Zeolite and method for producing the same

Abstract

To provide at least any one of a zeolite which is excellent in hydrothermal durability, which shows excellent SCR catalytic activity even after a hydrothermal durability treatment, a production method thereof, and a selective reduction catalyst containing the same. The zeolite of the present invention has a paragenetic crystal structure containing a CHA structure and a GME structure, has at least the peaks in the following table in a powder X-ray diffraction chart, contains calcium and copper, and in an XPS spectrum, the ratio of the spectrum area in the range of 930.0 eV or more and 933.0 eV or less to the spectrum area in the range of 930.0 eV or more and 940.0 eV or less is less than 34%.[Table 1]

Description

Technical Field

[0001] This disclosure relates to zeolites containing calcium and copper. Background Technology

[0002] Zeolites are used in a wide range of applications, including as catalysts, adsorbents, and ion exchangers. In particular, zeolites with pores formed by oxygen eight-membered rings and oxygen double six-membered rings in their framework structure have attracted attention as selective reduction catalysts (hereinafter also known as "SCR catalysts") for removing nitrogen oxides contained in automobile exhaust.

[0003] Patent Document 1 discloses a copper-containing GME / CHA intergrowth zeolite, which has pores formed by oxygen octagons and a framework structure containing double hexa-membered rings.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Publication No. 2019-524606 Summary of the Invention

[0005] The technical problem that the invention aims to solve The copper-containing GME / CHA symbiotic zeolite disclosed in Patent Document 1 exhibits low hydrothermal durability, thus presenting the following technical problem: if exposed to a high-temperature atmosphere containing moisture, the activity for reducing nitrogen oxides (hereinafter also referred to as "SCR catalytic activity") decreases. It should be noted that, hereinafter, the treatment involving exposure to a high-temperature atmosphere containing moisture is also referred to as hydrothermal durability treatment.

[0006] The purpose of this disclosure is to provide at least one of the following: a zeolite with excellent hydrothermal durability and exhibiting excellent SCR catalytic activity even after hydrothermal durability treatment; a method for manufacturing the zeolite; and a selective reduction catalyst comprising the zeolite.

[0007] Technical solutions for solving technical problems The inventors have studied zeolites with practical nitrogen oxide reduction properties as SCR catalysts. Their results showed that by allowing copper and calcium to coexist in a specific state within a zeolite having a specific crystal structure (intergrowth structure), excellent SCR catalytic activity was observed even after hydrothermal durability treatment.

[0008] That is, the present invention is as described in the claims; furthermore, the gist of this disclosure is as follows.

[0009] [1] A zeolite, characterized in that, It has a symbiotic crystal structure containing CHA and GME structures. The powder X-ray diffraction pattern should contain at least the peaks listed in the table below. Contains calcium and copper. In the XPS spectrum of the zeolite, the ratio of the spectral area in the range of 930.0 eV and below to the spectral area in the range of 930.0 eV and below to less than 34% is [Table 1] .

[0010] [2] According to the zeolite described in [1] above, wherein, in the powder X-ray diffraction pattern of the zeolite, the interplanar spacing d = 4.29 ± 0.08 The half-width of the peak relative to the interplanar spacing d = 4.97 ± 0.08 The ratio of the half-width of the peak is greater than 2.0 and less than 7.0.

[0011] [3] According to the zeolite described in [1] or [2] above, the molar ratio of calcium to aluminum is 0.3 or less.

[0012] [4] The zeolite according to any one of [1] to [3] above, wherein the molar ratio of calcium to aluminum is 0.01 or more and 0.3 or less.

[0013] [5] The zeolite according to any one of [1] to [4] above, wherein the molar ratio of copper to aluminum is 0.05 or more and 0.4 or less.

[0014] [6] The zeolite according to any one of [1] to [5] above, wherein the molar ratio of silicon dioxide to aluminum oxide is 5.0 or more and 15 or less.

[0015] [7] The zeolite according to any one of [1] to [6] above, wherein, in the XPS spectrum of the zeolite, the ratio of the spectral area of ​​the range of 930.0 eV and above to 933.0 eV and below to the spectral area of ​​the range of 930.0 eV and above to 940.0 eV and below is 10% or more and less than 34%.

[0016] [8] The method for manufacturing zeolite according to any one of [1] to [7] above, characterized in that, Includes: a copper-containing process, wherein the calcium-containing zeolite is made to contain copper.

[0017] [9] According to the method for manufacturing zeolite described in [8] above, wherein, The manufacturing method further includes a crystallization step, wherein a composition containing an alumina source, a silicon dioxide source, an alkali source, a calcium source and water is crystallized in the presence of seed crystals to obtain the calcium-containing zeolite.

[0018]

[10] According to the method for manufacturing zeolite described in [8] above, wherein, The manufacturing method further includes: The crystallization process involves crystallizing a composition containing an alumina source, a silicon dioxide source, an alkali source, and water in the presence of seed crystals to obtain raw material zeolite; and The calcium-containing process involves introducing calcium into the raw material zeolite to obtain the calcium-containing zeolite.

