A CHA-type zeolite and its preparation method

Abstract

Compared to existing CHA-type zeolites, this invention provides CHA-type zeolites with more paired aluminum structures, catalysts containing such zeolites, and at least one method for their manufacture. One method for manufacturing a CHA-type zeolite includes a step of crystallizing a composition comprising an alumina source, a silica-alumina source, an alkali source, an organic structure directing agent, and water. Preferably, this composition is obtained by mixing the alumina source, the alkali source, the organic structure directing agent, and water, followed by mixing the silica-alumina source.

Description

Technical Field

[0001] This disclosure relates to a CHA-type zeolite and a method for manufacturing the same. In particular, it relates to a CHA-type zeolite suitable for industrial use as a nitrogen oxide reduction catalyst and a method for manufacturing the same. Background Technology

[0002] CHA-type zeolites (Chabazite-type zeolites) with a high SiO2 / Al2O3 ratio are artificially synthesized small-pore zeolites (e.g., Patent Documents 1 and 2, Non-Patent Document 1, etc.). In recent years, studies have been reported focusing on the distribution of aluminum in the framework structure of CHA-type zeolites, particularly the "paired aluminum (Japanese: ペアアルミニウム) structure."

[0003] As a report concerning paired aluminum structures, Non-Patent Literature 2 reports a CHA-type zeolite obtained by crystallizing a composition containing adamantyltrimethylammonium hydroxide and crystalline aluminum hydroxide (Al(OH)3) as a starting material, wherein the proportion of paired aluminum in the aluminum content is 5% or more and 17% or less. Non-Patent Literature 3 reports a CHA-type zeolite of the cationic sodium form obtained by crystallizing a composition containing adamantyltrimethylammonium hydroxide, wherein the proportion of paired aluminum in the aluminum content is 60% or less.

[0004] However, CHA-type zeolites containing (supported) copper have been used as nitrogen oxide reduction catalysts, particularly SCR catalysts. It has been reported that ion exchange sites on oxygen double six-membered ring structures with paired aluminum structures readily and stably retain copper; therefore, by introducing copper into these ion exchange sites, the nitrogen oxide reduction properties are improved (Non-Patent Literature 4).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2011-234599

[0008] Patent Document 2: International Publication No. 2013 / 182974

[0009] Non-patent literature

[0010] Non-patent literature 1: Ind. Eng. Chem. Res., 57(2018) 3914-3922

[0011] Non-patent literature 2: Chem. Mater., 28(2016) 2236-2247

[0012] Non-patent literature 3: Chem. Mater., 32(2020) 273-285

[0013] Non-patent literature 4: J. Am. Chem. Soc., 138(2016) 6028-6048 Summary of the Invention

[0014] The technical problem that the invention aims to solve

[0015] The purpose of this disclosure is to provide CHA-type zeolites having more paired aluminum than conventional CHA-type zeolites, catalysts containing the zeolites, and at least one of the methods for manufacturing them.

[0016] Means for solving technical problems

[0017] As described in the claims, the present invention is further described below.

[0018] [1] A CHA type zeolite, characterized in that the ratio of paired aluminum is 25% or more.

[0019] [2] According to the CHA type zeolite described in [1] above, the molar ratio of silicon dioxide to aluminum oxide is 10 or more.

[0020] [3] According to the CHA type zeolite described in [1] or [2] above, the molar ratio of silicon dioxide to aluminum oxide is 70 or less.

[0021] [4] The CHA type zeolite according to any one of [1] to [3] above, wherein the micropore volume is 0.2 mL / g or more.

[0022] [5] The CHA type zeolite according to any one of [1] to [4] above is characterized in that the average crystal diameter is 0.7 μm or less.

[0023] [6] The CHA-type zeolite according to any one of [1] to [5] above, wherein the BET specific surface area is 200 m². 2 / g or more and 1000m 2 / g or less.

[0024] [7] A method for manufacturing CHA-type zeolite, comprising the following steps:

[0025] A process for crystallizing a composition comprising an alumina source, a silica-alumina source, an alkali source, an organic structure directing agent, and water.

[0026] [8] According to the method for manufacturing CHA-type zeolite described in [7] above, the composition is obtained by mixing an alumina source, an alkali source, an organic structure directing agent and water, and then mixing a silica-alumina source.

[0027] [9] In the manufacturing method described in [7] or [8] above, the alumina source is an amorphous aluminum compound.

[0028]

[10] The manufacturing method according to any one of [7] to [9] above, wherein the silica-alumina source is FAU type zeolite.

[0029]

[11] The manufacturing method according to any one of [7] to

[10] above, wherein the composition comprises a silicon dioxide source.

[0030]

[12] A nitrogen oxide reduction catalyst, characterized in that it comprises any one of the above [1] to [6] CHA type zeolite.

[0031]

[13] A method for reducing nitrogen oxides, characterized in that the CHA type zeolite described in any one of [1] to [6] above is used.

[0032] Invention Effects

[0033] According to this disclosure, compared with existing CHA-type zeolites, it is possible to provide CHA-type zeolites having more paired aluminum structures, catalysts containing the zeolites, and at least one of their manufacturing methods. Attached Figure Description

[0034] Figure 1 These are the XRD patterns of copper-loaded CHA-type zeolite from (a) Comparative Example 1 and (b) Example 1 after hydrothermal durability treatment. Detailed Implementation

[0035] Hereinafter, an example of an embodiment of this disclosure will be described. It should be noted that the terminology used in this embodiment is as follows.

[0036] "Aluminosilicate" is a composite oxide having a repeating network structure containing aluminum (Al) and silicon (Si) via oxygen (O). In the powder X-ray diffraction (XRD) pattern of aluminosilicates, substances with crystalline XRD peaks are called "crystalline aluminosilicates", and substances without crystalline XRD peaks are called "amorphous aluminosilicates".

[0037] In this embodiment, the XRD pattern is measured using CuKα rays as the radiation source. The following conditions can be cited as measurement conditions.

