Method for producing sheet-phase pseudo-boehmite using a quiet-Taylor vortex reaction

Abstract

To provide a method for producing a sheet phase pseudo-boehmite with improved production efficiency.SOLUTION: The present disclosure relates to a method for producing sheet-phase pseudo-boehmite using the Couette-Taylor vortex reaction. In one aspect, the method for producing a sheet-phase pseudo-boehmite includes: a) providing an organic acid into an aqueous solution in which an aluminum precursor is dispersed; and b) supplying a product from the process of a) into a Taylor reactor, wherein a pressure of the Taylor reactor is 1 to 100 bar while producing the sheet phase pseudo-boehmite. The Taylor reactor utilizing the Couette-Taylor flow has even better stirring capacity than conventional batch reactors, and the production efficiency of the sheet-phase pseudo-boehmite can be improved by controlling the Taylor reactor under specific conditions of high-temperature and high-pressure.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing sheet-like pseudo-boehmite using a Coquette-Taylor vortex reaction. Specifically, the present disclosure relates to a method for manufacturing sheet-like pseudo-boehmite for ceramic coating on one or both sides of a separator for a battery using a Coquette-Taylor flow at high temperature and high pressure.

Background Art

[0002] A separator is a fine film that is used in batteries for electric vehicles, mobile phones, laptop computers, etc., and enhances safety by blocking the contact between the positive electrode and the negative electrode and preventing electrical contact between the electrodes. A separator for a battery has pores with a size of several tens of nanometers, and ions pass through such pores to enable the battery to function.

[0003] Generally used polyolefin-based separators have intense heat shrinkage at high temperatures and are physically weak in durability. Therefore, when an abnormality occurs in the battery and the internal temperature rises, the separator is likely to deform. In severe cases, it becomes impossible to sufficiently prevent contact between the electrodes, and an explosion due to a short circuit may occur.

[0004] To solve such stability problems, a ceramic-coated separator (CCS) in which an inorganic particle layer is formed using inorganic particles on one or both sides of an existing polyolefin-based separator has been developed. Examples of the inorganic particles used therein include alumina, aluminum hydroxide, silica, barium oxide, titanium oxide, magnesium oxide, magnesium hydroxide, clay, glass powder, boehmite, or a mixture thereof.

[0005] In particular, for a battery using a separator provided with a boehmite coating layer among inorganic particles, the phenomenon of detachment of inorganic particles in the coating layer due to battery swelling and surface friction is significantly improved, not only improving the thermal stability, but also having the advantage that the weight of the coating layer can be reduced compared to the case of using other inorganic particles such as alumina.

[0006] Boehmite can have various forms of phases. Needle-phase boehmite with a main phase of nanowire phase or nanorod phase is known to be obtainable by growing under acidic conditions, and sheet-phase boehmite with a main phase of sheet phase is known to be obtainable by growing under basic conditions. However, when producing boehmite in the sheet phase under basic conditions, there is a problem that a sufficiently thin thickness cannot be ensured.

[0007] As a method for synthesizing boehmite, conventionally, there is a method of synthesizing using a batch reactor. However, due to problems such as equipment limitations, a batch reactor cannot create a high-temperature and high-pressure atmosphere. To obtain sheet-phase boehmite using a batch reactor, usually, a reaction time of about 24 hours is required, resulting in a problem of reduced production efficiency. Summary of the Invention Problems to be Solved by the Invention

[0008] The first object of the present disclosure is to improve the production efficiency of boehmite, and in particular, to improve the production efficiency of sheet-phase boehmite among boehmites. The second object of the present disclosure is to improve the production efficiency of sheet-phase boehmite that can have a thin thickness under an acidic atmosphere. Means for Solving the Problems

[0009] According to one means for achieving the above object, according to one embodiment of the present disclosure, it includes: a) a step of adding an organic acid to an aqueous solution in which an aluminum precursor is dispersed; and b) a step of adding the product of the step a) to a Taylor reactor, to obtain a sheet-phase pseudo-boehmite, and a method for producing a sheet-phase pseudo-boehmite is provided, wherein the pressure of the Taylor reactor is 1 to 100 bar.

[0010] According to one embodiment, the temperature of the Taylor reactor may be 100 to 300 °C. According to one embodiment, the reaction time of the Taylor reactor may be 1 to 20 hours. According to one embodiment, the stirring speed of the Taylor reactor may be 100 to 800 rpm.

[0011] According to one embodiment, the aluminum precursor may include one or a mixture of aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum halide, aluminum sulfide, aluminum hydroxide, aluminum oxide, aluminum oxyhydroxide, aluminum alkoxide, Al2O3, Al(OH)3, Al2(SO4)3, AlCl3, Al(O-i-Pr)3, Al(NO3)3, and AlF3.

