Zeolite production method and zeolite

Abstract

Provided are a zeolite production method and a zeolite that enable the formation and / or enlargement of mesopores while still maintaining crystallinity.　This zeolite production method comprises: preparing a zeolite; bringing the zeolite and an alkaline solution into contact; and heating, in a gas, the zeolite containing the alkaline solution. When the zeolite containing the alkaline solution is heated, the content percentage of the zeolite is in the range of 30 mass% to 70 mass%, where the total of the alkaline solution and the zeolite is 100 mass%.

Description

Method for producing zeolite and zeolite

[0001] The present invention relates to a method for producing zeolite and zeolite.

[0002] Zeolite is a crystalline aluminosilicate and has uniform pores due to its crystal structure. Taking advantage of this feature, zeolite is industrially used as a molecular sieve adsorbent that adsorbs only molecules having a specific size, an adsorption separation agent that adsorbs molecules with strong affinity, or a catalyst substrate. For example, BEA type zeolite is used as a catalyst in the petrochemical industry and a catalyst for exhaust gas purification.

[0003] Zeolite has micropores with a pore diameter of 2 nm or less. The micropores of zeolite are an open and regular structure formed by the crystal structure of zeolite and have catalytic activity. When zeolite is used as a catalyst, a treatment for forming mesopores in the zeolite can also be performed. The mesopores of zeolite adsorb molecules and further transport the adsorbed molecules to the catalytic sites.

[0004] It is desired to increase the surface area of zeolite by forming and / or increasing mesopores while maintaining the crystal structure of zeolite, thereby enhancing the molecular adsorption ability and catalytic ability.

[0005] Patent Document 1 describes a method for producing mesoporous beta zeolite having an average pore diameter exceeding 8 nm by immersing parent beta zeolite in an aqueous metal hydroxide solution and mixing, and heating the mixture obtained by immersing the parent beta zeolite in an aqueous metal hydroxide solution at a mass ratio of 25 times or more based on 0.37 g of the mass of the parent beta zeolite to a temperature of 100° C. or higher.

[0006] Japanese Patent Application Laid-Open No. 2020-532480

[0007] However, when zeolite is immersed in an alkaline solution such as an aqueous metal hydroxide solution and the mixture of zeolite and the alkaline solution is heated to, for example, 100° C. or higher, defects may occur in the crystal structure of zeolite and the crystallinity may decrease.

[0008] Therefore, the present invention aims to provide a method for producing zeolite and a zeolite that can form and / or increase mesopores while maintaining the degree of crystallinity.

[0009] A first aspect of the present invention proposes a method for producing zeolite, comprising preparing zeolite, contacting the zeolite with an alkaline solution, and heating the zeolite containing the alkaline solution in a gas, wherein, when the heating is started, the content of the zeolite is in the range of 30% by mass or more and 70% by mass or less, when the total amount of the alkaline solution and the zeolite is 100% by mass.

[0010] A second aspect of the present invention is a zeolite in which the ratio A / B of the peak intensity A of the X-ray diffraction spectrum measured by X-ray diffraction of the zeolite to the peak intensity B of the (111) plane of the X-ray diffraction spectrum measured for Si, a standard material distributed by the National Institute of Standards and Technology, is 0.30 or more, and the ratio C (total specific surface area of ​​mesopores) / D (total specific surface area of ​​micropores) of the total specific surface area C of mesopores measured by the t-plot method of mesopores with a pore diameter in the range of more than 2 nm and less than or equal to 50 nm, measured by the BJH method, to the total specific surface area D of micropores measured by the t-plot method of micropores with a pore diameter of 2 nm or less, measured by the SF method, is in the range of 0.07 or more and 0.18 or less.

[0011] The present invention can provide a method for producing zeolite and a zeolite that can form and / or increase mesopores while maintaining crystallinity.

[0012] The X-ray diffraction spectra of the BEA-type zeolite obtained in Example 1 and Reference Example 1 are shown. The X-ray diffraction spectra of the BEA-type zeolite obtained in Example 2 and Comparative Example 2 are shown.

[0013] Next, the present invention will be described based on embodiments. However, the present invention is not limited to the embodiments described below.

[0014] The first embodiment is a method for producing zeolite, comprising preparing zeolite, contacting the zeolite with an alkaline solution, and heating the zeolite containing the alkaline solution in a gas, wherein, when the heating is started, the total amount of the alkaline solution and the zeolite is 100% by mass, and the zeolite content is in the range of 30% by mass or more and 70% by mass or less.

[0015] The hydroxyl groups in the alkaline solution react with the silicon in the zeolite, causing the silicon to dissolve into the alkaline solution and form mesopores in the zeolite framework. Furthermore, the hydroxyl groups in the alkaline solution react with the silicon in the zeolite, causing the silicon to dissolve into the alkaline solution and increasing the number of mesopores present in the zeolite framework. However, if a large volume of alkaline solution is present relative to the zeolite, it can cause excessive dissolution of silicon from the zeolite framework, potentially leading to a defect in the zeolite's skeletal structure. When heating of zeolite containing an alkaline solution begins, if the zeolite content is between 30% and 70% by mass (with the total of the alkaline solution and zeolite being 100% by mass), the amount of alkaline solution in contact with the zeolite is small, suppressing the defect in the zeolite's skeletal structure, maintaining crystallinity, and allowing for the formation and / or increase of mesopores, thereby increasing the surface area of ​​the zeolite. By forming and / or increasing mesopores within the zeolite framework, the surface area of ​​the zeolite can be increased, thereby enhancing the molecular adsorption, transport, and catalytic activity of the zeolite. For example, in the petrochemical industry, if mesopores can be formed and / or increased within the zeolite framework while maintaining the zeolite's crystalline structure, thereby increasing the surface area of ​​the zeolite, the reaction field for catalytic reactions can be increased, and the catalytic activity of the zeolite can further accelerate the decomposition of polymers to obtain the target substance. Furthermore, if the zeolite content, when the total amount of alkaline solution and zeolite is set to 100% by mass, is within the range of 30% to 70% by mass when heating of zeolite containing an alkaline solution begins, there is no need to separate the alkaline solution and zeolite solids and liquids after heating, and zeolite with an increased surface area can be efficiently obtained. When heating a zeolite containing an alkaline solution begins, if the zeolite content is less than 30% by mass when the total amount of alkaline solution and zeolite is considered to be 100% by mass, the amount of alkaline solution relative to the zeolite becomes large, making it easier for defects to occur in the zeolite's crystal structure.When heating zeolite containing an alkaline solution, if the zeolite content exceeds 70% by mass when the total of the alkaline solution and zeolite is set to 100% by mass, the mass of the alkaline solution for forming and / or increasing mesopores is insufficient relative to the mass of the zeolite, making it difficult to increase the surface area of ​​the zeolite. When starting to heat zeolite containing an alkaline solution, the zeolite content when the total of the alkaline solution and zeolite is set to 100% by mass is preferably in the range of 35% by mass or more and 65% by mass or less, and more preferably in the range of 40% by mass or more and 60% by mass or less. The zeolite content when the total of the alkaline solution and zeolite is set to 100% by mass can be calculated based on the following formula (I): Zeolite content in the total of alkaline solution and zeolite (mass%) = 100 - (moisture content (mass%) × specific gravity of alkaline solution) (I) The moisture content in formula (I) can be measured by a heat-drying type moisture meter described later.

