Beta-type zeolite and method for producing the same

Abstract

A method for producing beta zeolite, said method comprising contacting a beta zeolite matrix powder, which is synthesized without using an organic structure-directing agent, with an aqueous alkaline solution with a pH value of 12 or higher. It is preferred to set the liquid temperature of the aqueous alkaline solution to 40-100°C inclusive. Also, it is preferred to set the ratio of the matrix powder to the aqueous alkaline solution to 10-1000 g / L inclusive. Also, it is preferred to set the contact time to 0.5-48 hours inclusive. Also, it is preferred that the molar ratio of SiO2 / Al2O3 is 16 or lower.

Description

[Technical Field]

[0001] This invention relates to beta-type zeolite and a method for producing the same. [Background technology]

[0002] Beta-type zeolites are industrially used as molecular sieve adsorbents that adsorb only molecules of a specific size, adsorption separation materials that adsorb molecules with strong affinity, catalyst substrates, or catalytic active components.

[0003] Various methods have been proposed for synthesizing beta-type zeolites. A common method involves using tetraethylammonium ions as an organic structure-determining agent (hereinafter also referred to as "OSDA"). However, compounds containing tetraethylammonium ions are expensive, and since most of them decompose after beta-type zeolite crystallization is complete, recovery and reuse are impossible. For this reason, beta-type zeolites produced by this method are expensive. Therefore, methods for producing beta-type zeolites without using OSDA have been proposed.

[0004] For example, Patent Documents 1 to 3 propose a method for producing beta-type zeolite by mixing a seed crystal of beta-type zeolite with a gel containing a silica source, an alumina source, an alkali source, and water, and then heating the mixture in a sealed container. This method is economically advantageous because it allows for the production of beta-type zeolite without using the expensive substance OSDA, and it is also advantageous in that it reduces the environmental burden. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] US2012 / 190534A1 [Patent Document 2] US2018 / 022612A1 [Patent Document 3] US2019 / 177173A1 [Overview of the project]

[0006] However, in the methods described in Patent Documents 1 to 3, the beta-type zeolite is synthesized by leaving a mixture of seed crystals and gel in a static state, which makes it easy for the resulting beta-type zeolite particles to aggregate and produce coarse grains. In Patent Documents 1 to 3, fine particles are obtained by classifying the coarse grains, but this method results in a large loss of coarse particles, limiting the amount of fine particles that can be obtained. It is also conceivable to obtain fine particles by grinding, but in that case, there is a risk of destroying the crystal structure of the zeolite. Obtaining fine zeolite is important from the viewpoint of expanding the applications of zeolite and from the viewpoint of obtaining new zeolites by using the zeolite as a seed crystal. Therefore, the object of the present invention is to provide a beta-type zeolite that is fine in particle form and useful for the synthesis of zeolites without the use of organic structure-determining agents, and a method for producing the same.

[0007] The present invention provides a method for producing beta-type zeolite, which involves contacting a beta-type zeolite mother powder synthesized without the use of an organic structure-determining agent with an alkaline aqueous solution with a pH of 12 or higher.

[0008] Furthermore, the present invention has a molar ratio of SiO2 / Al2O3 of 16 or less. Volume cumulative particle size D at 90% cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. 90 It is 10 μm or less, Micropore volume is 0.15 cm 3 / g or more 0.30cm 3 This product provides beta-type zeolite with a weight of less than / g. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows a scanning electron microscope image of the beta-type zeolite obtained in Example 1. [Figure 2] Figure 2 shows a scanning electron microscope image of the beta-type zeolite obtained in Example 3. [Figure 3]Figure 3 is a scanning electron microscope image of the beta-type zeolite obtained in Example 5. [Figure 4] Figure 4 is a scanning electron microscope image of the beta-type zeolite of Comparative Example 1 (that is, the mother powder of the beta-type zeolite).

Mode for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described based on its preferred embodiments. The present invention relates to a method for producing beta-type zeolite. In this production method, the mother powder of beta-type zeolite is used as a raw material, and the mother powder is treated with an alkaline aqueous solution to obtain fine powder of the target beta-type zeolite. The mother powder used as a raw material is synthesized without using an organic structure-directing agent (hereinafter also referred to as "OSDA").

