Method for producing AEI zeolite, catalyst, and adsorbent

Abstract

To provide a production method which can safely and economically produce AEI zeolite having a low Si / Al ratio and high purity.SOLUTION: Provided is a production method of AEI zeolite, comprising the steps of: preparing a composition containing silicon atoms, aluminum atoms, alkali metal atoms, and water; aging the composition; adding, after the aging, zeolite containing in its skeleton d6r defined as a composite building unit by International Zeolite Association (IZA); and subjecting the composition after addition of the zeolite to a hydrothermal synthesis.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing AEI zeolite, and a catalyst and an adsorbent containing the obtained AEI zeolite. [Background technology]

[0002] Zeolites have properties such as a molecular sieve effect due to the pores derived from their framework structure, as well as ion exchange capacity, catalytic capacity, and adsorption capacity, and are widely used as adsorbents, ion exchange agents, industrial catalysts, and environmental catalysts. Zeolites that support metals such as copper are known as catalysts for exhaust gas, and specifically, CHA-type aluminosilicate zeolites and silicoaluminophosphate (SAPO) zeolites have been developed. The designations AEI and CHA are codes that define the skeletal structure of zeolites, as determined by IZA (International Zeolite Association).

[0003] AEI zeolite has the same pore size as CHA zeolite, but is known to have a structure with higher catalytic activity. AEI zeolite is used, for example, as an SCR (Selective Catalytic Reduction) catalyst. When using zeolite as an SCR catalyst for exhaust gas treatment of automobiles, etc., it is thought that a catalyst with a low Si / Al ratio is more suitable for use in order to reliably treat exhaust gas, especially during low-temperature operation such as at start-up. This is because in the case of aluminosilicate zeolites, the coordination sites of transition metals, etc., which serve as active sites, become aluminum sites, so a catalyst with a low Si / Al ratio, which has more active sites, is more advantageous.

[0004] A method disclosed in Patent Document 1 is known as a general method for producing AEI zeolite. Patent Document 1 specifically describes a method for producing Y zeolite (Framework density: 12.7T / 1000Å). 3It is disclosed that AEI zeolite is obtained by adding, as an organic structure directing agent (SDA), for example, DMDMPOH (N,N-dimethyl-3,5-dimethylpiperidinium hydroxide) to the raw materials, stirring in the presence of NaOH, and carrying out hydrothermal synthesis for 8 days. In the examples of Patent Document 1, experiments were conducted by changing SDA using actual Y-type zeolite as the raw material. Thus, it is currently common knowledge that AEI-type zeolite cannot be synthesized without using Y-type zeolite. This is explained, for example, in Non-Patent Document 1, where it is stated that "Al(OH) 3 This is also supported by the statement that "We attempted synthesis using as a raw material, but were unable to obtain a crystalline oxide."

[0005] Patent Document 2 discloses a method for producing AEI zeolite using inexpensive aluminum nitrate as a raw material, in which aluminum nitrate and TEOS (tetraethyl orthosilicate) are used, mixed with SDA, and then hydrofluoric acid is added to obtain AEI zeolite. The method disclosed in Patent Document 2 is a method for producing AEI zeolite with a Si / Al ratio of 200 or more by using hydrofluoric acid to minimize the incorporation of Al into the zeolite.

[0006] Patent Document 3 discloses a method for producing AEI zeolite having a Si / Al ratio of 50 or less, the method including the steps of preparing a mixture containing a silicon atom raw material, an aluminum atom raw material, an alkali metal atom raw material, an organic structure-directing agent, and water, and subjecting the mixture obtained in the above step to hydrothermal synthesis. In this manufacturing method, the aluminum atom raw material contains aluminum with a Si content of 20% by weight or less, and the framework density in the mixture is 14T / 1000Å. 3 The above zeolites are classified into those in which all of the Si in the mixture is SiO 2 When it is assumed that SiO 2 It is characterized in that it contains 0.1% by weight or more of the total weight of the material. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 5,958,370 [Patent Document 2] International Publication No. 2005 / 063624 [Patent Document 3] JP 2017-81809 A [Non-patent literature]

[0008] [Non-Patent Document 1] Chemical,Communications, 48, 8264-8266. Summary of the Invention [Problem to be solved by the invention]

[0009] The hydrofluoric acid used in Patent Document 2 is a very dangerous acid, and its use during hydrothermal synthesis, which is particularly subject to high temperatures, is not industrially practical. In addition, since Y-type zeolite is expensive, there is a cost issue when it is used in large quantities, such as in the selective catalytic reduction (SCR) catalyst for NOx contained in exhaust gases from automobiles, etc. Furthermore, in the method for producing AEI zeolite, as described above, it is considered preferable to lower the Si / Al ratio, but the production methods disclosed in Patent Documents 1 and 2 do not indicate that AEI zeolite with a lower Si / Al ratio can be produced.

[0010] On the other hand, Patent Document 3 also does not show that an AEI zeolite having a sufficiently low Si / Al ratio and high AEI purity can be obtained while suppressing the amount of the organic structure-directing agent, which is relatively expensive, used, and there is room for further improvement.

[0011] Therefore, an object of the present invention is to provide a method for safely and inexpensively producing AEI zeolite having a low Si / Al ratio and high purity. [Means for solving the problem]

[0012] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by mixing and maturing raw materials for zeolite, adding a zeolite containing d6r, which is defined as a composite building unit by the International Zeolite Association (IZA), in its framework, and then carrying out hydrothermal synthesis, thereby completing the present invention described below. That is, the present invention provides the following [1] to

[11] . [1] preparing a composition containing silicon atoms, aluminum atoms, alkali metal atoms, and water; Aging the composition; After the aging, adding a zeolite containing d6r in its framework, which is defined as a composite building unit by the International Zeolite Association (IZA); a step of hydrothermally synthesizing the composition after adding the zeolite; A method for producing AEI zeolite, comprising: [2] The method for producing the AEI zeolite described in [1] above, characterized in that, when the molar ratio of silicon atoms / aluminum atoms in the solid content of the composition before aging is "B" and the molar ratio of silicon atoms / aluminum atoms in the solid content of the composition after aging is "C", the molar ratio calculated as C / B × 100 is less than 100%. [3] The method for producing the AEI zeolite according to [1] or [2] above, characterized in that the aging is carried out by heating. [4] The method for producing the AEI zeolite according to the above [3], wherein the heating is carried out at 30 to 180° C. for 10 minutes to 24 hours. [5] A method for producing an AEI zeolite described in any one of [1] to [4] above, characterized in that the molar ratio of silicon atoms / aluminum atoms of the AEI zeolite is 10 or less. [6] A method for producing an AEI zeolite described in any one of [1] to [5] above, characterized in that amorphous silica is used as the silicon atoms contained in the composition before aging. [7] A method for producing an AEI zeolite according to any one of [1] to [6] above, wherein the silicon atoms contained in the composition before aging do not contain zeolite, or the silicon atoms derived from zeolite contained in the composition before aging are 10 mol % or less relative to the total amount of silicon atoms. [8] A method for producing an AEI type zeolite described in any one of [1] to [7] above, characterized in that the composition after the addition of the zeolite contains an organic structure-directing agent in a molar ratio of 0.01 or more and 1 or less relative to silicon atoms. [9] A catalyst comprising an AEI zeolite produced by the method for producing an AEI zeolite according to any one of [1] to [8] above.

[10] The catalyst according to the above [9], which is a catalyst for reducing nitrogen oxides.