[0016] Contact between zeolite and alkaline solution can be carried out, for example, by immersing the zeolite in the alkaline solution, or by dropping, coating, or spraying the alkaline solution onto the zeolite. Contact between zeolite and alkaline solution may be carried out by combining two or more methods. Preferably, the contact between zeolite and alkaline solution is adjusted so that the zeolite content, when the total amount of alkaline solution and zeolite is 100% by mass, falls within the above range.

[0017] When immersing zeolite in an alkaline solution, the immersion time is preferably adjusted so that the zeolite content, when the total of the alkaline solution and zeolite is considered to be 100% by mass, falls within the above range. The immersion time is not particularly limited, but is preferably 1 minute or more, more preferably 5 minutes or more, and even more preferably 10 minutes or more. The upper limit of the immersion time can be adjusted as appropriate. The immersion time may be, for example, 60 minutes or less, or 120 minutes or less. The method for recovering the zeolite immersed in the alkaline solution is not particularly limited. For example, the zeolite immersed in the alkaline solution can be recovered by filtration.

[0018] When adding, coating, or spraying an alkaline solution onto zeolite, it is preferable that the amount of alkaline solution added, coated, or sprayed be adjusted so that the zeolite content, when the total of the alkaline solution and zeolite is considered to be 100% by mass, falls within the above range.

[0019] Zeolites have a tetrahedral structure. ４ This refers to a crystalline material in which units (T being the central atom) are linked three-dimensionally by sharing oxygen (O) atoms, forming open, regular micropores. Specifically, zeolites are such crystalline materials that are assigned a three-letter alphabetical structural code defined by the International Zeolite Association (IZA). The skeletal structure of zeolites can be found in the database of the IZA's Structural Committee (Databases of Zeolite Structures, Structure Committee of the International Zeolite Association).

[0020] The skeletal structure of the zeolite to be prepared is not particularly limited. Examples of zeolites include BEA (e.g., beta zeolite), MSE, -SVR, FAU (e.g., zeolite Y), MOR, CON, SOF, MFI (e.g., ZSM-5), IMF, FER, MWW, MTT, TON, EUO, MRE, NAT, CHA, or combinations thereof. Zeolites may also be described as "type zeolite" in addition to the three-letter alphabetical skeletal structure defined by the International Zeolite Society.

[0021] The zeolite is preferably at least one selected from the group consisting of BEA-type zeolite, MSE-type zeolite, -SVR-type zeolite, FAU-type zeolite, MOR-type zeolite, CON-type zeolite, SOF-type zeolite, MFI-type zeolite, IMF-type zeolite, FER-type zeolite, MWW-type zeolite, MTT-type zeolite, TON-type zeolite, EUO-type zeolite, MRE-type zeolite, NAT-type zeolite, and CHA-type zeolite.

[0022] The zeolite before heating preferably has a SiO ２ / Al ２ O ３ molar ratio within the range of 10 or more and 100 or less. The zeolite before heating preferably has a SiO ２ / Al ２ O ３ molar ratio within the range of 12 or more and 80 or less, more preferably within the range of 15 or more and 70 or less, and even more preferably within the range of 18 or more and 60 or less. When the SiO ２ / Al ２ O ３ molar ratio of the zeolite is within the range of 10 or more and 100 or less, the crystal structure is stable and it has excellent heat resistance. Due to the framework structure of the zeolite, the crystal structure is stabilized and the SiO ２ / Al ２ O ３ molar ratio ranges are different. For example, in the case of BEA-type zeolite with a BEA framework structure, the SiO ２ / Al ２ O ３ molar ratio is preferably within the range of 10 or more and 80 or less, more preferably within the range of 12 or more and 70 or less, and even more preferably within the range of 15 or more and 60 or less. When the SiO ２ / Al ２ O ３ molar ratio of the BEA-type zeolite is 10 or more and 100 or less, the molar ratio of Al ２ O ３ in the zeolite is relatively high, and tetracoordinate Al that functions relatively easily as an acid site is present in the framework structure. The acid site adjacent to the Al atom in the framework structure of the zeolite becomes a Bronsted acid site that is the center of catalytic activity, and the catalytic ability can be enhanced. The trivalent Al in the framework structure of the zeolite becomes a Lewis acid site, which is an acid site other than the acid site that is the center of catalytic activity. The SiO ２ / Al ２ O ３ molar ratio is measured by using a fluorescent X-ray analyzer (for example, manufactured by Rigaku Corporation) as a composition analyzer to measure the amount of aluminum (Al) and silicon (Si) in the zeolite, and SiO ２ / Al２ O ３ The molar ratio can be calculated.

[0023] The zeolite to be prepared may be synthesized using an Organic Structure-Directing Agent (OSDA, also referred to as a "template molecule"), or it may be synthesized without using OSDA. For example, BEA-type zeolite can be synthesized by reacting a mixture containing a silica source, an alumina source, an alkali metal source, OSDA, and water.

[0024] The zeolite to be prepared is preferably one synthesized without the use of OSDA. Since OSDA is relatively expensive, using a zeolite synthesized without OSDA allows for the production of a zeolite with reduced manufacturing costs. The zeolite is synthesized without the use of OSDA and contains SiO ２ / Al ２ O ３ Zeolites with a molar ratio between 10 and 100 can be obtained while reducing manufacturing costs, maintaining high heat resistance and high crystallinity, and forming mesopores. For example, the crystal shape of BEA-type zeolites differs between those synthesized using OSDA and those synthesized without OSDA. BEA-type zeolites synthesized without OSDA have a roughly octahedral shape. For example, it is possible to confirm that a zeolite is a BEA-type zeolite synthesized without OSDA by observing it with a scanning electron microscope.