[0011] Beta-type zeolite synthesized without using OSDA (hereinafter also referred to as "OSDA-free zeolite") is a known substance. The OSDA-free zeolite can be synthesized, for example, by mixing a seed crystal of beta-type zeolite (this seed crystal may be synthesized using OSDA), a reaction mixture containing a silica source, an alumina source, an alkali source, and water, and heating this mixture under high temperature and high pressure.

[0012] The particle size of the seed crystal of beta-type zeolite used for synthesizing the above mother powder is represented by the volume cumulative particle size D at 90% by volume in the cumulative volume measured by the laser diffraction scattering method of particle size distribution, preferably 0.1 μm or more and 50 μm or less, more preferably 0.1 μm or more and 20 μm or less, still more preferably 0.1 μm or more and 10 μm or less. The method for measuring the particle size by the laser diffraction scattering method of particle size distribution is as described in the examples. 90 Note that the method for measuring the particle size by the laser diffraction scattering method of particle size distribution is as described in the examples.

[0013] The reaction mixture to which the seed crystal is added is preferably obtained by mixing a silica source, an alumina source, an alkali source, and water in the molar ratios shown below. By setting the composition of the reaction mixture within this range, the desired beta-type zeolite mother powder can be successfully obtained. • SiO2 / Al2O3 = 10 to 200, especially 10 to 45. • Na2O / SiO2 = 0.18 to 0.4, especially 0.2 to 0.3. H2O / SiO2 = 10 to 50, especially 13 to 25.

[0014] Silica sources used to obtain the reaction mixture having the aforementioned molar ratio include silica itself and silicon-containing compounds capable of generating silicate ions in water. Specifically, these include wet-process silica, dry-process silica, colloidal silica, sodium silicate, and aluminosilicate gel. These silica sources can be used individually or in combination of two or more. Among these silica sources, the use of silica (silicon dioxide) or aluminosilicate gel is preferred because it allows for the production of beta-type zeolite mother powder without the production of unwanted by-products.

[0015] As an alumina source, for example, water-soluble aluminum-containing compounds can be used. Specifically, these include sodium aluminate, aluminum nitrate, and aluminum sulfate. Aluminum hydroxide is also a suitable alumina source. These alumina sources can be used individually or in combination of two or more. Of these alumina sources, sodium aluminate and aluminum hydroxide are preferred because they allow the production of beta-type zeolite mother powder without the production of unwanted by-products (such as sulfates and nitrates).

[0016] For example, sodium hydroxide can be used as an alkali source. Note that when sodium silicate is used as a silica source or sodium aluminate as an alumina source, the sodium contained in it is also considered as NaOH and is therefore an alkali component. Consequently, the aforementioned Na2O is calculated as the sum of all alkali components in the reaction mixture.

[0017] The amount of beta-type zeolite used as seed crystal is preferably 0.1% to 20% by mass relative to the silica component in the reaction mixture, in order to successfully obtain the beta-type zeolite mother powder. More preferably, it is 0.1% to 10% by mass, and even more preferably, 0.1% to 5% by mass.

[0018] When preparing the reaction mixture, the order in which the raw materials are added should be chosen to ensure a homogeneous reaction mixture is obtained. For example, a homogeneous reaction mixture can be obtained by adding an alumina source to an aqueous sodium hydroxide solution at room temperature, dissolving it, and then adding a silica source and stirring. Seed crystals can be added while mixing with the silica source or added after the silica source has been added. After that, the mixture should be stirred to ensure that the seed crystals are uniformly dispersed. There are no particular restrictions on the temperature when preparing the reaction mixture; generally, it can be done at room temperature (20°C to 25°C).

