Zeolite manufacturing method

Abstract

To provide a method capable of manufacturing zeolite in a short time.SOLUTION: A manufacturing method of zeolite uses an amorphous seed crystal or a precursor composition, each having a crystallinity degree of 80% or lower.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Zeolite usually requires a long time to produce, and there is a need to establish a production method in a short time. For example, in Non-Patent Document 1, it takes 16 days to synthesize PAU-type zeolite.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention has been made to solve the above problems, and an object thereof is to propose a method for producing zeolite in a short time.

Means for Solving the Problems

[0005] The inventors of the present invention have intensively studied to solve the above problems. As a result, they have found that the above problems can be solved by performing zeolite synthesis using an amorphous seed crystal or a precursor composition, and have reached the present invention. That is, the present invention provides the following [1] to [5]. [1] A method for producing zeolite having a step of hydrothermally synthesizing a raw material composition, wherein the raw material composition contains an amorphous seed crystal or a precursor composition having a crystallinity of 80% or less. [2] The method for producing zeolite according to [1], wherein the zeolite is an aluminosilicate. [3] A method for producing the zeolite according to [1] or [2] above, wherein the average primary particle size of the zeolite is 10 nm to 100 μm. [4] A method for producing a zeolite according to any one of [1] to [3] above, wherein the zeolite has 8 as an SBU. [5] A method for producing a zeolite according to any one of [1] to [4] above, wherein the zeolite has d8r as CBU. [Effects of the Invention]

[0006] According to the present invention, a method for producing zeolite in a short time can be provided.

[0007] The present invention relates to a method for producing zeolite (hereinafter sometimes referred to as "the method for producing zeolite of the present invention" or simply "the method for producing the present invention"), characterized in that it uses seed crystals of a specific degree of crystallinity as a raw material composition for hydrothermal synthesis. That is, the method for producing the present invention is characterized in that it uses amorphous seed crystals or precursor compositions with a degree of crystallinity of 80% or less. The embodiments of the present invention will be described in detail below, but the following description is merely an example of an embodiment of the present invention, and the present invention is not limited in any way to these embodiments. Furthermore, as one of the physical properties of the zeolite obtained by the manufacturing method of the present invention, carbon dioxide adsorption properties will be described, with its use as a carbon dioxide adsorbent being a representative example, but the present invention is not limited to these uses.

[0008] [Zeolite] First, we will describe the zeolite produced by the manufacturing method of the present invention (hereinafter, it may be referred to as "the zeolite of the present invention" or simply "zeolite"). Zeolites are compounds composed of silicon or aluminum, and oxygen, with TO4 units (where T is an element other than oxygen that makes up the framework) as their basic unit. Zeolites are made up of structural units (SBUs or CBUs) formed by the linkage of multiple TO4 units (several to tens of units). As a result, they have regular channels (tubular pores) and cavities. The SBUs (Secondary Building Units) and CBUs (Composite Building Units) of each zeolite structure can be found in the Zeolite Structure Database 2018 edition (http: / / www.iza-structure.org / databases / ). Zeolites specifically include crystalline porous aluminosilicates (hereinafter referred to as "aluminosilicates"), crystalline porous aluminophosphates (ALPO), or crystalline porous silicoaluminophosphates (SAPO). Whether a zeolite is aluminosilicate, aluminophosphate, or silicoaluminophosphate can be confirmed by the methods described in the examples below (XRD measurement, compositional analysis). Here, "XRD" refers to X-ray diffraction.

[0009] <Structure> The structure of zeolites can be determined based on the X-ray diffraction pattern obtained using an X-ray structural analysis instrument (for example, the BRUKER D2PHASER desktop X-ray diffraction instrument) and the 2018 Zeolite Structure Database (http: / / www.iza-structure.org / databases / ).

[0010] <Aluminosilicate> The present invention's method for producing zeolites is effective for producing zeolites of various structures, and is particularly suitable for producing aluminosilicates containing at least aluminum atoms and silicon atoms in their skeletal structure.