[0019]

[11] A selective reduction catalyst for nitrogen oxides, characterized in that it comprises any one of [1] to [7].

[0020] Invention Effects According to the present invention, at least one of the following can be provided: a zeolite with excellent hydrothermal durability and exhibiting excellent SCR catalytic activity even after hydrothermal durability treatment, a method for manufacturing the zeolite, and a selective reduction catalyst comprising the zeolite. Detailed Implementation

[0021] The following describes an example of an embodiment of the zeolite disclosed herein. The terminology used in this embodiment is as follows.

[0022] "Zeolite" refers to a compound having a regular structure in which framework atoms (hereinafter also referred to as "T atoms") are formed via oxygen (O), and where the T atoms are composed of at least one of metal atoms and half-metal atoms. Examples of metal atoms include one or more selected from aluminum (Al), iron (Fe), and gallium (Ga). Examples of half-metal atoms include one or more selected from boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te).

[0023] "Zeolite-like substances" refer to compounds having a regular structure in which T atoms are formed via oxygen, and where the T atoms contain at least atoms other than metals and half-metals (hereinafter referred to as "non-metallic atoms"). Phosphorus (P) is an example of a non-metallic atom, and aluminum phosphate (AlPO) and aluminum silicate phosphate (SAPO) are examples of complex phosphorus compounds that contain phosphorus as a non-metallic atom. In this embodiment, for convenience, "zeolite-like substances" are used to distinguish them from "zeolites" in which the T atoms are composed of at least one of metal atoms and half-metal atoms.

[0024] "Aluminosilicate" is a composite oxide having a repeating structure comprising a network of aluminum (Al) and silicon (Si) via oxygen (O). In this embodiment, aluminosilicate also includes counterparts having a repeating structure comprising a network of aluminum (Al) and silicon (Si) via oxygen (O), and in which a portion of the aluminum (e.g., less than 30% of the aluminum as T atoms) is replaced by other metal atoms. In the powder X-ray diffraction (hereinafter also referred to as "XRD") pattern of aluminosilicates, substances with crystalline XRD peaks are "crystalline aluminosilicates," and substances without crystalline XRD peaks are "amorphous aluminosilicates." It should be noted that zeolites whose T atoms are substantially composed of aluminum (Al) and silicon (Si) belong to "crystalline aluminosilicates." Here, "T atoms are substantially composed of aluminum (Al) and silicon (Si)" means not only allowing the T atoms to be composed solely of aluminum (Al) and silicon (Si), but also allowing the inclusion of T atoms other than aluminum (Al) and silicon (Si) within the scope of the effects of the present invention.

[0025] The XRD pattern in this embodiment uses CuK α When radiation is used as a radiation source for measurement, the following conditions can be cited as measurement conditions.

[0026] Accelerating current and voltage: 40mA·40kV X-ray source: CuK α ray( l =1.5405Å) Measurement mode: Continuous scanning Scanning conditions: 40° / minute Measurement range: 2 i =3° to 43° Longitudinal diverging slit: 10mm Diverging / Incident Slit: 1° Light-receiving slit: open Light-receiving Soler slit: 5° Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter XRD patterns can be determined using a conventional powder X-ray diffractometer (e.g., Ultima IV, manufactured by Rigaku). Additionally, the XRD peaks for crystallinity are defined as the peaks within 2 degrees of their apex in XRD pattern analysis using conventional analytical software (e.g., SmartLab Studio II, manufactured by Rigaku). i The detected peaks can be used as analytical conditions for XRD patterns, as exemplified by the following.

[0027] Fitting conditions: Automatic, refine background Dispersed pseudo-Voigt function (peak shape) Background removal method: Fitting method K α 2. Removal method: K α 1 / K α 2 = 0.497 Smoothing method: B-Spline curve Smoothing conditions: Quadratic differentiation method, σ cut value = 3, χ threshold = 1.5 In zeolites and zeolite analogues, the "regular structure" (hereinafter also referred to as the "skeletal structure") refers to the skeletal structure defined by the Skeletal Structure Code (hereinafter also simply referred to as the "skeletal code") specified by the Structure Commission of the International Zeolite Association. For example, the "CHA structure" is a skeletal structure with the skeletal code CHA, and the "GME structure" is a skeletal structure with the skeletal code GME. The skeletal structure of zeolites and zeolite analogues can also be represented by each structural unit (repeating unit). Such structural units are usually called composite building units (CBUs). Composite building units are formed by connecting several (e.g., several to dozens) TOx units (e.g., TO4 units) consisting of T atoms and oxygen (O) bonded to them.