[0038] X-ray source: CuKα rays

[0039] Measurement mode: Step scan

[0040] Scanning speed: 4.0° per minute

[0041] Measurement range: 2θ = 3.0°~50.0°

[0042] As a more preferred condition, the following conditions can be cited.

[0043] Accelerating current and voltage: 40mA·40kV

[0044] X-ray source: CuKα rays

[0045] Measurement mode: Continuous scanning

[0046] Scanning conditions: 40° / minute

[0047] Measurement range: 2θ = 3° to 43°

[0048] Longitudinal diverging slit: 10mm

[0049] Diverging / Incident Slit: 1°

[0050] Light-receiving slit: open

[0051] Detector: D / teX Ultra

[0052] Using a Ni filter

[0053] XRD patterns can be determined using general powder X-ray diffraction equipment (e.g., D8 Advance, manufactured by Bruker). Furthermore, crystalline XRD peaks are specific 2θ peaks detected in the analysis of XRD patterns using general analysis software (e.g., SmartLab StudioII, manufactured by Rigaku), and can be exemplified as XRD peaks with a half-width of 2θ = 0.50° or less.

[0054] "Zeolite" refers to a compound having an ordered structure of framework atoms (hereinafter also referred to as "T atoms") formed by oxygen (O), and the T atoms comprising at least one of metal atoms and / or half-metal atoms. Examples of half-metal atoms include one or more selected from boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te).

[0055] "Zeolite analogues" refer to compounds that have an ordered structure formed by T atoms through oxygen, and that contain at least atoms other than metals and half-metals in the T atoms. Examples of zeolite analogues include complex phosphorus compounds such as aluminum phosphate (AlPO) and silica aluminum phosphate (SAPO), which contain phosphorus (P) as T atoms.

[0056] The "ordered structure" (hereinafter also referred to as "zeolite structure") in zeolites or zeolite-like substances refers to the framework structure identified by the structure code (hereinafter also simply "structure code") specified by the Structure Commission of the International Zeolite Association. For example, the CHA structure is the framework structure (CHA structure) identified by the structure code "CHA". Zeolite structures can be identified by comparing them with the XRD patterns of the various structures described in the Collection of simulated XRD powder patterns for zeolites, Fifth revised edition, p. 483 (2007) (hereinafter also referred to as "reference patterns"). Regarding zeolite structures, framework structure, crystal structure, or crystalline phase are used synonymously.

[0057] In this embodiment, “CHA-type zeolite” and other “~-type zeolite” mean a zeolite with the structure code of that zeolite, and preferably means a crystalline aluminosilicate with the structure code of that zeolite.

[0058] Hereinafter, an example of an embodiment of the method for manufacturing the CHA-type zeolite disclosed herein will be described.

[0059] The CHA-type zeolite of this embodiment is obtained by a manufacturing method comprising a step of crystallizing a composition containing an alumina source, a silica-alumina source, an organic structure directing agent source, an alkali source, and water. The CHA-type zeolite of this embodiment is crystallized through a step (hereinafter also referred to as a "crystallization step") of crystallizing a composition containing an alumina source, a silica-alumina source, an organic structure directing agent source, an alkali source, and water.

[0060] The alumina source is a compound containing aluminum oxide (Al₂O₃) or aluminum (Al) as a precursor thereto, particularly a compound containing aluminum and free of silicon (Si). Specific alumina sources include one or more selected from the group consisting of aluminum hydroxide, aluminum chloride, aluminum sulfate, aluminum nitrate, and sodium aluminate. In this embodiment, the alumina source is preferably an amorphous aluminum compound, i.e., an amorphous compound containing aluminum, such as at least one of dried aluminum hydroxide gel and sodium aluminate, or dried aluminum hydroxide gel. The alumina source preferably contains at least an amorphous aluminum compound, and more preferably an amorphous aluminum compound.

[0061] The silica-alumina source is a compound containing silicon and aluminum. Specific examples of silica-alumina sources include at least one of aluminosilicates, amorphous aluminosilicates, and crystalline aluminosilicates, or crystalline aluminosilicates. The molar ratio of silicon dioxide to alumina in the silica-alumina source (hereinafter also referred to as the "SiO2 / Al2O3 ratio") is 1.25 or more or 5 or more, and can also be 100 or less, 50 or less, 10 or less, or 9.5 or less. Examples of cationic silica-alumina sources include sodium form (Na form) and proton form (H form). + It contains one or more of the following: silica-alumina type (NH4 type) and ammonium type (NH4 type), or sodium type. The BET specific surface area of ​​the silica-alumina source is 200 m². 2 / g or more or 500m 2 / g or more, and preferably 1000m 2 / g or less or 800m 2 / g or less.

[0062] As particularly preferred silica-alumina sources, examples include crystalline aluminosilicates, and further, at least one of FAU-type zeolites, zeolite X, and zeolite Y, or zeolite Y. It should be noted that the silica-alumina source does not contain crystalline aluminosilicates (i.e., seed crystals) used to promote the crystallization of the raw material composition; the raw material composition may contain both seed crystals and a silica-alumina source. Examples of silica-alumina sources include crystalline aluminosilicates other than CHA-type zeolites. In the manufacturing method of this embodiment, it is believed that by crystallizing a raw material composition containing an alumina source and a silica-alumina source, i.e., two or more aluminum compounds, preferably crystalline aluminum compounds and amorphous aluminum compounds, a CHA-type zeolite with a high Al-to-pair ratio can be obtained.

[0063] The raw material composition may not contain a silica source, but may also contain a silica source as needed to fine-tune the SiO2 / Al2O3 ratio. The silica source is silicon dioxide (SiO2) or silicon as a precursor thereof, particularly a compound containing silicon but not aluminum. Specific silica sources include at least one selected from the group consisting of colloidal silica, amorphous silica, sodium silicate, tetraethoxysilane, tetraethyl orthosilicate, precipitated silica, and fumed silica; at least one selected from the group consisting of colloidal silica, amorphous silica, sodium silicate, precipitated silica, and fumed silica; at least any one selected from precipitated silica and fumed silica; or fumed silica.