[0025] Prepare the SiO in the zeolite ２ When the total is set to 100 mol%, it is preferable that the amount of hydroxyl groups in the alkaline solution contained in the zeolite at the start of heating the zeolite containing the alkaline solution is in the range of 0.05 mol% to 10.00 mol%. ２When the amount of hydroxyl groups in the alkaline solution at the start of heating the zeolite containing the alkaline solution is set to 100 mol%, the amount of SiO constituting the zeolite's framework is within the range of 0.05 mol% to 10.00 mol%. ２ For this purpose, the amount of hydroxyl groups in the alkaline solution is appropriate, and when heated, it is possible to form and / or increase mesopores while suppressing defects that occur in the crystal structure of the zeolite, thereby increasing the surface area of ​​the zeolite. ２ When the total is set to 100 mol%, the amount of hydroxyl groups in the alkaline solution is more preferably in the range of 0.06 mol% to 8.00 mol%, even more preferably in the range of 0.07 mol% to 6.00 mol%, and even more preferably in the range of 0.08 mol% to 5.00 mol%. SiO in zeolite ２ The molar amount is SiO ２ / Al ２ O ３ Similar to when measuring the molar ratio, the amount of silicon (Si) in the zeolite was measured using a compositional analyzer, such as an X-ray fluorescence analyzer (e.g., manufactured by Rigaku Corporation), and the obtained measurement values ​​were used to determine the amount of SiO ２ The molar amount can be calculated. The amount of hydroxyl groups in an alkaline solution hardly changes from about 60 minutes before heating to the start of heating, provided that the temperature of the zeolite containing the alkaline solution is at room temperature (25°C ± 5°C).

[0026] SiO in zeolite ２When the alkali source is 100 mol%, the amount of hydroxyl groups in the alkaline solution can be calculated based on the following formulas (II) and (III) when the alkaline solution uses alkali metal hydroxide as the alkali source. Mass of alkaline solution (g) = Mass of zeolite containing alkaline solution (g) × Moisture content (mass%) × Specific gravity of alkaline solution (II) (In formula (II), the moisture content can be measured by a heat drying type moisture meter described later.) Molar amount of alkali metal hydroxide (mol) = (Mass of alkaline solution (g) / Density of alkaline solution (g / L)) × Concentration of alkali metal hydroxide in alkaline solution (mol / L) (III) The molar amount of alkali metal hydroxide (mol) calculated based on the above formulas (II) and (III) is used to measure the amount of alkali metal hydroxide in the zeolite. ２ This was defined as the amount of hydroxyl groups in the alkaline solution when the concentration was set to 100 mol%.

[0027] Alkali sources included in alkaline solutions include alkali metal hydroxides. It is preferable to use at least one alkali metal hydroxide selected from the group consisting of lithium hydroxide, potassium hydroxide, and sodium hydroxide. The alkali source included in the alkaline solution may be a single type or a combination of two or more types. As the alkali source included in the alkaline solution, it is preferable to use potassium hydroxide and / or sodium hydroxide, which are inexpensive and readily available.

[0028] The concentration of the alkali source in the alkaline solution is the SiO2 in the zeolite. ２ When the total is set to 100 mol%, the amount of hydroxyl groups in the alkaline solution is within the range of 0.05 mol% to 10.00 mol%, but there are no particular limitations. If the alkali source contained in the alkaline solution is an alkali metal hydroxide, the concentration of the alkali metal hydroxide in the alkaline solution may be in the range of 0.005 mol / L to 1.0 mol / L, in the range of 0.01 mol / L to 0.8 mol / L, or in the range of 0.01 mol / L to 0.7 mol / L.

[0029] When heating zeolite containing an alkaline solution, the temperature is preferably in the range of above room temperature (e.g., 25°C ± 5°C) and below 120°C. If the temperature when heating zeolite containing an alkaline solution is in the range of above room temperature (e.g., 25°C ± 5°C) and below 120°C, it is possible to suppress the formation of defects in the crystal structure of the zeolite, maintain a high degree of crystallinity, and increase the surface area of ​​the zeolite by forming and / or increasing mesopores. In order to suppress defects in the crystal structure of the zeolite when heating, the temperature when heating zeolite containing an alkaline solution is more preferably in the range of above 50°C to 110°C, even more preferably in the range of above 60°C to 100°C, and still more preferably in the range of above 70°C to 90°C.

[0030] The heating time for the zeolite containing the alkaline solution is preferably between 1 hour and 48 hours, but may also be between 2 hours and 36 hours, or between 3 hours and 25 hours. If the heating time for the zeolite containing the alkaline solution is between 1 hour and 48 hours, it is possible to suppress the formation of defects in the crystal structure of the zeolite, maintain a high degree of crystallinity, and increase the surface area of ​​the zeolite by forming and / or increasing mesopores.

[0031] The heat treatment of zeolite containing an alkaline solution is carried out in a gaseous environment. That is, the heat treatment of zeolite containing an alkaline solution is carried out in an environment filled with gas (hereinafter referred to as "atmosphere"). Examples of atmospheres include oxidizing atmospheres and inert atmospheres. An oxidizing atmosphere is an atmosphere containing one or more oxidizing gases. In addition to one or more oxidizing gases, an oxidizing atmosphere may also contain one or more other gases (for example, one or more inert gases). An inert atmosphere is an atmosphere composed of one or more inert gases. Examples of oxidizing gases include air (atmosphere), oxygen, water vapor, and mixtures of two or more of these. Examples of inert gases include nitrogen gas, carbon dioxide gas, argon gas, and mixtures of two or more of these.

[0032] The heat treatment of zeolite containing an alkaline solution may be carried out while humidifying the zeolite containing the alkaline solution. For example, the heat treatment of the zeolite containing an alkaline solution may be carried out while supplying water vapor to the zeolite containing the alkaline solution, or the heat treatment of the zeolite containing an alkaline solution may be carried out with water present in the container containing the zeolite (provided that the water is not in contact with the zeolite containing the alkaline solution).

[0033] The heat treatment of zeolite containing an alkaline solution is preferably carried out under conditions that maintain the zeolite's state of containing the alkaline solution.

[0034] In one embodiment, the heat treatment of the zeolite containing the alkaline solution is performed while the zeolite containing the alkaline solution is contained in a sealed or sealed container. For example, by covering the container containing the zeolite containing the alkaline solution, the opening of the container containing the zeolite containing the alkaline solution can be closed, thereby creating a sealed or sealed state.