[0012] According to one embodiment, the aqueous solution in which the aluminum precursor is dispersed may be prepared by dispersing the aluminum precursor in distilled water and then distilling it. According to one 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.

[0013] According to one embodiment, the pH of the product of the step a) may be 2 to 6. According to one embodiment, the Taylor reactor is a continuous Taylor reactor, and the product of the step a) may be introduced into the Taylor reactor at an introduction rate of 0.1 to 10 ml / min.

[0014] According to one embodiment, the Taylor reactor is a batch Taylor reactor, and the product of step a) may be charged into 80% or more of the total volume of the Taylor reactor.

[0015] Also, as another means for achieving the above object, according to one embodiment of the present disclosure, it is possible to provide sheet-phase pseudo-boehmite having a major axis of 1 to 200 nm, a minor axis of 1 to 200 nm, and a thickness of 1 to 10 nm. According to one embodiment, the ratio of the major axis to the minor axis may be 5.0 or less.

[0016] According to one embodiment, the sheet-phase pseudo-boehmite may be produced including: a) a step of adding an organic acid to an aqueous solution in which an aluminum precursor is dispersed; and b) a step of charging the product of step a) into a Taylor reactor having a pressure of 1 to 100 bar. According to one embodiment, the temperature of the Taylor reactor may be 100 to 300 °C.

[0017] Also, as yet another means for achieving the above object, according to one embodiment of the present disclosure, it is possible to provide a sheet-phase pseudo-boehmite solution containing, by weight, 0.1 to 30% by weight of the sheet-phase pseudo-boehmite of the above-described embodiment, more than 0% by weight and 5% by weight or less of an organic acid, and the remaining solvent.

[0018] Also, as yet another means for achieving the above object, according to one embodiment of the present disclosure, it is possible to provide a separator having a coating layer containing the sheet-phase pseudo-boehmite of the above-described embodiment disposed on one or both sides.

[0019] Also, as yet another means for achieving the above object, according to one embodiment of the present disclosure, it is possible to provide an electrochemical element including the separator of the above-described embodiment.

Advantages of the Invention

[0020] According to one embodiment of the present disclosure, the Taylor reactor utilizing the Couette-Taylor flow is further excellent in stirring ability compared to the conventional batch reactor, and the production efficiency of sheet-phase pseudo-boehmite can be improved by controlling the Taylor reactor under specific high-temperature and high-pressure conditions.

[0021] Conventional batch reactors are difficult to create high-pressure conditions without another pressure vessel, and the deviation of the reaction pressure due to the initial pressure is large. However, the Taylor reactor according to one embodiment of the present disclosure can easily create high-pressure conditions, and the deviation of the reaction pressure due to the initial pressure is small. Therefore, it has the effect of being advantageous for mass production.

[0022] When using a conventional batch reactor, there is a problem that it is difficult to adjust the reaction conditions during the progress of the reaction after the reactants are charged. However, the Taylor reactor according to one embodiment of the present disclosure can easily adjust the reaction conditions even during the progress of the reaction. Therefore, immediate feedback on the reaction process is possible, and it is excellent in industrial advantages.

[0023] According to one embodiment of the present disclosure, a large amount of sheet-phase pseudo-boehmite can be produced by utilizing a continuous Taylor reactor, so it is excellent in industrial advantages. According to one embodiment of the present disclosure, the production efficiency of sheet-phase pseudo-boehmite with a thin thickness can be improved under an acidic atmosphere.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0025] The advantages and features of the present disclosure, and the methods for achieving them, will become apparent by referring to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below, and can be realized in various different forms. The present embodiments are provided merely to complete the present disclosure and to fully inform those with ordinary knowledge in the technical field to which the present disclosure belongs of the scope of the disclosure. The present disclosure is only defined by the scope of the claims. Hereinafter, specific contents for implementing the present disclosure will be described in detail with reference to the accompanying drawings. The same member numbers refer to the same components regardless of the drawings, and "and / or" includes each of the items mentioned and all combinations of one or more of them.

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used in this specification may be used with a meaning commonly understood by those having ordinary knowledge in the technical field to which the present disclosure belongs. Throughout the specification, when a certain part states that a certain component "includes", this means that, unless otherwise stated to the contrary, it does not exclude other components, but may further include other components. Also, the singular form includes the plural form unless specifically mentioned in the text.

[0027] In this specification, when it is stated that a part such as a layer, film, region, plate, etc. is "above" or "on top of" another part, this includes not only the case where it is directly above the other part, but also the case where there are other parts in between.

[0028] In this specification, the "Taylor reactor" means all forms of reactors capable of generating Couette-Taylor vortices or Couette-Taylor flows. The Taylor reactor may be, for example, a commercial Taylor reactor, but is not limited thereto.