[0011] (Zeolite SBU) The SBU of the zeolite obtained by the manufacturing method of the present invention is not particularly limited, as long as the effects of the present invention are not impaired. Among these, zeolites having an SBU of 8 are preferred because they have a complex structure and are known to take a long time to synthesize, and this process can be shortened by the manufacturing method of the zeolite of the present invention. Zeolites with an SBU of 8 include ABW, ACO, AFN, APC, APD, ATN, BCT, GIS, GME, KFI, LTA, MAR, MER, PAU, PHI, RHO, RWY, SBE, SBS, SIV, TSC, UFI, VFI, and YUG.

[0012] (Zeolite CBU) The CBU of the zeolite obtained by the manufacturing method of the present invention is not particularly limited, as long as the effects of the present invention are not impaired. Among these, zeolites having d8r as CBU are preferred because they have a complex structure and are known to take a long time to synthesize, and the manufacturing method of the zeolite of the present invention can shorten this time. Zeolites that contain d8r as a CBU include MER, PAU, RHO, SBE, TSC, MWF, YFI, PWN, and PST-20. For example, a zeolite produced by the manufacturing method of the present invention is a zeolite having a PAU-type structure. This zeolite has a large number of CO2-containing cages due to its PAU-type structure, and is capable of adsorbing a large amount of carbon dioxide effectively. The manufacturing method of the present invention allows for the efficient production of such a zeolite in a short amount of time.

[0013] (Molar ratio of silica to alumina) The silica / alumina molar ratio (SiO2 / Al2O3, sometimes referred to as "SAR") is important for controlling active sites such as acid sites in zeolites. In the manufacturing method of the present invention, the silica / alumina molar ratio of the zeolite can be controlled by controlling the silica source and alumina source in the raw material composition. In terms of ease of zeolite synthesis, the SAR is usually 10,000 or less, preferably 5,000 or less, more preferably 1,000 or less, and even more preferably 500 or less. Having an SAR below these upper limits makes it easier to manufacture at low cost, which is advantageous in terms of zeolite manufacturing costs. On the other hand, in terms of minimizing the generation of by-products during hydrothermal synthesis, a high SAR is preferable, specifically, usually 2.0 or more, preferably 2.5 or more, more preferably 3.0 or more, and even more preferably 3.5 or more.

[0014] (Average primary particle size) The average primary particle size of the zeolite obtained by the manufacturing method of the present invention is preferably large in terms of high thermal conductivity. A larger particle size reduces the heat transfer resistance at the interface, increasing thermal conductivity, leading to faster temperature tracking under temperature swing conditions, and rapid adsorption and desorption. On the other hand, a smaller particle size is preferable in terms of a larger pore surface area per unit mass, which facilitates gas diffusion between particles. Specifically, the average primary particle size of the zeolite is preferably 10 nm or more, more preferably 20 nm or more, even more preferably 50 nm or more, and particularly preferably 100 nm or more. Furthermore, it is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 20 μm or less, and particularly preferably 10 μm or less. The average primary particle diameter of zeolite can be measured by observing the particles using a scanning electron microscope (SEM). In this invention, the primary particle diameter of zeolite is defined as the diameter of the circle with the largest diameter (equivalent circle diameter) in the SEM image. Alternatively, the average value of any 10 zeolites is defined as the average primary particle diameter.

[0015] (Zeolite countercations) Zeolites usually have a negative charge and have counter cations that neutralize this charge. The counter cations are not particularly limited as long as the effects of the present invention are not impaired. The counter cations of zeolites usually include structure-directing agents; protons; alkali metal ions such as Li, Na, and K; alkaline earth metal ions such as Mg and Ca; rare earth element ions such as La and Ce; transition metals such as Fe, Co, and Ni, etc., and preferably, structure-directing agents, protons, alkali metal ions, and alkaline earth metal ions. When the counter cation of zeolite is a structure-directing agent, it is preferable in that the framework is more stable and the durability of the adsorption / desorption cycle is more likely to be improved compared to the case where it is an alkali metal ion or an alkaline earth metal ion. In addition, since the interaction between alkali metal ions or alkaline earth metal ions and carbon dioxide is strong, it is particularly preferable for the present invention in which the zeolite produced by the production method of the present invention is used as an adsorbent for carbon dioxide. Note that the counter cation does not necessarily have to be one type, and may contain a plurality of cations such as protons and Na ions, or Na ions and K ions. As described above, as the zeolite, it is preferable that it is as-made (structure-directing agent-containing type), proton type, alkali metal type, or alkaline earth metal type. Note that the structure-directing agent refers to the template used in the production of zeolite.