[11] An adsorbent comprising AEI zeolite produced by the method for producing AEI zeolite according to any one of [1] to [8] above. Effect of the Invention

[0013] According to the present invention, it is possible to safely and inexpensively produce AEI zeolite having a low Si / Al ratio and high purity. [Brief description of the drawings]

[0014] [Figure 1] 1 is a chart showing the XRD pattern of the AEI zeolite synthesized in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail. However, the following description is merely an example (representative example) of the embodiments of the present invention, and the present invention is not limited to the contents thereof.

[0016] The method for producing AEI zeolite of the present invention (hereinafter, sometimes referred to as "the present production method") is characterized by comprising a step of preparing a composition containing silicon atoms, aluminum atoms, alkali metal atoms, and water, an aging step of aging the composition, an addition step of adding, after the aging, a zeolite containing d6r, which is defined as a composite building unit by the International Zeolite Association (IZA), in its framework, and a hydrothermal synthesis step of hydrothermally synthesizing the composition after the addition of the zeolite. In the following description, the composition to be subjected to aging may be referred to as the "pre-aging composition." Furthermore, the composition to be subjected to hydrothermal synthesis after the addition of the zeolite may be referred to as the "pre-reaction composition" or the "post-aging composition."

[0017] <Preparation of Composition> In this production method, the pre-aging composition containing silicon atoms, aluminum atoms, alkali metal atoms and water can be prepared by any method. Here, silicon atoms, aluminum atoms and alkali metal atoms are used as silicon atom raw materials, aluminum atom raw materials and alkali metal atom raw materials, respectively. However, raw materials containing each may be used, or a compound containing multiple raw materials such as a compound containing silicon atoms and aluminum atoms may be used. In this specification, unless otherwise specified, the silicon atom raw material and the aluminum atom raw material mean the silicon atom raw material and the aluminum atom raw material used in the pre-reaction composition other than the zeolite added after aging. In the following description, the zeolite containing d6r in the framework added to the pre-aging composition may be simply called "d6r zeolite".

[0018] The method for preparing the pre-ripening composition is not particularly limited, but from the viewpoint of easily dissolving each raw material uniformly, it is preferable to add the silicon atom raw material and the aluminum atom raw material to an alkaline solution. Here, the alkaline solution is preferably an aqueous solution of an alkali metal atom raw material (an aqueous alkali metal solution).

[0019] When an organic structure-directing agent is used in the present production method, the organic structure-directing agent may be contained in the pre-ripening composition. In this case, the organic structure-directing agent is preferably contained in the alkaline solution. The raw materials used in the preparation of the pre-ripening composition may be mixed at the same time, or may be mixed in any order or amount. When the raw materials are mixed in parts, they may be mixed in two or more parts, or may be mixed before and after ripening. The organic structure-directing agent may be added at any time before the hydrothermal synthesis, and may be added before ripening as described above, may be added after ripening, or may be added both before and after ripening.

[0020] However, since it is considered that the aluminum atom raw material is easily incorporated into the solid content by aging, it is preferable to charge a large amount of the aluminum atom raw material before aging. Specifically, it is preferable that the aluminum atoms contained in the aluminum atom raw material are charged before aging in an amount of preferably 50 mol % or more, more preferably 70 mol % or more, and particularly preferably 90 mol % or more, based on the total amount of the aluminum atom raw material used. In addition, for silicon atom raw materials, it is preferable to lower the Si / Al molar ratio before aging, since aging makes it easier to form a zeolite precursor with a high aluminum atom content. Specifically, the Si / Al molar ratio before aging is preferably 10 or less, more preferably 8 or less, and particularly preferably 7 or less. Here, unless otherwise specified, the total amount used means the total amount of aluminum atoms or the total amount of silicon atoms contained in the pre-reaction composition other than d6r zeolite, and the same applies hereinafter.

[0021] The raw materials used in the production method of the present invention will be described in more detail below. (Silicon atom source) The silicon atom source is a compound having a silicon atom. The silicon atom source is preferably a silicon-containing compound other than Y-type zeolite, and more preferably a compound other than zeolite. The silicon atom raw material is preferably an amorphous silicon compound, since it is thought to be easily mixed with the aluminum atom raw material and to be easily dissolved in the aging step so as to have a Si / Al ratio suitable for crystallization of AEI zeolite. As the amorphous silicon compound, amorphous silica such as colloidal silica, amorphous silica, fumed silica, and sodium silicate; trimethylethoxysilane, tetraethylorthosilicate, and aluminosilicate gel can be used. These may be used alone or in any combination of two or more kinds in any ratio. Among these, amorphous silica is preferred because it is easily dissolved and inexpensive. Also, colloidal silica, trimethylethoxysilane, tetraethylorthosilicate, and aluminosilicate gel are preferred because they are easily mixed uniformly with other raw materials and are particularly easily dissolved in water. Among the above, colloidal silica is more preferred as the silicon atom raw material.

[0022] The silicon atom raw material preferably has a large proportion of amorphous silica, which is easy to dissolve and inexpensive.Therefore, the silicon atom of amorphous silica is preferably 50 mol% or more, more preferably 70 mol% or more, based on the total amount of silicon atoms contained in the silicon atom raw material (the silicon atom raw material used in the composition before aging), and the silicon atom raw material is most preferably entirely amorphous silica.

[0023] In addition, the amount of d6r zeolite added after aging is usually small, as described later, so it is preferable that the silicon atom raw material used in the pre-reaction composition also contains a large amount of amorphous silica.Specifically, the silicon atom of amorphous silica is preferably 50 mol% or more, more preferably 70 mol% or more, based on the total amount of silicon atoms contained in the silicon atom raw material used in the pre-reaction composition.

[0024] As described above, the present production method can produce AEI zeolite using inexpensive amorphous silica as a silicon atom raw material. That is, the silicon atom raw material of the pre-aging composition does not contain zeolite, or the silicon atoms derived from zeolite in the pre-aging composition are preferably 10 mol% or less, more preferably 5 mol% or less, based on the total amount of silicon atoms, and further preferably the zeolite does not contain silicon atoms. Similarly, the silicon atom raw material of the pre-aging composition preferably does not contain Y-type zeolite, or the Y-type zeolite content is 10 mol% or less, more preferably 5 mol% or less, relative to the total amount of silicon atoms, and even more preferably does not contain silicon atoms as Y-type zeolite.

[0025] The amount of d6r zeolite added after aging is preferably 10% by mass or less, more preferably 8% by mass or less, and particularly preferably 5% by mass or less, based on the total amount of silicon atom raw material including d6r zeolite, and is preferably 1% by mass or more, more preferably 3% by mass or more.

[0026] (Aluminum atom source) The aluminum atom source is a compound containing aluminum atoms. The aluminum atom source is preferably a compound containing aluminum other than Y-type zeolite, more preferably a compound containing aluminum other than zeolite. The aluminum atom raw material is preferably a compound that is easily soluble in water. Also, it is preferable that the compound is well mixed with the silicon atom raw material and is easily soluble so that the Si / Al ratio is suitable for crystallization of AEI type zeolite in the aging process. Therefore, the aluminum atom raw material is preferably amorphous aluminum hydroxide, aluminum hydroxide having a gibbsite structure, aluminum hydroxide having a bayerite structure, aluminum nitrate, aluminum sulfate, aluminum oxide, sodium aluminate, boehmite, pseudo-boehmite, aluminum alkoxide, etc. These may be used alone or in any ratio and combination of two or more. Among these, particularly preferred are amorphous aluminum hydroxide, aluminum hydroxide having a gibbsite structure, and aluminum hydroxide having a bayerite structure. It is also preferable to use an amorphous aluminum atom source as the aluminum atom source, and among the above, amorphous aluminum hydroxide is particularly preferable.