[0064] The organic structure directing agent (hereinafter also referred to as "SDA") source is selected from at least one of the salts and compounds containing cations that direct the CHA structure, one or more of the group consisting of sulfates, nitrates, halides and hydroxides of SDA, at least one of the halides or hydroxides of SDA, or a hydroxide of SDA.

[0065] SDA can be any cation of a CHA-type zeolite. Examples of cations selected for CHA-type zeolites include one or more selected from the group consisting of N,N,N-trialkyladamantane ammonium cation, N,N,N-trimethylbenzylammonium cation, N-alkyl-3-quinol cation, N,N,N-trialkylexoaminonorbornene cation, and N,N,N-trialkylcyclohexylammonium cation, preferably N,N,N-trialkyladamantane ammonium cation (hereinafter also referred to as "TAAd"). + N,N,N-trimethylbenzylammonium cation (hereinafter also referred to as "TMBA") + ), and N,N,N-trialkylcyclohexylammonium cation (hereinafter also referred to as "TACH"), and N,N,N-trialkylcyclohexylammonium cation (hereinafter also referred to as "TACH"). + More than one of the group consisting of “”, preferably TAAd + and TACH + At least one of them, particularly preferably TAAd + and TACH + .

[0066] As the preferred TAAd + Examples include N,N,N-trimethyladamantane ammonium cation (hereinafter, TMAd). + Additionally, TACH is the preferred option. + Examples include N,N,N-dimethylethylcyclohexylammonium cation (hereinafter also referred to as "CDMEA"). + ") and N,N,N-methyldiethylcyclohexylammonium cation (hereinafter, also known as "MDECH") ... + At least one of the following, and further, CDMEA+ can be cited.

[0067] An alkali source is a compound containing an alkali metal element. Examples include compounds containing one or more elements selected from the group consisting of sodium, potassium, rubidium, and cesium; compounds containing one or more elements selected from the group consisting of sodium, potassium, and cesium; compounds containing at least one element selected from sodium and potassium; or compounds containing sodium. Examples of alkali sources include one or more elements selected from the group consisting of hydroxides, fluorides, bromides, iodides, sulfates, nitrates, and carbonates containing the aforementioned alkali metal elements; one or more elements selected from the group consisting of hydroxides, bromides, and iodides; or hydroxides (hereinafter, alkali sources containing sodium are referred to as "sodium sources," and alkali sources containing potassium are referred to as "potassium sources," etc.). The raw material composition particularly preferably contains sodium and potassium sources. When starting materials such as alumina sources contain alkali metal elements, these starting materials are also considered alkali sources.

[0068] In addition to pure water and ion-exchanged water, water contained in other starting materials such as structural water, hydrated water, and solvents is also considered as water in the raw material composition.

[0069] As a preferred composition of the raw material composition, the following molar compositions can be exemplified. In the following compositions, SDA is an organic structure directing agent, M is an alkali metal element, and OH is a hydroxide ion. The SDA / SiO2 ratio is TMAda when SDA is... + In the case of setting it to "TMAda" + / SiO2 ratio", in SDA is CDMEA + In the case of setting it to "CDMEA" + The M / SiO2 ratio can be set to "Na / SiO2 ratio" when M is sodium, and "(Na+K) / SiO2 ratio" when M is sodium and potassium.

[0070] SiO2 / Al2O3 ratio: 10 or higher, or 20 or higher but below 100, 90 or below 90, 70 or below 70, 50 or below 40.

[0071] SDA / SiO2 ratio: ≥0.01 or ≥0.05 but ≤0.50, ≤0.40 or ≤0.30

[0072] M / SiO2 ratio: ≥0.05, ≥0.1, or ≥0.15 but ≤1.5, ≤1.0, or ≤0.4

[0073] OH / SiO2 ratio: ≥0.1 or ≥0.3 and ≤1.0 or ≤0.6

[0074] H2O / SiO2 ratio: 3 or higher, 5 or higher, or 8 or higher but below 200, or below 50, or below 30.

[0075] In the raw material composition, the molar ratio [mol / mol] of aluminum in the amorphous aluminum compound converted from Al2O3 (hereinafter also referred to as "amorphous Al ratio") relative to the aluminum in the raw material composition converted from Al2O3 is greater than 0 and is 0.05 or more or 0.1 or more, and preferably 0.45 or less, 0.30 or less or 0.22 or less. Therefore, it is easy to obtain CHA-type zeolites with a high pairing Al ratio, as described later.

[0076] The raw material mixture can be obtained by any method that makes the starting materials such as alumina sources homogeneous. Mixing can be carried out by any method, but it is preferred to mix the alumina source, the alkali source, the organic structure directing agent and water, and then mix the silica-alumina source to obtain the raw material mixture.

[0077] To promote crystallization, the raw material composition may contain seed crystals, if in a sufficiently small amount compared to the silica-alumina source, as needed. Seed crystals are crystalline aluminosilicates that promote the crystallization of the raw material composition; further examples include zeolites other than FAU-type zeolites, and even more specifically, CHA-type zeolites. Seed crystals are mixed with the raw material composition in a manner where the total mass of silicon and aluminum in the raw material composition (excluding seed crystals) converted to SiO2 and Al2O3 (hereinafter also referred to as "seed content") is 0.1% by mass or more, 1.0% by mass or more, or 1.5% by mass or more, and less than 30.0% by mass, less than 10.0% by mass, or less than 5.0% by mass.

[0078] The feedstock composition preferably does not contain fluorine (F) and phosphorus (P). Considering the detection limit of the determination value obtained by conventional compositional analysis, the fluorine content of the feedstock composition is preferably 0 ppm or more and 100 ppm or less, more preferably 0 ppm or more and 50 ppm or less.

[0079] In the crystallization process, the raw material composition can be crystallized by hydrothermal treatment. The following conditions can be cited as examples of hydrothermal treatment conditions.