[0035] In another embodiment, the heat treatment of the zeolite containing the alkaline solution is carried out with the zeolite containing the alkaline solution contained in an open container. For example, the container can be left open by not covering it, or by covering it with a lid that has holes. The holes in the lid function to allow steam from inside the container to escape. Examples of lids with holes include airtight lids with holes formed in them, porous lids (e.g., paper), and the like.

[0036] The zeolite after heating may undergo post-treatment such as washing, solid-liquid separation, and drying. For washing, water or deionized water can be used. Solid-liquid separation can be performed by industrially commonly used methods such as filtration, suction filtration, or heat filtration. Drying is preferably performed at a temperature of room temperature (e.g., 25°C ± 5°C) to 120°C.

[0037] The second embodiment is a zeolite in which the ratio A / B of the peak intensity A of the X-ray diffraction spectrum measured by X-ray diffraction of the zeolite to the peak intensity B of the (111) plane of the X-ray diffraction spectrum measured for Si, a standard material distributed by the National Institute of Standards and Technology, is 0.30 or more, and the ratio C (specific surface area of ​​total mesopores) / D (specific surface area of ​​total micropores) of the total mesopores measured by the t-plot method of mesopores with a pore diameter in the range of more than 2 nm and less than or equal to 50 nm, measured by the BJH method of the zeolite, to the total specific surface area D of micropores measured by the t-plot method of micropores with a pore diameter of 2 nm or less, measured by the SF method, is in the range of 0.07 or more and 0.18 or less. The zeolite is preferably a zeolite obtained after heating in the above-described manufacturing method.

[0038] The crystallinity of zeolites is indicated by the ratio A / B, which is the ratio of the peak intensity A in the X-ray diffraction spectrum of the zeolite to the peak intensity B of the (111) plane in the X-ray diffraction spectrum of Si, a standard material distributed by the National Institute of Standards and Technology (NIST). If the ratio A / B is 0.30 or higher, the zeolite maintains a high degree of crystallinity and has a stable crystal structure. In the manufacturing method of zeolite, if the ratio A / B of the zeolite after heating the zeolite containing an alkaline solution is 0.30 or higher, the high degree of crystallinity of the zeolite is maintained even after heating the zeolite containing the alkaline solution and has a stable crystal structure. The ratio A / B may be 0.31 or higher, 0.32 or higher, 0.33 or higher, preferably 0.55 or lower, but may also be 0.50 or lower, or 0.45 or lower. The X-ray diffraction spectrum of the zeolite can be measured using an X-ray diffractometer (e.g., RINT-TTR III, manufactured by Rigaku Corporation) with CuKα rays (0.15406 nm, 50 kV, 300 mA) as the X-ray source.

[0039] For zeolites, the ratio C (specific surface area of ​​mesopores total) / D (specific surface area of ​​micropores total) of the total surface area C of mesopores (mesopores with a pore diameter of more than 2 nm and less than or equal to 50 nm, measured by the t-plot method of zeolites) and the total surface area D of micropores (mesopores with a pore diameter of 2 nm or less, measured by the t-plot method of zeolites) serves as an indicator of whether or not mesopores are being formed and / or increasing. A larger ratio C / D indicates that mesopores are being formed and / or increasing relative to micropores. If the ratio C / D is within the range of 0.07 to 0.18, it means that mesopores are being formed and / or increasing while maintaining a high degree of crystallinity, suppressing the formation of defects in the zeolite's crystal structure, and thus increasing the surface area of ​​the zeolite. If the zeolite has a C / D ratio of 0.07 to 0.18, even after heating the zeolite containing an alkaline solution, it maintains a high degree of crystallinity while mesopores are formed and / or enlarged, increasing the surface area of ​​the zeolite. In other words, mesopores are formed and / or enlarged in the framework while retaining micropores derived from the zeolite. The inventors speculate that silicon preferentially dissolves from parts that are more easily eluted than the silicon forming the zeolite framework (for example, amorphous material contained in the zeolite), and the silicon forming the framework is less likely to dissolve, thus enabling the formation and / or enlargement of mesopores while maintaining micropores in the zeolite framework. The zeolite preferably has a C / D ratio in the range of 0.08 to 0.17, but may also be 0.08 to 0.15.

[0040] Zeolites include mesopores, which are measured by the BJH method (Barrett-Joyner-Halenda method) with a pore diameter in the range of greater than 2 nm and less than or equal to 50 nm, and micropores, which are measured by the SF method (Saito-Foley method) with a pore diameter in the range of less than or equal to 2 nm. Here, pore diameter refers to the crystallographic free diameter of the channels as defined by IZA. If the shape of the pore (channel) is perfectly circular, the pore diameter refers to its average diameter. If the shape of the pore is elongated in one direction, such as an ellipse, it refers to the minor axis. The pore diameter of mesopores of zeolites measured by the BJH method may be between 2.1 nm and 50 nm. The pore diameter of micropores of zeolites measured by the SF method may be greater than 0 nm and less than or equal to 2 nm. The lower limit of the pore diameter of the micropores of the zeolite measured by the SF method may be the detection limit measured by the SF method.

[0041] The specific surface area measured by the t-plot method can be determined by nitrogen physicoadsorption. The specific surface area measured by the t-plot method is determined from a graph plotting the thickness of the nitrogen adsorption layer on the horizontal axis and the amount of adsorption on the vertical axis, based on the adsorption isotherms of mesopores or micropores obtained by nitrogen adsorption measurement.

[0042] Zeolites with the aforementioned ratio A / B of 0.30 or higher, and ratio C / D of 0.07 or higher and 0.18 or lower, are SiO ２ / Al ２ O ３ The molar ratio is preferably in the range of 10 to 100, more preferably in the range of 12 to 80, even more preferably in the range of 15 to 70, and still more preferably in the range of 18 to 60. The SiO of the zeolite has the aforementioned ratio A / B of 0.30 or more and ratio C / D of 0.07 or more and 0.18 or less. ２ / Al ２ O ３When the molar ratio is within the range of 10 to 100, the crystalline structure of the zeolite remains stable even after heating, and it exhibits excellent heat resistance. Furthermore, when the aforementioned ratio A / B is 0.30 or higher and the ratio C / D is 0.07 to 0.18, the SiO of the zeolite is stable. ２ / Al ２ O ３ If the molar ratio is within the range of 10 to 100, then Al in the zeolite ２ O ３ The molar ratio of is relatively high, and four-coordinate Al, which is relatively easy to function as an acid site, is present in the skeletal structure. Acid sites adjacent to Al atoms in the zeolite skeletal structure become Brønsted acid sites, which are the centers of catalytic activity, and thus the catalytic activity can be enhanced.