[0019] Put the reaction mixture containing the crystals into a container, seal it, heat it to cause a reaction, and generate crystals of beta-type zeolite. This reaction mixture does not contain OSDA. As one method of generating crystals, a method of heating and standing still under high temperature and high pressure can be mentioned. The heating temperature is preferably in the range of 100°C or higher and 200°C or lower, more preferably in the range of 120°C or higher and 180°C or lower. By heating at 100°C or higher, a satisfactory crystallization rate can be obtained. On the other hand, by heating at 200°C or lower, it becomes difficult to generate other zeolite species, such as mordenite. The heating time is not critical in this manufacturing method, and it may be heated until a beta-type zeolite mother powder with sufficiently high crystallinity is generated. Generally, by heating for about 5 hours to 150 hours, a mother powder of beta-type zeolite with satisfactory crystallinity can be obtained.

[0020] When heating by the standing method, aging of the liquid may be performed prior to that. Aging refers to an operation of holding at a certain temperature at a temperature lower than the reaction temperature for a certain period of time. In aging, generally, it is left standing without stirring. By performing aging, effects such as preventing the by-production of impurities, enabling heating under stirring without the by-production of impurities, and increasing the reaction rate can be achieved. The temperature and time of aging are set so that the above effects are maximally exerted. In the present invention, aging is preferably performed at 20 to 80°C, more preferably at 20 to 60°C, and preferably in the range of 2 hours to 1 day.

[0021] The above heating yields a mother powder of beta-type zeolite. After the heating is completed, the generated mother powder is separated from the liquid by filtration, then washed with water or warm water and dried. Since it does not contain OSDA in the dried state, there is no need for calcination. The mother powder in this state contains Na + ions. This state of the mother powder may be subjected to the next step, or the mother powder in which Na + ions are exchanged with NH4 + ions may be subjected to the next step. Furthermore, after being exchanged with NH4 + ions, the mother powder in the H + form obtained by calcination may be subjected to the next step. From the viewpoint of industrial productivity, Na +It is advantageous to use the mold's base powder in the next process.

[0022] Na + The mold's base powder, and the firing process, result in H + In any case of molded master powder, the particle size of the master powder is the volume cumulative particle size D at 90% of the cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. 90 The particle size is approximately 10 μm to 200 μm. In this mother powder, primary particles aggregate to form aggregates. Primary particles are crystalline particles of a polycrystalline material formed by the aggregation of single crystals. In this invention, the smallest unit observed as an independent particle in observation using an electron microscope is the primary particle.

[0023] Na + When using a type of mother powder, NH4 is obtained by ion exchange. + When using molded mother powder and when firing, H + In any case where molded mother powder is used, it is preferable to remove coarse particles and adjust the particle size by subjecting the mother powder to a grinding or classification process that does not impair its crystallinity, in order to efficiently bring it into contact with the alkaline aqueous solution in the next step. For grinding, for example, a jet mill, ball mill, and bead mill can be used. For classification, for example, a method of separation by sedimentation using a slurry in which the mother powder is dispersed in a dispersion medium, a wet classification method, and a dry classification method can be used. The particle size of the mother powder after classification is the cumulative particle size D at 90% of the cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. 90 It is preferably expressed as 0.1 μm or more and 20 μm or less, and more preferably 0.1 μm or more and 10 μm or less.

[0024] Next, the mother powder is subjected to a contact process with an alkaline aqueous solution. For example, the mother powder and the alkaline aqueous solution can be mixed to bring them into contact. Although the mother powder of OSDA free zeolite produced by the above method has the advantage of being highly crystalline, the particles tend to aggregate. As a result of the inventors' diligent research into methods to dissolve this aggregation, they found that by contacting the aggregated OSDA free zeolite mother powder with an alkaline aqueous solution, it is possible to selectively dissolve the grain boundaries of the aggregates and disperse them into primary particles.

[0025] The alkaline aqueous solution brought into contact with the mother powder of OSDA free zeolite can be an aqueous solution of various basic substances. Examples of basic substances include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, and ammonia.

[0026] When an alkaline aqueous solution is brought into contact with the mother powder of OSDA free zeolite, the pH is preferably 12 or higher, more preferably 13 or higher, and even more preferably 14 or higher, in order to selectively dissolve the grain boundaries of the OSDA free zeolite particles.