[0016] When producing zeolite for use as a carbon dioxide absorbent by the production method of the present invention, since the counter cations possessed by the zeolite act strongly as adsorption sites for carbon dioxide, alkali metals are preferable, and it is more preferable to have sodium and potassium. When the zeolite of the present invention has sodium and potassium as counter cations, it is preferable that there is more sodium in terms of the amount of carbon dioxide adsorbed being likely to increase. On the other hand, in terms of the temperature dependence of the amount of carbon dioxide adsorbed being likely to increase, it is preferable that there is more potassium. Therefore, specifically, the Na / (Na + K) ratio (molar ratio) is preferably 0.01 or more, more preferably 0.02 or more, and on the other hand, is preferably 0.80 or less, preferably 0.70 or less.

[0017] [Method for Producing Zeolite] The method for producing zeolite of the present invention will be described below. [Hydrothermal Synthesis] The method for producing zeolite of the present invention has a step of hydrothermally synthesizing a raw material composition. As the raw material composition, it usually contains a silica source and an alumina source, and in the production method of the present invention, it is characterized in that the raw material composition contains an amorphous seed crystal or a precursor composition. The method for producing zeolite of the present invention can produce zeolite in a short time compared to known zeolite production methods because the raw material composition contains an amorphous seed crystal or a precursor composition.

[0018] [Raw Materials, etc.] The raw materials used in the method for producing zeolite of the present invention will be described. In the production of zeolite of the present invention, a silica source, an alumina source, and water are used. And as a part of this silica source and alumina source, an amorphous seed crystal or a precursor composition is used. This amorphous seed crystal or precursor composition will be described later. Note that as the silica source and alumina source, zeolite containing both elements may be used. Of course, other components may be included and an organic structure-directing agent may be included as long as the effects of the present invention are not inhibited.

[0019] [Silica Source] A silica source refers to a raw material compound that becomes the silicon atoms that make up a zeolite. Examples of silica sources include fumed silica, silica sol, colloidal silica, water glass, ethyl silicate, and methyl silicate, and one or more of these are used. Of these, fumed silica and colloidal silica are preferred because they are easy to handle and highly reactive.

[0020] (Alumina source) Alumina sources refer to raw material compounds that become the aluminum atoms constituting zeolites. Common alumina sources include aluminum alkoxides such as pseudoboehmite, gibbsite, aluminum isopropoxide, and aluminum triethoxide; aluminum hydroxide; alumina sol; and sodium aluminate. One or more of these are typically used. Of these, aluminum hydroxide, aluminum isopropoxide, and pseudoboehmite are preferred due to their ease of handling and high reactivity.

[0021] (Amorphous seed crystals and precursor composition) In the zeolite production method of the present invention, the raw material composition contains an amorphous seed crystal or precursor composition. The amorphous seed crystal or precursor composition used in the zeolite production method of the present invention can be obtained by hydrothermal synthesis of a raw material composition containing a silica source and an alumina source. The gel after hydrothermal synthesis is called the precursor composition, and the solid obtained by hydrothermal synthesis is called an amorphous seed crystal. The raw material composition used in the production of the amorphous seed crystal or precursor composition may contain components such as alkali metal compounds, alkaline earth metal compounds, organic structure-regulating materials, and seed crystals, as described later, as long as they do not significantly impair the effects of the present invention. The precursor composition or amorphous seed crystal typically has a part of the structure of the target zeolite. The zeolite production method of the present invention allows for the rapid production of the target zeolite by including this precursor composition or amorphous seed crystal in the raw material composition.