[0043] Zeolites having the aforementioned ratio A / B of 0.30 or higher and ratio C / D of 0.07 or higher and 0.18 or lower are preferably zeolites synthesized without the use of OSDA. By using zeolites synthesized without OSDA, it is possible to obtain zeolites with reduced manufacturing costs.

[0044] The zeolite having the aforementioned ratio A / B of 0.30 or more and ratio C / D of 0.07 or more and 0.18 or less is preferably at least one selected from the group consisting of BEA type zeolite, MSE type zeolite, -SVR type zeolite, FAU type zeolite, MOR type zeolite, CON type zeolite, SOF type zeolite, MFI type zeolite, IMF type zeolite, FER type zeolite, MWW type zeolite, MTT type zeolite, TON type zeolite, EUO type zeolite, MRE type zeolite, NAT type zeolite, and CHA type zeolite.

[0045] Embodiments of the present invention encompass the following technical ideas: [1] A method for producing zeolite, comprising: preparing zeolite; contacting the zeolite with an alkaline solution; and heating the zeolite containing the alkaline solution in a gas, wherein, when the heating is started, the content of the zeolite is in the range of 30% by mass or more and 70% by mass or less, when the total amount of the alkaline solution and the zeolite is 100% by mass. [2] The SiO of the zeolite before heating. ２ / Al ２ O ３ A method for producing the zeolite described in [1], wherein the molar ratio is in the range of 10 to 100. [3] SiO in the zeolite ２A method for producing a zeolite according to [1] or [2], wherein when the amount is 100 mol%, the amount of hydroxyl groups in the alkaline solution is in the range of 0.05 mol% to 10.00 mol%. [4] A method for producing a zeolite according to any one of [1] to [3], wherein the zeolite is a zeolite synthesized without using an organic structure-determining agent. [5] A method for producing a zeolite according to any one of [1] to [4], wherein the zeolite is a zeolite having at least one skeletal structure selected from the group consisting of BEA type zeolite, MSE type zeolite, -SVR type zeolite, FAU type zeolite, MOR type zeolite, CON type zeolite, SOF type zeolite, MFI type zeolite, IMF type zeolite, FER type zeolite, MWW type zeolite, MTT type zeolite, TON type zeolite, EUO type zeolite, MRE type zeolite, NAT type zeolite, and CHA type zeolite. [6] A method for producing a zeolite according to any one of [1] to [5], wherein the ratio A / B of the peak intensity A of the X-ray diffraction spectrum of the heated zeolite measured by X-ray diffraction and the peak intensity B of the (111) plane of the X-ray diffraction spectrum of Si, a standard material distributed by the National Institute of Standards and Technology, is 0.30 or more, and the ratio C (specific surface area of ​​total mesopores) / D (specific surface area of ​​total micropores) of the total mesopores measured by the t-plot method of mesopores with a pore diameter in the range of more than 2 nm and less than or equal to 50 nm, measured by the BJH method of the heated zeolite, and the ratio C (specific surface area of ​​total mesopores) / D (specific surface area of ​​total micropores) of the total micropores measured by the t-plot method of micropores with a pore diameter of 2 nm or less, measured by the SF method, is in the range of 0.07 or more and 0.18 or less.[7] A zeolite in which the ratio A / B of the peak intensity A of the X-ray diffraction spectrum measured by X-ray diffraction of the zeolite to the peak intensity B of the (111) plane of the X-ray diffraction spectrum measured for Si, a standard material distributed by the National Institute of Standards and Technology, is 0.30 or more, and the ratio C (total specific surface area of ​​mesopores) / D (total specific surface area of ​​micropores) of the total specific surface area C of mesopores measured by the t-plot method of mesopores with a pore diameter of more than 2 nm and less than or equal to 50 nm, measured by the BJH method, to the total specific surface area D of micropores measured by the t-plot method of micropores with a pore diameter of 2 nm or less, measured by the SF method, is in the range of 0.07 or more and 0.18 or less. [8] SiO of the zeolite. ２ / Al ２ O ３ [7] The zeolite according to [7], wherein the molar ratio is in the range of 10 to 100. [9] The zeolite according to [7] or [8], wherein the zeolite is a zeolite synthesized without using an organic structure-determining agent.

[10] The zeolite according to any one of [7] to [9], wherein the zeolite is a zeolite having at least one skeletal structure selected from the group consisting of BEA type zeolite, MSE type zeolite, -SVR type zeolite, FAU type zeolite, MOR type zeolite, CON type zeolite, SOF type zeolite, MFI type zeolite, IMF type zeolite, FER type zeolite, MWW type zeolite, MTT type zeolite, TON type zeolite, EUO type zeolite, MRE type zeolite, NAT type zeolite, and CHA type zeolite.

[0046] The present invention will be described in further detail below based on examples, comparative examples, and reference examples. The present invention is not limited to these examples.

[0047] Preparation of Zeolites Used in Example 1 and Reference Example 1 OSDA-free BEA-type zeolite was prepared in accordance with the method described in the examples of International Publication No. 2021 / 002322, specifically as follows: (1) Preparation of Seed Crystals Tetraethylammonium hydroxide was used as OSDA, sodium aluminate as the alumina source, and finely powdered silica (Mizusawa Chemical Industries, Ltd., P707) as the silica source. These were heated with stirring at 165°C for 96 hours to synthesize BEA-type zeolite with a Si / Al molar ratio of 12. The obtained BEA-type zeolite was calcined in an electric furnace at 550°C for 10 hours while circulating air to produce organic matter-free seed crystals. The seed crystals did not contain OSDA.

[0048] (2) Preparation of OSDA-free sodium-type BEA zeolite (Na-BEA) OSDA-free sodium-type BEA zeolite was prepared in accordance with the method described in the examples of Japanese Patent No. 4904417, specifically as follows: 2.35 g of sodium aluminate and 18.28 g of 36% by mass sodium hydroxide were dissolved in 139 g of deionized water to obtain an aqueous solution. A mixture of 20.24 g of finely powdered silica (M-5, manufactured by CABOT) and 2.02 g of the seed crystal was gradually added to the aqueous solution and stirred to obtain a reaction mixture. This reaction mixture was placed in a 60 mL stainless steel sealed container and heated at 140°C for 46 hours under self-stimulating pressure without aging or stirring. After the sealed container cooled, the product was filtered and washed with hot water to obtain a white powder.

