CHA-type zeolite and method for producing the same

Abstract

The present invention provides an improvement in the heat resistance of CHA-type zeolite by a method different from conventional heat resistance improvement methods, a method for producing CHA-type zeolite with improved heat resistance, and at least one of such CHA-type zeolites. [Solution] 1 In the H-MAS-NMR spectrum, the ratio of the integrated intensity of the maximum peak with a peak top at a chemical shift of 3.0–3.5 ppm to the integrated intensity of the maximum peak with a peak top at a chemical shift of 4.0–4.5 ppm is greater than 0.12 and less than or equal to 0.5, and in the IR spectrum, the wavenumber is 3590 cm⁻¹. -1 More than 3610cm -1 Below is the maximum peak height of the absorption peak with the peak top, corresponding to a wavenumber of 3630 cm². -1 More than 3650cm -1 A CHA-type zeolite characterized in that the ratio of the maximum peak heights of the absorption peaks having the following peak tops is 0.40 or more and 1.0 or less.

Description

[Technical Field]

[0001] This disclosure relates to CHA-type zeolite. [Background technology]

[0002] CHA-type zeolites such as SSZ-13 and SSZ-62 are prone to structural collapse when exposed to high-temperature, high-humidity atmospheres. Therefore, research has focused on developing CHA-type zeolites with heat resistance suitable for use as nitrogen oxide reduction catalysts (SCR catalysts) via selective catalytic reduction.

[0003] For example, a CHA-type zeolite having an average crystal diameter of 1.5 μm or more and a SiO2 / Al2O3 ratio of 15 or more (Patent Document 1), and a zeolite having a SiO2 / Al2O3 ratio of 15 or more and a molar ratio of silanol groups to silicon of 1.6 × 10 -2 The following CHA-type zeolites are disclosed (Patent Document 2), characterized in that the average crystal diameter is 0.5 μm or more and less than 1.5 μm, and the 50% volume diameter relative to the 10% volume diameter is 3.2 or less; and the CHA-type zeolite has a chabazite structure, contains Si and Al, has a lattice constant ≤ 13.74 Å, and has a crystallinity of ≤ 140% (Patent Document 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] U.S. Patent Publication 2011 / 0251048 [Patent Document 2] Japanese Patent Publication No. 2018-135261 [Patent Document 3] Japanese Patent Publication No. 2017-218367 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Conventionally, including Patent Documents 1 and 2, improvement of heat resistance by methods such as controlling the particle diameter of crystals, the SiO2 / Al2O3 ratio, or silanols has been studied. Furthermore, in Patent Document 3, the heat resistance of CHA-type zeolite with a low SiO2 / Al2O3 ratio obtained from a raw material not containing an organic structure-directing agent was only slightly improved. In contrast, the present disclosure aims to provide improvement of the heat resistance of CHA-type zeolite by a method different from the conventional heat resistance improvement methods, a method for producing CHA-type zeolite with improved heat resistance, and at least one of the CHA-type zeolites with improved heat resistance.

Means for Solving the Problems

[0006] In the present disclosure, attention is paid to the state of protons at the solid acid sites of CHA-type zeolite, particularly CHA-type zeolite with a SiO2 / Al2O3 ratio of 8 or more, and it has been found that the heat resistance is further improved by treating the CHA-type zeolite under specific conditions.

[0007] That is, the present invention is as described in the invention described in the claims, and the gist of the present disclosure is as follows. [1] 1 In the H-MAS-NMR spectrum, the ratio of the integrated intensity of the maximum peak having a peak top at a chemical shift of 3.0 to 3.5 ppm to the integrated intensity of the maximum peak having a peak top at a chemical shift of 4.0 to 4.5 ppm exceeds 0.12 and is 0.5 or less. In addition, in the IR spectrum, the ratio of the maximum peak height of the absorption peak having a peak top at a wavenumber of 3630 cm -1 or more and 3650 cm -1 or less to the maximum peak height of the absorption peak having a peak top at a wavenumber of 3590 cm -1 or more and 3610 cm -1 or less is 0.40 or more and 1.0 or less. A CHA-type zeolite characterized by this. [2] In the IR spectrum, the ratio of the maximum peak height of the absorption peak having a peak top at a wavenumber of 3630 cm -1 or more and 3650 cm -1 or less to the maximum peak height of the absorption peak having a peak top at a wavenumber of 3590 cm -1More than 3650cm -1 The CHA-type zeolite described in [1] above, characterized in that the ratio of the maximum peak heights of the absorption peaks having the following peak tops is 0.55 or more and 1.0 or less. [3] The above 1 The CHA-type zeolite described in [1] or [2] above, wherein, in the H-MAS-NMR spectrum, the ratio of the integrated intensity of the maximum peak having a peak top at a chemical shift of 3.0 to 3.5 ppm to the integrated intensity of the maximum peak having a peak top at a chemical shift of 4.0 to 4.5 ppm is 0.13 or more and 0.5 or less. [4] A CHA-type zeolite according to any one of the above [1] to [3], wherein the molar ratio of silica to alumina is 8.0 or more and 50.0 or less. [5] A CHA-type zeolite containing a transition metal element, as described in any one of [1] to [4] above. [6] A method for producing a CHA-type zeolite, characterized by comprising the step of treating a CHA-type zeolite precursor containing an organic structure-directing agent in an aqueous atmosphere. [7] The method for producing the product according to [6] above, wherein the organic structure directing agent is one or more selected from the group consisting of N,N,N-trialkyladamantanammonium cation, N,N,N-trimethylbenzylammonium cation, N-alkyl-3-quinuclidinol cation, N,N,N-trialkylexoaminonorbornane cation, and N,N,N-trialkylcyclohexylammonium cation. [8] The manufacturing method according to [6] or [7], wherein the molar ratio of silica to alumina in the CHA-type zeolite precursor is 8.0 or more. [9] The method for producing the CHA-type zeolite precursor according to any one of the above [6] to [8], wherein the cation type of the CHA-type zeolite precursor is sodium-potassium type.

[10] The method for producing the CHA-type zeolite precursor according to any one of the above [6] to [9], wherein the alkali metal element content of the CHA-type zeolite precursor is 0.1% by mass or more.

[11] The manufacturing method according to any one of [6] to

[10] above, wherein the water-containing atmosphere is an air atmosphere with a water content of 5% by volume or more and 95% by volume or less relative to the saturated water vapor amount.

[12] The manufacturing method according to any one of [6] to

[11] above, wherein the water incorporation treatment is a process of raising the temperature of the CHA-type zeolite precursor to the water incorporation treatment temperature after it has been placed in a calcination furnace.

[13] The manufacturing method according to any one of [6] to

[12] above, wherein the water treatment is a process of introducing the CHA-type zeolite precursor into a calcination furnace heated to the water treatment temperature.

[14] The manufacturing method according to any one of [6] to

[13] above, wherein the water treatment temperature of the water treatment is 400°C or higher.

[15] A CHA-type zeolite obtained by the manufacturing method described in any one of the above [6] to

[14] .

[16] In the IR spectrum, wavenumber 3590 cm⁻¹ -1 More than 3610cm -1 Below is the maximum peak height of the absorption peak with the peak top, corresponding to a wavenumber of 3630 cm². -1 More than 3650cm -1 The CHA-type zeolite described in

[15] above, characterized in that the ratio of the maximum peak heights of the absorption peaks having the following peak tops is 0.55 or more and 1.0 or less.

[17] A nitrogen oxide reduction catalyst characterized by containing the CHA-type zeolite described in any one of [1] to [5],

[15] and

[16] above.