[0027] The concentration of basic substances in an alkaline aqueous solution is adjusted so that the pH of the alkaline aqueous solution reaches the value mentioned above. - The ion concentration is preferably 0.01 mol / L or higher, more preferably 0.1 mol / L or higher, and even more preferably 1.0 mol / L or higher. There is no particular upper limit to the concentration, but if it is around 5.0 mol / L, preferably around 2.3 mol / L, the aggregated mother powder of OSDA free zeolite can be sufficiently dispersed into the primary particles.

[0028] The amount of OSDA free zeolite mother powder and alkaline aqueous solution used is preferably set so that the ratio of mother powder to alkaline aqueous solution is 10 g / L or more and 1000 g / L or less, in order to sufficiently disperse the aggregated OSDA free zeolite mother powder into primary particles. More preferably, the ratio is 20 g / L or more and 500 g / L or less, and even more preferably 30 g / L or more and 200 g / L or less, and 30 g / L or more and 180 g / L or less.

[0029] Contact between the OSDA free zeolite mother powder and the alkaline aqueous solution can be carried out at room temperature. Room temperature refers to the ambient temperature, which is the temperature when no intentional heating or cooling is performed. Instead of contact at room temperature, contact can be carried out under heating. For example, the OSDA free zeolite mother powder can be added to an alkaline aqueous solution heated to a predetermined temperature. The heating temperature of the alkaline aqueous solution is preferably, for example, 40°C to 100°C, which allows for selective dissolution of the grain boundaries of the OSDA free zeolite particles, more preferably 40°C to 80°C, and even more preferably 50°C to 70°C. When contacting the OSDA free zeolite mother powder with the alkaline aqueous solution, it is preferable to stir the alkaline aqueous solution.

[0030] The contact time between the OSDA free zeolite mother powder and the alkaline aqueous solution is appropriately adjusted to allow sufficient dispersion of the aggregated OSDA free zeolite mother powder into primary particles. Generally, satisfactory results can be obtained by contacting the two for a time of 0.5 hours to 48 hours, more preferably 1 hour to 12 hours, and even more preferably 1 hour to 4 hours.

[0031] As described above, by contacting the aggregated mother powder of OSDA free zeolite with an alkaline aqueous solution, it becomes possible to selectively dissolve the grain boundaries of each particle constituting the aggregate. Since the alkaline aqueous solution acts mainly on the grain boundaries of the primary particles in the aggregate of primary particles, the crystal structure of the beta-type zeolite constituting the particles is less affected by the alkaline aqueous solution. Therefore, the crystallinity of the beta-type zeolite before and after contact with the alkaline aqueous solution is substantially the same, and the high crystallinity before contact with the alkaline aqueous solution is maintained after contact. This is in contrast to conventional methods of grinding the mother powder of OSDA free zeolite. When grinding is performed, the crystallinity of the beta-type zeolite tends to decrease due to the external force applied during grinding, and in some cases, amorphous material may be generated.

[0032] Furthermore, conventional methods for classifying the mother powder of OSDA free zeolite to remove coarse particles have the disadvantage of a large loss of coarse particles and a low yield. In contrast, the method of contacting the mother powder of OSDA free zeolite with an alkaline aqueous solution only dissolves the aggregation of primary particle aggregates, so there is no loss of coarse particles, and it has the advantage of a high yield. In fact, when the inventors performed microscopic observations, they confirmed that the particle size of the primary particles constituting the aggregates was almost identical to the particle size distribution measured by laser diffraction scattering particle size distribution measurement after contact with the alkaline aqueous solution.

[0033] Furthermore, contact between the mother powder of OSDA free zeolite and an alkaline aqueous solution can cause desiliconization of the particles, which may result in a slight decrease in the SiO2 / Al2O3 molar ratio compared to before treatment with the alkaline aqueous solution.