[0029] When sheet-phase pseudo-boehmite is utilized for the coating application of battery CCS, compared with existing common inorganic particles, the phenomena of battery swelling and detachment of coating particles due to surface friction are significantly improved. That is, when sheet-phase pseudo-boehmite is adopted as the main component of the coating layer of battery CCS, the thermal stability of the battery is further improved, and there is an effect that the weight of the coating layer can be reduced by substituting inorganic particles such as relatively high-weight alumina. Currently, the technology for efficiently producing sheet-phase pseudo-boehmite has not been established.

[0030] As a result of repeated research to solve such problems, the inventors have found that the production efficiency of sheet-phase pseudo-boehmite can be improved by controlling a Taylor reactor under specific conditions to produce pseudo-boehmite. According to one embodiment of the present disclosure, sheet-phase pseudo-boehmite can be obtained including: a) a step of introducing an organic acid into an aqueous solution in which an aluminum precursor is dispersed; and b) a step of introducing the product of step a) into a Taylor reactor. Each step will be described in detail.

[0031] According to one embodiment, a) an organic acid can be introduced into an aqueous solution in which an aluminum precursor is dispersed. According to one embodiment, an aqueous solution in which an aluminum precursor is dispersed may be prepared by dispersing the aluminum precursor in distilled water and then distilling it. According to the above embodiment, the condensation reaction by-products of the aluminum precursor aqueous solution can be removed by the distillation step. At this time, the distillation may be performed by vacuum distillation, and the vacuum distillation may be performed, for example, at 100 to 900 mbar, 200 to 800 mBar, or 300 to 700 mBar. The temperature of the aqueous solution may be, for example, 50 to 100 °C, specifically 60 to 97 °C, and more specifically 70 to 95 °C.

[0032] The aluminum precursor according to one embodiment may be any aluminum-containing substance and is not particularly limited. The aluminum precursor may contain one or a mixture of aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum halide, aluminum sulfide, aluminum hydroxide, aluminum oxide, aluminum oxyhydroxide, aluminum alkoxide, or may contain, for example, one or a mixture of Al2O3, Al(OH)3, Al2(SO4)3, AlCl3, Al(O-i-Pr)3, Al(NO3)3, AlF3, but is not limited thereto.

[0033] Considering the removal of the condensation reaction by-products during the distillation step described above, the aluminum precursor may be, for example, aluminum alkoxide. Aluminum alkoxide has the characteristics of higher hydrolysis reactivity and easier removal of by-products. The aluminum alkoxide may be, for example, an aluminum alkoxide having an alkoxy group with 2 to 5 carbon atoms, and may contain, for example, one or a mixture of aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, and aluminum sec-butoxide.

[0034] The organic acid according to one embodiment is added for the purpose of adjusting the pH to produce boehmite, and any organic acid may be used as long as it can achieve the above purpose. The organic acid may include, for example, one or a mixture of acetic acid, propionic acid, butyric acid, lactic acid, oxalic acid, malic acid, tartaric acid, and citric acid.

[0035] The product of the step a) may be, for example, an aluminum gel solution. The product of the step a) may have a pH of, for example, 2 to 6, or 3 to 5. According to the embodiment, by using the acidic product of the step a) into which an organic acid is introduced, sheet-phase boehmite having a thin thickness can be produced under acidic conditions. The thickness may be, for example, 1 to 10 nm, 1 to 5 nm, or 1 to 2 nm.

[0036] According to one embodiment, b) the product of the step a) can be introduced into a Taylor reactor. The Taylor reactor according to one embodiment may be any reactor capable of generating a Couette-Taylor vortex or a Couette-Taylor flow. The Taylor reactor according to one embodiment includes a production chamber having a space inside, a heater that divides the inner space of the production chamber into a plurality of parts and controls the temperature of the plurality of divided spaces, an inner cylinder provided 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 a reactant to the production chamber. Hereinafter, the present disclosure will be described with reference to the above-described exemplary Taylor reactor and its configuration for the purpose of facilitating understanding, but it should be noted that the present disclosure is not limited thereto.

[0037] According to one embodiment, the product of step a) can be provided to a Taylor reactor after being stored in another storage container. According to one embodiment, a pressure pump provided on one side of the Taylor reactor can be utilized to provide the product of step a) to the production chamber. The pressure pump only needs to achieve the above-mentioned purpose and there is no particular limitation on its configuration. For example, it may be one or a combination of an HPLC (High Performance Liquid Chromatography) 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.

[0038] According to another embodiment, while utilizing a pressure pump provided on one side of the Taylor reactor, a pressure regulating device is provided on the other side, and the product of step a) can be provided to the production chamber more efficiently. The pressure regulating device may be, for example, one or a combination of a back pressure regulator (BPR), a pressure regulating ball valve, and a needle valve. According to one embodiment, another storage container capable of storing the product may be provided downstream of the pressure regulating device.