[18] A method for reducing nitrogen oxides, characterized by using a CHA-type zeolite described in any one of [1] to [5],

[15] , and

[16] above. [Effects of the Invention]

[0008] This disclosure provides a CHA-type zeolite having higher heat resistance than conventional CHA-type zeolites, as well as at least one of a catalyst containing the CHA-type zeolite, a nitrogen oxide reduction catalyst, and a nitrogen oxide reduction catalyst by selective catalytic reduction. [Modes for carrying out the invention]

[0009] The following describes an example of an embodiment of the CHA-type zeolite described herein. The terms used in this embodiment are defined as follows.

[0010] Aluminosilicate is a composite oxide having a structure consisting of repeating networks of aluminum (Al) and silicon (Si) mediated by oxygen (O). Among aluminosilicates, those that have crystalline XRD peaks in their powder X-ray diffraction (hereinafter also referred to as "XRD") patterns are called "crystalline aluminosilicate," and those that do not have crystalline XRD peaks are called "amorphous aluminosilicate."

[0011] In this embodiment, the XRD pattern is measured using CuKα radiation as the source, and the following conditions are used for the measurement.

[0012] Radiation source: CuKα radiation (λ=1.5406Å) Measurement mode: Step scan Scan speed: 4.0° per minute Measurement range: 2θ = 3.0° to 40.0° The following conditions are considered desirable: Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Step scan Scanning conditions: 40° / min Measurement time: 3 seconds Measurement range: 2θ = 3° to 43° Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Light-receiving slit: open Solar light receiving slit: 5° Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter

[0013] Crystalline XRD peaks are peaks whose peak top 2θ is identified and detected in XRD pattern analysis using general analysis software (e.g., SmartLab Studio II, manufactured by Rigaku Corporation), and are exemplified by XRD peaks with a full width at half maximum of 2θ = 0.50° or less.

[0014] A "zeolite" is a compound in which the skeletal atoms (hereinafter also referred to as "T atoms") have a regular structure mediated by oxygen (O), and the T atoms consist of at least one of a metal atom and / or a metalloid atom. Examples of metalloid atoms include one or more selected from the group consisting of boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te).

[0015] A "zeolite-like substance" is a compound in which the T atom has a regular structure mediated by oxygen, and which contains at least one atom other than a metal or metalloid in the T atom. Examples of zeolite-like substances include aluminophosphate (AlPO) and silicoaluminophosphate (SAPO), which are complex phosphorus compounds containing phosphorus (P) as the T atom.

[0016] The "regular structure" (hereinafter also referred to as "zeolite structure") in zeolites and zeolite-like materials is a skeletal structure identified by a structural code (hereinafter simply referred to as "structural code") defined by the Structure Commission of the International Zeolite Association. For example, the CHA structure is a skeletal structure identified by the structural code "CHA". Zeolite structures can be identified by comparing them with the XRD patterns (hereinafter also referred to as "reference patterns") of each structure described in Collection of simulated XRD powder patterns for zeolites, Fifth revised edition, p. 483 (2007). In relation to zeolite structures, the terms skeletal structure, crystalline structure, and crystalline phase are used synonymously.

[0017] In this embodiment, "CHA-type zeolite" and other "~-type zeolites" refer to zeolites having the zeolite structure of the said structural code, and preferably refer to crystalline aluminosilicates having the zeolite structure of the said structural code.

[0018] An "IR spectrum" is the IR spectrum of a CHA-type zeolite that does not contain an organic structure-directing agent and has a proton-type cation, measured under the following conditions. Measurement method: Diffuse reflectance method Measurement wavefrequency range: 400~4000cm -1 Resolution: 4cm -1 Total number of times: 128 Reference: KBr

[0019] IR spectra can be measured using a general-purpose FT-IR instrument (e.g., Varian 660-IR, manufactured by Agilent Technologies). The obtained IR spectra can then be converted to absorbance values, baseline corrected, and analyzed using a general-purpose spectral data analysis program (e.g., GRAMS / AI, manufactured by Thermo Fisher Scientific).

[0020] " 1 The "H-MAS-NMR spectrum" is measured under the following conditions for CHA-type zeolites that do not contain organic structure-directing agents and have a proton-type cation. 1 This is an H-MAS-NMR spectrum. Resonance frequency: 400.0MHz Pulse width: Π / 2 Measurement waiting time: 10 seconds Total number of times: 32 Rotation frequency: 15kHz Chemical shift criteria: TMS

[0021] 1H-MAS-NMR spectra can be measured using a general-purpose NMR analyzer (e.g., VNMRS-400, Varian), and the obtained NMR spectra can be baseline-corrected and analyzed using a general-purpose spectral data analysis program (e.g., GRAMS / AI, Thermo Fisher Scientific).

[0022] "Average grain size" refers to the average grain size based on SEM observation, which is the average value of the particle diameter of primary particles (primary particle diameter) measured from the observation image obtained by a scanning electron microscope (SEM). More specifically, it refers to the average value of the grain diameter obtained by measuring the length of one side of the rhombohedron of the CHA-type zeolite present in the field of view of an SEM observation image observed at an arbitrary magnification (e.g., 5000 to 10000x) in which crystal grains consisting of 150 or more, preferably 200 ± 50, primary particles can be observed.

[0023] The method for producing the CHA-type zeolite described herein will be explained below with reference to an example of an embodiment.

[0024] The manufacturing method of this embodiment is a method for producing CHA-type zeolite, characterized by comprising the step of treating a CHA-type zeolite precursor containing an organic structure-directing agent in an aqueous atmosphere. By treating a CHA-type zeolite containing an organic structure-directing agent (hereinafter also referred to as "SDA") in an aqueous atmosphere, the removal of SDA and the improvement of the heat resistance of the CHA-type zeolite can be performed simultaneously, and the CHA-type zeolite obtained by the manufacturing method of this embodiment can serve as a precursor for nitrogen oxide reduction catalysts that exhibit a higher NOx reduction rate.

[0025] <Progenitor CHA> The CHA-type zeolite precursor (hereinafter also referred to as "precursor CHA") subjected to the process of treating a CHA-type zeolite precursor containing an organic structure-directing agent in a hydrated atmosphere (hereinafter also referred to as the "hydrated treatment process") is an artificially synthesized CHA-type zeolite (synthetic CHA-type zeolite), and any CHA-type zeolite containing SDA is acceptable. Preferably, the precursor CHA is a zeolite that does not contain phosphorus as a skeletal element.

[0026] The SDA contained in the precursor CHA may be any cation that has the function of directing to CHA-type zeolite (more specifically, a CHA structure; the same applies hereinafter). Examples of cations that have the function of directing to CHA-type zeolite include one or more selected from the group consisting of N,N,N-trialkyladamantaneneammonium cation, N,N,N-trimethylbenzylammonium cation, N-alkyl-3-quinuclidinol cation, N,N,N-trialkylexoaminonorbornane cation and N,N,N-trialkylcyclohexylammonium cation, and preferably, N,N,N-trialkyladamantaneneammonium cation (hereinafter referred to as "TAAd + It is also called "TMBA". ), N,N,N-trimethylbenzylammonium cation (hereinafter referred to as "TMBA") + Also called "TACH"), and N,N,N-trialkylcyclohexylammonium cation (hereinafter referred to as "TACH") + It is also called ". ) One or more selected from the group, more preferably TAAd + and TACH + At least one of the following, particularly preferably TAAd + and TACH + That is the case.

[0027] Preferred TAAd + As N,N,N-trimethyladamantan ammonium cation (hereinafter referred to as "TMAd") + It is also called ). ) is one example. Also, a favorable TACH + As N,N,N-dimethylethylcyclohexylammonium cation (hereinafter referred to as "CDMEA") +) and N,N,N-methyldiethylcyclohexylammonium cation (hereinafter referred to as "MDECH") + It is also called "at least one of the following, and furthermore, CDMEA + , are some examples.