[0080] Hydrothermal treatment temperature: above 80℃, above 100℃, or above 120℃ but below 200℃, or below 180℃, or below 160℃

[0081] Hydrothermal treatment time: more than 1 hour, more than 10 hours, more than 1 day but less than 10 days, or less than 6 days.

[0082] Hydrothermal treatment pressure: self-generated pressure

[0083] Hydrothermal treatment state: at least one of stirring state and static state, preferably stirring state.

[0084] In the manufacturing method of this embodiment, after the crystallization step, one or more of the following can be selected as needed: a group consisting of a cleaning step, a drying step, an ion exchange step, and a metal-containing step (hereinafter also referred to as "post-processing steps").

[0085] In the cleaning process, CHA-type zeolite is cleaned. Recovery and cleaning can be carried out using any method; for example, fine-porous zeolite obtained by solid-liquid separation after crystallization and washing with pure water as the solid phase can be used.

[0086] In the drying process, moisture is removed from the CHA-type zeolite. The drying conditions are arbitrary; for example, the fine-pore zeolite can be treated in the atmosphere at a temperature above 50°C and below 150°C for more than 2 hours.

[0087] In the ion exchange process, the CHA-type zeolite can be set to any cationic form. If the cationic form is ammonium, an example is mixing the CHA-type zeolite with an aqueous solution of ammonium chloride. Alternatively, if the cationic form is proton-type, an example is calcining the CHA-type zeolite into an ammonium form.

[0088] In the metal-containing process, any active metal element is incorporated into the CHA-type zeolite, preferably any transition metal element is loaded onto the CHA-type zeolite. This yields a metal-containing CHA-type zeolite (or a metal-loaded CHA-type zeolite). The metal incorporation can be achieved by contacting the CHA-type zeolite with a transition metal source, for example, one or more methods selected from the group consisting of ion exchange, impregnation loading, evaporation drying, precipitation loading, and physical mixing, with impregnation loading being preferred.

[0089] The transition metal source is at least one of the salts and compounds containing a transition metal element. As a specific transition metal source, one or more may be selected from the group consisting of nitrates, sulfates, acetates, chlorides, complex salts, oxides and complex oxides containing a transition metal element, and further selected from the group consisting of nitrates, sulfates and chlorides.

[0090] The transition metal element contained in the transition metal source is one or more selected from the group consisting of Groups 8, 9, 10 and 11 of the periodic table, preferably one or more selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), iron (Fe), copper (Cu), cobalt (Co), manganese (Mn) and indium (In), at least one of iron and copper, or copper.

[0091] In the manufacturing method of this embodiment, a step of calcining a metal-containing CHA-type zeolite may also be included, if necessary. Impurities are removed by calcination. The calcination method is arbitrary, and examples include processing in at least one of an oxidizing atmosphere and a reducing atmosphere at a temperature of 100°C or higher and 600°C or lower, preferably in the atmosphere at a temperature of 400°C or higher and 600°C or lower.

[0092] Next, the CHA-type zeolite of this embodiment will be described.

[0093] The CHA-type zeolite of this embodiment is characterized in that it is a CHA-type zeolite with a paired aluminum ratio of 25% or more, that is, a CHA-type zeolite characterized in that the molar ratio of aluminum belonging to the paired aluminum structure in the aluminum contained in the CHA-type zeolite (hereinafter also referred to as "paired Al ratio") is 25% or more.

[0094] The paired Al ratio is 25% or more, 30% or more, or 35% or more, and is also 100% or less, 80% or less, 60% or less, 50% or less, or 45% or less. By having such a paired Al ratio, when the transition metal element is contained (loaded) in the CHA-type zeolite, there is a tendency to suppress the agglomeration and sintering of the transition metal element.

[0095] In this embodiment, the "paired Al ratio" can be determined by quantifying cobalt at the ion exchange sites of divalent ions having paired aluminum structures. Specifically, the paired Al ratio can be determined by measuring the cobalt (Co) content of CHA-type zeolite impregnated with a cobalt nitrate aqueous solution after the ratio of alkali metal elements and alkaline earth metal elements to aluminum (hereinafter also referred to as the "M / Al ratio") is 0.01 or less.

[0096] Paired Al ratio [%] = (MCo [mol] / MAl [mol]) × 2 × 100

[0097] In the above formula, MCo[mol] is the cobalt content determined by ICP measurement, and MAl[mol] is the aluminum content determined by ICP measurement.

[0098] In addition, the following conditions can be cited as impregnation conditions for cobalt nitrate aqueous solution.

[0099] Impregnation temperature: above 10℃ and below 40℃

[0100] Soaking time: 1 hour or more but less than 40 hours

[0101] Cobalt nitrate concentration: ≥0.001 mol / L and ≤2.0 mol / L

[0102] Solid-liquid ratio (mass ratio): (CHA type zeolite / cobalt nitrate aqueous solution) ≤ 0.5

[0103] CHA-type zeolites with an M / Al ratio of 0.01 or less can be exemplified by CHA-type zeolites with proton or ammonium cationic forms.

[0104] It should be noted that even when performing the same treatment on CHA-type zeolites with an M / Al ratio exceeding 0.01 (e.g., sodium, potassium, calcium forms), the pairwise Al ratio can still be determined. However, the pairwise Al ratio determined from CHA-type zeolites with an M / Al ratio exceeding 0.01 includes cobalt complexes and other components derived from the ion exchange sites of divalent ions with paired aluminum structures. 2+ Cobalt other than that. Therefore, the value of the formal pairing Al ratio does not reflect the content of the pairing aluminum structure in the CHA-type zeolite, but is a value larger than the pairing Al ratio of this embodiment (i.e., the actual proportion of the pairing aluminum structure). The formal pairing Al ratio (hereinafter also referred to as "formal pairing Al ratio") obtained from CHA-type zeolites with an M / Al ratio exceeding 0.01 is different from the pairing Al ratio of this embodiment, so it is not possible to compare the pairing Al ratio of this embodiment with the formal pairing Al ratio.