[0049] (3) OSDA-free ammonium type BEA type zeolite (NH ３Preparation of BEA-type zeolite 1000 g of the obtained OSDA-free sodium-type BEA-type zeolite and 2000 g of pure water were mixed to obtain a zeolite mixture. The weight of the BEA-type zeolite is the weight in the dry state. Here, the dry state refers to a state in which the change (range of variation) of the moisture content measured with a heating and drying type moisture meter (MX-50, manufactured by A&D Co., Ltd.) is 0.01% or less. The zeolite mixture was placed in a flask and heated to 100°C, and while stirring, 75% sulfuric acid was continuously supplied (dropped) at a rate of 0.78 mL / min for 6.2 hours. After continuously supplying sulfuric acid to the zeolite mixture, the zeolite was allowed to mature in contact with sulfuric acid for 8.8 hours without separating the sulfuric acid and zeolite. After cooling, the product was filtered and washed with warm water to obtain a white powder. 10 g of the obtained white powder was dispersed in 300 mL of 2 mol / L aqueous solution of ammonium nitrate. This dispersion was kept at 80°C for 24 hours. The dispersion was then filtered, washed with a sufficient amount of distilled water, and dried overnight at 100°C. In this manner, OSDA-free ammonium type BEA-type zeolite (NH4) was obtained. ３ -BEA) was obtained.

[0050] (4) Preparation of OSDA-free proton-type BEA-type zeolite (H-BEA) The obtained OSDA-free ammonium-type BEA-type zeolite was calcined at 600°C for 2 hours under an ammonia atmosphere to obtain OSDA-free proton-type BEA-type zeolite (H-BEA). X-ray diffraction measurement described later confirmed that the obtained product, a white powder, was OSDA-free proton-type BEA-type zeolite (H-BEA) free of impurities. SiO of the obtained OSDA-free BEA-type zeolite ２ / Al ２ O ３ The molar ratio was measured using a scanning X-ray fluorescence analyzer, as described later.

[0051] Preparation of zeolites used in Examples 2 to 6 and Comparative Examples 1 to 3: OSDA free ammonium type BEA type zeolite (NH ３ The zeolite used in Example 1 was prepared in the same manner as in Example 1, except that the method for preparing the BEA was as follows.

[0052] OSDA-free ammonium type BEA type zeolite (NH ３ Preparation of BEA-type zeolite 1000 g of the obtained OSDA-free sodium-type BEA-type zeolite and 2000 g of pure water were mixed to obtain a zeolite mixture. The weight of the BEA-type zeolite is the weight in the dry state. Here, the dry state refers to a state in which the change (range of variation) of the moisture content measured with a heating and drying type moisture meter (MX-50, manufactured by A&D Co., Ltd.) is 0.01% or less. The zeolite mixture was placed in a flask and heated to 100°C, and while stirring, 75% sulfuric acid was continuously supplied (drop-in) at a rate of 0.78 mL / min for 9.9 hours. After continuously supplying sulfuric acid to the zeolite mixture, the zeolite was allowed to mature in contact with sulfuric acid for 5 hours without separating the sulfuric acid and zeolite. After cooling, the product was filtered and washed with warm water to obtain a white powder. 10 g of the obtained white powder was dispersed in 300 mL of 2 mol / L aqueous solution of ammonium nitrate. This dispersion was kept at 80°C for 24 hours. The dispersion was then filtered, washed with a sufficient amount of distilled water, and dried overnight at 100°C. In this manner, OSDA-free ammonium type BEA-type zeolite (NH4) was obtained. ３ -BEA) was obtained.

[0053] Examples 1 to 6 Sodium hydroxide (NaOH) was prepared as an alkali source, and an alkaline solution was prepared to the concentration shown in Table 1. The zeolite used in Example 1 and the zeolite used in Examples 2 to 6 were immersed in the alkaline solution for 1 minute, and after contacting the alkaline solution with the zeolite, solid-liquid separation was performed by filtration to prepare zeolite containing the alkaline solution. The zeolite content when the total of the alkaline solution and zeolite is set to 100% by mass was specifically calculated based on the following formula (I-1): Zeolite content in the total of alkaline solution and zeolite (mass%) = 100 - (moisture content (mass%) × specific gravity of alkaline solution) (I-1) The moisture content in formula (I-1) can be measured by the heating-drying type moisture meter described above. The zeolite containing the alkaline solution was placed in a drying oven and heated in an air atmosphere (standard pressure: 0.101 MPa, oxygen concentration of approximately 20% by volume) at the temperature and time shown in Table 1. Heating was performed with the zeolite containing the alkaline solution in a sealed container, i.e., with the opening closed (sealed). A magnetic dish was used as the container, and aluminum foil was used as the lid. The moisture content (mass%) in formula (I-1) can be similarly measured for moisture content (mass%) in other formulas. After heating, the zeolite was removed from the drying oven, cooled to room temperature (25°C ± 5°C), washed with deionized water, separated into solid and liquid by suction filtration, and then dried in a drying oven at 120°C for 12 hours to obtain the heated zeolite.

[0054] Comparative Examples 1 to 3: Sodium hydroxide (NaOH) was prepared as an alkali source, and an alkaline solution was prepared to the concentrations shown in Table 1. The zeolite and the alkaline solution were mixed and brought into contact in the mass ratio shown in Table 1, and while immersed in an alkaline solution 100 times the mass of the zeolite, the mixture was heated in an air atmosphere (standard pressure: 0.101 MPa, oxygen concentration of approximately 20 vol%) at the temperature and time shown in Table 1. After heating, the zeolite in the alkaline solution was separated into solid and liquid by suction filtration, and after solid and liquid separation, it was dried in a drying oven at 120°C for 12 hours to obtain the heated zeolite.

[0055] Reference Example 1: The zeolite before contact with the alkaline solution is referred to as Reference Example 1. Reference Example 1 is the zeolite used in Example 1.

[0056] The following evaluations were performed on the zeolites of Examples 1 to 6, the comparative examples, and the reference examples. The results are shown in Table 1. In Table 1, "-" indicates that there is no numerical value for the corresponding item.