[0039] The Taylor reactor according to this embodiment utilizes a coaxial-Taylor flow, and is further superior in stirring ability compared to a conventional batch reactor, and can create a high-temperature and high-pressure atmosphere inside the reactor to improve the production efficiency of sheet-phase pseudo-boehmite.

[0040] According to one embodiment, the temperature of the Taylor reactor may be 100 to 300 °C. If the temperature of the Taylor reactor is less than 100 °C, crystals may not grow smoothly, so the proportion of the amorphous phase, needle phase, or rod phase in which no crystals are formed may increase. On the other hand, if the temperature of the Taylor reactor exceeds 300 °C, the crystals may grow excessively and it may be difficult to obtain a thin sheet-phase pseudo-boehmite, and the time or cost for obtaining the pseudo-boehmite at room temperature may become excessive. In terms of further improving the above-described effects, the temperature of the Taylor reactor may be, for example, 150 to 250 °C, or may be 170 to 200 °C.

[0041] According to one embodiment, the pressure of the Taylor reactor may be 1 to 100 bar. If the pressure of the Taylor reactor is less than 1 bar, crystals may not grow smoothly, so the proportion of the amorphous phase, needle phase, or rod phase in which no crystals are formed may increase. On the other hand, it is difficult to control the pressure of the Taylor reactor to exceed 100 bar due to the limitations of continuous process equipment. In terms of further improving the above-described effects, the pressure of the Taylor reactor may be, for example, 5 to 40 bar, 5 to 30 bar, 10 to 40 bar, 10 to 30 bar, 20 to 40 bar, or 20 to 30 bar.

[0042] According to one embodiment, when controlling the temperature and pressure of the Taylor reactor within the above-described ranges to create a high-temperature and high-pressure atmosphere and growing boehmite in the high-temperature and high-pressure atmosphere, the reaction time for securing boehmite in the sheet phase type can be significantly reduced. The reaction time for securing sheet-phase type boehmite may be, for example, 1 to 20 hours, specifically 3 to 10 hours, and more specifically 5 to 7 hours. If attempting to secure sheet-phase type boehmite using a conventional batch reactor without using another additional device or instrument, a long time of about 24 hours or more is required. However, according to one embodiment, the reaction time for securing the sheet phase is significantly reduced. For example, the reaction time for securing sheet-phase type boehmite can be significantly reduced to about 6 hours. Thus, it can be seen that the production efficiency of sheet-phase type boehmite can be improved by about four times compared to the conventional case.

[0043] According to one embodiment, for the high-temperature and high-pressure atmosphere, when controlling the pressure of the Taylor reactor to 5 bar or more, the temperature of the Taylor reactor is preferably 180°C or more. At this time, the pressure and temperature of the Taylor reactor may be, for example, 5 to 40 bar and 180 to 300°C, 5 to 40 bar and 180 to 250°C, or 5 to 40 bar and 180 to 200°C.

[0044] According to another embodiment, for the high-temperature and high-pressure atmosphere, when controlling the pressure of the Taylor reactor to 10 bar or more, the temperature of the Taylor reactor is preferably 170°C or more. At this time, the pressure and temperature of the Taylor reactor may be, for example, 10 to 40 bar and 170 to 300°C, 10 to 40 bar and 170 to 250°C, or 10 to 40 bar and 170 to 200°C.

[0045] According to one embodiment, the stirring speed of the Taylor reactor may be 100 to 800 rpm, 200 to 700 rpm, or 300 to 600 rpm. In order to ensure a further improved stirring ability, for example, the stirring speed may be 100 rpm or more. Considering equipment limitations and costs, the stirring speed is preferably 800 rpm or less. According to one embodiment, the operation mode of the Taylor reactor may be continuous or batch.

[0046] In the continuous Taylor reactor according to one embodiment, the product of step a) can be fed on one side, and the product of the reaction can be obtained on the other side. The product of step a) may be fed into the Taylor reactor at a feeding rate of 0.1 to 10 ml / min. Considering the residence time of the reactants in the reactor, the feeding rate may be, for example, 0.5 to 5 ml / min, or 1 to 3 ml / min. The residence time of the product of step a) fed into the continuous Taylor reactor may be, for example, 1 to 20 hours, or 3 to 10 hours considering the production efficiency, or 5 to 7 hours considering the production efficiency more.