[0028] Precursor CHA is at least CDMEA + Preferably contains TMAd + and CDMEA + It is more preferable that it contains [a specific compound]. In addition, the precursor CHA is TMAd + and CDMEA + It may contain at least one of the following.

[0029] The presence of SDA in the precursor CHA, i.e., that it is a CHA-type zeolite containing SDA, can be confirmed by its XRD pattern. Preferably, the precursor CHA has an XRD peak in its XRD pattern that has a peak top at least at the interplanar spacing d shown in the table below.

[0030] [Table 1]

[0031] In addition to the XRD peaks mentioned above, the precursor CHA may also contain the following XRD peaks.

[0032] [Table 2]

[0033] Furthermore, the precursor CHA may include any XRD peak whose intensity relative to the intensity of an XRD peak having a peak top at an interplanar spacing d = 4.22 to 4.32 Å (hereinafter also referred to as "relative intensity") is less than 5.

[0034] Precursor CHA is characterized by a molar ratio of SDA to alumina (hereinafter also referred to as "SDA content") that is greater than 0, 0.1 or greater, 0.3 or greater, 0.6 or greater, 0.7 or greater, or 0.8 or greater, and also 1.0 or less.

[0035] The precursor CHA preferably has a molar ratio of silica to alumina (hereinafter also referred to as the "SiO2 / Al2O3 ratio") of 8.0 or higher, 10.0 or higher, or 12.0 or higher, and is 30.0 or lower, 25.0 or lower, 20.0 or lower, 19.5 or lower, or 15.0 or lower.

[0036] The SDA content in this embodiment is a value obtained from the following formula.

[0037] SDA content = 1 - {(M1 + 1 / n × M2) / Al} [mol / mol] In this formula, M1 is a monovalent metal cation and M2 is an n-valent metal cation. For example, in the case of a precursor CHA containing sodium, potassium, and magnesium, the SDA content can be calculated from 1 - {(Na + K + 1 / 2 × Mg) / Al} [mol / mol].

[0038] The precursor CHA has an average crystal grain size of 0.3 μm or more or 0.4 μm or more, and preferably 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, or 0.8 μm or less.

[0039] The cation type of the precursor CHA is thought to improve the heat resistance of sodium-type (Na-type), potassium-type (K-type), and CHA-type zeolites.

[0040] The precursor CHA has a molar ratio of alkali metal to aluminum of 0.05 or more, or 0.1 or more, and more preferably 1.0 or less, 0.8 or less, or 0.5 or less.

[0041] Since the heat resistance is more easily improved by water treatment, the precursor CHA preferably contains alkali metals, and the alkali metal element content (e.g., sodium and potassium) is 0.1% by mass or more, more than 0.5% by mass, 1.0% by mass or more, 1.5% by mass or more, or 2.0% by mass or more, and also 10.0% by mass or less, 8.0% by mass or less, or 5.0% by mass or less. The alkali metal content is the mass ratio (mass%) of the alkali metal as an oxide to the total amount of alkali metal, silicon, and aluminum in the precursor CHA, each as an oxide, and can be calculated from {M2O[g] / (SiO2+Al2O3+M2O)[g]}×100.

[0042] The precursor CHA is preferably free of phosphorus (P) and fluorine (F). For example, the phosphorus and fluorine content is preferably 500 ppm by mass or less and 100 ppm by mass or less, respectively, and is below the detection limit of compositional analysis such as ICP measurement (for example, 100 ppm by mass or less).

[0043] <Method for producing precursor CHA> The precursor CHA can be any CHA-type zeolite obtained by a manufacturing method that includes a step of crystallizing a composition containing SDA. An example of a method for producing precursor CHA is a manufacturing method that includes a step of crystallizing a composition containing a silica source, an alumina source, an alkali source, an organic structure directing agent, and water (hereinafter also referred to as the "raw material composition") (hereinafter also referred to as the "crystallization step").

[0044] The silica source is a silicon (Si)-containing compound, and can be one or more selected from the group consisting of colloidal silica, precipitated silica, amorphous silica, sodium silicate, tetraethyl orthosilicate, and amorphous aluminosilicate, preferably amorphous aluminosilicate.

[0045] The alumina source is a compound containing aluminum (Al), and can be one or more selected from the group consisting of aluminum sulfate, sodium aluminate, aluminum hydroxide, aluminum chloride, and amorphous aluminosilicate, preferably at least one of aluminum hydroxide and amorphous aluminosilicate, and preferably amorphous aluminosilicate.

[0046] The alkali source is a compound containing an alkali metal element, and examples include a compound containing one or more elements selected from the group of sodium, potassium, rubidium, and cesium, a compound containing one or more elements selected from the group of sodium, potassium, and cesium, a compound containing at least one of sodium and potassium, or a compound containing sodium. Examples of alkali sources include one or more elements selected from the group of hydroxides, fluorides, bromides, iodides, sulfates, nitrates, and carbonates containing the aforementioned alkali metal elements, one or more elements selected from the group of hydroxides, bromides, and iodides, or hydroxides (hereinafter, an alkali source containing sodium will also be called a "sodium source," an alkali source containing potassium will also be called a "potassium source," etc.). The raw material composition is particularly preferably to contain a sodium source and a potassium source, and if the starting material such as a silica source contains an alkali metal element, these starting materials are also considered alkali sources.

[0047] In addition to pure water and deionized water, water in the raw material composition also includes structural water, hydration water, and water used as a solvent contained in the starting materials.

[0048] The organic structure directing agent (SDA) is a cation that has the function of directing CHA-type zeolite (CHA structure), and is the cation described above. The raw material composition may contain SDA as at least one of a salt and / or compound (hereinafter also referred to as "SDA source"). The SDA source is one or more selected from the group consisting of hydroxides, bromides, iodides, carbonates, methyl carbonate salts and sulfates, and preferably one or more selected from the group consisting of hydroxides, bromides and iodides.

[0049] The following molar compositions are preferred for the raw material composition. In the following molar compositions, SDA is an organic structure directing agent and M is an alkali metal element. + In that case, the SDA / SiO2 ratio is "TMAd + It is sufficient to use " / SiO2 ratio", and also TMAd + and CDMEA + In that case, the SDA / SiO2 ratio is "(TMAd + +CDMEA + The ratio should be expressed as "(Na+K) / SiO2 ratio". If M is sodium, the M / SiO2 ratio should be "Na / SiO2 ratio", and if M is sodium and potassium, the M / SiO2 ratio should be "(Na+K) / SiO2 ratio". SiO2 / Al2O3 ratio = 5.0 or higher or 10.0 or higher, 20.0 or less, or 15.0 or less. SDA / SiO2 ratio = 0.06 or higher or 0.07 or higher, 0.12 or less, or 0.10 or less. M / SiO2 ratio = 0.10 or higher or 0.15 or higher, 0.30 or less, or 0.25 or less. H2O / SiO2 ratio = 8.0 or higher or 10.0 or higher, 25.0 or less, or 20.0 or less.

[0050] The raw material composition may contain seed crystals. The seed crystals are zeolites that have the function of promoting the crystallization of CHA-type zeolites, and are preferably CHA-type zeolites. The seed crystal content is such that, relative to the mass of silicon (Si) contained in the seed crystals converted to silica (SiO2) as opposed to the mass of silicon (Si) contained in the raw material composition (without seed crystals), the amount of silicon (Si) contained in the seed crystals converted to silica (SiO2) is 0% by mass or more, and 10% by mass or less or 5% by mass or less.