[0057] The zeolite used to prepare the zeolite framework was confirmed to be a BEA-type zeolite by measuring the X-ray diffraction spectrum of the zeolite obtained using a powder X-ray diffractometer. In the X-ray diffraction spectrum using CuKα rays obtained with a powder X-ray diffractometer, if diffraction peaks are found at diffraction angles 2θ of 8±1.5° and 22.8±1°, it can be confirmed that it is a BEA-type zeolite. The positions of the diffraction peaks at diffraction angles 2θ (°) in the above X-ray diffraction spectrum are the same as the positions of the diffraction peaks at diffraction angles 2θ (°) in the X-ray diffraction spectrum of BEA-type zeolites published by the International Zeolite Society.

[0058] Zeolite SiO ２ / Al ２ O ３ Using a molar ratio scanning X-ray fluorescence analyzer (ZSX Primus II, manufactured by Rigaku Corporation), the Si and Al content in each zeolite sample before and after heating was measured by elemental analysis, and SiO was calculated from the measured Si and Al content. ２ / Al ２ O ３ The molar ratio was calculated. The sample was prepared by packing zeolite into a 30 mm diameter polyvinyl chloride tube and compressing it.

[0059] Amount of hydroxyl groups (OH (mol%)) of zeolite SiO ２ / Al ２ O ３ SiO when the molar ratio is measured ２Assuming a concentration of 100 mol%, the amount of hydroxyl groups in the alkaline solution (NaOH solution) when sodium hydroxide (NaOH) was used as the alkali source was calculated based on the following formulas (II-1) and (III-1). Mass of NaOH aqueous solution (g) = Mass of zeolite containing alkaline solution (g) × Water content (mass%) × Specific gravity of alkaline solution (II-1) Molar amount of NaOH (mol) = (Mass of NaOH solution (g) / Density of NaOH solution (g / L)) × Concentration of NaOH in NaOH solution (mol / L) (III-1) The molar amount of NaOH (mol) calculated based on the above formulas (II-1) and (III-1) was used to determine the amount of SiO in the zeolite. ２ This was defined as the amount of hydroxyl groups in the alkaline solution when the concentration was set to 100 mol%.

[0060] Ratio A / B (Crystallization) X-ray diffraction spectra were measured by XRD using an X-ray diffractometer (Rigaku Corporation, RINT-TTR III) with CuKα rays (0.15406 nm, 50 kV, 300 mA) as the X-ray source. The measurement range was 2θ = 5° to 80°, with a scan speed of 20° / min and a scan step width of 0.02°. The software "PDXL2" was used for the analysis of diffraction intensity. After background removal, the intensity of the diffraction peak was obtained by fitting the Kα1 position as the peak position with a segmented pseudo-Voigt function. The peak intensity B of the (111) plane was determined from the X-ray diffraction spectrum of Si, which is standard material 640c distributed by the National Institute of Standards and Technology, and the maximum diffraction intensity A of the peaks was determined from the X-ray diffraction spectra of each zeolite measured in the examples, reference examples, and comparative examples. The ratio A / B of the maximum diffraction intensity of the peaks to the peak intensity B was determined. Figure 1 shows the X-ray diffraction spectra of the zeolite according to Example 1 and Reference Example 1, and Figure 2 shows the X-ray diffraction spectra of the zeolite according to Example 2 and Comparative Example 2.

[0061] Specific C / D (Specific surface area of ​​total mesopores / Specific surface area of ​​total micropores) Nitrogen adsorption isotherm measurement The nitrogen adsorption isotherm of the zeolite was measured using a high-precision gas / vapor adsorption amount measuring device (model: BELSORP-maxII, manufactured by Microtrac Bell Co., Ltd.) by adsorbing high-purity nitrogen gas onto the sample at 77K and measuring by volumetric method. 0.1g to 0.2g of the dry weight sample was weighed into a sample tube. Pre-treatment for measurement was performed by vacuum evacuation at 510°C (1 × 10⁻⁶). －５ The process was carried out at kPa for more than 8 hours. The nitrogen adsorption isotherm was measured at relative pressure (P / P). ０ Measurements were taken from 10.5 or below.

[0062] The total specific surface area C of the mesopores was calculated using the t-plot method from nitrogen adsorption isotherms obtained by measuring according to the mesopore distribution determination method (BJH method) by Barrett, Joyner, and Halenda described in ISO 15901-2. Desorption curves were used for the calculation, and the adsorption cross-section of nitrogen molecules was 0.1620 nm. ２ The calculation was performed as follows: Pores with a diameter in the range of over 2 nm and up to 50 nm were defined as mesopores. The total specific surface area of ​​mesopores using the t-plot method was calculated by plotting the amount of adsorption originating from mesopores on a graph with the thickness of the nitrogen adsorption layer on the horizontal axis and the amount of adsorption on the vertical axis, based on the adsorption isotherm obtained by nitrogen adsorption measurement. Based on the obtained amount of adsorption, the total pore volume, micropore volume, and mesopore volume of the zeolite were calculated, and these values ​​were used to determine the total specific surface area.

[0063] The total specific surface area D of the micropores was calculated from the nitrogen adsorption isotherm obtained by measurement according to the SF method (Saito-Foley method), and the micropore distribution was calculated (A. Saito, H.C. Foley, Microporous Materials, 3 (1995) 531). The physical constants, adsorbent, and adsorbate gas parameters used in calculating the total specific surface area of ​​the micropores were those described in Physical Parameters for Microporous Size Calculation (ISO 15901-3, JIS Z8831-3). The adsorption cross-section of nitrogen molecules was 0.1620 nm. ２The calculation was performed as follows: Pores with a diameter greater than 0 nm and less than or equal to 2 nm were defined as micropores. The total specific surface area of ​​micropores using the t-plot method was calculated by plotting the thickness of the nitrogen adsorption layer on the horizontal axis and the amount of adsorption on the vertical axis, based on the adsorption isotherm obtained by nitrogen adsorption measurement. The amount of adsorption originating from the micropores was then calculated from the obtained amount of adsorption, and the total pore volume, micropore volume, and mesopore volume of the zeolite were calculated, and these values ​​were used to determine the specific surface area.

[0064]

[0065] In Examples 1 to 6, the zeolite was brought into contact with an alkaline solution, and heating was started when the zeolite content was in the range of 30% to 70% by mass when the total of the alkaline solution and zeolite was 100% by mass. This suppressed the formation of defects in the crystal structure of the zeolite, maintaining a high degree of crystallinity while forming and / or increasing mesopores and increasing the surface area of ​​the zeolite. In Examples 1 to 6, the zeolite content was 1% by mass when the total of the alkaline solution and zeolite was 100% by mass, and the zeolite was heated in a gas. Compared to the zeolite in Comparative Example 1, which was heated while immersed in an alkaline solution, the ratio C / D was larger, indicating the formation and / or increase of mesopores and a larger surface area of ​​the zeolite. Furthermore, even after heating, the zeolite in Examples 1 to 6 had a ratio A / B of 0.30 or higher, indicating a high degree of crystallinity.