[0047] In the batch Taylor reactor according to one embodiment, the product of step a) is fed on one side. At this time, the product of step a) fed may be 80% or more of the total volume of the Taylor reactor. The reaction time of the product of step a) fed into the batch Taylor reactor may be, for example, 1 to 20 hours, or 3 to 10 hours considering the production efficiency, or 5 to 7 hours considering the production efficiency more. In order to mass-produce pseudo-boehmite, according to a specific embodiment of the present disclosure, the operation conditions of the Taylor reactor may be continuous.

[0048] To facilitate understanding, the Taylor reactor according to a specific embodiment will be described by making use of the attached FIG. 1. The attached FIG. 1 is a device diagram of the Taylor reactor. When the Taylor reactor is configured in a batch mode, it can be configured excluding the pressure regulating device 400 in the device diagram of FIG. 1. When the Taylor reactor is configured in a continuous mode, it can be configured to include all the components shown in FIG. 1. In the batch mode, since the reaction is carried out when the pressure reaches the Taylor reactor 300, an additional pressure regulating device 400 is not required. In contrast, in the continuous mode, in order to continuously discharge the product, a pressure regulating device 400 for regulating the pressure is further configured at the rear stage of the reactor to prevent the phenomenon that the internal pressure of the Taylor reactor 300 decreases.

[0049] Referring to FIG. 1, according to a batch-mode Taylor reactor according to an embodiment, the stirred reactant (aluminum gel) from the gel slurry storage container 100 can be transferred to the Taylor reactor 300 at a constant speed by the pressure pump 200. Inside the Taylor reactor 300, the reaction proceeds by making use of the Couette-Taylor flow. Then, the product after the reaction is completed is transferred to the storage container 500.

[0050] Referring to FIG. 1, according to a continuous-mode Taylor reactor according to an embodiment, the stirred reactant (aluminum gel) from the gel slurry storage container 100 can be transferred to the Taylor reactor 300 at a constant speed by the pressure pump 200. Inside the Taylor reactor 300, the reaction proceeds by making use of the Couette-Taylor flow. Then, the product after the reaction is completed is transferred to the storage container 500. At this time, the pressure regulating device 400 is arranged at the rear stage of the Taylor reactor 300 to prevent the internal pressure of the Taylor reactor 300 from decreasing, whereby the product can be continuously discharged.

[0051] According to an embodiment, the pseudo-boehmite produced by one or a combination of the above-described steps may be sheet-phase pseudo-boehmite. The sheet-phase pseudo-boehmite according to one embodiment may have a major axis length of 1 to 200 nm and a minor axis length of 1 to 200 nm when observed by TEM. According to a specific embodiment, the ratio of the major axis length to the minor axis length may be 5.0 or less, or 3.0 or less. In this specification, the "major axis length" means the length in the longest major axis direction on the pseudo-boehmite observed by TEM, and the "minor axis length" means the longest length on the pseudo-boehmite in the direction orthogonal to the major axis length.

[0052] According to one embodiment, in order to perform TEM observation in a direction perpendicular to the thickness direction of the sheet-phase pseudo-boehmite, the sheet-phase pseudo-boehmite has a thin thickness. According to one embodiment, the thickness of the sheet-phase pseudo-boehmite may be 1 to 10 nm, 1 to 5 nm, or 1 to 2 nm.

[0053] According to one embodiment, a sheet-phase pseudo-boehmite solution containing, by weight, 0.1 to 30% by weight of the above-described sheet-phase pseudo-boehmite, more than 0% by weight and 5% by weight or less of an organic acid, and the remaining solvent can be provided. According to one embodiment, the sheet-phase pseudo-boehmite solution may be sprayed and dried on one or both sides of the separator via another device or instrument.

[0054] According to one embodiment, a separator having a coating layer containing the above-described sheet-phase pseudo-boehmite disposed on one or both sides can be provided. According to one embodiment, an electrochemical element including the above-described separator can be provided. The electrochemical element is not particularly limited, and examples thereof include a primary battery, a secondary battery, a fuel cell, and a capacitor. When the electrochemical element is a battery, it can be assembled by disposing a separator between a negative electrode, a positive electrode, and between the negative electrode and the positive electrode, and injecting an electrolyte to complete it.

[0055] The positive electrode active material is not limited as long as it is a normal material. For example, it includes lithiumated magnesium oxide, lithiumated cobalt oxide, lithiumated nickel oxide, or composite oxides formed by combinations thereof.

[0056] As the negative electrode active material, a normal negative electrode active material can be used. Non-limiting examples include carbon-based materials such as lithium metal, activated carbon, and graphite, but it is not particularly limited thereto.

[0057] The positive electrode active material and the negative electrode active material are used by being bound to a positive electrode current collector or a negative electrode current collector, respectively. As the positive electrode current collector, aluminum foil, nickel foil, etc. may be used. As the negative electrode current collector, it is selected from copper, nickel, etc., but any one can be used without limitation as long as it is commonly used, so it is not restricted. Also, the electrolyte is not limited as long as it is used in the art, so it will not be further described in this disclosure.