[0105] The SiO2 / Al2O3 ratio of the CHA-type zeolite in this embodiment is 10 or more, 15 or more, or 18 or more. Examples of other ratios include 70 or less, 40 or less, or 30 or less. Particularly preferred SiO2 / Al2O3 ratios include 20 or more, 25 or more, or 28 or more, and 60 or less, 50 or less, or 45 or less.

[0106] The preferred BET specific surface area of ​​the CHA-type zeolite in this embodiment is 200 m². 2 / g or more, 500m 2 / g or more or 600m 2 / g or more, in addition, 1000m 2 / g or less, 800m 2 / g or less or 750m 2 / g or less.

[0107] The BET specific surface area can be determined using the BET 1-point method based on nitrogen adsorption, as specified in JIS Z8830:2013. Nitrogen adsorption only needs to be measured on the pretreated sample. The pretreatment and nitrogen adsorption conditions are shown below.

[0108] Measurement method: Volumetric method

[0109] Measurement temperature: 77K (-196℃)

[0110] Pretreatment: Vacuum drying at 150℃ for 1 hour, and vacuum drying at 350℃ for 2 hours.

[0111] Nitrogen adsorption can be measured using common nitrogen adsorption devices (such as BELSORP-mini II, manufactured by MicrotracBEL).

[0112] Examples of the micropore volume (hereinafter also referred to as "micropore volume") of the CHA-type zeolite in this embodiment include 0.20 mL / g or more, 0.25 mL / g or more, or 0.30 mL / g or more, and 0.70 mL / g or less, 0.50 mL / g or less, or 0.35 mL / g or less.

[0113] The micropore volume can be determined by t-plot analysis of the nitrogen adsorption isotherm obtained using the same method as the BET surface area determination. t-plot analysis can be performed under the following conditions, provided that the analysis software (e.g., BELMaster, MicrotracBEL) accompanying the nitrogen adsorption device is used.

[0114] Adsorbate cross section: 0.162 nm 2

[0115] Saturated water vapor pressure: 103.72 kPa

[0116] The first straight line: a straight line obtained by combining the point t = 0 nm and the point t = 0.26 ± 0.01 nm, or a straight line obtained by combining the point t = 0 nm and the point t = 0.27 ± 0.03 nm, preferably the straight line obtained by combining the point t = 0 nm and the point t = 0.27 ± 0.03 nm.

[0117] The second straight line is a straight line obtained by combining the tangent line at the inflection point of the sigmoid-shaped t-plot curve with the points t = 0.60 ± 0.15 nm and t = 0.90 ± 0.10 nm, or the straight line obtained by combining the points t = 0.35 ± 0.01 nm and t = 0.66 ± 0.01 nm. Preferably, it is a straight line obtained by combining the tangent line at the inflection point of the sigmoid-shaped t-plot curve with the points t = 0.60 ± 0.15 nm and t = 0.90 ± 0.10 nm.

[0118] In this embodiment, the average primary particle size of CHA-type zeolite is 0.7 μm or less, preferably 0.6 μm or less. Additionally, the average crystal diameter is 0.1 μm or more, 0.2 μm or more, or 0.3 μm or more. The particle size of the primary particles is confirmed by an SEM image obtained from observation using a scanning electron microscope (hereinafter also referred to as "SEM"). The average primary particle size is the average value of the particle sizes of these primary particles. As a method for determining the average primary particle size, 80 to 150 observed primary particles are extracted, and the average value of the longest and shortest diameters of these primary particles is measured to obtain the crystal diameter of the primary particles. The average value of this crystal diameter is used as the average primary particle size. When extracting primary particles for measuring the primary particle size, an SEM image size of 1 or more is acceptable.

[0119] In this embodiment, the primary particles of CHA-type zeolite are those observed as independent particles in SEM observations at magnifications of 10,000 to 20,000.

[0120] The CHA-type zeolite of this embodiment preferably contains a transition metal element. The transition metal element is one or more elements selected from the group consisting of Groups 8, 9, 10 and 11 of the periodic table, and more specifically, one or more elements selected from the group consisting of platinum (Pt), palladium (Pd), rhodium (Rh), iron (Fe), copper (Cu), cobalt (Co), manganese (Mn) and indium (In). Furthermore, it is at least one of iron and copper, and even more specifically, copper.

[0121] The transition metal content of the CHA-type zeolite in this embodiment is 1.0% by mass or more, 1.5% by mass or more, or 2.0% by mass or more, or 5.0% by mass or less, 4.5% by mass or less, or 4.0% by mass or less.

[0122] Example

[0123] The following examples illustrate this implementation. However, this implementation is not limited to these examples.

[0124] (Crystal Structure)

[0125] The XRD analysis of the samples was performed using a standard powder X-ray diffraction apparatus (Ultima IV Protectus, manufactured by Rigaku). The measurement conditions are as follows.

[0126] Accelerating current and voltage: 40mA·40kV

[0127] X-ray source: CuKα rays

[0128] Measurement mode: Continuous scanning

[0129] Scanning conditions: 40° / minute

[0130] Measurement range: 2θ = 3° to 43°

[0131] Longitudinal diverging slit: 10mm

[0132] Diverging / Incident Slit: 1°

[0133] Light-receiving slit: open

[0134] Detector: D / teX Ultra

[0135] Using a Ni filter

[0136] The obtained XRD pattern is compared with the reference pattern to identify the crystal structure of the sample.

[0137] (Component Analysis)

[0138] The sample was dissolved in a mixed aqueous solution of hydrofluoric acid and nitric acid to prepare a sample solution. The sample solution was then analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES) with a standard ICP apparatus (Apparatus Name: OPTIMA 5300DV, manufactured by PerkinElmer) to determine the composition of the sample.

[0139] (BET specific surface area and micropore volume)

[0140] The amount of nitrogen adsorbed relative to the sample was determined using a standard nitrogen adsorption apparatus (Apparatus Name: BELSORP-mini II, manufactured by MicrotracBEL Co., Ltd.). The BET specific surface area of ​​the sample was determined by applying the BET method to the nitrogen adsorption results. Furthermore, the micropore volume was determined by applying the t-plot method to the nitrogen adsorption results. The t-plot method used the analytical software accompanying the nitrogen adsorption apparatus (Product Name: BELMaster, manufactured by MicrotracBEL Co., Ltd.). It should be noted that the nitrogen adsorption was performed using a conventional volumetric method. The measurement conditions are shown below.