[0066] Figure 1 shows the X-ray diffraction spectra of BEA-type zeolites obtained in Example 1 and Reference Example 1. The BEA-type zeolite in Example 1 was obtained by heating a BEA-type zeolite containing an alkaline solution in which the zeolite content was 45% by mass, with the total amount of alkaline solution and zeolite at the start of heating being 100% by mass. The X-ray diffraction spectra of the BEA-type zeolite in Example 1 and the BEA-type zeolite in Reference Example 1, which was not in contact with the alkaline solution, show that the diffraction angles (2θ) of each peak are almost the same, and the peak intensities (a.u.) are also almost the same, confirming that the crystal structures are identical.

[0067] In Comparative Example 1, the zeolite content is 1% by mass when the total of the alkaline solution and zeolite is 100% by mass. Because it is heated while immersed in a large volume of alkaline solution with a mass nearly 100 times greater than the zeolite, the ratio C / D is less than 0.07, mesopores are not formed and / or enlarged, the ratio A / B is less than 0.30, and defects have occurred in the crystal structure. In Comparative Examples 2 and 3, the zeolite is brought into contact with an alkaline solution, and when the total of the alkaline solution and zeolite is 100% by mass, the zeolite content is 1% by mass. Because it is heated while immersed in a large volume of alkaline solution with a mass nearly 100 times greater than the zeolite, the ratio C / D is larger than 0.18, mesopores are formed and / or enlarged, but the ratio A / B is 0.30 or less, and defects have occurred in the crystal structure.

[0068] Figure 2 shows the X-ray diffraction spectra of BEA-type zeolites obtained in Example 2 and Comparative Example 2. Comparing the X-ray diffraction spectra of the BEA-type zeolite according to Example 2 and the BEA-type zeolite according to Comparative Example 2, the diffraction angles (2θ) of each peak are almost the same. The maximum diffraction intensity of the peak in the X-ray diffraction spectrum of the BEA-type zeolite according to Comparative Example 2 is smaller than the maximum diffraction intensity of the peak in the X-ray diffraction spectrum of the BEA-type zeolite according to Example 2. The ratio A / B of the BEA-type zeolite according to Comparative Example 2 is less than 0.30.

[0069] The zeolite obtained by the zeolite manufacturing method of this disclosure can form and / or increase mesopores while maintaining its crystallinity, and can be suitably used as a catalyst in the petrochemical industry or as a catalyst for exhaust gas purification.

Claims

1. A method for producing zeolite, comprising: preparing zeolite; contacting the zeolite with an alkaline solution; and heating the zeolite containing the alkaline solution in a gas, wherein, when the heating is started, the content of the zeolite is in the range of 30% by mass or more and 70% by mass or less, when the total amount of the alkaline solution and the zeolite is 100% by mass.

2. The SiO of the zeolite before heating ２ / Al ２ O ３ A method for producing zeolite according to claim 1, wherein the molar ratio is in the range of 10 to 100.

3. SiO in the zeolite ２ A method for producing zeolite according to claim 1 or 2, wherein, when the amount is taken as 100 mol%, the amount of hydroxyl groups in the alkaline solution is in the range of 0.05 mol% to 10.00 mol%.

4. The method for producing a zeolite according to claim 1 or 2, wherein the zeolite is a zeolite synthesized without using an organic structure-determining agent.

5. The method for producing a zeolite according to claim 1 or 2, wherein the zeolite is a zeolite having at least one skeletal structure selected from the group consisting of BEA-type zeolite, MSE-type zeolite, -SVR-type zeolite, FAU-type zeolite, MOR-type zeolite, CON-type zeolite, SOF-type zeolite, MFI-type zeolite, IMF-type zeolite, FER-type zeolite, MWW-type zeolite, MTT-type zeolite, TON-type zeolite, EUO-type zeolite, MRE-type zeolite, NAT-type zeolite, and CHA-type zeolite.

6. A method for producing a zeolite according to claim 1 or 2, wherein the ratio A / B of the peak intensity A of the X-ray diffraction spectrum of the heated zeolite measured by X-ray diffraction to the peak intensity B of the (111) plane of the X-ray diffraction spectrum of Si, a standard material distributed by the National Institute of Standards and Technology, is 0.30 or more, and the ratio C (specific surface area of ​​total mesopores) / D (specific surface area of ​​total micropores) of the total mesopores measured by t-plot method of mesopores with a pore diameter in the range of more than 2 nm and less than or equal to 50 nm, measured by the BJH method of the heated zeolite, and D (specific surface area of ​​total micropores) is in the range of 0.07 or more and 0.18 or less.

7. A zeolite in which the ratio A / B of the peak intensity A of the X-ray diffraction spectrum measured by X-ray diffraction of the zeolite to the peak intensity B of the (111) plane of the X-ray diffraction spectrum measured for Si, a standard material distributed by the National Institute of Standards and Technology, is 0.30 or greater, and the ratio C (total specific surface area of ​​mesopores) / D (total specific surface area of ​​micropores) of the total specific surface area C of mesopores measured by the t-plot method of mesopores with a pore diameter of more than 2 nm and less than or equal to 50 nm, measured by the BJH method, to the total specific surface area D of micropores measured by the t-plot method of micropores with a pore diameter of 2 nm or less, measured by the SF method, is in the range of 0.07 to 0.

18.

8. SiO of the zeolite ２ / Al ２ O ３ The zeolite according to claim 7, wherein the molar ratio is in the range of 10 or more and 100 or less.

9. The zeolite according to claim 7 or 8, wherein the zeolite is a zeolite synthesized without the use of an organic structure-determining agent.

10. The zeolite according to claim 7 or 8, wherein the zeolite is a zeolite having at least one skeletal structure selected from the group consisting of BEA-type zeolite, MSE-type zeolite, -SVR-type zeolite, FAU-type zeolite, MOR-type zeolite, CON-type zeolite, SOF-type zeolite, MFI-type zeolite, IMF-type zeolite, FER-type zeolite, MWW-type zeolite, MTT-type zeolite, TON-type zeolite, EUO-type zeolite, MRE-type zeolite, NAT-type zeolite, and CHA-type zeolite.

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