gel slurry storage container 100 to Taylor reactor 300 via a pressure pump 200. In Taylor reactor 300, the reaction is carried out using a Couette-Taylor flow. The completed reaction products are then transported to storage container 500.

[0081] Reference Figure 1 According to a specific embodiment of a continuous Taylor reactor, stirred reactants (aluminum gel) are pumped at a constant rate from a gel slurry storage container 100 to a Taylor reactor 300 via a pressure pump 200. In the Taylor reactor 300, the reaction is carried out using a Couette-Taylor flow. The completed reaction product is then transported to a storage container 500. At this point, a pressure regulating device 400 can be installed at the rear end of the Taylor reactor 300 to prevent a decrease in the internal pressure of the Taylor reactor 300, thereby allowing for continuous product discharge.

[0082] According to a specific implementation plan, the pseudoboehmite prepared by one or a combination of the above-mentioned processes can be platy pseudoboehmite.

[0083] When observing the platy boehmite phase according to a specific embodiment using TEM, the major axis can be 1-200 nm, and the minor axis can be 1-200 nm. According to a specific embodiment, the ratio of the major axis to the minor axis can be 5.0 or less, or 3.0 or less. In this specification, "major axis" refers to the longest length along the major axis of the boehmite phase observed by TEM, and "minor axis" refers to the longest length of the boehmite phase in a direction orthogonal to the major axis.

[0084] According to one specific embodiment, TEM observation is performed in a direction perpendicular to the thickness direction of the platy boehmite, thus the platy boehmite has a thin thickness. According to one specific embodiment, the thickness of the platy boehmite can be 1-10 nm, 1-5 nm, or 1-2 nm.

[0085] According to one embodiment, a platy boehmite-like solution can be provided, comprising, by weight, 0.1-30% of the aforementioned platy boehmite, more than 0% and less than 5% by weight of an organic acid, and the balance being a solvent. According to one embodiment, the platy boehmite-like solution can be sprayed onto one or both sides of a diaphragm using a separate device or instrument and then dried.

[0086] According to one specific embodiment, a diaphragm may be provided having a coating on one or both sides, the coating comprising the aforementioned sheet-like boehmite.

[0087] According to one specific embodiment, an electrochemical device can be provided, the electrochemical device including the aforementioned separator. The electrochemical device is not particularly limited, but examples include primary batteries, secondary batteries, fuel cells, capacitors, etc. When the electrochemical device is a battery, it can be assembled by setting a negative electrode, a positive electrode, and a separator between the negative and positive electrodes, and then injecting an electrolyte.

[0088] There are no restrictions on the positive electrode active material; any conventional material is acceptable. Examples include lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, or composite oxides formed by combinations of these.

[0089] The negative electrode active material can be any conventional negative electrode active material. Examples of non-limiting examples include lithium metal, activated carbon, graphite, and other carbon-based materials, but there is no particular limitation.

[0090] The positive and negative active materials are respectively bonded to the positive or negative current collector. The positive current collector can be made of aluminum foil, nickel foil, etc., and the negative current collector is selected from copper, nickel, etc. However, any commonly used current collector can be used without restriction, so it is not limited to these.

[0091] The electrolyte is not limited, as long as it is an electrolyte used in the art, therefore it will not be described in this invention.

[0092] The following describes specific embodiments and comparative examples of this specific implementation scheme. However, the following embodiments are merely one specific embodiment of this specific implementation scheme, and this specific implementation scheme is not limited to the following embodiments.

[0093] Example

[0094] In Examples 1 to 2 and Comparative Examples 1 to 8 below, the initial pressure refers to the pressure inside the reactor before or immediately after the addition of reactants. Reaction pressure and reaction time refer to the pressure and reaction time inside the reactor after the target temperature has been reached following the addition of reactants. Residence time refers to the time the reactants remain in the reactor when the Taylor reactor is operating continuously.

[0095] (Example 1)

[0096] 306 g of aluminum precursor, using aluminum isopropoxide, was added to 1600 g of distilled water and dispersed. The isopropanol was then removed by vacuum distillation at 500 mbar and 95 °C, thus preparing an aqueous solution containing the dispersed aluminum precursor.