[0027] The aluminum atom raw material is preferably used so that the molar ratio of the total amount of silicon atoms to the total amount of aluminum atoms in the pre-reaction composition (Si / Al molar ratio) is 2.5 or more and 10 or less. The Si / Al ratio is more preferably 3 or more, and even more preferably 5 or more, while more preferably 8 or less, and even more preferably 7 or less. By setting the Si / Al molar ratio in the above-mentioned preferred range, it becomes easier to obtain an AEI zeolite having the desired Si / Al ratio.

[0028] In addition, since aging makes it easier to form a zeolite precursor with a higher aluminum atom content, the Si / Al molar ratio of the composition before aging is preferably low. The molar ratio of silicon atoms to aluminum atoms in the composition before aging (Si / Al molar ratio, hereinafter also referred to as "feed ratio (A)") is also preferably within the same range as the above-mentioned Si / Al molar ratio.

[0029] (alkali metal atom) The alkali metal atom used in the present production method is not particularly limited, and any known alkali metal used in the synthesis of zeolite can be used, but it is preferably at least one selected from the group consisting of lithium, sodium, potassium, rubidium and cesium. By containing these alkali metal atoms, the crystallization progresses easily, and by-products (impurity crystals) are less likely to be generated. As described above, the alkali metal atom is used as an alkali metal atom raw material.

[0030] The alkali metal atoms particularly preferably contain sodium atoms. The reason is as follows. That is, when a zeolite is used, for example, as an adsorbent or catalyst, the alkali metal atoms incorporated into the crystal structure during the synthesis of the zeolite may be removed from the crystals by ion exchange. At this time, in order to simplify the alkali metal atom removal process, it is preferable that the alkali metal atoms used in the synthesis are sodium atoms. Therefore, the alkali metal atoms contained in the alkali metal atom raw material are preferably 50 mol % or more, more preferably 80 mol % or more, and particularly preferably substantially all sodium atoms.

[0031] Of course, the alkali metal atoms contained in the alkali metal atom raw material may be less than 50 mol % sodium atoms. In this case, the main alkali metal atoms contained in the pre-reaction composition are preferably, for example, potassium atoms, cesium atoms, or a mixture of potassium atoms and cesium atoms.

[0032] The alkali metal atom is preferably contained in the pre-reaction composition as an alkali metal ion. As the alkali metal atom raw material, the above-mentioned alkali metal atom may be used in the form of an inorganic acid salt such as hydroxide, oxide, sulfate, nitrate, phosphate, chloride, bromide, or an organic acid salt such as acetate, oxalate, citrate, etc. The alkali metal atom raw material may be used alone or in any combination of two or more kinds in any ratio.

[0033] When using an organic structure directing agent, as described later, it is considered that the alkali metal atom raw material can easily form a crystal structure by making the organic structure directing agent easily coordinate with aluminum atom in a suitable state.The molar ratio of the alkali metal atom to the organic structure directing agent in the pre-reaction composition is preferably 0.5 or more, more preferably 1.0 or more, even more preferably 2.0 or more, particularly preferably 3.0 or more, especially preferably 4.0 or more, and most preferably 6.0 or more.On the other hand, it is preferably 20 or less, more preferably 15 or less, even more preferably 12 or less, particularly preferably 10 or less, especially preferably 8.0 or less, and most preferably 6.0 or less.

[0034] (water) From the viewpoint of facilitating crystal formation, the amount of water, in terms of a molar ratio to silicon atoms other than d6r zeolite contained in the pre-reaction composition, is usually 5 or more, preferably 7 or more, more preferably 9 or more, and even more preferably 10 or more. In order to reduce the amount of waste liquid treatment and obtain a cost reduction effect, the amount of water, in terms of a molar ratio to silicon atoms other than d6r zeolite contained in the pre-reaction composition, is usually 50 or less, preferably 40 or less, more preferably 30 or less, and even more preferably 25 or less.

[0035] (Zeolite containing d6r in the framework) In this production method, as described above, a zeolite containing d6r in its framework is added to the aged composition. The added zeolite serves as a seed crystal in the synthesis of AEI zeolite. Note that d6r means d6r (double 6-membered ring) defined as a composite building unit by the International Zeolite Association (IZA). Specific examples of zeolites containing d6r in the framework include AEI, AFT, AFX, CHA, EAB, ERI, GME, KFI, LEV, LTL, LTN, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SZR, and WEN. Among these, more preferred are AEI, AFT, AFX, CHA, ERI, KFI, LEV, LTL, MWW, and SAV, even more preferred are AEI, AFT, and CHA, even more preferred are CHA and AEI, and particularly preferred is CHA. The zeolite containing d6r in its framework to be added to the composition may be used alone or in any combination of two or more kinds in any ratio.

[0036] The zeolite used in the present production method may be either an uncalcined product that has not been calcined after hydrothermal synthesis or a calcined product that has been calcined after hydrothermal synthesis, but an uncalcined product is preferred because it is less soluble in alkali and more likely to function as a crystal nucleus. However, depending on the composition of the composition or temperature conditions, etc., a calcined product may be used when the uncalcined product is less soluble.

[0037] The amount of d6r zeolite added is determined so that all silicon atoms in the pre-reaction composition other than d6r zeolite are SiO 2 SiO when it is assumed that 2 The amount of zeolite is preferably 0.1% by mass or more, and in order to facilitate the reaction, the amount is more preferably 0.5% by mass or more, even more preferably 2% by mass or more, particularly preferably 3% by mass or more, and most preferably 4% by mass or more. Since zeolite is expensive, the amount of zeolite added is preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 8% by mass or less, and particularly preferably 6% by mass or less, from the viewpoint of reducing costs.

[0038] (Organic structure directing agent) The pre-reaction composition preferably contains an organic structure-directing agent, since this makes it easier to obtain a high-purity AEI zeolite. As the organic structure directing agent (also called "template." Hereinafter, the organic structure directing agent may be referred to as "SDA."), various known substances such as tetraethylammonium hydroxide (TEAOH) and tetrapropylammonium hydroxide (TPAOH) can be used. For example, the following substances can be used as the organic structure directing agent.

[0039] N,N-diethyl-2,6-dimethylpiperidinium cation, N,N-dimethyl-9-azoniabicyclo[3.3.1]nonane cation, N,N-dimethyl-2,6-dimethylpiperidinium cation, N-ethyl-N-methyl-2,6-dimethylpiperidinium cation, N,N-diethyl-2-ethylpiperidinium cation, N,N-dimethyl-2-(2-hydroxyethyl)piperidinium cation, N,N-dimethyl-2-ethylpiperidinium cation, N,N-dimethyl-3,5-dimethylpiperidinium cation, N-ethyl-N-methyl-2-ethylpiperidinium cation, 2,6-dimethyl-1-azonium[5.4]decane cation, N-ethyl-N-propyl-2,6-dimethylpiperidinium cation, and the like. The organic structure-directing agent is preferably a nitrogen-containing organic structure-directing agent or a phosphorus-containing organic structure-directing agent, and as the nitrogen-containing organic structure-directing agent, N,N-dimethyl-3,5-dimethylpiperidinium cation is more preferable, and N,N-dimethyl-3,5-dimethylpiperidinium hydroxide is even more preferable.

[0040] Also, as the phosphorus-containing organic structure directing agent, materials such as tetrabutylphosphonium and diphenyldimethylphosphonium can be used. However, since phosphorus compounds may generate diphosphorus pentoxide, a harmful substance, when the synthesized zeolite is calcined to remove SDA, nitrogen-containing organic structure directing agents are preferred. These organic structure-directing agents may be used alone or in any combination of two or more kinds in any ratio.