[0141] Measurement temperature: -196℃

[0142] Pretreatment: Vacuum drying at 350℃ for 2 hours

[0143] (Paired Al ratio)

[0144] The sample was immersed in an aqueous solution of cobalt nitrate under the following conditions.

[0145] Impregnation temperature: room temperature

[0146] Soaking time: 20 hours

[0147] Cobalt nitrate concentration: 0.25 mol / L

[0148] Solid-liquid ratio (mass ratio): (sample / cobalt nitrate aqueous solution) ≤ 0.5

[0149] The impregnated samples were recovered, washed with pure water, and then dried in the atmosphere at 110°C for 1 hour. The dried samples were subjected to ICP analysis, and the paired Al ratio was determined using the above formula.

[0150] As a pretreatment for impregnation with cobalt nitrate aqueous solution, the cationic form of the sample is converted to either the ammonium or proton form (both with a Na / Al ratio ≤ 0.01) by the following method. Specifically, for the ammonium form, the sample is subjected to ion exchange with a 20% ammonium chloride aqueous solution to convert the cationic form to the ammonium form (Na / Al ratio ≤ 0.01). Alternatively, after converting the proton form to the ammonium form, the sample is dried overnight in the atmosphere at 110°C, followed by calcination in the atmosphere at 500°C, thereby converting the cationic form to the proton form (Na / Al ratio ≤ 0.01).

[0151] (Residual strength)

[0152] For samples before and after hydrothermal durability treatment, XRD patterns were determined using the same method as for (crystal structure). Using the analytical software accompanying the XRD apparatus (commercial name: PDXL 2, manufactured by Rigaku), the integrated intensity of the XRD peak (hereinafter also referred to as the "main peak") at 2θ = 21.0 ± 0.5° in the XRD pattern was calculated. The residual intensity was then calculated from the obtained integrated intensity using the following formula.

[0153] Residual strength (%) = (Integral strength of the main peak of CHA-type zeolite after durability treatment) / (Integral strength of the main peak of CHA-type zeolite before durability treatment) × 100

[0154] Example 1

[0155] The following were added: TMAdaOH aqueous solution, pure water, sodium hydroxide, fumed silica, dried aluminum hydroxide gel (amorphous aluminum compound), and FAU-type zeolite (zeolite Y, cationic: Na-type, SiO2 / Al2O3 ratio = 5.7, BET specific surface area: 790 m²). 2 The raw material composition with the following composition was obtained by mixing (g) to obtain a raw material composition having the following composition. It should be noted that the mixing was carried out by mixing dried aluminum hydroxide gel, sodium hydroxide, TMAdaOH aqueous solution and pure water, and then mixing FAU type zeolite thereto. Then, fumed silica was added and mixed.

[0156] SiO2 / Al2O3 ratio = 37.6

[0157] TMAda / SiO2 ratio = 0.195

[0158] OH / SiO2 ratio = 0.436

[0159] Na / SiO2 ratio = 0.241

[0160] H2O / SiO2 ratio = 9.70

[0161] The amorphous Al ratio of the raw material composition was 0.18. After adding mixed CHA-type zeolite to the obtained raw material composition to achieve a seed crystal content of 2.0% by mass, the mixture was filled into a sealed container. The original composition was stirred while the sealed container was rotated at 40 rpm, and hydrothermal treatment was performed at 150°C for 5 days. The hydrothermally treated crystals were subjected to solid-liquid separation, washed with pure water, and then calcined at 550°C in atmospheric conditions to obtain the CHA-type zeolite of this embodiment.

[0162] CHA-type zeolite is a single phase of CHA-type zeolite, with a paired Al ratio of 31.6%, a SiO2 / Al2O3 ratio of 26.0, and a BET specific surface area of ​​737 m². 2 / g, micropore volume of 0.31mL / g, and average crystal diameter of 0.32μm.

[0163] Example 2

[0164] Except for using a raw material composition having the following composition, the CHA-type zeolite of this embodiment was obtained by the same method as in Example 1.

[0165] SiO2 / Al2O3 ratio = 33.3

[0166] TMAda / SiO2 ratio = 0.188

[0167] OH / SiO2 ratio = 0.438

[0168] Na / SiO2 ratio = 0.250

[0169] H2O / SiO2 ratio = 9.30

[0170] The amorphous Al content of the raw material composition is 0.20. The CHA-type zeolite in this embodiment is a single phase of CHA-type zeolite, with a paired Al ratio of 39.9%, a SiO2 / Al2O3 ratio of 25.1, and a BET specific surface area of ​​679 m². 2 / g, micropore volume of 0.29mL / g, and average crystal diameter of 0.38μm.

[0171] Example 3

[0172] Except for using a raw material composition having the following composition, the CHA-type zeolite of this embodiment was obtained by the same method as in Example 1.

[0173] SiO2 / Al2O3 ratio = 40.0

[0174] TMAda / SiO2 ratio = 0.200

[0175] OH / SiO2 ratio = 0.400

[0176] Na / SiO2 ratio = 0.200

[0177] H2O / SiO2 ratio = 10.0

[0178] The amorphous Al content of the raw material composition is 0.20. The CHA-type zeolite in this embodiment is a single phase of CHA-type zeolite, with a paired Al ratio of 35.1%, a SiO2 / Al2O3 ratio of 31.4, and a BET specific surface area of ​​705 m². 2 / g, micropore volume of 0.34mL / g, and average crystal diameter of 0.57μm.

[0179] Example 4

[0180] Except for using a raw material composition having the following composition, the CHA-type zeolite of this embodiment was obtained by the same method as in Example 1.