[0097] a) An organic acid is added to the prepared aqueous solution containing the aluminum precursor to prepare an aluminum gel solution with a pH of 4 to 5. In this case, 10 g of lactic acid is used as the organic acid.

[0098] (b) A Taylor flow was created by rotating the Taylor reactor shaft at 600 rpm. The prepared aluminum gel solution was added to the Taylor reactor, filling it to 90% of its total volume. The reactor was then secured, and the internal temperature was raised to 180°C. The reaction pressure inside the Taylor reactor was then controlled at 10 bar, and the reaction time was maintained as described in Table 1. After the reaction, the temperature was cooled to room temperature while the shaft remained running, and the product was obtained at the bottom of the reactor. The Taylor reactor was then operated under batch conditions.

[0099] (Example 2)

[0100] The aluminum gel solution of Example 2 was prepared under the same conditions as in Example 1. For the prepared aluminum gel solution, a back pressure regulator (BPR) was installed at the rear end of the Taylor reactor, and the shaft of the Taylor reactor was rotated at 600 rpm to form a Taylor flow. The internal temperature of the Taylor reactor was raised to 180°C. The aluminum gel solution was added to the Taylor reactor from one side at a rate of 1 ml / min, and the product passing through the reaction was obtained from the other side. The initial pressure inside the Taylor reactor was controlled at 10 bar, the reaction pressure was controlled at 10 bar, and the residence time of the reactants inside the Taylor reactor was as shown in Table 1. The Taylor reactor was operated continuously.

[0101] (Comparative Example 1)

[0102] Except for the reaction times listed in Table 1, the product was obtained under the same conditions as in Example 1. The reaction time for Comparative Example 1 was 3 hours. In this case, the Taylor reactor was operated under batch conditions.

[0103] (Comparative Example 2)

[0104] Except for the reaction times listed in Table 1, the product was obtained under the same conditions as in Example 1. The reaction time for Comparative Example 2 was 1 hour. In this case, the Taylor reactor was operated under batch conditions.

[0105] (Comparative Example 3)

[0106] The aluminum gel solution of Comparative Example 3 was prepared under the same conditions as in Example 1. The prepared aluminum gel solution was added to an existing batch reactor equipped with a propeller. The stirring speed was 300 rpm, and the temperature was increased to 180°C at a rate of 5°C / min, and then maintained at 180°C for 24 hours to carry out the reaction. The reaction pressure inside the batch reactor during the reaction time was at most less than 5 bar. Afterwards, the product was obtained by cooling to room temperature.

[0107] (Comparative Example 4)

[0108] Using the reaction times described in Table 1, and pressurized with nitrogen (N2) using a separate pressurizer, the initial pressure in the existing batch reactor was maintained at 5 bar during the reaction time, and the reaction was carried out at 180°C for 6 hours. The maximum reaction pressure in the batch reactor during the reaction time was less than 10 bar. The product was then obtained after cooling to room temperature.

[0109] (Comparative Example 5)

[0110] Except for the reaction time recorded in Table 1, the product was obtained in a conventional batch reactor under the same conditions as Comparative Example 3.

[0111] (Comparative Example 6)

[0112] Except for using the reaction time described in Table 1, and the reaction pressure of the batch reactor in the open system during the reaction time being atmospheric pressure (1 bar), the product was obtained under the same conditions as in Comparative Example 3.

[0113] (Compare Example 7 and Comparative Example 8)

[0114] Except for the residence times listed in Table 1, the products were obtained under the same conditions as in Example 2. The residence time for Comparative Example 7 was 1.42 hours, and the residence time for Comparative Example 8 was 0.94 hours. In this case, the Taylor reactor was operated under continuous conditions.