[0022] When producing amorphous seed crystals or precursor compositions, the hydrothermal synthesis temperature is preferably low in order to facilitate the initiation of seed crystal growth. On the other hand, a high temperature is preferable in order to ensure that the raw materials are sufficiently dissolved. Here, amorphous seed crystals or precursor compositions are usually produced under milder hydrothermal synthesis conditions compared to the production of the zeolite of the present invention. That is, when producing amorphous seed crystals or precursor compositions, the production is usually carried out at a lower temperature and for a shorter time compared to the hydrothermal synthesis used for the production of the zeolite of the present invention. Specifically, hydrothermal synthesis is preferably carried out at 60 to 150°C for 1 to 48 hours. Note that hydrothermal synthesis may be carried out at a constant temperature or by gradually increasing the temperature. In the zeolite production method of the present invention, since the raw material composition includes amorphous seed crystals or precursor compositions, compared to the case where crystalline zeolite is used as the seed crystal, the dissolution of the seed crystal in the solution is promoted, and a state is created in which there are many growth starting points for the target zeolite, thereby enabling the production of the target zeolite more quickly.

[0023] The amorphous nature (crystallinity) of an amorphous seed crystal or precursor composition can be evaluated from the crystallinity calculated from the powder X-ray diffraction peak (Cu-Kα line). Specifically, the crystallinity is the value obtained from (diffraction intensity area from the crystalline phase) / (diffraction intensity area from the crystalline phase + diffraction intensity area from the amorphous phase) in the powder X-ray diffraction peak of zeolite in the range of 2θ = 3° to 50°. In the manufacturing method of the present invention, the degree of crystallinity of the amorphous seed crystal or precursor composition is preferably low because it allows for a faster dissolution rate in the solution. Specifically, it is preferably 70% or less, more preferably 60% or less, even more preferably 50% or less, and particularly preferably 40% or less. On the other hand, since the amorphous seed crystal or precursor composition needs to contain the partial structure that constitutes the target zeolite, it is preferable that it has a certain degree of crystallinity. Specifically, it is usually 0.005% or more, preferably 0.01% or more, more preferably 0.02% or more, and even more preferably 0.05% or more.

[0024] The amount of amorphous seed crystal or precursor composition contained in the raw material composition is preferably high in terms of the ease with which the effect of promoting crystallization is exhibited. On the other hand, it is preferable that the amount is low in terms of the ease with which the seed crystal dissolves and functions. Therefore, the amount of amorphous seed crystal or precursor composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1.0% by mass or more, and particularly preferably 2.0% by mass or more, relative to the silica source contained in the raw material composition. On the other hand, it is preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less. When multiple types of amorphous seed crystals are included, when multiple types of precursor compositions are included, and when both amorphous seed crystals and precursor compositions are included, it is preferable that their total amount is within the above range.

[0025] As described above, the manufacturing method of the present invention requires the use of amorphous seed crystals or precursor compositions. However, seed crystals other than amorphous seed crystals and precursor compositions may be used in combination, as long as they do not inhibit the effects of the amorphous seed crystals or precursor compositions. Conventional crystalline zeolites can be used as seed crystals. If the zeolite to be manufactured is an aluminosilicate, then an aluminosilicate zeolite is preferred as the seed crystal. Furthermore, when manufacturing a zeolite having 8 as the SBU, a seed crystal of a zeolite having 8 as the SBU is preferred, and when manufacturing a zeolite containing d8r as the CBU, a seed crystal of a zeolite containing d8r as the CBU is preferred. The zeolite used as a seed crystal may or may not contain an organic structure-controlling agent. The method for manufacturing the zeolite that will become the seed crystal is not particularly limited, and zeolites manufactured by the zeolite manufacturing method of the present invention or zeolites manufactured by known zeolite manufacturing methods can be used.

[0026] (Alkali metals or alkaline earth metals) The raw material composition used in zeolite production preferably contains a compound containing an alkali metal. The alkali metal-containing compound can be alkali metal hydroxides such as NaOH or KOH. The type of alkali metal is not particularly limited, but typically includes Na, K, Li, and Rb, with Na and K being preferred. Furthermore, when using a compound containing an alkali metal, two or more types may be used in combination. Furthermore, compounds containing alkaline earth metals may be used. Examples of compounds containing alkaline earth metals include Ca(OH)2. The type of alkaline earth metal is not particularly limited, but typically includes Ca, Mg, Sr, and Ba. In addition, when using compounds containing alkaline earth metals, two or more types may be used in combination.