[0034] The above method makes it possible to disperse the aggregated OSDA-free zeolite mother powder into primary particles. The beta-type zeolite obtained in this way is synthesized without the use of organic structure-determining agents. The SiO2 / Al2O3 molar ratio in this beta-type zeolite is approximately the same as that of the mother powder OSDA-free zeolite. Specifically, the SiO2 / Al2O3 molar ratio is preferably 16 or less, more preferably 12 or less, and even more preferably 10 or less. Furthermore, the SiO2 / Al2O3 molar ratio is preferably 2 or more, more preferably 4 or more, and even more preferably 6 or more.

[0035] Beta-type zeolite dispersed in an alkaline aqueous solution into primary particles has a particle size of D 90 Preferably, the thickness is 10 μm or less, and more preferably 7 μm. below The particle size D of the beta-type zeolite is more preferably 5 μm or less, and even more preferably 1 μm or less. 90 The thickness is preferably 10 nm or more, more preferably 50 nm or more, and even more preferably 0.1 μm or more.

[0036] Furthermore, beta-type zeolite dispersed in an alkaline aqueous solution into primary particles has a large pore volume. Specifically, beta-type zeolite has a micropore volume of 0.15 cm³. 3 / g or more 0.30cm 3 A value of 0.18 cm² or less is preferable because it is advantageous when using the beta-type zeolite in various applications, such as catalysts, and is even more preferable. 3 It is 0.22m or more, and more preferably 0.22m 3 The value is 1 / g or more. The method for measuring the micropore volume is as described in the examples.

[0037] The beta-type zeolite obtained by the manufacturing method of the present invention can be used in a variety of applications by taking advantage of its high crystallinity and fine particle size. For example, it is suitably used as a catalytic material for purifying exhaust gases generated from internal combustion engines. Examples of catalytic materials include substrates and catalytically active components. Furthermore, it is suitably used in various industrial fields as an adsorbent that adsorbs only molecules of a specific size, and as a catalyst for organic compound synthesis reactions in the petrochemical industry. Furthermore, the beta-type zeolite obtained by the manufacturing method of the present invention can also be used as a seed crystal for synthesizing beta-type zeolite. Since this seed crystal is synthesized without the use of OSDA, the environmental impact can be minimized by using this seed crystal and synthesizing beta-type zeolite without OSDA. The method for synthesizing beta-type zeolite using a seed crystal and without OSDA is as described above. In detail, the seed crystal and a reaction mixture of a specific composition are mixed in a ratio of 0.1% to 20% by mass of the seed crystal relative to the silica component in the reaction mixture, and then heated in a sealed container at 100°C to 200°C. [Examples]

[0038] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. Unless otherwise specified, "%" means "mass%".

[0039] [Example 1] (1) Synthesis of OSDA-free beta-type zeolite mother powder As a seed crystal, a beta-type zeolite (HSZ931HOA (SiO2 / Al2O3 molar ratio = 28): manufactured by Tosoh Corporation) was prepared. An aluminosilicate gel with an SiO2 / Al2O3 molar ratio of 16 was prepared using sodium silicate No. 3, aluminum sulfate aqueous solution, sulfuric acid, and pure water. The synthesized gel slurry was filtered using a centrifuge and washed with pure water to obtain a hydrated aluminosilicate gel. The water content was 71.0%. A reaction mixture with the prepared aluminosilicate gel, a 50 w / v% sodium hydroxide aqueous solution, and pure water was prepared with a composition of SiO2 / Al2O3 molar ratio = 16, Na2O / SiO2 molar ratio = 0.23, and H2O / SiO2 molar ratio = 15, and this was mixed with the seed crystal. Then, the mixture was placed in a sealed container and heated at 150°C for 43 hours to synthesize beta-type zeolite without the use of OSDA. After cooling the sealed container, the product was filtered and washed with hot water to obtain a white powder. X-ray diffraction analysis of this product confirmed that it was a beta-type zeolite free of impurities. This beta-type zeolite was used as the mother powder. A SEM image of the mother powder is shown in Figure 4. Compositional analysis by ICP-MS revealed that the SiO2 / Al2O3 molar ratio of the mother powder was 9.8. The cumulative particle size D at a cumulative volume of 90% was measured by laser diffraction scattering particle size distribution analysis. 90 It was 23 μm.