[0115] Table 1 shows the results after TEM images of each example and comparative example were taken using a Tecnai F30 transmission electron microscope (TEM) from FEI Corporation. The examples and comparative examples are classified into lamellar phase type (Example 1, Example 2, Comparative Example 3 and Comparative Example 4) and amorphous phase type (Comparative Example 2). It was observed that Comparative Examples 1, 5 to 8, which are both lamellar and amorphous phases, did not complete crystallization, and therefore, a mixture of lamellar and amorphous phases existed.

[0116] In the results in Table 1, "lamellar phase" can refer to a phase that forms a certain amount of lamellar phase based on the observed TEM image, and "amorphous phase" can refer to a phase that forms a certain amount of amorphous phase based on the observed TEM image. In this case, "lamellar phase" can refer to a phase where the thickness of the pseudoboehmite is less than its major or minor axis and the major / minor axis ratio is less than 5.0, or it can refer to a phase that exhibits an electron diffraction pattern during TEM analysis. "Amorphous phase" can refer to an amorphous form with an irregular shape or a phase that does not exhibit an electron diffraction pattern during TEM analysis.

[0117] To aid in understanding the terms "lamellar phase" and "amorphous phase," for example in... Figure 2 and Figure 9 The regions of the aforementioned phases are shown in the figure, but it should be noted that they are not limited to these.

[0118] [Table 1]

[0119]

[0120]

[0121] Hereinafter, with reference to Table 1 and the accompanying drawings, the various embodiments and comparative examples are compared and evaluated. In Embodiments 1 and 2 according to this specific embodiment, although the reaction time and residence time are relatively short, less than 6 hours, the Taylor reactor can be used to ensure the formation of lamellar boehmite.

[0122] When the Taylor reactor was operated under batch conditions, the results of Example 1, Comparative Example 1, and Comparative Example 2, where only the reaction time was controlled at different times, were compared to evaluate the effect of reaction time. In Example 1, with a reaction time of 6 hours, lamellar boehmite (…) was prepared. Figure 2 In Comparative Example 1, where the reaction time was 3 hours, platy pseudoboehmite and amorphous pseudoboehmite were observed. Figure 4 In Comparative Example 2, with a reaction time of 1 hour, amorphous pseudoboehmite was prepared. Figure 5 As can be seen from the above results, in order to ensure the platy phase of boehmite, the reaction time specified in this specific implementation scheme needs to be met.

[0123] When the Taylor reactor was operated under continuous conditions, the results of Example 2, Comparative Example 7, and Comparative Example 8, where only the reaction time was controlled at different times, were compared to evaluate the effect of reaction time. In Example 2, where the reaction time or residence time was 2.83 hours, lamellar boehmite (…) was prepared. Figure 3 In Comparative Example 7, with a reaction time of 1.42 hours, and Comparative Example 8, with a reaction time of 0.94 hours, platy boehmite and amorphous boehmite were prepared. Figure 10 and Figure 11 In comparison Figure 3 , Figure 10 and Figure 11 Although platy boehmite was obtained in Examples 2, 7, and 8, Figure 3 The sheet phase is most prominent, therefore the crystal growth degree of Example 2 is the highest. Figure 3 and Figure 10 In Comparative Example 7, compared to Example 2, the lamellar phase did not form well, but in the comparative example... Figure 10 and Figure 11 Compared to Comparative Example 8, Comparative Example 7 showed a more pronounced platy phase. These results indicate that a longer reaction time is more conducive to ensuring the formation of the platy boehmite-like phase.

[0124] To evaluate the effect of reactor type, the results of Example 1 and Comparative Example 4, with the same reaction time, were compared. In Example 1, lamellar boehmite was prepared with a reaction time of 6 hours without initial pressurization. Figure 2 On the other hand, in Comparative Example 4, boehmite was prepared by pressurizing with an initial pressure of 5 bar using an existing batch reactor and under the same reaction conditions as in Example 1. Figure 7 This is because, under the same reaction time, the Taylor reactor utilizes the Couet-Taylor flow, thus providing superior stirring capabilities. Furthermore, the Taylor reactor employing this Couet-Taylor flow can ensure higher production efficiency of platy boehmite under high temperature and high pressure conditions compared to conventional batch reactors.