[0027] (organic structure defining material) The raw material composition used in the production of zeolite preferably includes an organic structure directing agent (SDA). Examples of organic structure directing agents include amines and quaternary ammonium salts, and usually one or more of these can be used depending on the desired structure of the zeolite. For example, when producing PAU-type zeolite, compounds containing tetraethylammonium ions, such as tetraethylammonium hydroxide and tetraethylammonium bromide, are preferred.

[0028] <Preparation of raw material composition> The raw material composition is usually prepared by mixing at least one of the amorphous seed crystals and precursor compositions (hereinafter, amorphous seed crystals and precursor compositions may be collectively referred to as "specific amorphous components") with the raw material gel. Here, the raw material gel is a gel containing the silica source and alumina source described above. The raw material gel may also contain alkali metals, alkaline earth metals, organic structure-regulating materials, etc. It is preferable to mix the raw material gel and amorphous component such that the molar ratio of silicon atoms in the amorphous component to silicon atoms in the raw material gel is 0.01 or more and 1.00 or less. A higher molar ratio is preferable in terms of increasing crystallinity. On the other hand, a lower molar ratio is preferable in terms of reducing the effort and cost of manufacturing. Therefore, this molar ratio is more preferably 0.02 or more, even more preferably 0.03 or more, particularly preferably 0.05 or more, and most preferably 0.10 or more. Furthermore, the upper limit is preferably 0.90 or less, more preferably 0.50 or less, even more preferably 0.40 or less, and particularly preferably 0.30 or less. As mentioned above, the precursor composition refers to the gel after hydrothermal synthesis. In the preparation of the raw material composition described above, an amorphous component and a raw material gel were mixed, but it is also possible to produce the zeolite of the present invention by forming a precursor composition containing amorphous seed crystals from the raw material gel by slow hydrothermal synthesis, and then hydrothermally synthesizing the precursor composition.

[0029] <Hydrothermal synthesis> The zeolite of the present invention can be produced by hydrothermal synthesis of the above-mentioned raw material composition. The hydrothermal synthesis temperature of the raw material composition is preferably low in order to prevent structural defects from occurring. On the other hand, it is preferable to use a high temperature in order to facilitate the reaction. Therefore, the hydrothermal synthesis temperature of the raw material composition is usually 10°C or higher, preferably 50°C or higher, and more preferably 70°C or higher, and on the other hand, it is usually 240°C or lower, preferably 220°C or lower, and more preferably 200°C or lower.

[0030] <Cation exchange> The method for producing zeolite according to the present invention may further include a step of exchanging the cation type of the zeolite obtained by the hydrothermal synthesis described above. Furthermore, the step of producing the precursor composition described above may also include a step of exchanging the cation type of the zeolite obtained by the hydrothermal synthesis. The zeolite obtained by hydrothermal synthesis can, if necessary, be cation-exchanged to a desired cation form. Cation exchange is not limited to the following, but for example, nitrates such as NH4NO3, LiNO3, NaNO3, KNO3, RbNO3, CsNO3, Be(NO3)2, Ca(NO3)2, Mg(NO3)2, Sr(NO3)2, Ba(NO3)2, or salts in which the nitrate ions contained in these nitrates are replaced with halide ions, sulfate ions, carbonate ions, hydrogen carbonate ions, acetate ions, phosphate ions, hydrogen phosphate ions, and acids such as nitric acid and hydrochloric acid can be used. The temperature for performing cation exchange is not particularly limited as long as it is a temperature for performing general cation exchange, but it is usually 10°C or higher and 100°C or lower. Also, the ammonium-type zeolite can be converted to a proton-type zeolite by firing the zeolite.