[0040] Volume cumulative particle size D at 90% cumulative volume, as measured by laser diffraction scattering particle size distribution analysis. 90 The measurements were performed as follows: Using a laser diffraction scattering particle size distribution analyzer (Beckman Coulter "LS 13 320, Universal Liquid Module"), zeolite was added to pure water, dispersed by irradiating with ultrasound for 180 seconds at a flow rate of 40%, and then the particle size distribution was measured. The measurement conditions were: solvent refractive index 1.33, particle refractive index 1.50, measurement time 90 seconds, and measurement range 0.020 to 2000 μm.

[0041] (2) Treatment of mother powder with alkaline aqueous solution The mother powder of the beta-type zeolite was added to a 1.0 mol / L aqueous sodium hydroxide solution and stirred for 2 hours. The ratio of the mass of the beta-type zeolite mother powder to the volume of the aqueous sodium hydroxide solution was 40 g / L. The liquid temperature was maintained at 60°C during stirring. After that, solid-liquid separation was performed to recover the solid component. This solid component was washed with water and dried to obtain the target beta-type zeolite powder. The obtained beta-type zeolite was subjected to compositional analysis, and the SiO2 / Al2O3 molar ratio was measured. Furthermore, the micropore volume of the obtained beta-type zeolite was calculated. The micropore volume was calculated using the Microtrac-Bel "BELSORP MINI X" by analyzing the nitrogen adsorption isotherm measured at 77K after pretreatment at 400°C for 3 hours under vacuum, using the t-plot method. Furthermore, volume cumulative particle size D at a cumulative volume of 90% 90 The particle size distribution was measured using the laser diffraction scattering type particle size analyzer described above. The results are shown in Table 1. Figure 1 shows a scanning electron microscope (SEM) image of the beta-type zeolite.

[0042] (3) Synthesis of beta-type zeolites The beta-type zeolite obtained in (2) above (this beta-type zeolite was not manufactured using OSDA) was used as a seed crystal to synthesize the beta-type zeolite. Using the aluminosilicate gel prepared in (1) above, a 50 w / v% aqueous sodium hydroxide solution, and pure water, a reaction mixture with the following compositions was prepared: SiO2 / Al2O3 molar ratio = 16, Na2O / SiO2 molar ratio = 0.23, and H2O / SiO2 molar ratio = 15. This mixture was then mixed with a seed crystal, placed in a sealed container, and heated at 150°C for 48 hours to synthesize beta-type zeolite without the use of OSDA. After cooling the sealed container, the product was filtered and washed with warm water to obtain a white powder. X-ray diffraction measurements of this product confirmed that it was a beta-type zeolite free of impurities.

[0043] [Examples 2-5] In Example 1 (2), a beta-type zeolite was obtained in the same manner as in Example 1, except that the concentration of the aqueous sodium hydroxide solution was prepared as shown in Table 1. The SiO2 / Al2O3 molar ratio, micropore volume, and particle size D of the obtained beta-type zeolite were determined. 90 The values ​​were measured in the same manner as in Example 1. The results are shown in Table 1. The obtained beta-type zeolite was used as a seed crystal, and beta-type zeolite was synthesized in the same manner as in Example 1 (3). X-ray diffraction measurements of the obtained beta-type zeolite confirmed that the beta-type zeolite in Examples 2 and 3 was free of impurities.

[0044] [Example 6] In Example 1(2), 150 g of beta-type zeolite mother powder was added to 926 mL of a 2.0 mol / L aqueous sodium hydroxide solution. The volume of the aqueous sodium hydroxide solution relative to the mass of the beta-type zeolite mother powder was 162 g / L. Beta-type zeolite was obtained in the same manner as in Example 1. The SiO2 / Al2O3 molar ratio, micropore volume, and particle size D of the obtained beta-type zeolite were determined. 90 The values ​​were measured in the same manner as in Example 1. The results are shown in Table 1. The obtained beta-type zeolite was used as a seed crystal, and beta-type zeolite was synthesized in the same manner as in (3) of Example 1. X-ray diffraction measurements of the obtained beta-type zeolite confirmed that it was a beta-type zeolite free of impurities.