[0181] SiO2 / Al2O3 ratio = 80.0

[0182] TMAda / SiO2 ratio = 0.200

[0183] OH / SiO2 ratio = 0.400

[0184] Na / SiO2 ratio = 0.200

[0185] H2O / SiO2 ratio = 10.0

[0186] The amorphous Al content of the raw material composition is 0.40. The CHA-type zeolite in this embodiment is a single phase of CHA-type zeolite, with a paired Al ratio of 48.4%, a SiO2 / Al2O3 ratio of 45.4, and a BET specific surface area of ​​761 m². 2 / g, and the micropore volume is 0.32mL / g.

[0187] Example 5

[0188] Except for using a raw material composition having the following composition, the CHA-type zeolite of this embodiment was obtained by the same method as in Example 1.

[0189] SiO2 / Al2O3 ratio = 28.0

[0190] TMAda / SiO2 ratio = 0.188

[0191] OH / SiO2 ratio = 0.538

[0192] Na / SiO2 ratio = 0.350

[0193] H2O / SiO2 ratio = 9.3

[0194] The amorphous Al content of the raw material composition is 0.20. The CHA-type zeolite in this embodiment is a single phase of CHA-type zeolite, with a paired Al ratio of 37.9%, a SiO2 / Al2O3 ratio of 17.5, and a BET specific surface area of ​​761 m². 2 / g, micropore volume of 0.32mL / g, and average crystal diameter of 0.25μm.

[0195] Example 6

[0196] Except for using a raw material composition having the following composition, the CHA-type zeolite of this embodiment was obtained by the same method as in Example 1.

[0197] SiO2 / Al2O3 ratio = 33.0

[0198] TMAda / SiO2 ratio = 0.188

[0199] OH / SiO2 ratio = 0.508

[0200] Na / SiO2 ratio = 0.320

[0201] H2O / SiO2 ratio = 9.3

[0202] The amorphous Al content of the raw material composition is 0.20. The CHA-type zeolite in this embodiment is a single phase of CHA-type zeolite, with a paired Al ratio of 46.7%, a SiO2 / Al2O3 ratio of 20.4, and a BET specific surface area of ​​706 m². 2 / g, with a micropore volume of 0.30mL / g and an average crystal diameter of 0.26μm.

[0203] Comparative Example 1

[0204] The CHA-type zeolite of this comparative example was obtained by the same method as in Example 1, except that aluminum hydroxide (dried aluminum hydroxide gel) was not used and a raw material composition having the following composition was used.

[0205] SiO2 / Al2O3 ratio = 33.3

[0206] TMAda / SiO2 ratio = 0.188

[0207] OH / SiO2 ratio = 0.438

[0208] Na / SiO2 ratio = 0.250

[0209] H2O / SiO2 ratio = 9.30

[0210] The amorphous Al content of the raw material composition is 0. The CHA-type zeolite in this comparative example is a single phase of CHA-type zeolite with a paired Al ratio of 22.1% and a SiO2 / Al2O3 ratio of 22.9.

[0211] Comparative Example 2

[0212] CHA-type zeolite was obtained according to the method of SSZ-13 (15, 1.00) in Table 2 of Non-Patent Document 2. That is, TMAdaOH aqueous solution, pure water, sodium hydroxide, colloidal silica, and aluminum hydroxide (crystalline aluminum hydroxide) were mixed to obtain a raw material composition having the following composition.

[0213] SiO2 / Al2O3 ratio = 30.63

[0214] TMAda / SiO2 ratio = 0.25

[0215] OH / SiO2 ratio = 0.50

[0216] Na / SiO2 ratio = 0.25

[0217] H2O / SiO2 ratio = 44.0

[0218] The amorphous Al ratio of the raw material composition was 0. The obtained raw material composition was filled into a sealed container, and the raw material composition was stirred while the sealed container was rotated at 40 rpm. Hydrothermal treatment was carried out at 160°C for 6 days. The crystals after hydrothermal treatment were subjected to solid-liquid separation, washed with pure water, and then calcined at 550°C in the atmosphere to obtain the CHA-type zeolite of this comparative example.

[0219] The CHA-type zeolite in this comparative example is a single phase of CHA-type zeolite with a paired Al ratio of 1.0% and a SiO2 / Al2O3 ratio of 22.8.

[0220] In Non-Patent Literature 2, the paired Al ratio was calculated to be 16% based on the cobalt exchange amount when the cation type was sodium. In contrast, the paired Al ratio calculated based on the cobalt exchange amount when the cation type was proton was 1.0%. It can be confirmed that the paired Al ratio varies greatly depending on the cation type of the CHA-type zeolite. The paired Al ratio in Non-Patent Literature 2 can be confirmed as a paired Al ratio in the form of sodium.

[0221] Comparative Example 3

[0222] Except that dry aluminum hydroxide (crystalline aluminum hydroxide) was used instead of dry aluminum hydroxide gel, and a raw material composition having the following composition was used, the CHA-type zeolite of this comparative example was obtained by the same method as in Example 1.

[0223] SiO2 / Al2O3 ratio = 32.8

[0224] TMAda / SiO2 ratio = 0.195

[0225] OH / SiO2 ratio = 0.428

[0226] Na / SiO2 ratio = 0.233

[0227] H2O / SiO2 ratio = 9.70

[0228] The amorphous Al content of the raw material composition is 0. The molar ratio of aluminum hydroxide (Al(OH)3) to silicon dioxide is 0.012. The CHA-type zeolite of this comparative example is a single phase of CHA-type zeolite with a paired Al ratio of 18.6% and a SiO2 / Al2O3 ratio of 26.6.

[0229] The results are shown in the table below.