Example

[0031] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. <XRD measurement> X-ray diffraction measurement was performed using an X-ray structure analyzer (desktop X-ray diffractometer "D2PHASER" manufactured by BRUKER). The obtained X-ray diffraction pattern was analyzed using a zeolite structure database (http: / / www.iza-structure.org / databases / ). Here, the measurement conditions for X-ray diffraction were as follows.

[0032]

Table 1

[0033] <Composition analysis> The compositional analysis of the zeolite was performed as follows: After heating and dissolving the zeolite standard sample in an aqueous hydrochloric acid solution, the content (mass%) of silicon and aluminum atoms was determined using an ICP analyzer (Inductively Coupled Plasma Atomic Emission Spectrometer) "ULTIMA 2C" manufactured by Horiba, Ltd. Then, a calibration curve was created between the atomic concentration of the analyte elements in the standard sample and the fluorescence X-ray intensity using a Rigaku X-ray fluorescence analyzer (XRF) "Supermini200". Using this calibration curve, the content (mass%) of silicon, aluminum, sodium, and potassium atoms in the sample was determined by X-ray fluorescence analysis (XRF).

[0034] <Amorphous> The amorphous nature of amorphous seed crystals was evaluated by the degree of crystallinity in the range of 2θ = 3° to 50°, obtained by XRD measurement using Cu-Kα rays. The degree of crystallinity was determined using the X-ray diffraction analysis software JADE from the (diffraction intensity area from the crystalline phase) / (diffraction intensity area from the crystalline phase + diffraction intensity area from the amorphous phase) of the powder X-ray diffraction peak of the zeolite. Here, the amorphous nature of the precursor composition was evaluated similarly after extracting the solid material. Note that a lower degree of crystallinity indicates higher amorphousness.

[0035] [Example 1] (Preparation of amorphous seed crystal 1) In a container, 0.36 g of sodium hydroxide and 0.29 g of potassium hydroxide from Kishida Chemical Co., Ltd., 6.52 g of 35% by mass aqueous solution of tetraethylammonium hydroxide (TEAOH) from Seichem Co., Ltd. as an organic structure directing agent (SDA), 5.4 g of desalinated water, 1.05 g of "Kyoward 200s (alumina content 54.3% by mass)" from Kyowa Chemical Industry Co., Ltd. as aluminum hydroxide, and 7.45 g of colloidal silica "Snowtex 40" from Nissan Chemical Corporation as silica were added sequentially. The composition and molar ratio of the resulting mixture were SiO2:Al2O3:NaOH:KOH:TEAOH:H2O = 1:0.11:0.2:0.089:0.31:15.6. After thoroughly mixing these raw materials, the resulting mixture was placed in a pressure vessel and hydrothermal synthesis was carried out in a 120°C oven for 120 hours under static conditions. The gel obtained here was washed with suction filtration and desalinated water, and then dried to obtain a powder, which was designated as amorphous seed crystal 1. XRD analysis of the obtained powder revealed a crystallinity of 4.5%.

[0036] (Manufacturing of Zeolite 1) In a container, 0.36 g of sodium hydroxide and 0.29 g of potassium hydroxide from Kishida Chemical Co., Ltd., 6.52 g of 35% by mass aqueous solution of tetraethylammonium hydroxide (TEAOH) from Seichem Co., Ltd. as an organic structure directing agent (SDA), 5.4 g of desalinated water, 1.05 g of "Kyoward 200s (alumina content 54.3% by mass)" from Kyowa Chemical Industry Co., Ltd. as aluminum hydroxide, and 7.45 g of colloidal silica "Snowtex 40" from Nissan Chemical Corporation as silica were added sequentially. The composition and molar ratio of the resulting mixture were SiO2:Al2O3:NaOH:KOH:TEAOH:H2O = 1:0.11:0.2:0.089:0.31:15.6. To this mixture, 0.15 g of amorphous seed crystal 1 at 5% by mass relative to SiO2 (silica) was added and mixed until homogeneous. The obtained gel was placed in a pressure vessel and subjected to hydrothermal synthesis in a 140°C oven for 48 hours under static conditions. After suction filtration and washing with demineralized water, zeolite 1 powder was obtained by drying. XRD analysis of the obtained powder confirmed that it was of the PAU type based on the peak position.