[0041] The pre-reaction composition preferably contains an organic structure-directing agent in a molar ratio of 0.01 to 1 relative to the silicon atoms contained in the pre-reaction composition. By setting the content of the organic structure-directing agent within the above range, it is possible to reduce the amount of expensive organic structure-directing agent used, and to easily obtain a high-purity AEI zeolite at low cost. In addition, the Si / Al molar ratio of the AEI zeolite is also easily reduced. From the above viewpoints, the content of the organic structure directing agent is more preferably 0.02 or more, even more preferably 0.04 or more, even more preferably 0.06 or more, and more preferably 0.5 or less, even more preferably 0.3 or less, even more preferably 0.2 or less, and particularly preferably 0.15 or less.

[0042] (Other Ingredients) In this production method, in addition to the above aluminum atom raw material, silicon atom raw material, alkali metal atom raw material, zeolite containing d6r in the framework, water, and organic structure directing agent, an auxiliary agent that is a component for helping the synthesis of zeolite, for example, an acid component that promotes the reaction, an additive such as a metal stabilizer such as polyamine, etc. may be added at any step as necessary to prepare a pre-reaction composition. In addition, as described later, a metal such as copper that acts as a catalyst may be added during hydrothermal synthesis.

[0043] In addition, in the present production method, an alkaline earth metal may be added during the hydrothermal synthesis. It is generally known that the addition of an alkaline earth metal to a zeolite improves the hydrothermal resistance. In the present production method, an AEI zeolite can also be produced by adding a compound containing an alkaline earth metal to the pre-reaction composition. The alkaline earth metal may be magnesium, calcium, strontium, barium, etc., preferably magnesium or calcium, and most preferably calcium. The alkaline earth metal can be usually supplied in the form of a compound, such as an oxide, hydroxide, sulfide, etc., but is not particularly limited thereto, and is preferably added in the form of a hydroxide.

[0044] <Aging> In the present production method, the pre-aging composition obtained as described above is aged. In the present production method, the molar ratio of silicon atoms / aluminum atoms in the solid content of the pre-aging composition is reduced by aging, which is presumed to result in the production of high-purity AEI zeolite. The principle by which the molar ratio is reduced by aging and the principle by which high-purity AEI zeolite is obtained are not clear, but are presumed to be as follows. The aluminum atom raw material added to the alkali metal aqueous solution is easily dissolved. Here, when the silicon atom raw material is added, it reacts with the aluminum atoms in the liquid to form an aluminosilicate gel. The aluminosilicate gel is a colloid with water as a dispersion medium, and is a solid that forms a cross-linked structure by silicon and aluminum. At this time, some of the aluminum atoms do not react with the silicon atom raw material, and are not included in the aluminosilicate gel and are dissolved in the liquid. Therefore, the Si / Al ratio of the aluminosilicate gel becomes higher than the added feed ratio. And, if the composition in which the Si / Al ratio remains higher than the feed ratio, that is, the Si / Al ratio deviates from the feed ratio, is hydrothermally synthesized, impurities other than the AEI type are also crystallized, and it is considered that the purity of the AEI type decreases. On the other hand, by carrying out aging, silicon atoms in the solid (aluminosilicate gel) dissolve into the liquid phase, and aluminum atoms in the liquid phase are incorporated into the solid, lowering the Si / Al ratio of the solid and making it a composition suitable for obtaining an AEI type, which is thought to result in the production of a high-purity AEI type.

[0045] The aging is preferably carried out so that the molar ratio of silicon atoms to aluminum atoms (Si / Al molar ratio) in the solid content of the composition is as follows: If the molar ratio of silicon atoms to aluminum atoms (Si / Al molar ratio) in the solid content of the composition before aging is "B" and the molar ratio of silicon atoms to aluminum atoms (Si / Al molar ratio) in the solid content of the composition after aging is "C", the molar ratio calculated as C / B x 100 is preferably less than 100%, more preferably 90% or less, even more preferably 80% or less, and particularly preferably 74% or less, from the viewpoint of easily obtaining a high-purity AEI zeolite. On the other hand, by increasing the ratio of the above molar ratio, it is possible to prevent an increase in the silicon atom raw material that does not contribute to zeolite production due to dissolution, and to increase the yield of AEI zeolite. Therefore, from the viewpoint of the yield of AEI zeolite, the ratio of the molar ratio calculated by C / B×100 is preferably 30% or more, more preferably 40% or more, and particularly preferably 50% or more. For the same reason, the Si / Al molar ratio (C) relative to the charge ratio (A) in the composition before aging (C / A×100) is preferably 110% or less, more preferably 100% or less, while the ratio is preferably 20% or more, more preferably 30% or more, particularly preferably 40% or more, and particularly preferably 50% or more. The molar ratio of silicon atoms to aluminum atoms in the solid content of the composition can be obtained by filtering the composition at room temperature (25°C) to separate the solid content from the liquid content, and then analyzing the solid content by X-ray fluorescence spectrometry (hereinafter referred to as XRF) to measure the molar ratio of silicon atoms to aluminum atoms (Si / Al molar ratio).

[0046] The maturation is preferably carried out by heating since the maturation proceeds more quickly. Heating is preferably performed at a low temperature in that impurities are less likely to crystallize during aging. On the other hand, heating is preferably performed at a high temperature in that aging is likely to proceed in a short time. Specifically, the composition is heated to a temperature of preferably 180°C or less, more preferably 140°C or less, and particularly preferably 120°C or less for aging. On the other hand, the heating temperature is preferably 30°C or more, and more preferably 40°C or more. The temperature may be constant during aging, or may be changed stepwise or continuously.

[0047] The maturation time is not particularly limited. A short time is preferable from the viewpoint of production efficiency, but a long time is preferable from the viewpoint of purity and uniformity. When maturation is performed at high temperature or high pressure, maturation is likely to occur in a short time. The maturation time is preferably 10 minutes or more, more preferably 30 minutes or more, and particularly preferably 1 hour or more. On the other hand, 48 hours or less is preferable, more preferably 36 hours or less, and particularly preferably 24 hours or less. The aging is preferably carried out under normal pressure because the equipment required is simple. Although the temperature, time, and pressure of the aging are interrelated, it is particularly preferable to carry out the aging by heating at 30 to 180° C. for 10 minutes to 24 hours. The maturation is preferably carried out with stirring since the raw materials are easily homogenized. The stirring method is not particularly limited.

[0048] <Addition of zeolite> In this production method, after the pre-aging composition is aged, a zeolite containing d6r in its framework is added. In this production method, by adding d6r zeolite to the composition after aging, it becomes easier to safely and inexpensively produce AEI zeolite with a low Si / Al ratio and high purity. The d6r zeolite added to the composition serves as seed crystals for obtaining AEI zeolite. The zeolite containing d6r in its framework is added after aging and before hydrothermal synthesis, which will be described later. The method of adding the zeolite is not particularly limited, but it may be added to the composition in a heated state after aging, or it may be added after the composition is cooled after aging. After the addition, the composition is usually stirred.

[0049] <Hydrothermal synthesis> In this production method, the reaction precursor composition after the addition of zeolite is hydrothermally synthesized. By hydrothermal synthesis, AEI-type zeolite is synthesized. Hydrothermal synthesis is usually carried out by placing the composition after the addition of zeolite in a pressure-resistant container and holding it at a predetermined temperature under self-generated pressure or under gas pressure that does not inhibit crystallization, with stirring or while rotating or rocking the container, or in a static state.