[0230] [Table 1]

[0231] <![CDATA[SiO2 / Al2O a Compare Paired Al ratio Example 1 26.0 31.6％ Example 2 25.1 39.9％ Example 3 31.4 35.1％ Example 4 45.4 48.4％ Example 5 17.5 37.9％ Example 6 20.4 46.7％ Comparative Example 1 22.9 22.1％ Comparative Example 2 22.8 1.0％ Comparative Example 3 26.6 18.6％

[0232] The CHA-type zeolites obtained in Comparative Examples 1 and 2 were both obtained by crystallizing a raw material composition that did not contain either a silica-alumina source or an alumina source. Compared with Examples 1 to 4, they all contained a large amount of aluminum (Al) (i.e., a high SiO2 / Al2O3 ratio). Nevertheless, it can be confirmed that the paired Al ratios of Comparative Examples 1 and 2 are lower than those of Examples 1 to 4. In addition, by comparing Examples 2 to 4 and Comparative Examples 1 and 2, it can be confirmed that the SiO2 / Al2O3 ratio is not directly related to the paired Al ratio.

[0233] Test Example

[0234] The CHA-type zeolites obtained in Examples 1 and 3, and Comparative Examples 1 and 3, were subjected to ion exchange with a 20% ammonium chloride aqueous solution, dried overnight at 110°C in the atmosphere, and then calcined at 500°C in the atmosphere to establish the cationic form as the proton form (Na / Al ratio ≤ 0.01). Next, copper nitrate aqueous solution was added dropwise, and the mixture was mortared and pestle mixed for 10 minutes. After mixing, the mixture was dried overnight at 110°C in the atmosphere and then calcined at 550°C in the atmosphere for 1 hour to produce a CHA-type zeolite containing 3% by mass copper (copper-loaded CHA-type zeolite).

[0235] (Hydrothermal durability treatment)

[0236] Copper-loaded CHA-type zeolite was shaped and crushed to form aggregated particles with a diameter of 12–20 mesh. After filling 3 mL of aggregated particles into an atmospheric pressure fixed-bed flow-through reaction tube (hereinafter also referred to as "reaction tube"), hydrothermal durability treatment was carried out under the following conditions.

[0237] Processing atmosphere: Circulating air atmosphere with a moisture content of 10% by volume.

[0238] Space velocity: 9,000 h -1

[0239] Processing temperature: 900℃

[0240] Processing time: 2 hours

[0241] The XRD patterns of Example 1 and Comparative Example 1 after hydrothermal durability treatment are shown in the figure. Figure 1 The residual strengths of Examples 1, 3, Comparative Example 1 and Comparative Example 3 after hydrothermal durability treatment are shown in the table below.

[0242] [Table 2]

[0243] <![CDATA[SiO2 / Al2O3 ratio]]> Paired Al ratio Residual strength (%) Example 1 26.0 31.6％ 36.8 Example 3 31.4 35.1％ 72.6 Comparative Example 1 22.9 22.1％ 0 Comparative Example 3 26.6 18.6％ 0

[0244] Depend on Figure 1 As shown in the table above, compared with the CHA-type zeolite of the comparative examples, the CHA-type zeolite of the examples exhibits higher crystallinity and higher residual strength. In particular, although the SiO2 / Al2O3 ratios of Examples 1 and 3 are the same, in Comparative Example 3, which has a lower paired Al ratio, crystal disintegration was confirmed by hydrothermal durability treatment. Thus, by increasing the paired Al ratio, it was confirmed that crystals are less prone to disintegration after hydrothermal durability treatment.

[0245] Industrial availability

[0246] The method for manufacturing CHA-type zeolite disclosed herein provides a method for manufacturing CHA-type zeolite that can be used as a zeolite catalyst incorporated into an exhaust gas treatment system and as a base material for such systems. The CHA-type zeolite obtained by the method disclosed herein, particularly in the presence of a reducing agent, can be used as an SCR catalyst for the reduction and removal of nitrogen oxides from exhaust gases from vehicles such as diesel engines, and further can be used as an SCR catalyst integrated with a DPF (Digital Fluid Power Generation Facility).

[0247] The entire contents of the specification, claims, drawings and abstract drawings of Japanese Patent Application No. 2020-144834, filed on August 28, 2020, are incorporated herein by reference as disclosure and inclusion in this publication.

Claims

1. A CHA-type zeolite characterized in that, The pair ratio of aluminum is 25% or more, and the BET specific surface area of the CHA type zeolite is 200 m 2 / g or less 2 / g or less The CHA-type zeolite is obtained by a production method including a process of crystallizing a raw material composition containing an alumina source, a silica-alumina source, an organic structure directing agent source, an alkali source, and water, the silica-alumina source being a FAU-type zeolite, the alumina source being an amorphous aluminum compound, a molar ratio of aluminum in the raw material composition converted into Al2O3 to aluminum contained in the amorphous aluminum compound converted into Al2O3 being 0.18 or more and 0.4 or less, the molar ratio being in mol / mol.

2. The CHA-type zeolite of claim 1, wherein, The molar ratio of silica to alumina is 10 or more.

3. The CHA-type zeolite of claim 1 or 2, wherein, The molar ratio of silica to alumina is 70 or less.

4. The CHA-type zeolite of claim 1 or 2, wherein, The micropore volume is 0.2 mL / g or more.

5. The CHA-type zeolite of claim 1 or 2, wherein, The average crystal diameter is 0.7 μm or less.

6. A method for producing a CHA-type zeolite, characterized by, including: a process of crystallizing a composition containing an alumina source, a silica-alumina source, an alkali source, an organic structure directing agent, and water, the silica-alumina source being a FAU-type zeolite, the alumina source being an amorphous aluminum compound, a molar ratio of aluminum in the raw material composition converted into Al2O3 to aluminum contained in the amorphous aluminum compound converted into Al2O3 being 0.18 or more and 0.4 or less, the molar ratio being in mol / mol, The BET specific surface area of the CHA type zeolite is 200 m 2 / g or less. 2 / g or less.

7. The method of making a CHA-type zeolite according to claim 6, wherein, The composition is obtained by mixing the silica-alumina source after mixing the alumina source, the alkali source, the organic structure directing agent, and the water.

8. The production method according to claim 6 or 7, wherein The composition contains a silica source.

9. A nitrogen oxide reduction catalyst characterized by, The CHA-type zeolite according to any one of claims 1 to 5.

10. A method for reducing nitrogen oxides, characterized by, The CHA-type zeolite according to any one of claims 1 to 5.

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