[0045] [Comparative Example 1] This comparative example is an example in which the treatment of the mother powder with the alkaline aqueous solution as in Example 1(2) was not performed. In this comparative example, the OSDA-free zeolite mother powder from Example 1 (2) was used as a seed crystal, and beta-type zeolite was synthesized in the same manner as in Example 1 (3). X-ray diffraction measurements of the obtained beta-type zeolite confirmed that it was a beta-type zeolite containing mordenite and amorphous material.

[0046] [Comparative Example 2] This comparative example shows that the OSDA free zeolite mother powder obtained in Example 1(2) was treated with an acidic aqueous solution instead of an alkaline aqueous solution. The OSDA free zeolite mother powder obtained in Example 1 (2) was added to a 0.1 mol / L sulfuric acid aqueous solution and stirred for 2 hours. The volume of the sulfuric acid aqueous solution relative to the mass of the OSDA free zeolite mother powder was 40 g / L. The liquid temperature was maintained at 60°C during stirring. After that, solid-liquid separation was performed to recover the solid component. This solid component was washed with water and dried to obtain beta-type zeolite powder. The SiO2 / Al2O3 molar ratio, micropore volume, and particle size D of the obtained beta-type zeolite were determined. 90 The parameters were measured in the same manner as in Example 1. The results are shown in Table 1. In this comparative example, the beta-type zeolite obtained underwent dealuminization due to the treatment of the mother powder with an acidic aqueous solution, resulting in an increased SiO2 / Al2O3 molar ratio compared to before treatment with the acidic aqueous solution. The obtained beta-type zeolite was used as a seed crystal, and beta-type zeolite was synthesized in the same manner as in Example 1 (3). X-ray diffraction measurements of the obtained beta-type zeolite confirmed that it was a beta-type zeolite containing a small amount of mordenite.

[0047] [Table 1]

[0048] As is clear from the results shown in Table 1, the beta-type zeolite obtained in each example has a particle size D 90 However, it is smaller than the beta-type zeolite in the comparative example, and it can be further atomized by treatment with an alkaline aqueous solution. Note that in Example 5, D 90 The reason why the value is larger than in the other examples is presumed to be that in Example 5, the mother powder of the beta-type zeolite aggregate was dispersed into primary particles and then re-aggregated. [Industrial applicability]

[0049] As described in detail above, the present invention provides a beta-type zeolite that is finely granular and useful for the synthesis of zeolites without the use of organic structure-determining agents, as well as a method for producing the same.

Claims

1. A method for producing beta-type zeolite, comprising: contacting a beta-type zeolite mother powder, synthesized without the use of organic structure-determining agents and having a cumulative volume particle size D90 of 10 μm or more and 200 μm or less at a cumulative volume of 90% by laser diffraction scattering particle size distribution measurement, with an alkaline aqueous solution with a pH of 14 or higher and an OH- ion concentration of 1.0 mol / L or higher, by mixing the mother powder / alkaline aqueous solution in a ratio of 30 g / L or more and 180 g / L or less, thereby reducing the particle size D90 to 7 μm or less.

2. The manufacturing method according to claim 1, wherein the temperature of the alkaline aqueous solution is set to 40°C or higher and 100°C or lower, and the mother powder and the alkaline aqueous solution are brought into contact.

3. The manufacturing method according to claim 1 or 2, comprising: mixing the beta-type zeolite obtained by contacting the mother powder with the alkaline aqueous solution with a reaction mixture having the composition shown below in molar ratios, in a ratio of 0.1% by mass or more and 20% by mass or less of the silica component in the reaction mixture, and then heating in a sealed environment at 100°C or more and 200°C or less. SiO 2 / Al 2 O 3 =10 to 200 Na 2 O / SiO 2 = 0.18 or higher, 0.4 or lower H 2 O / SiO 2 =10 or more, 50 or less

Images