[0050] Hydrothermal synthesis is usually carried out at 120°C or higher. Also, hydrothermal synthesis is usually carried out at 230°C or lower, preferably 220°C or lower, more preferably 200°C or lower, and still more preferably 190°C or lower. The reaction time is not particularly limited, but is usually 2 hours or more, preferably 3 hours or more, more preferably 5 hours or more, particularly preferably 1 day or more, and on the other hand, usually 30 days or less, preferably 10 days or less, more preferably 7 days or less, and still more preferably 5 days or less. The reaction temperature may be constant during the reaction or may be changed stepwise or continuously. By performing hydrothermal synthesis under the above conditions, the yield of the target AEI-type zeolite is improved, and it is difficult to generate zeolites of unintended types, which is preferable.

[0051] <Recovery of AEI-type zeolite> After hydrothermal synthesis, the AEI-type zeolite as the product is separated from the composition after hydrothermal synthesis (hydrothermal synthesis reaction solution). The obtained zeolite usually contains alkali metal atoms in the pores. Also, when an organic structure-directing agent is used, the organic structure-directing agent is usually contained in the pores. Hereinafter, substances contained in the pores of the zeolite after hydrothermal synthesis, such as the organic structure-directing agent and alkali metal, may be referred to as "organic structure-directing agent, etc.", and the zeolite containing this in the pores may be referred to as "zeolite containing SDA, etc.". The method for separating the zeolite containing SDA, etc. from the hydrothermal synthesis reaction solution is not particularly limited, but usually includes filtration, decantation, or direct drying, etc.

[0052] The zeolite containing SDA, etc. separated and recovered from the hydrothermal synthesis reaction solution is appropriately washed with water, dried, and then calcined, etc. to remove the organic structure-directing agent, etc. in order to remove the organic structure-directing agent, etc. used during production. When using AEI zeolite in applications such as catalysts (including catalyst carriers) and adsorbents, it is usually used after removing organic structure-directing agents and the like.

[0053] As methods for removing organic structure-directing agents and the like from zeolites containing SDA and the like, liquid-phase treatment using an acidic solution or a chemical solution containing decomposition components of the organic structure-directing agent, ion exchange treatment using a resin or the like, and thermal decomposition treatment can be employed, and these treatments can be used in combination. Usually, the contained organic structure-directing agents and the like can be removed by methods such as calcining at a temperature of 300 to 1000 °C in air or an inert gas containing oxygen, or extracting with an organic solvent such as an aqueous ethanol solution. From the viewpoint of productivity, removal of organic structure-directing agents and the like by calcination is preferable. In this case, the calcination temperature is preferably 400 °C or higher, more preferably 450 °C or higher, still more preferably 500 °C or higher, preferably 900 °C or lower, more preferably 850 °C or lower, and still more preferably 800 °C or lower. As the inert gas, nitrogen or the like can be used.

[0054] <Recycling of the separation liquid containing the organic structure-directing agent> The separation liquid remaining after separating and recovering AEI zeolite from the hydrothermal synthesis reaction liquid usually contains unreacted organic structure-directing agents and the like. Therefore, the separation liquid may be recycled. The recycling method is not particularly limited. For example, a pre-aging composition may be prepared by adding a deficient amount of a silicon atom raw material, an aluminum atom raw material, an organic structure-directing agent, water, and the like to the separation liquid containing the unreacted organic structure-directing agent. Then, the obtained pre-aging composition may be used to produce AEI zeolite by performing aging, addition of zeolite, and hydrothermal synthesis in this order as described above.

[0055] <AEI zeolite> The AEI zeolite produced by this production method (hereinafter, sometimes referred to as "AEI zeolite of the present invention") is a code that specifies the skeletal structure of zeolite, as defined by the International Zeolite Association (IZA), and indicates an AEI structure. The structure is characterized by X-ray diffraction data. However, when actually measuring a produced zeolite, the intensity ratio and peak position of each peak are affected by the growth direction of the zeolite, the ratio of constituent elements, adsorbed substances, the presence of defects, the drying state, etc., and therefore the values ​​obtained are not completely the same as the parameters of the AEI structure specified by the IZA, and a margin of about 10% is allowed. Major peaks seen in X-ray diffraction in AEI zeolite, for example, when CuKα radiation is used as the radiation source, include the 110 plane peak at 2θ=9.5°±0.2°, the 202 and -202 plane peaks (which are very close and often overlap) at 2θ=16.1°±0.2°, the 022 plane peak at 16.9°±0.2°, and the 310 plane peak at 20.6°±0.2°.

[0056] The zeolite obtained by this production method is a zeolite as defined by the International Zeolite Association (IZA), and is preferably an aluminosilicate zeolite. An aluminosilicate zeolite contains at least oxygen (O), aluminum (Al), and silicon (Si) as atoms constituting the framework structure, and some of these atoms may be substituted with other atoms (Me). The other atoms Me may contain one type or two or more types. The preferred Me is an element belonging to the third or fourth period of the periodic table.

[0057] The total amount of Si atoms and Al atoms contained in the AEI zeolite is preferably 70 mass% or more, and more preferably 80 mass% or more, based on the total amount of Al atoms, Si atoms, and Me atoms, while the total amount of Si atoms and Al atoms contained in the zeolite is preferably 99 mass% or less.

[0058] This production method makes it possible to obtain AEI zeolite with high purity and a low Si / Al molar ratio without using Y zeolite and while reducing the amount of organic structure-directing agent used.

[0059] Specifically, the molar ratio of silicon atoms to aluminum atoms (Si / Al molar ratio) in the AEI zeolite of the present invention is preferably 10 or less. A low Si / Al molar ratio in the AEI zeolite results in a large number of active sites, and therefore, for example, when the AEI zeolite of the present invention is used as an SCR catalyst, it is possible to have high purification performance for exhaust gases containing nitrogen oxides. From the viewpoint of increasing the active sites and improving the catalytic performance, the Si / Al molar ratio is more preferably 8 or less, even more preferably 6.5 or less, and most preferably 5 or less. In addition, by reducing the amount of Al in the zeolite framework, the hydrothermal durability of the zeolite is improved, and even when the zeolite comes into contact with a gas containing water vapor, the structure is less likely to be destroyed due to the elimination of Al from the framework. From these viewpoints, the Si / Al ratio is preferably 2 or more, more preferably 3 or more, particularly preferably 4 or more, and particularly preferably 4.5 or more.

[0060] As the purity of AEI zeolite increases, its performance such as catalytic activity when used as a catalyst improves. Therefore, the purity of AEI zeolite is preferably 83% or more, more preferably 85% or more, even more preferably 88% or more, and particularly preferably 90% or more. The higher the purity of AEI zeolite, the better, and the upper limit is 100%.

[0061] The purity of AEI zeolite can be calculated by the following procedure. First, the by-product content in the zeolite is calculated. The by-product content can be calculated from the following formula (1) using an XRD pattern obtained by XRD measurement using CuKα radiation as a radiation source. By-product content (%) =I(byproduct) / (I(AEI)+I(byproduct))×100 ···(1)

[0062] In the above formula, I(AEI) is the intensity of the main peak of AEI zeolite. The main peak is the most intense peak among the XRD peaks that characterize each zeolite, and in AEI zeolite, it is typically the peak at 2θ=9.5°±0.2°. I(by-product) is the intensity of the main peak of the by-product zeolite. I(by-product) is the intensity of the XRD peak that characterizes the structure of the by-product zeolite. For example, when the by-product zeolite is a MOR type zeolite, I(by-product) is the intensity of the XRD peak having a peak top at 2θ=6.5±0.1°. When the by-product zeolite is a GME type zeolite, I(by-product) is the intensity of the XRD peak having a peak top at 2θ=7.5±0.1°. When there are two or more types of by-products, I(by-product) is calculated by adding up the peak intensities.