[0051] The crystallization process causes the raw material composition to crystallize, yielding a CHA-type zeolite (precursor CHA) containing SDA. Crystallization can be carried out by filling the raw material composition into a sealed container and subjecting it to hydrothermal treatment. The crystallization conditions are arbitrary, but the following conditions are examples. Crystallization temperature: 100°C or higher or 140°C or higher, 200℃ or below, or 170℃ or below Crystallization time: 1 hour or more or 10 hours or more, 100 hours or less or 80 hours or less Crystallization state: At least one of the following: stirring state and standing state. Preferably in a stirred state Crystallization pressure: Autoclaving pressure

[0052] The precursor CHA after the crystallization process can be recovered by solid-liquid separation and, if necessary, washed and treated to remove moisture and impurities (for example, heat treatment such as drying, such as heat treatment below 400°C, or even heat treatment between 300°C and 400°C). In other words, the precursor CHA can be any CHA-type zeolite that has not undergone heat treatment above 400°C after crystallization.

[0053] <Water treatment> In the hydrated treatment process, the precursor CHA is treated in a hydrated atmosphere (hereinafter also referred to as "hydrated treatment"). This removes SDA from the precursor CHA and simultaneously improves the heat resistance of the precursor CHA. One reason why CHA-type zeolite with improved heat resistance can be obtained by hydrated treatment of the precursor CHA is that the CHA-type zeolite obtained by crystallizing the raw material composition containing SDA is heat-treated in an atmosphere in which sufficient moisture is present. In other words, it is thought that the SDA exists in a state in which it can compensate for the electrical value with specific aluminum constituting the CHA structure. Therefore, at sites where SDA exists, interaction occurs between the SDA and the moisture in the atmosphere, and heat treatment proceeds under an appropriate load. As a result, it is thought that the heat load on the entire zeolite framework is suppressed, even though the heat treatment is performed in a hydrated atmosphere, and furthermore, the heat resistance is improved.

[0054] The hydrated atmosphere is an atmosphere (especially an air atmosphere) in which the amount of water per unit volume relative to the saturated water vapor amount (hereinafter also referred to as "water content") is 5% or more by volume, 10% or more by volume, 30% or more by volume, or 50% or more by volume, and also an atmosphere (especially an air atmosphere) in which the amount of water per unit volume is 100% or less by volume, 90% or less by volume, or 70% or less by volume. Since the CHA-type zeolite after hydrate treatment tends to have a high amount of solid acid, the hydrated atmosphere is preferably an air atmosphere with a water content of 15% to 90% by volume, or an air atmosphere with a water content of 45% to 80% by volume. The water content can be adjusted by methods such as circulating a mixed gas of air and water vapor, filling the reaction vessel with water and heating it, or using a hydrated precursor CHA.

[0055] The hydration treatment is preferably carried out while circulating air with the above-mentioned moisture content, and can be performed using a known firing furnace such as one or more selected from the group consisting of a muffle furnace, a tubular furnace, and a kiln.

[0056] The water treatment temperature can be 400°C or higher, 500°C or higher, or 550°C or higher, and also 800°C or lower, 650°C or lower, or 600°C or lower. In order to efficiently remove SDA while suppressing the breakdown of the CHA structure, a water treatment temperature of 500°C or higher and 700°C or lower is particularly preferred.

[0057] The hydrate treatment time varies depending on the hydrate treatment temperature and the amount of precursor CHA subjected to the hydrate treatment, but it can be any time required for SDA to be removed, and examples include a time of 10 minutes or more or 1 hour or more, and 24 hours or less or 5 hours or less. Note that the hydrate treatment time is the treatment time at the hydrate treatment temperature (maximum achievable temperature).

[0058] The hydration treatment can be a process of introducing precursor CHA into a firing furnace heated to the hydration treatment temperature, or a process of heating the precursor CHA to the hydration treatment temperature after it has been placed in the firing furnace. The rate at which the firing furnace is heated to the hydration treatment temperature and the rate at which it is cooled after the hydration treatment are arbitrary, but for example, the heating rate and cooling rate can be 1°C / min or more or 2°C / min or more, and 10°C / min or less or 5°C / min or less. The heating rate and cooling rate may be different.

[0059] <Post-processing steps> The manufacturing method of this embodiment may, after the water treatment step, optionally include at least one of an ion exchange step and a metal encapsulation step.

[0060] In the ion exchange process, CHA-type zeolite is subjected to ion exchange to obtain the desired cation type. The cation types include sodium type (Na type) and ammonium type (NH4 type). + (H) and proton type (H + Examples include at least one of the following types, and even a proton type. Any ion exchange method can be used for ion exchange. For example, the cation type is NH4 + When using a specific type, an example is a method in which CHA-type zeolite is mixed and stirred in an aqueous solution of ammonium chloride, and the cation type is H + If it is a type, the cationic type is NH4 + Examples of methods include calcining the CHA-type zeolite and mixing and stirring it in an aqueous hydrochloric acid solution.

[0061] The metal-containing process involves contacting a CHA-type zeolite with a metal compound. This causes the CHA-type zeolite to contain any metal element that functions as an active metal. The metal elements include one or more selected from the group consisting of catalytic metal elements, specifically transition metal elements, and further including platinum, palladium, rhodium, iron, copper, cobalt, manganese, and indium; one or more selected from the group consisting of cobalt, nickel, iron, and copper; at least one of iron and copper; or copper. The metal-containing method is arbitrary, but it is preferably a method of supporting a metal element on the CHA-type zeolite. Specifically, one or more selected from the group consisting of an ion exchange method, an impregnation support method, an evaporation to dryness method, a precipitation support method, and a physical mixing method are included. At least one of the ion exchange method and the impregnation support method is preferred, and the impregnation support method is more preferred.

[0062] The metal compound is arbitrary, but one or more selected from the group consisting of metal nitrates, sulfates, acetates, chlorides, complex salts, and oxides are included. One or more selected from the group consisting of nitrates, sulfates, and acetates are preferred.

[0063] After contacting the CHA-type zeolite with the metal compound, if necessary, the CHA-type zeolite containing metal (hereinafter also referred to as "metal-containing CHA-type zeolite") may be calcined. As the calcination conditions, in the atmosphere, 500°C or higher and 700°C or lower, for 0.5 hours or longer and 5 hours or shorter, can be exemplified. Note that the "atmosphere" is an air atmosphere in which the moisture content is not controlled, and air with a moisture content exceeding 0% by volume and not exceeding 3% by volume can be exemplified.

[0064] <CHA-type zeolite> Hereinafter, an example of an embodiment of the CHA-type zeolite of the present disclosure will be described while showing an example.

[0065] The CHA-type zeolite of this embodiment is 1 In the H-MAS-NMR spectrum, the ratio of the integrated intensity of the maximum peak having a peak top at a chemical shift of 3.0 to 3.5 ppm to the integrated intensity of the maximum peak having a peak top at a chemical shift of 4.0 to 4.5 ppm exceeds 0.12 and is 0.5 or less. In addition, in the IR spectrum, a wave number of 3590 cm-1 More than 3610cm -1 Below is the maximum peak height of the absorption peak with the peak top, corresponding to a wavenumber of 3630 cm². -1 More than 3650cm -1 The following is a CHA-type zeolite characterized in that the ratio of the maximum peak heights of the absorption peaks having peak tops is between 0.40 and 1.0.