[0125] To evaluate the effect of reaction pressure, the results of Example 1, Comparative Example 5, and Comparative Example 6, with the same reaction time, were compared. The reaction time for Comparative Examples 5 and 6 was 6 hours, the same as in Example 1. However, Comparative Example 5 was a closed-system batch reactor without a separate pressurizer, therefore the reaction pressure was 5 bar. Comparative Example 6 used an open-system batch reactor, therefore the reaction pressure was atmospheric pressure (1 bar). In Example 1, lamellar boehmite (…) was prepared. Figure 2However, the reaction pressures of Comparative Examples 5 and 6 were lower than those of Example 1, thus yielding platy boehmite and amorphous boehmite. Figure 8 and Figure 9 In comparison Figure 8 and Figure 9 In Comparative Example 5, which had a higher reaction pressure than Comparative Example 6, a more pronounced lamellar phase was formed. These results indicate that higher reaction pressure is more conducive to ensuring the formation of the lamellar pseudoboehmite phase.

[0126] To evaluate the reaction conditions required to ensure the formation of platy boehmite, the results of Example 1 and Comparative Example 3 were compared. In Example 1, platy boehmite was prepared with a reaction time of 6 hours. Figure 2 On the other hand, in Comparative Example 3, which only uses a batch reactor including a conventional propeller, the reaction time for preparing platy boehmite was 24 hours, resulting in a production efficiency difference of more than four times. Figure 6 These results are due to the lower stirring capacity of existing batch reactors compared to Taylor reactors. In Comparative Example 4, using a separate pressurizer, the initial pressure was set to 5 bar, the reaction pressure to 10 bar, and a reaction time of 6 hours to ensure the formation of platy boehmite (…). Figure 7 However, in terms of requiring a separate pressurizer, the industrial advantage is reduced compared to Example 1. The results above show that the Taylor reactor utilizes a Cuyet-Taylor flow, thus providing superior stirring capabilities, and the Taylor reactor using this Cuyet-Taylor flow can ensure higher production efficiency of platy boehmite under high temperature and high pressure conditions than conventional batch reactors.

[0127] As described above, exemplary embodiments of this specific implementation have been illustrated, but this specific implementation is not limited thereto. Those skilled in the art will understand that various changes and modifications can be made without departing from the scope of the claims.

Claims

1. A method for preparing platy boehmite, wherein the method obtains platy boehmite by comprising the following steps: a) Add an organic acid to an aqueous solution in which an aluminum precursor is dispersed; and b) Add the product of step a) into the Taylor reactor. in, The pressure of the Taylor reactor is 1-100 bar. The temperature of the Taylor reactor is 100-300℃. The aluminum precursor comprises one or a mixture of aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum halide, aluminum sulfide, aluminum hydroxide, aluminum hydroxyoxide, and aluminum alkoxide. When the Taylor reactor is a continuous Taylor reactor, the residence time of the product of step a) in the Taylor reactor is 2.83-20 ​​hours; when the Taylor reactor is a batch Taylor reactor, the reaction time of the product of step a) in the Taylor reactor is 5-20 hours.

2. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The stirring speed of the Taylor reactor is 100-800 rpm.

3. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The aluminum halides are AlCl3 and AlF3.

4. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The aluminum alkoxide is Al(Oi-Pr)3.

5. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The aqueous solution containing the aluminum precursor is prepared by dispersing the aluminum precursor in distilled water and then distilling it.

6. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The organic acid includes one or a mixture of acetic acid, propionic acid, butyric acid, lactic acid, oxalic acid, malic acid, tartaric acid, and citric acid.

7. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The pH of the product of step a) is 2 to 6.

8. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The Taylor reactor is a continuous Taylor reactor, and the product of step a) is added to the Taylor reactor at a rate of 0.1-10 ml / min.

9. The process for preparing platelet-shaped pseudo-boehmite according to claim 1, wherein, The Taylor reactor is a batch Taylor reactor, and the product of step a) is added at a rate of more than 80% of the total volume of the Taylor reactor.

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