[0063] From the by-product content (%) calculated as above, the purity of the AEI zeolite can be calculated from the following formula (2). Purity of AEI zeolite (%) = 100 - by-product content (%) (2)

[0064] The AEI zeolite produced by this method is an alkali metal atom source, or an aluminum atom source, a silicon atom source, an organic structure directing agent, and an alkali metal portion derived from the alkali metal atoms contained in d6r zeolite, which is converted into an H type or NH 4 The compound can be used after being converted into the above-mentioned form, and the method for converting the compound into the above-mentioned form can be performed by using a known technique. For example, the compound can be converted into the above-mentioned form, 4 NO 3 , NaNO 3 or an acid such as hydrochloric acid at room temperature to 100° C., followed by washing with water.

[0065] <Improved heat resistance through post-loading of metal> As a method for improving the hydrothermal resistance of the AEI-type zeolite obtained by this manufacturing method, the AEI-type zeolite after hydrothermal synthesis or the catalyst after loading a metal (for example, Cu) to be used as the catalyst described later may be loaded with the metal. Examples of the metal to be loaded include Mg, Ca, Sr, La, Pr, B, Zr, Ce, Fe, etc. These metals may be used alone or in combination of two or more kinds in an arbitrary ratio. Further, a salt of these metals may be added to the gel before hydrothermal synthesis of the AEI-type zeolite to produce an AEI-type zeolite containing the metal. In this case, usually, inorganic acid salts such as sulfates, phosphates, nitrates, chlorides, bromides, etc. of transition metals, organic acid salts such as acetates, oxalates, citrates, etc., and organometallic compounds such as pentacarbonyl, ferrocene, etc. are used. Among these salts, inorganic acid salts and organic acid salts are preferable from the viewpoint of solubility in water. As the effect of supporting these metals, it is considered that a protective effect from water vapor can be obtained by the coordination of the metal to Al in the zeolite framework.

[0066] <Use of AEI-type zeolite> The use of the AEI-type zeolite of the present invention is not particularly limited, but it is preferably used as a catalyst, an adsorbent, a separation material, etc. Among them, it is preferably used as a catalyst and an adsorbent. The AEI-type zeolite is particularly preferably used as a catalyst for purifying exhaust gas from automobiles and the like. Further, the AEI-type zeolite is also preferably used as an adsorbent for purifying exhaust gas from automobiles and the like.

[0067] [Catalyst] When the AEI-type zeolite of the present invention is used as a catalyst, the catalyst contains the AEI-type zeolite produced by the above manufacturing method. The catalyst is used as various industrial catalysts and environmental catalysts, but it is preferably used as a reduction catalyst for nitrogen oxides. The nitrogen oxide reduction catalyst can be used in exhaust purification systems and the like, and can be used, for example, as an exhaust gas treatment catalyst capable of purifying nitrogen oxides contained in a wide variety of exhaust gases emitted from various diesel engines for diesel automobiles, gasoline automobiles, stationary power generation, ships, agricultural machinery, construction machinery, motorcycles, and aircraft, boilers, gas turbines, etc. The catalyst containing the AEI zeolite of the present invention can exhibit high purification performance for exhaust gases containing nitrogen oxides by lowering the Si / Al molar ratio as described above. The exhaust gas may contain components other than nitrogen oxides, such as hydrocarbons, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxides, and water.

[0068] In addition, the exhaust purification system may use known reducing agents such as ammonia, urea, hydrazine, nitrogen-containing compounds (excluding nitrogen oxides), such as ammonium carbonate, ammonium carbamate, ammonium hydrogen carbonate, and ammonium formate, and hydrocarbons. In an exhaust purification system, a catalyst containing AEI zeolite may be used as a selective catalytic reduction catalyst (SCR catalyst), in which a reducing agent such as ammonia is adsorbed on the SCR catalyst, and nitrogen oxides are selectively reduced by the adsorbed reducing agent. An exhaust gas purification system using an SCR catalyst has a reducing agent supplying unit that supplies a reducing agent, and the reducing agent is supplied from the reducing agent supplying unit to the SCR catalyst. The reducing agent supplying unit may supply the reducing agent to the SCR catalyst by a known means, for example, by spraying the reducing agent and supplying it to the SCR catalyst. The reducing agent supplied may be ammonia itself, or a compound capable of generating ammonia. An example of a compound capable of generating ammonia is urea.

[0069] When the AEI zeolite of the present invention is used as a catalyst, it may be used as it is, or an AEI zeolite containing a metal may be used as necessary. The metal may be any metal other than Si and Al, and for example, transition metals are preferred as metal elements used in SCR catalysts, and among them, it is more preferred to select from the group consisting of iron (Fe), cobalt (Co), palladium (Pd), iridium (Ir), platinum (Pt), copper (Cu), silver (Ag), gold (Au), cerium (Ce), lanthanum (La), praseodymium (Pr), titanium (Ti), zirconium (Zr), etc., and copper (Cu) is even more preferred.

[0070] Specific examples of methods for incorporating metals include impregnation and ion exchange in the liquid or solid phase. As described above, a metal (which may be a simple substance or a compound) may be added before hydrothermal synthesis to directly synthesize a metal-containing zeolite. The state of existence of the metal in a metal-containing zeolite may be that it is contained in the framework structure or that it is not.

[0071] The catalyst containing the AEI zeolite of the present invention can be used by mixing with a binder and granulating it or by forming it into a predetermined shape such as a honeycomb shape. Specifically, for example, the catalyst is mixed with an inorganic binder such as silica, alumina, or clay mineral, or an inorganic fiber such as alumina fiber or glass fiber, and then granulated or formed into a predetermined shape such as a honeycomb shape by an extrusion method or a compression method, and then fired to obtain a granular catalyst, honeycomb catalyst, or catalyst molded product.

[0072] The catalyst containing the AEI zeolite of the present invention may also be used by applying it to a substrate such as a sheet or honeycomb. Specifically, for example, a method may be used in which the catalyst containing the AEI zeolite of the present invention is mixed with an inorganic binder such as silica, alumina, or clay mineral to prepare a slurry, which is then applied to the surface of a substrate made of an inorganic material such as cordierite, and then fired. Preferably, the catalyst is applied to a substrate having a honeycomb shape, thereby obtaining a honeycomb-shaped honeycomb catalyst coated with the catalyst.

[0073] In the above description, an inorganic binder is used because an exhaust gas treatment catalyst is used as an example, but it goes without saying that an organic binder may be used depending on the application and conditions of use.

[0074] [Adsorbent] When the AEI zeolite of the present invention is used as an adsorbent, the adsorbent contains the AEI zeolite produced by the above-mentioned production method. The adsorbent is preferably used as a nitrogen oxide adsorbent for adsorbing nitrogen oxides, and the nitrogen oxide adsorbent is used, for example, in an exhaust gas purification system. More specifically, the exhaust gas purification system comprises the above-mentioned nitrogen oxide adsorbent and a nitrogen oxide reduction catalyst, and it is preferable that the nitrogen oxide adsorbent is disposed upstream of the nitrogen oxide reduction catalyst in the exhaust path of the exhaust gas. The nitrogen oxide reducing catalyst is preferably a selective catalytic reduction catalyst (SCR catalyst) that reduces nitrogen oxides with a reducing agent, and the reducing agent and the reducing agent supply unit for supplying the reducing agent are as described above. As the SCR catalyst, a known SCR catalyst may be a catalyst containing the AEI zeolite of the present invention.