[0066] The CHA-type zeolite of this embodiment exhibits a wavenumber of 3590 cm⁻¹ in the IR spectrum. -1 More than 3610cm -1 The maximum peak height of the absorption peak with the peak top is shown below (hereinafter referred to as "IR"). P1 It is also called ". ) for wave number 3630cm -1 More than 3650cm -1 The maximum peak height of the absorption peak with the peak top is shown below (hereinafter referred to as "IR"). P2 It is also called the ratio of IR (hereinafter referred to as "IR"). P2 / IR P1 Also called the "ratio" or "IR ratio," the ratio is 0.4 or more and 1.0 or less, preferably 0.45 or more and 1.0 or less, and more preferably 0.55 or more and 1.0 or less.

[0067] The CHA structure contains oxygen atoms in different atomic positions (i.e., non-equivalent oxygen atoms) in its zeolite structure, including oxygen atoms that form a four-membered oxygen ring structure and an eight-membered oxygen ring structure, located at the position connecting two six-membered oxygen rings that form a double six-membered oxygen ring (hereinafter also referred to as "O(1)"), oxygen atoms that form a four-membered oxygen ring and an eight-membered oxygen ring, located at the position connecting two double six-membered oxygen rings (hereinafter also referred to as "O(2)"), oxygen atoms that form a six-membered ring, and also form a four-membered oxygen ring and an eight-membered oxygen ring (hereinafter also referred to as "O(3)"), and oxygen atoms that form a six-membered oxygen ring, but form a four-membered oxygen ring but not an eight-membered oxygen ring (hereinafter also referred to as "O(4)").

[0068] IR P1 and IR P2These are thought to be the peak heights of the IR peaks corresponding to protons via O(1) and protons via O(2), respectively. By satisfying the above-mentioned IR ratio, the skeletal structure becomes less likely to collapse even when exposed to high temperature and high humidity. The IR ratio is preferably 0.58 or higher or 0.60 or higher, and preferably 0.80 or lower or 0.70 or lower.

[0069] The CHA-type zeolite of this embodiment is 1 In the H-MAS-NMR spectrum, the integrated intensity of the largest peak with a peak top at a chemical shift of 4.0-4.5 ppm (hereinafter referred to as "NMR") is the integral intensity of the largest peak (hereinafter referred to as "NMR"). P1 Also called "NMR".) The integrated intensity of the largest peak with a peak top at a chemical shift of 3.0 to 3.5 ppm (hereinafter referred to as "NMR") P2 It is also called the ratio of NMR (hereinafter referred to as "NMR"). P2 / NMR P1 The NMR ratio (also called the "ratio" or "NMR ratio") is greater than 0.12 and less than or equal to 0.5, preferably between 0.13 and 0.5. Preferably, the NMR ratio is 0.13 or greater, 0.14 or greater, or 0.15 or greater, and less than or equal to 0.5, 0.3 or less, or 0.2 or less. P1 and NMR P2 These represent the integrated intensity of the peaks caused by protons bonded to O(1) and O(3), respectively, and the NMR spectrum. P2 This is thought to be the integrated intensity of the peak caused by the proton bonded to O(2), and satisfying the above-mentioned NMR ratio tends to increase the heat resistance of CHA-type zeolites.

[0070] In this embodiment, the CHA-type zeolite has a molar ratio of silica to alumina (hereinafter also referred to as the "SiO2 / Al2O3 ratio") of 5.0 or more, 8.0 or more, or 12.0 or more, and preferably 50.0 or less, less than 30.0, 25.0 or less, 20.0 or less, or 15.0 or less.

[0071] The CHA-type zeolite of this embodiment preferably has an average crystal grain size of 0.3 μm or more, 0.4 μm or more, or 0.45 μm or more, and more preferably 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, 0.8 μm or less, or 0.6 μm or less. It is preferable that the average crystal grain size is less than 2.0 μm, 1.8 μm or less, or 1.5 μm or less, as this makes it easier to improve operability (slurry handling) without impairing crystallinity.

[0072] The cation type of the CHA-type zeolite in this embodiment is arbitrary, and can be sodium-potassium type (Na-K type) or proton type (H + (NH4 type) and ammonium type (NH4 + One or more selected from the group of (types), sodium type (Na type), proton type (H + (NH4 type) and ammonium type (NH4 + Examples include one or more selected from the group of (types), at least one of the proton type and ammonium type, or being of the proton type. The cation type may also be the sodium-potassium type.

[0073] The CHA-type zeolite of this embodiment preferably contains a catalytic metal element, and more preferably a transition metal element. The transition metal element is one or more elements selected from groups 8, 9, 10, and 11 of the periodic table, and further, one or more elements selected from the group of platinum (Pt), palladium (Pd), rhodium (Rh), iron (Fe), copper (Cu), cobalt (Co), manganese (Mn), and indium (In), one or more elements selected from the group of cobalt (Co), nickel (Ni), iron (Fe), and copper (Cu), at least one of iron and copper, or copper.

[0074] The form in which the transition metal element is contained is arbitrary; it is sufficient that the transition metal element is contained either inside or outside the zeolite framework. For example, the transition metal element may be supported outside the zeolite framework, such as in at least one of the pores and ion exchange sites. It is preferable that the transition metal element is contained outside the zeolite framework, and more preferably, supported on the zeolite.

[0075] The CHA-type zeolite of this embodiment may have a transition metal content of 1.0% by mass or more, 1.5% by mass or more, or 2.0% by mass or more, and may also have a transition metal content of 5.0% by mass or less, 4.5% by mass or less, or 4.0% by mass or less. [Examples]

[0076] The embodiment will be described below based on examples and comparative examples. However, this embodiment is not limited to the following examples.

[0077] (Identification of crystals) XRD measurements of the sample were performed using a standard powder X-ray diffractometer (instrument name: Ultima IV, manufactured by Rigaku Corporation). The measurement conditions were as follows:

[0078] Acceleration current / voltage: 40mA / 40kV Radiation source: CuKα radiation (λ=1.5405Å) Measurement mode: Step scan Scanning conditions: 40° / min Measurement time: 3 seconds Measurement range: 2θ = 3° to 43° Divergence vertical limiting slit: 10mm Divergence / Induction Slit: 1° Light-receiving slit: open Solar light receiving slit: 5° Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter The obtained XRD pattern was compared with a reference pattern to identify the crystal structure of the sample.

[0079] (SiO2 / Al2O3 ratio) The composition of the sample was measured by X-ray fluorescence. The SiO2 / Al2O3 ratio was calculated using a calibration curve based on the X-ray intensity ratio of Si to Al.

[0080] (IR spectrum) The IR spectrum was measured for the sample pretreated under the following conditions. <Pretreatment> Sample: CHA-type zeolite (cation type: H + type, without SDA) Treatment atmosphere: Vacuum Treatment temperature: 400 °C Treatment time: 2 hours Pretreatment was carried out by treating at the treatment temperature. <IR measurement> For the sample after pretreatment, a general FT-IR device (device name: Varian 660-IR, manufactured by Agilent Technologies) was used, and the IR spectrum was measured while maintaining the pretreatment temperature. The measurement conditions are shown below.

[0081] Measurement method: Diffuse reflection method Measurement wavenumber range: 400 - 4000 cm -1 Resolution: 4 cm -1 Number of accumulations: 128 times Reference: KBr The obtained IR spectrum was subjected to conversion to absorbance values, baseline correction, and analysis using a spectral data analysis program (for example, product name: GRAMS / AI, manufactured by Thermo Fisher Scientific).