[0058] Hereinafter, specific examples and comparative examples of this embodiment will be described. However, the following examples are only specific examples of this embodiment, and this embodiment is not limited to the following examples.

[0059] Examples In the following Examples 1-2 and Comparative Examples 1-8, the initial pressure means the pressure in the reactor before the introduction of the reactants or immediately after the introduction of the reactants. The reaction pressure and reaction time mean the pressure and reaction time in the reactor after the reactants are introduced and the temperature is raised to reach the target temperature. The residence time means the time that the reactants stay in the reactor when the operating conditions of the Taylor reactor are continuous.

[0060] (Example 1) 306 g of an aluminum precursor was added to 1600 g of distilled water and dispersed. At this time, aluminum isopropoxide was used as the aluminum precursor. Then, it was distilled under reduced pressure at 500 mbar and 95 °C to remove isopropyl alcohol, and an aqueous solution in which the aluminum precursor was dispersed was prepared.

[0061] a) An organic acid was added to the prepared aqueous solution in which the aluminum precursor was dispersed to prepare an aluminum gel solution with a pH of 4 to 5. At this time, 10 g of lactic acid was used as the organic acid.

[0062] b) The prepared aluminum gel solution was put into the Taylor reactor while operating the shaft of the Taylor reactor at 600 rpm to generate a Taylor flow, filled to 90% of the total volume of the Taylor reactor and then fastened, and the internal temperature of the Taylor reactor was raised to 180 °C. Then, the reaction pressure in the Taylor reactor was controlled to 10 bar and maintained for the reaction time described in Table 1 for reaction. After the reaction, while the shaft was operating, it was cooled only to room temperature, and the product was obtained from the lower side of the reactor. At this time, the operating conditions of the Taylor reactor were of the batch type.

[0063] (Example 2) The aluminum gel solution of Example 2 was prepared under the same conditions as in Example 1. After arranging a back pressure regulator (BPR) at the rear stage of the Taylor reactor, the prepared aluminum gel solution was operated with the shaft of the Taylor reactor at 600 rpm to generate a Taylor flow, and the internal temperature of the Taylor reactor was raised to 180 °C. The aluminum gel solution was introduced into the Taylor reactor at a rate of 1 ml / min from one side, and the product from the reaction was obtained from the other side. At this time, the initial pressure in the Taylor reactor was 10 bar, the reaction pressure was controlled to 10 bar, and the reactants in the Taylor reactor stayed for the residence time described in Table 1. The operating conditions of the Taylor reactor were of the continuous type.

[0064] (Comparative Example 1) Except for the reaction time described in Table 1, the product was obtained under the same conditions as in Example 1. The reaction time of Comparative Example 1 was 3 hours. At this time, the operating conditions of the Taylor reactor were batch type.

[0065] (Comparative Example 2) Except for the reaction time described in Table 1, the product was obtained under the same conditions as in Example 1. The reaction time of Comparative Example 2 was 1 hour. At this time, the operating conditions of the Taylor reactor were batch type.

[0066] (Comparative Example 3) The aluminum gel solution of Comparative Example 3 was prepared under the same conditions as in Example 1. The prepared aluminum gel solution was put into a conventional batch reactor equipped with a propeller. At this time, the stirring speed was 300 rpm, and after the temperature was raised to 180 °C at 5 °C / min, it was maintained at 180 °C for 24 hours for reaction. The reaction pressure in the batch reactor during the reaction time was less than 5 bar at maximum. Then, after cooling to room temperature, the product was obtained.

[0067] (Comparative Example 4) The reaction time described in Table 1 was used, and N2 gas was pressurized with another pressure vessel, and the initial pressure in the conventional batch reactor during the reaction time was maintained at 5 bar and reacted at 180 °C for 6 hours. The reaction pressure in the batch reactor during the reaction time was less than 10 bar at maximum. Then, after cooling to room temperature, the product was obtained.

[0068] (Comparative Example 5) Except for the reaction time described in Table 1, the product was obtained under the same conditions as in Comparative Example 3 using a conventional batch reactor.

[0069] (Comparative Example 6) Except for the reaction time described in Table 1 and that the reaction pressure was normal pressure (1 bar) using an open system batch reactor during the reaction time, the product was obtained under the same conditions as in Comparative Example 3.

[0070] (Comparative Examples 7, 8) Except for the residence time described in Table 1, the product was obtained under the same conditions as in Example 2. The residence time of Comparative Example 7 was 1.42 hours, and the residence time of Comparative Example 8 was 0.94 hours. At this time, the operating conditions of the Taylor reactor were continuous.