[0075] Nitrogen oxide adsorbents normally adsorb nitrogen oxides in exhaust gas when the temperature of the exhaust gas is in the low temperature range (e.g., below 150°C). When the temperature of the exhaust gas is in the high temperature range (e.g., 150°C or higher), the nitrogen oxides adsorbed to the adsorbent are desorbed as high-temperature exhaust gas. On the other hand, SCR catalysts are catalysts that can reduce nitrogen oxides with a reducing agent in the high temperature range (e.g., 150°C or higher). Generally, exhaust gas is at a low temperature at the beginning of operation, but becomes high temperature after a certain amount of time has passed since the start of operation.

[0076] Therefore, in an exhaust gas treatment system using the AEI zeolite of the present invention, when low-temperature exhaust gas is discharged and passes through the nitrogen oxide adsorbent, the nitrogen oxides contained in the exhaust gas are adsorbed by the nitrogen oxide adsorbent, thereby reducing the amount of nitrogen oxides in the exhaust gas. On the other hand, when high-temperature exhaust gas is discharged and passes through the nitrogen oxide adsorbent, the nitrogen oxides are not adsorbed by the nitrogen oxide adsorbent, and the adsorbed nitrogen oxides are desorbed. Therefore, the exhaust gas including the desorbed nitrogen oxides is sent from the nitrogen oxide adsorbent to the SCR catalyst. In the SCR catalyst, the nitrogen oxides contained in the exhaust gas are reduced to nitrogen and the like by a reducing agent. As a result, the exhaust gas treatment system using the AEI zeolite of the present invention is able to reduce the amount of nitrogen oxides contained in the exhaust gas even when the exhaust gas is at a high temperature. EXAMPLES

[0077] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples in any way as long as the gist of the present invention is not exceeded.

[0078] [Analysis and Evaluation] The analysis and performance evaluation of the zeolites obtained in the following Examples and Comparative Examples were carried out by the following methods.

[0079] [Powder XRD Measurement] <Sample preparation> 100 mg of zeolite sample was manually crushed using an agate mortar and set in a sample holder of the same shape so that the sample amount was constant. <Instrument specifications and measurement conditions> The specifications of the powder XRD measuring device and the measuring conditions are as follows.

[0080] [Table 1] [Table 2]

[0081] [Purity of AEI zeolite] In the XRD pattern obtained by the XRD measurement, the purity of the AEI zeolite was calculated from the intensity of the main peak of the AEI zeolite and the intensity of the main peak of each by-product according to the above-mentioned formulas (1) and (2).

[0082] [Si / Al ratio measurement by X-ray fluorescence analysis] The zeolite standard specimens were dissolved by heating in an alkaline solution and an aqueous solution of hydrofluoric acid, and the Si / Al ratio was determined by inductively coupled plasma (ICP) emission spectrometry. Then, a calibration curve of the fluorescent X-ray intensity of the analyzed element in the standard specimen and the atomic concentration of the analyzed element was created. Using this calibration curve, the zeolite obtained in each example was analyzed by X-ray fluorescence spectrometry (XRF) to determine its Si / Al ratio. The ICP analysis was performed using a Thermo Fisher Scientific device named iCAP7600 Duo. The XRF was performed using a Rigaku device named Supermini200. By this method, the Si / Al molar ratios (B) and (C) in the solid content of the composition and the Si / Al ratio in the zeolite framework were determined.

[0083] Example 1 Amorphous Al(OH) was dissolved in a mixture of 5.9 g of water, 1.1 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide (35% by mass, manufactured by Seichem Co., Ltd.) as an organic structure directing agent (SDA), and 0.48 g of NaOH (97% by mass, manufactured by Kishida Chemical Co., Ltd.). 3 (Al 2 O 3 0.43g of 1,2-dichlorophenylsilica (silica concentration: 54.3% by mass, manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred to dissolve the solution, forming a transparent solution. 4.5g of Snowtex 40 (colloidal silica, silica concentration: 40% by mass, manufactured by Nissan Chemical Industry Co., Ltd.) was added thereto and stirred at room temperature (25°C) for 2 hours to obtain a pre-ripening composition. Here, the Si / Al molar ratio (A) was 6.5. The molar ratio of the organic structure directing agent to the silicon atoms contained in the composition was 0.08. This pre-aging composition was placed in a pressure-resistant container, aged in an oven at 40°C for 4 hours, and then cooled to room temperature. The compositions before and after aging were filtered under reduced pressure for 30 minutes using a glass funnel (Kiriyama Seisakusho, diameter 60 mm) and cellulose filter paper (Kiriyama Seisakusho, diameter 60 mm, thickness 0.21 mm, retention particles 1 μm, model No. 5C) at room temperature (25°C). The Si / Al molar ratio of the solid component obtained was 8.85 before aging (B) and 6.7 after aging (C). The ratio of the Si / Al molar ratio (C) of the solid component after aging to the charge ratio (A) was 103%. 0.1 g of uncalcined CHA-type zeolite (Si / Al molar ratio = 12) was added as a seed crystal to the aged composition, and the mixture was stirred for 1 hour to obtain a pre-reaction composition. Here, the amount of zeolite added was determined so that all the silicon atoms contained in the pre-reaction composition other than zeolite were SiO 2 SiO when it is assumed that 2 It was 5% by mass. This pre-reaction composition was placed in a pressure-resistant container and rotated (15 rpm) in an oven at 180 ° C. for 1 day to carry out hydrothermal synthesis. After cooling the reaction liquid after this hydrothermal synthesis reaction, the produced zeolite was collected by filtration. The collected zeolite was dried at 100 ° C. for 12 hours, and the XRD of the obtained zeolite powder was measured. It was confirmed that AEI type zeolite 1 was synthesized, which shows an XRD pattern with peaks and relative intensities at the positions shown in Table 3 in lattice spacing representation. The XRD pattern of this zeolite 1 is shown in Figure 1. In Figure 1, the vertical axis is intensity (cps) and the horizontal axis is diffraction angle 2θ (°). The Si / Al ratio of zeolite 1 by XRF analysis was 4.8.

[0084] [Table 3]

[0085] Example 2 Zeolite powder was obtained in the same manner as in Example 1, except that the aging conditions were 40°C and 6 hours. The compositions before and after aging were filtered, and the Si / Al molar ratios of the solid components obtained were 8.85 before aging (B) and 6.4 after aging (C). The ratio of the Si / Al molar ratio (C) of the solid component after aging to the feed ratio (A) was 98%. When the XRD of the obtained zeolite powder was measured, it was confirmed that AEI type zeolite 2 was synthesized, which exhibited an XRD pattern having peaks and relative intensities at the positions shown in Table 4 in lattice spacing notation. The Si / Al ratio of zeolite 2 by XRF analysis was 4.7.

[0086] [Table 4]

[0087] Example 3 Zeolite powder was obtained in the same manner as in Example 1, except that the aging conditions were 80°C and 2 hours. The compositions before and after aging were filtered, and the Si / Al molar ratios of the solid components obtained were 8.85 before aging (B) and 5.7 after aging (C). The ratio of the Si / Al molar ratio of the solid component after aging (C) to the feed ratio (A) was 87%. When the XRD of the obtained zeolite powder was measured, it was confirmed that AEI type zeolite 3 was synthesized, which exhibited an XRD pattern having peaks and relative intensities at the positions shown in Table 5 in lattice spacing notation. The Si / Al ratio of zeolite 3 by XRF analysis was 4.8.