[0082] ( 1 H-MAS-NMR spectrum) For the sample pretreated under the following conditions 1 the H-MAS-NMR spectrum was measured. <Pretreatment> [[ID=4G]]Sample: CHA-type zeolite (cation type: H + type, without SDA) Treatment atmosphere: Vacuum Treatment temperature: 400 °C Treatment time: 5 hours After treatment at the treatment temperature, nitrogen was introduced, and the sample was cooled to room temperature under a nitrogen atmosphere for pretreatment. <NMR measurement> For the sample after pretreatment, a general NMR analyzer (instrument name: VNMRS-400, manufactured by Varian) was used. 1 The H-MAS-NMR spectrum was measured. The measurement conditions are as follows.

[0083] Resonance frequency: 400.0MHz Pulse width: Π / 2 Measurement waiting time: 10 seconds Total number of times: 32 Rotation frequency: 15kHz Chemical shift criteria: TMS The obtained NMR spectra were baseline-corrected and analyzed using a spectral data analysis program (e.g., product name: GRAMS / AI, manufactured by Thermo Fisher Scientific).

[0084] (Average grain size) The average grain size was determined by measuring the length of one side of the rhombohedron of 150 CHA-type zeolite primary particles observed in a scanning electron microscope (SEM name: JSM-IT200, manufactured by JEOL Ltd.) at a magnification of 10,000x, and then averaging these lengths.

[0085] (50% volume diameter) A slurry was obtained by mixing 1 g of powdered sample with 99 g of pure water, and this slurry was used as the measurement sample. The obtained slurry was treated with an ultrasonic homogenizer for 2 minutes to disperse the powdered sample in the slurry. The 50% volume diameter of the treated slurry was measured by laser diffraction scattering.

[0086] Example 1 A raw material composition having the following composition was obtained by mixing a 25% by mass aqueous solution of N,N,N-trimethyladamantan ammonium hydroxide (hereinafter also referred to as "TMADAOH"), a 49% by mass aqueous solution of N,N,N-dimethylethylcyclohexylammonium bromide (hereinafter also referred to as "CDMEABr"), pure water, a 48% by mass aqueous solution of sodium hydroxide, a 48% by mass aqueous solution of potassium hydroxide, and amorphous aluminosilicate. SiO2 / Al2O3 = 13.0 (TMAdA + +CDMEA + ) / SiO2 = 0.08 TMAdA + / SiO2=0.01 CDMEA + / SiO2=0.07 (Na+K) / SiO2=0.20 Na / SiO2 = 0.12 K / SiO2 = 0.08 H2O / SiO2 = 15 OH / SiO2 = 0.21

[0087] After mixing 1.0% by mass of seed crystals into the raw material composition, the raw material composition was sealed in a stainless steel autoclave and crystallized at 150°C for 48 hours under stirring conditions while rotating at 55 rpm. The obtained crystallized product was subjected to solid-liquid separation, washed with a sufficient amount of pure water, and then dried to remove moisture and impurities, which was used as the precursor CHA of this example. The precursor CHA consisted of a single phase of CHA-type zeolite, with a cation type of sodium-potassium, SiO2 / Al2O3 = 14.0, (Na+K) / Al = 0.56 (4.7% by mass), and an average crystal grain size of 0.49 μm. The precursor CHA was also designated as TMAda as SDA. + and CDMEA + It contained , and its SDA content was 0.44. The XRD peaks with a relative intensity of 5 or higher in the precursor CHA are shown in the table below.

[0088] [Table 3]

[0089] The precursor CHA was heated to 550°C at a heating rate of 3°C / min in an atmosphere through which a mixed gas (air with a water content of 67% by volume) obtained by mixing water vapor with dry air (water content 0% by volume) was passed, and then subjected to a water-containing treatment at 550°C for 2 hours to obtain the CHA-type zeolite of this example. The CHA-type zeolite of this example consisted of a single phase of CHA-type zeolite, had a sodium-potassium type cation, SiO2 / Al2O3 = 13.9, and an average crystal particle size of 0.49 μm.

[0090] The CHA-type zeolite of this example was treated with a 2 mol / L hydrochloric acid aqueous solution for ion exchange, then dried in the atmosphere at 110°C overnight to convert the cation type to the proton type. The CHA-type zeolite after ion exchange had, respectively, IR P1 a peak intensity with a peak top at 3599 cm -1 and IR P2 a peak intensity with a peak top at 3638 cm -1 corresponding to the peak intensity, and an IR ratio of 0.62. Also, NMR P1 and NMR P2 corresponded to the integrated intensity of the peak with a peak top at 4.2 ppm and the integrated intensity of the peak with a peak top at 3.2 ppm, respectively, and the NMR ratio was 0.15.

[0091] Example 2 The CHA-type zeolite of this example was obtained in the same manner as in Example 1, except that the precursor CHA was subjected to a water-containing treatment in an atmosphere through which a mixed gas (air with a water content of 17% by volume) obtained by mixing water vapor with dry air was passed. The CHA-type zeolite of this example consisted of a single phase of CHA-type zeolite, had a sodium-potassium type cation, SiO2 / Al2O3 = 13.9, and an average crystal particle size of 0.49 μm.

[0092] The cation type of the CHA-type zeolite of this example was converted to the proton type in the same manner as in Example 1 to obtain a CHA-type zeolite with a proton type cation. The IR ratio of the CHA-type zeolite with a proton type cation was 0.45, and the NMR ratio was 0.17.

[0093] Example 3 The CHA-type zeolite of this example was obtained in the same manner as in Example 1, except that the precursor CHA was treated with a mixed gas (air with a moisture content of 89 vol%) obtained by mixing dry air with water vapor, and the treatment temperature was set to 600°C. The CHA-type zeolite of this example consisted of a single phase of CHA-type zeolite, with a cation type of sodium-potassium, SiO2 / Al2O3 = 13.9, and an average crystal grain size of 0.49 μm.

[0094] The CHA-type zeolite of this example was converted to a proton-type cation using the same method as in Example 1, thereby obtaining a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.45, and the NMR ratio was 0.19.

[0095] Example 4 The CHA-type zeolite of this example was obtained using the same method as in Example 1, except that the water treatment temperature was set to 600°C. The CHA-type zeolite of this example consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 13.9, and an average crystal grain size of 0.49 μm.

[0096] The CHA-type zeolite of this example was converted to a proton-type cation using the same method as in Example 1, thereby obtaining a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.54, and the NMR ratio was 0.24.

[0097] Comparative Example 1 The precursor CHA obtained by the same method as in Example 1 was treated at 600°C for 2 hours under a flow of dry air (moisture content 0 vol%) to obtain the CHA-type zeolite of this comparative example.

[0098] The CHA-type zeolite in this comparative example consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 13.8, and an average crystal grain size of 0.49 μm.

[0099] In the same manner as in Example 1, the cation type was ion-exchanged to the H + type (proton type), and IR measurement and NMR measurement were performed. The CHA-type zeolite after ion exchange had, respectively, IR P1 with a peak top at 3599 cm -1 the intensity of the peak having a peak top at and IR P2 with a peak top at 3639 cm -1 corresponding to the intensity of the peak having a peak top at, and IR P2 / IR P1 ratio was 0.51. Also, NMR P1 and NMR P1 corresponded to the integrated intensity of the peak having a peak top at 4.2 ppm and the integrated intensity of the peak having a peak top at 3.2 ppm, respectively, and the NMR P2 / NMR P1 ratio was 0.12.