[0071] For the results in Table 1, after taking TEM photographs of each example and comparative example using a Tecnai F30 transmission electron microscope (TEM) device manufactured by FEI Company, they were classified into a sheet phase type (Examples 1 and 2, Comparative Examples 3 and 4) and an amorphous phase type (Comparative Example 2) and shown. In Comparative Examples 1 and 5 to 8 where both the sheet phase type and the amorphous phase type were observed, crystallization could not be completed, which means that the sheet phase and the amorphous phase were mixed.

[0072] From the results in Table 1, the sheet phase type can refer to those in which a certain amount or more of the sheet phase is formed based on the observed TEM photographs, and the amorphous phase type can refer to those in which a certain amount or more of the amorphous phase is formed based on the observed TEM photographs. At this time, the "sheet phase" means a phase in which the thickness of the pseudoboehmite is smaller than the major axis or the minor axis and the ratio of the major axis / minor axis is 5.0 or less, or a phase in which an electron diffraction pattern appears during TEM analysis. The "amorphous phase" can mean a phase having an amorphous shape without a regular shape or a phase in which an electron diffraction pattern does not appear during TEM analysis.

[0073] In order to assist the understanding of the "sheet phase" and the "amorphous phase", for example, the regions of the phases are shown in FIGS. 2 and 9 respectively, but it should be noted that it is not limited thereto.

[0074]

Table 1

[0075] Hereinafter, each example and comparative example will be comparatively evaluated with reference to Table 1 and the accompanying drawings. In Examples 1 and 2 according to this embodiment, although the reaction time and the residence time were relatively short within 6 hours respectively, it was possible to secure sheet phase type pseudoboehmite using a Taylor reactor.

[0076] When the operating conditions of the Taylor reactor were configured in a batch mode, in order to evaluate the influence according to the reaction time, the results of Example 1, Comparative Examples 1 and 2, in which only the reaction time was controlled to be different, were compared. In Example 1 where the reaction time was 6 hours, sheet-phase pseudo-boehmite was produced (Figure 2). In Comparative Example 1 where the reaction time was 3 hours, sheet-phase and amorphous-phase pseudo-boehmite were produced (Figure 4). In Comparative Example 2 where the reaction time was 1 hour, amorphous-phase pseudo-boehmite was produced (Figure 5). From the above-described results, it can be seen that in order to ensure sheet-phase pseudo-boehmite, the reaction time limited in this embodiment must be satisfied.

[0077] When the operating conditions of the Taylor reactor were configured in a continuous mode, in order to evaluate the influence according to the reaction time, the results of Example 2, Comparative Examples 7 and 8, in which only the reaction time was controlled to be different, were compared. In Example 2 where the reaction time or residence time was 2.83 hours, sheet-phase pseudo-boehmite was produced (Figure 3). In Comparative Example 7 where the reaction time was 1.42 hours and Comparative Example 8 where the reaction time was 0.94 hours, sheet-phase and amorphous-phase pseudo-boehmite were produced (Figures 10 to 11). Comparing Figures 3, 10 and 11, although sheet-phase pseudo-boehmite was produced in all of Example 2, Comparative Examples 7 and 8, the sheet phase in Figure 3 was the clearest, and the degree of crystal growth in Example 2 was the highest. Comparing Figure 3 and Figure 10, in Comparative Example 7, the sheet phase was not formed smoothly compared to Example 2. Comparing Figure 10 and Figure 11, in Comparative Example 7, the sheet phase was formed relatively clearly compared to Comparative Example 8. From the above-described results, it can be seen that the longer the reaction time, the more advantageous it is to ensure sheet-phase pseudo-boehmite.

[0078] To evaluate the influence on the reactor type, the results of Example 1 and Comparative Example 4 with the same reaction time were compared. In Example 1, sheet-phase pseudo-boehmite was produced with a reaction time of 6 hours without initial pressurization (Figure 2), while in Comparative Example 4, pressurization was carried out at an initial pressure of 5 Bar using a conventional batch reactor, and pseudo-boehmite was produced under the same reaction conditions as in Example 1 (Figure 7). This is because in the case of the same reaction time, the Taylor reactor utilizes the plug-flow, so it is even more excellent in stirring ability. The Taylor reactor utilizing such a plug-flow can ensure a higher production efficiency of sheet-phase pseudo-boehmite than a normal batch reactor under high-temperature and high-pressure conditions.