[0088] [Table 5]

[0089] Example 4 Zeolite powder was obtained in the same manner as in Example 1, except that the aging conditions were 120°C and 1 hour. The compositions before and after aging were filtered, and the Si / Al molar ratios of the solid components obtained were 8.85 before aging (B) and 5.4 after aging (C). The ratio of the Si / Al molar ratio of the solid component after aging (C) to the feed ratio (A) was 82%. When the XRD of the obtained zeolite powder was measured, it was confirmed that AEI type zeolite 4 was synthesized, which exhibited an XRD pattern having peaks and relative intensities at the positions shown in Table 6, expressed in lattice spacing. The Si / Al ratio of zeolite 4 by XRF analysis was 4.7.

[0090] [Table 6]

[0091] Example 5 Zeolite powder was obtained in the same manner as in Example 1, except that the aging conditions were 120°C and 24 hours. The compositions before and after aging were filtered, and the Si / Al molar ratios of the solid components obtained were 8.85 before aging (B) and 5.2 after aging (C). The ratio of the Si / Al molar ratio (A) of the solid component after aging to the feed ratio (A) was 79%. When the XRD of the obtained zeolite powder was measured, it was confirmed that AEI type zeolite 5 was synthesized, which exhibited an XRD pattern having peaks and relative intensities at the positions shown in Table 7 in terms of lattice spacing. The Si / Al ratio of zeolite 5 by XRF analysis was 4.7.

[0092] [Table 7]

[0093] Comparative Example 1 The same procedure as in Example 9 of JP 2017-081809 A was carried out to obtain zeolite powder. Specifically, all raw materials were added and stirred at room temperature for 2 hours to obtain a pre-reaction composition. The Si / Al molar ratio of the solid component obtained by filtering the pre-reaction composition was 11.5, and the ratio of the Si / Al molar ratio of the solid component to the charge ratio (A) was 126%. When the XRD of the obtained zeolite powder was measured, it was confirmed that AEI type zeolite 6 was synthesized, which showed an XRD pattern with peaks and relative intensities at the positions shown in Table 8 in lattice spacing notation. The Si / Al ratio of zeolite 7 by XRF analysis was 5.1.

[0094] [Table 8]

[0095] Comparative Example 2 Zeolite powder was obtained in the same manner as in Example 1, except that aging was not performed. That is, the seed crystals were added to a pre-aged composition obtained by stirring the raw materials other than the seed crystals at room temperature (25°C) for 2 hours. The Si / Al molar ratio of the solid component obtained by filtering the pre-reaction composition obtained by mixing the raw materials was 8.85, and the ratio of the Si / Al molar ratio of the solid component to the charge ratio (A) was 136%. When the XRD of the obtained zeolite powder was measured, it was confirmed that zeolite 7, which is a mixed phase of AEI type and impurities GME type and MOR type, was synthesized, which shows an XRD pattern with peaks and relative intensities at the positions shown in Table 9 in lattice spacing notation. The Si / Al ratio of zeolite 7 by XRF analysis was 4.8.

[0096] [Table 9]

[0097] Comparative Example 3 Zeolite powder was obtained in the same manner as in Example 1, except that seed crystals were added before aging and aging conditions were set at 80°C for 2 hours. The compositions before and after aging were filtered, and the Si / Al molar ratios of the solid components obtained were 8.85 before aging (B) and 5.8 after aging (C). The ratio of the Si / Al molar ratio of the solid component after aging (C) to the feed ratio (A) was 88%. When the XRD of the obtained zeolite powder was measured, it was confirmed that zeolite 8 was synthesized, which is a mixed phase of AEI type and impurities such as GME type and MOR type, which show an XRD pattern with peaks and relative intensities at the positions shown in Table 10 in lattice spacing representation. XRF analysis showed that the Si / Al ratio of zeolite 8 was 4.7.

[0098] [Table 10]

[0099] The results are summarized in Tables 11 and 12. [Table 11] In Table 11, SDA / Si is the molar ratio of the organic structure directing agent to the silicon atoms contained in the pre-reaction composition. The amount of seed crystals added is the amount of silicon (Si) contained in the pre-reaction composition other than the seed crystals that is converted to SiO 2 SiO when it is assumed that 2 This is mass % of the total.

[0100] [Table 12] In Table 12, the Si / Al molar ratio (B) in Comparative Examples 1 and 2 indicates the Si / Al molar ratio of the pre-reaction composition obtained by mixing the respective raw materials.

[0101] From the above examples, it was confirmed that AEI zeolite with low Si / Al and high AEI purity can be obtained by aging a composition containing each raw material, adding d6r zeolite, and then performing hydrothermal synthesis. Here, in each example, since no Y zeolite is used as a raw material other than the seed crystals, and the amount of organic structure-directing agent used is small, it was found that AEI zeolite with low Si / Al and high AEI purity can be produced at low cost. In contrast, in Comparative Examples 1 and 2, the step of adding d6r zeolite after aging was not performed, and therefore, when the amount of the organic structure-directing agent used was reduced as in Comparative Example 2, an AEI zeolite having a low Si / Al ratio and high AEI purity could not be obtained. Also, it was found that in order to obtain AEI zeolite, it is necessary to use a large amount of an expensive organic structure-directing agent as in Comparative Example 1. Furthermore, it was found from Comparative Example 3 that even if seed crystals are added to the composition before aging, an AEI zeolite having a low Si / Al ratio and high purity cannot be obtained.

Claims

1. preparing a composition comprising silicon atoms, aluminum atoms, alkali metal atoms, an organic structure directing agent, and water; Aging the composition; adding a zeolite containing d6r in its framework, which is defined as a composite building unit by the International Zeolite Association (IZA), after the aging; a step of hydrothermally synthesizing the composition after adding the zeolite; A method for producing AEI zeolite, comprising:

2. The method for producing AEI zeolite according to claim 1, characterized in that, when the molar ratio of silicon atoms / aluminum atoms in the solid content of the composition before aging is "B" and the molar ratio of silicon atoms / aluminum atoms in the solid content of the composition after aging is "C", the molar ratio calculated as C / B x 100 is less than 100%.

3. The method for producing AEI zeolite according to claim 1 or 2, wherein the aging is carried out by heating.

4. The method for producing AEI zeolite according to claim 3, wherein the heating is carried out at 30 to 140° C. for 10 minutes to 24 hours.

5. 5. The method for producing AEI zeolite according to claim 1, wherein the AEI zeolite has a molar ratio of silicon atoms / aluminum atoms of 10 or less.

6. A method for producing AEI zeolite according to any one of claims 1 to 5, characterized in that amorphous silica is used as the silicon atoms contained in the composition before aging.

7. The method for producing AEI zeolite according to any one of claims 1 to 6, wherein the silicon atoms contained in the composition before aging do not contain zeolite, or the silicon atoms derived from zeolite contained in the composition before aging are 10 mol% or less relative to the total amount of silicon atoms.

8. A method for producing AEI zeolite described in any one of claims 1 to 7, characterized in that the composition after the addition of the zeolite contains an organic structure-directing agent in a molar ratio of 0.01 or more and 1 or less relative to silicon atoms.

9. A method for producing an AEI type zeolite as described in claim 4, wherein the heating is carried out at 120°C or less, and the silicon atom raw material contains amorphous silica.

10. A method for producing a nitrogen oxide reduction catalyst, comprising using an AEI zeolite produced by the method for producing an AEI zeolite according to any one of claims 1 to 9.

11. A method for producing an adsorbent, which uses AEI zeolite produced by the method for producing AEI zeolite according to any one of claims 1 to 9.

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