[0100] Example 5 An aqueous solution of CDMEABr at 49% by mass, an aqueous solution of N,N,N-dimethylethylcyclohexylammonium hydroxide at 35% by mass, pure water, an aqueous solution of sodium hydroxide at 48% by mass, an aqueous solution of potassium hydroxide at 48% by mass, and amorphous aluminosilicate were mixed to obtain a raw material composition having the following composition. SiO2 / Al2O3 = 18.5 CDMEA + / SiO2 = 0.08 (Na + K) / SiO2 = 0.20 Na / SiO2 = 0.04 K / SiO2 = 0.12 H2O / SiO2 = 18 OH / SiO2 = 0.18

[0101] ​​After mixing 1.0 mass% of seed crystals, the raw material composition was sealed in a stainless steel autoclave and crystallized at 150°C for 48 hours under stirring conditions while rotating at 55 rpm. The resulting crystals were separated into solid and liquid phases, washed with a sufficient amount of pure water, and then dried to remove moisture and impurities, which was used as the precursor CHA of this example. The precursor CHA consisted of a single phase of CHA-type zeolite, with a cation type of sodium-potassium, SiO2 / Al2O3 = 18.9, (Na+K) / Al = 0.36 (2.6 mass%), and an average crystal grain size of 0.78 μm. Furthermore, the precursor CHA was converted to CDMEA as SDA. + It contained [the specified substance], and the SDA content was 0.64.

[0102] The precursor CHA was subjected to a water-infusion treatment at 600°C for 2 hours in an atmosphere through which a mixed gas (air with a moisture content of 67% by volume) was passed, thereby obtaining the CHA-type zeolite of this example. The CHA-type zeolite of this example consisted of a single phase of CHA-type zeolite, with a cation type of sodium-potassium, SiO2 / Al2O3 = 18.9, and an average crystal grain size of 0.78 μm.

[0103] The CHA-type zeolite of this example was converted to a proton-type cation using the same method as in Example 1 to obtain a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.71 and the NMR ratio was 0.38.

[0104] Comparative Example 2 The precursor CHA obtained by the same method as in Example 5 was treated at 600°C for 2 hours under a flow of dry air (0% moisture content) to obtain the CHA-type zeolite of this comparative example. The CHA-type zeolite of this comparative example consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 18.9, and an average crystal grain size of 0.78 μm.

[0105] The CHA-type zeolite in this comparative example was converted to a proton-type cation using the same method as in Example 1, thereby obtaining a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.24, and the NMR ratio was 0.23.

[0106] Example 6 The precursor CHA of this example was obtained in the same manner as in Example 1, except that the composition of the raw material composition was as follows and the crystallization temperature was 160°C. SiO2 / Al2O3 = 13.2 (TMAdA + +CDMEA + ) / SiO2 = 0.08 TMAdA + / SiO2=0.01 CDMEA + / SiO2=0.07 (Na+K) / SiO2=0.20 Na / SiO2 = 0.11 K / SiO2 = 0.09 H2O / SiO2 = 15 OH / SiO2 = 0.21

[0107] The precursor CHA consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 13.9, (Na+K) / Al = 0.56 (4.7 mass%), and an average crystal grain size of 0.58 μm.

[0108] The precursor CHA was subjected to a water-infusion treatment at 550°C for 2 hours in an atmosphere through which a mixed gas (air with a moisture content of 17% by volume) was passed, thereby obtaining the CHA-type zeolite of this example.

[0109] The CHA-type zeolite in this embodiment consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 13.9, and an average crystal grain size of 0.58 μm.

[0110] The CHA-type zeolite of this example was converted to a proton-type cation using the same method as in Example 1 to obtain a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.50, and the NMR ratio was 0.18.

[0111] Comparative Example 3 The precursor CHA obtained by the same method as in Example 6 was treated at 600°C for 2 hours under a flow of dry air (moisture content 0 vol%) to obtain the CHA-type zeolite of this comparative example.

[0112] The CHA-type zeolite in this comparative example consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 13.9, and an average crystal grain size of 0.58 μm.

[0113] The CHA-type zeolite in this comparative example was converted to a proton-type cation using the same method as in Example 1, thereby obtaining a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.39, and the NMR ratio was 0.08.

[0114] Comparative Example 4 A CHA-type zeolite with a sodium-potassium cation type, obtained by the same method as in Comparative Example 1, was used as a precursor CHA. This precursor CHA was subjected to a water-infusion treatment at 550°C for 2 hours in an atmosphere through which a mixed gas (air with a moisture content of 17% by volume) was passed, resulting in the CHA-type zeolite of this comparative example.

[0115] The CHA-type zeolite in this comparative example consisted of a single phase of CHA-type zeolite, with a sodium-potassium cation type, SiO2 / Al2O3 = 13.8, and an average crystal grain size of 0.49 μm.

[0116] The CHA-type zeolite in this comparative example was converted to a proton-type cation using the same method as in Example 1, thereby obtaining a CHA-type zeolite with a proton-type cation. The IR ratio of the CHA-type zeolite with a proton-type cation was 0.55, and the NMR ratio was 0.08.

[0117] Comparative Example 5 A CHA-type zeolite with a sodium-potassium cation type, obtained by the same method as in Comparative Example 1, was subjected to ion exchange in the same method as in Example 1 to obtain a CHA-type zeolite with a proton cation type, which was used as the precursor CHA. This precursor CHA was subjected to a water-infusion treatment at 550°C for 2 hours in an atmosphere through which a mixed gas (air with a moisture content of 17% by volume) of dry air (moisture content of 0% by volume) and water vapor was passed, thereby obtaining the CHA-type zeolite of this comparative example.

[0118] The CHA-type zeolite in this comparative example consisted of a single phase of CHA-type zeolite, with a proton-type cation, SiO2 / Al2O3 = 13.8, an average crystal grain size of 0.49 μm, an IR ratio of 0.82, and an NMR ratio of 0.06.

[0119] Measurement Example 1 After converting the cation type of the CHA-type zeolite obtained in Examples 1 to 5 and Comparative Example 1 to the proton type, an aqueous copper nitrate solution was added dropwise to each, and the mixture was mixed in a mortar for 10 minutes. After mixing, the mixture was dried overnight in the air at 110°C, and then calcined in the air at 550°C for 1 hour to obtain copper-supported metal-containing CHA-type zeolite (copper-supported CHA-type zeolite). The results are shown in the table below.

[0120] [Table 4]

[0121] (Hydrothermal resistant treatment) Copper-supported CHA-type zeolite was molded and crushed to produce aggregated particles with an aggregation diameter of 12 to 20 mesh. 3 mL of the aggregated particles was packed into a fixed-bed flow-through reaction tube at atmospheric pressure (hereinafter also simply referred to as the "reaction tube"), and then subjected to hydrothermal endurance treatment under the following conditions.

[0122] Processing atmosphere: Air circulation atmosphere with a moisture content of 10% by volume. Air circulation rate: 300 mL / min Processing temperature: 900℃ Processing time: 1 hour (Nitrogen oxide reduction rate) 1.5 mL of aggregated particles after hydrothermal treatment was packed into a reaction tube, and nitrogen oxide-containing gas was circulated while maintaining the temperature as described below. The nitrogen oxide concentrations at the inlet and outlet of the reaction tube were then measured. The conditions for the distribution of nitrogen oxide-containing gases are as follows:

[0123] Composition of nitrogen oxide-containing gas: NO 200 ppm NH3200ppm O210% by volume H2O 3% by volume N2 remainder Flow rate of nitrogen oxide-containing gas: 1.5 L / min Space velocity: 60,000hr -1 Measurement temperature: 150°C or 600°C The nitrogen oxide reduction rate (NOx reduction rate) was calculated from the obtained nitrogen oxide concentration using the following formula.

[0124] Nitrogen oxide reduction rate (%) ={([NOx]in-[NOx]out) / [NOx]in}×100 [NOx]in is the nitrogen oxide concentration of the nitrogen oxide-containing gas at the inlet of the reaction tube, and [NOx]out is the nitrogen oxide concentration of the nitrogen oxide-containing gas at the outlet of the reaction tube.