[0037] [Comparative Example 1] (Preparation of crystalline seed crystal 1) In a container, 0.36 g of sodium hydroxide and 0.29 g of potassium hydroxide from Kishida Chemical Co., Ltd., 6.52 g of 35% by mass aqueous solution of tetraethylammonium hydroxide (TEAOH) from Seichem Co., Ltd. as an organic structure directing agent (SDA), 5.4 g of desalinated water, 1.05 g of "Kyoward 200s (alumina content 54.3% by mass)" from Kyowa Chemical Industry Co., Ltd. as aluminum hydroxide, and 7.45 g of colloidal silica "Snowtex 40" from Nissan Chemical Corporation as silica were added sequentially. The composition and molar ratio of the resulting mixture were SiO2:Al2O3:NaOH:KOH:TEAOH:H2O = 1:0.11:0.2:0.089:0.31:15.6. After thoroughly mixing these raw materials, the resulting mixture was placed in a pressure vessel, and hydrothermal synthesis was carried out in a 100°C oven for 28 days under static conditions to obtain a powder. XRD analysis of the obtained powder confirmed that it was a PAU type with 100% crystallinity (crystalline seed crystal 1).

[0038] (Manufacturing of Zeolite 2) In a container, 0.36 g of sodium hydroxide and 0.29 g of potassium hydroxide from Kishida Chemical Co., Ltd., 6.52 g of 35% by mass aqueous solution of tetraethylammonium hydroxide (TEAOH) from Seichem Co., Ltd. as an organic structure directing agent (SDA), 5.4 g of desalinated water, 1.05 g of "Kyoward 200s (alumina content 54.3% by mass)" from Kyowa Chemical Industry Co., Ltd. as aluminum hydroxide, and 7.45 g of colloidal silica "Snowtex 40" from Nissan Chemical Corporation as silica were added sequentially. The composition and molar ratio of the resulting mixture were SiO2:Al2O3:NaOH:KOH:TEAOH:H2O = 1:0.11:0.2:0.089:0.31:15.6. To this mixture, 0.15 g of crystalline seed crystal 1 at 5% by mass relative to SiO2 (silica) was added and mixed until homogeneous. The obtained gel was placed in a pressure vessel and subjected to hydrothermal synthesis in a 140°C oven for 48 hours under static conditions. After suction filtration and washing with demineralized water, zeolite 2 powder was obtained by drying. XRD analysis of the obtained powder showed no evidence of crystalline zeolite formation from the peaks observed.

[0039] From the results of Example 1 and Comparative Example 1 described above, it was found that by using amorphous seed crystals, PAU-type zeolites, which have a complex structure and usually take a long time to synthesize, can be produced by hydrothermal synthesis in an oven at 140°C for 48 hours. On the other hand, when using crystalline seed crystals, which is the conventional manufacturing method, zeolites could not be produced under the same conditions. In other words, the present invention's method for producing zeolite has been proven to enable the production of zeolite in a short amount of time. [Industrial applicability]

[0040] According to the present invention, various zeolites can be manufactured in a short time, making it an industrially significant invention.

Claims

1. A method for producing zeolite, comprising the step of hydrothermally synthesizing a raw material composition, wherein the raw material composition contains amorphous seed crystals or precursor compositions with a degree of crystallinity of 80% or less, the amorphous seed crystals or precursor compositions contain partial structures constituting the target zeolite, and the method comprises the step of hydrothermally synthesizing the amorphous seed crystals or precursor compositions in an oven at 60 to 150°C, and the step of hydrothermally synthesizing zeolite using the hydrothermally synthesized amorphous seed crystals or precursor compositions.

2. The method for producing a zeolite according to claim 1, wherein the zeolite is an aluminosilicate.

3. A method for producing zeolite according to claim 1 or 2, wherein the average primary particle size of the zeolite is 10 nm to 100 μm.

4. A method for producing a zeolite according to any one of claims 1 to 3, wherein the zeolite has 8 as the SBU.

5. A method for producing a zeolite according to any one of claims 1 to 4, wherein the zeolite has d8r as a CBU.

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