[0079] To evaluate the influence on the reaction pressure, the results of Example 1, Comparative Examples 5 and 6 with the same reaction time were compared. Comparative Examples 5 and 6 were the same as Example 1 with a reaction time of 6 hours. However, Comparative Example 5 was a closed-system batch reactor without another pressurizer, so the reaction pressure was 5 bar, and Comparative Example 6 used an open-system batch reactor with a reaction pressure of normal pressure (1 bar). In Example 1, sheet-phase pseudo-boehmite was produced (Figure 2), while in Comparative Examples 5 and 6, since the reaction pressure was lower than that in Example 1, sheet-phase and amorphous-phase pseudo-boehmite were produced (Figures 8 and 9). Comparing Figure 8 and Figure 9, in Comparative Example 5 with a relatively high reaction pressure, the sheet phase was formed more clearly compared to Comparative Example 6. From the above results, it can be seen that the higher the reaction pressure, the more advantageous it is to ensure sheet-phase pseudo-boehmite.

[0080] To evaluate the required reaction conditions for securing sheet-phase pseudo-boehmite, the results of Example 1 and Comparative Example 3, in which sheet-phase pseudo-boehmite was formed, were compared. In Example 1, sheet-phase pseudo-boehmite was produced with a reaction time of 6 hours (Fig. 2), whereas in Comparative Example 3, which consisted only of a normal batch reactor with a propeller, the reaction time for producing sheet-phase pseudo-boehmite was 24 hours, resulting in a more than four-fold difference in production efficiency (Fig. 6). This result is because the conventional batch reactor has inferior stirring ability compared to the Taylor reactor. In Comparative Example 4, another pressure vessel was utilized to configure the initial pressure at 5 bar and the reaction pressure at 10 bar, and sheet-phase pseudo-boehmite was secured with a reaction time of 6 hours (Fig. 7), but it lacks industrial advantages compared to Example 1 in that another pressure vessel must always be utilized. From the above-described results, since the Taylor reactor utilizes the Coquette-Taylor flow, it is even more excellent in stirring ability, and it can be seen that the Taylor reactor utilizing such Coquette-Taylor flow can secure a higher production efficiency of sheet-phase pseudo-boehmite than a normal batch reactor under high-temperature and high-pressure conditions.

[0081] As described above, the exemplary embodiments of the present embodiment have been explained. However, the present embodiment is not limited thereto, and it will be understood that those having ordinary knowledge in the relevant technical field can make various changes and modifications without departing from the scope of the claims described below.

Explanation of Signs

[0082] 100: Gel slurry storage container 200: Pressure pump 300: Taylor reactor 400: Pressure regulating device 500: Storage container

Claims

1. a) A step of adding an organic acid to an aqueous solution in which an aluminum precursor is dispersed; b) A step of introducing the product of step a) into a Taylor reactor, to obtain a sheet-phase pseudo-boehmite, A method for producing a sheet-phase pseudo-boehmite, wherein the pressure of the Taylor reactor is 1 to 100 bar.

2. The method for producing a sheet-phase pseudo-boehmite according to claim 1, wherein the temperature of the Taylor reactor is 100 to 300 °C.

3. The method for producing a sheet-phase pseudo-boehmite according to claim 1, wherein the reaction time of the Taylor reactor is 1 to 20 hours.

4. The method for producing a sheet-phase pseudo-boehmite according to claim 1, wherein the stirring speed of the Taylor reactor is 100 to 800 rpm.

5. The method for producing a sheet-phase pseudo-boehmite according to claim 1, wherein the aluminum precursor contains one or a mixture of aluminum acetate, aluminum nitrate, aluminum sulfate, aluminum halide, aluminum sulfide, aluminum hydroxide, aluminum oxide, aluminum oxyhydroxide, and aluminum alkoxide.

6. The aluminum halide is AlCl ３ or AlF ３ The method for producing a sheet-phase pseudo-boehmite according to claim 5.

7. The aluminum alkoxide is Al(O-i-Pr) ３ The method for producing a sheet-phase pseudo-boehmite according to claim 5.

8. The aqueous solution in which the aluminum precursor is dispersed is Prepared by dispersing the aluminum precursor in distilled water and then distilling. The method for producing a sheet-phase pseudo-boehmite according to claim 1.

9. The method for producing the sheet-phase pseudo-boehmite according to claim 1, wherein the organic acid contains one or a mixture of acetic acid, propionic acid, butyric acid, lactic acid, oxalic acid, malic acid, tartaric acid, and citric acid.

10. The method for producing the sheet-phase pseudo-boehmite according to claim 1, wherein the pH of the product in the step a) is 2 to 6.

11. The Taylor reactor is a continuous Taylor reactor, The method for producing the sheet-phase pseudo-boehmite according to claim 1, wherein the product of the step a) is introduced into the Taylor reactor at an input rate of 0.1 to 10 ml / min.

12. The Taylor reactor is a batch Taylor reactor, The method for producing the sheet-phase pseudo-boehmite according to claim 1, wherein the product of the step a) is introduced at 80% or more of the total volume of the Taylor reactor.

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