[0125] The table below shows the ratio of the NOx reduction rates of Examples 1 to 4 to the NOx reduction rate of Comparative Example 1 (= NOx reduction rate of each example [%] / NOx reduction rate of Comparative Example 1 [%]).

[0126] [Table 5]

[0127] Compared to Comparative Example 1, the example that underwent the water-infusion treatment process of this embodiment showed higher NOx reduction rates in both the low-temperature range of 150°C and the high-temperature range of 600°C. In particular, the NOx reduction rate at 600°C in Example 1 was 1.25 times that of Comparative Example 1, confirming that the water-infusion treatment process significantly improves the NOx reduction rate in the high-temperature range.

[0128] Measurement Example 2 The NOx reduction rate was measured in the same manner as in Measurement Example 1, except that the CHA-type zeolite obtained in Example 5 and Comparative Example 2 was used, the hydrothermal endurance treatment time was set to 4 hours, and the nitrogen oxide reduction rate was measured at a measurement temperature of 600°C. The ratio of the NOx reduction rate of Example 5 to the NOx reduction rate of Comparative Example 2 (= NOx reduction rate of each example [%] / NOx reduction rate of Comparative Example 2 [%]) is shown in the table below.

[0129] [Table 6]

[0130] In Example 5, the NOx reduction rate at 600°C was 1.15 times that of Comparative Example 2, confirming that the water treatment process improves the NOx reduction rate in the high-temperature range.

[0131] Example 7 A precursor CHA was prepared and treated with water in the same manner as in Example 6 to obtain a CHA-type zeolite with a sodium-potassium cation type. The obtained CHA-type zeolite was treated with a 2 mol / L hydrochloric acid aqueous solution for ion exchange. Then, it was dried overnight in the air at 110°C to obtain a CHA-type zeolite with a proton cation type, which was used as the CHA-type zeolite of this example. The 50% volume diameter of the CHA-type zeolite of this example was 19.8 μm.

[0132] Example 8 The CHA-type zeolite obtained by crystallization in the same manner as in the production of the precursor CHA in Example 6 was mixed with pure water to form a slurry with a CHA-type zeolite content of 30% by mass. The slurry was continuously wet-milled (bead milled) using a continuous bead mill (device name: DYNO-MILL typ KDL, manufactured by Shinmaru Enterprises) under the following conditions.

[0133] Grinding medium: 1mm diameter glass beads Filling amount of grinding medium: 80% by volume Slurry dwell time: 1 minute Agitation speed (disk peripheral speed): 10 m / s After pulverization, the slurry was subjected to solid-liquid separation. The recovered solid phase was dried overnight in air at 110°C to obtain the precursor CHA of this example. After drying, the CHA-type zeolite was subjected to hydration treatment in the same manner as in Example 6, and the resulting CHA-type zeolite was treated with a 2 mol / L hydrochloric acid aqueous solution for ion exchange. Subsequently, it was dried overnight in air at 110°C to obtain a CHA-type zeolite with a proton-type cation, thus obtaining the CHA-type zeolite of this example. The 50% volume diameter of the CHA-type zeolite of this example was 2.4 μm.

[0134] Example 9 A CHA-type zeolite with a proton-type cation was obtained using the same method as in Example 7. This was pulverized using the same method as in Example 8. After solid-liquid separation of the pulverized slurry, the recovered solid phase was dried overnight in the air at 110°C to obtain the CHA-type zeolite of this example. The 50% volume diameter of the CHA-type zeolite of this example was 2.9 μm.

[0135] Comparative Example 6 The precursor CHA obtained by the same method as in Example 6 was treated at 600°C for 2 hours under a flow of dry air (0% moisture content) to obtain the CHA-type zeolite of this comparative example.

[0136] The CHA-type zeolite in this comparative example had an SiO2 / Al2O3 ratio of 14.0 and an average crystal grain size of 0.50 μm.

[0137] The CHA-type zeolite used in this comparative example was treated with a 2 mol / L hydrochloric acid aqueous solution for ion exchange, and then dried overnight in air at 110°C to obtain a CHA-type zeolite with a proton-type cation. The 50% volume diameter of the CHA-type zeolite with a proton-type cation was 19.8 μm.

[0138] Comparative Example 7 The precursor CHA obtained by the same method as in Example 8 was treated at 600°C for 2 hours under a flow of dry air (0% moisture content) to obtain CHA-type zeolite. The 50% volume diameter of the CHA-type zeolite in this comparative example was 2.4 μm.

[0139] The CHA-type zeolite of this comparative example was treated with a 2 mol / L hydrochloric acid aqueous solution to perform ion exchange, and then dried overnight in the air at 110°C to obtain a CHA-type zeolite with a proton-type cation.

[0140] Measurement Example 3 The NOx reduction rate was measured in the same manner as in Measurement Example 1, except that the CHA-type zeolite obtained in Examples 7 to 9 and Comparative Examples 6 and 7 was of the proton type, the step of converting the CHA-type zeolite to the proton type was omitted, and the nitrogen oxide reduction rate was measured at a measurement temperature of 600°C. The ratio of the NOx reduction rate of Examples 7 to 9 and Comparative Example 7 to the NOx reduction rate of Comparative Example 6 (= NOx reduction rate of each example or comparative example [%] / NOx reduction rate of Comparative Example 6 [%]) is shown in the table below.

[0141] [Table 7]

[0142] In Example 7, the NOx reduction rate at 600°C was 1.02 times that of Comparative Example 6, confirming that the water treatment process improves the NOx reduction rate in the high-temperature range.

[0143] In Comparative Example 7, the NOx reduction rate decreased compared to Comparative Example 6 due to the grinding treatment, whereas in Examples 8 and 9, which underwent water-inclusion treatment, the NOx reduction rate did not decrease even after grinding treatment.

Claims

1. １ A CHA-type zeolite characterized in that, in the H-MAS-NMR spectrum, the ratio of the integrated intensity of the maximum peak having a peak top at a chemical shift of 3.0 to 3.5 ppm to the integrated intensity of the maximum peak having a peak top at a chemical shift of 4.0 to 4.5 ppm is 0.13 or more and 0.5 or less, and the molar ratio of silica to alumina is 5.0 or more and 15.0 or less.

2. In the IR spectrum, wavenumber 3590 cm⁻¹ －１ More than 3d610cm －１ Below is the maximum peak height of the absorption peak with the peak top, corresponding to a wavenumber of 3630 cm². －１ More than 3650cm －１ The CHA-type zeolite according to claim 1, characterized in that the ratio of the maximum peak heights of the absorption peaks having the following peak tops is 0.40 or more and 1.0 or less.

3. In the IR spectrum, the maximum peak height of the absorption peak having a peak top at a wavenumber of 3590 cm －１ or higher and 3610 cm －１ or lower, with respect to the ratio of the maximum peak height of the absorption peak having a peak top at a wavenumber of 3630 cm －１ or higher and 3650 cm －１ or lower is 0.55 or higher and 1.0 or lower. The CHA-type zeolite according to claim 1 or 2, characterized in that.

4. A CHA-type zeolite according to any one of claims 1 to 3, wherein the average crystal grain size is 0.3 μm or more and 2.0 μm or less.

5. A CHA-type zeolite according to any one of claims 1 to 4, containing a transition metal element.

6. A nitrogen oxide reduction catalyst characterized by containing a CHA-type zeolite as described in any one of claims 1 to 5.

7. A method for reducing nitrogen oxides, characterized by using a CHA-type zeolite as described in any one of claims 1 to 5.

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