[0028] A "symbiotic crystal structure containing CHA and GME structures" is a framework structure in which composite structural units containing at least CHA structure (hereinafter also referred to as "CHA units") and GME structure (hereinafter also referred to as "GME units") form the framework structure of a zeolite (one zeolite), distinguishing it from mixed zeolites obtained by mixing CHA and GME structure zeolites. In a "symbiotic crystal structure containing CHA and GME structures," the arrangement order of CHA and GME units is not particularly limited; they can be arranged in an ordered or disordered manner. Besides CHA and GME units, a "symbiotic crystal structure containing CHA and GME structures" may also contain units with other framework codes different from the CHA and GME structures (hereinafter also referred to as "other units").

[0029] The "symbiotic crystal structure containing CHA and GME structures" exhibits a characteristic XRD pattern and can therefore be identified by the XRD pattern. While the XRD patterns of zeolites with the "symbiotic crystal structure containing CHA and GME structures" have similar characteristics, they exhibit different XRD patterns depending on the ratio of CHA units to GME units (hereinafter also referred to as the "symbiotic ratio"). A portion (of the specified symbiotic ratio) of zeolites with the "symbiotic crystal structure containing CHA and GME structures" shows an XRD pattern containing at least the peaks listed in Table 2 below. Therefore, it can be determined that zeolites displaying an XRD pattern containing the peaks listed in Table 2 below possess a "symbiotic crystal structure containing CHA and GME structures".

[0030] [Table 2]

[0031] Zeolites with a "symbiotic crystal structure containing CHA and GME structures" may include, in addition to the peaks listed in Table 2 above, peaks belonging to the symbiotic crystal structure containing CHA and GME structures (hereinafter also referred to as "other CHA / GME peaks"). Examples of other CHA / GME peaks are those appearing in the DIFFaX diagram described later.

[0032] "Co-existing crystal structures containing CHA and GME structures" can be identified as follows: by using simulations with DIFFaX (MMJTreacy et al., Proceedings of the Royal Chemical Society, London, A (1991), Vol. 433, pp. 499-520), powder X-ray diffraction patterns (hereinafter also referred to as "DIFFaX patterns") of multiple co-existing crystal structures with different ratios of CHA and GME structures are obtained, and the obtained DIFFaX patterns are compared with the XRD patterns of zeolites.

[0033] Next, the zeolite of this embodiment will be described.

[0034] The zeolite of this embodiment has a symbiotic crystal structure comprising CHA and GME structures, and its XRD pattern contains at least the peaks shown in Table 3 below. Furthermore, the zeolite of this embodiment contains calcium and copper, and the ratio of the spectral area in the range of 930.0 eV and above to 933.0 eV and below in the XPS spectrum to the spectral area in the range of 930.0 eV and above to 940.0 eV (hereinafter also referred to as the "XPS area ratio") is less than 34%. It should be noted that Table 3 below is the same as Table 2 above.

[0035] [Table 3]

[0036] The zeolite of this embodiment is a symbiotic crystal structure containing CHA and GME structures, and its framework structure (symbiotic crystal structure) contains at least CHA units and GME units. The zeolite of this embodiment exhibits excellent SCR catalytic activity due to its symbiotic crystal structure containing CHA and GME structures. In addition to CHA and GME units, the framework structure (symbiotic crystal structure) of the zeolite of this embodiment may also contain other units; from the viewpoint of further improving SCR catalytic activity, it is preferable to have a structure composed of only two types of units: CHA units and GME units.

[0037] The zeolite of this embodiment exhibits at least the peaks shown in Table 3 above in its XRD pattern. The zeolite of this embodiment, by possessing the peaks shown in Table 3 above, demonstrates excellent SCR catalytic activity. It should be noted that in this embodiment, having the peaks in the table refers to having peaks included in the interplanar spacing d shown in the table in its XRD pattern. A peak that has a peak within the range of relative intensities shown in the table, and whose maximum intensity is within the range of relative intensities shown in the table.

[0038] The zeolite in this embodiment only needs to contain at least the peaks shown in Table 3 above in its XRD pattern. From the viewpoint of further improving SCR catalytic activity, the interplanar spacing d in Table 3 is 4.29 ± 0.08. The half-width of the peak relative to the interplanar spacing d = 4.97 ± 0.08 The ratio of the half-width at half-maximum (WWHM) of the peaks is preferably 2.0 or higher and 7.0 or lower, more preferably 3.0 or higher and 5.0 or lower. The WWHM of each peak can be determined by analyzing the XRD pattern using conventional analysis software (e.g., SmartLab Studio II, Rigaku). It should be noted that the WWHM in this specification refers to the full half-width.

[0039] In addition, the zeolite of this embodiment only needs to contain at least the peaks in Table 3 above in its XRD pattern. From the viewpoint of further improving the SCR catalytic activity, it is preferable that each peak in Table 3 above is within the range of the half-value width shown in Table 4 below.

[0040] [Table 4]

[0041] The zeolite of this embodiment contains calcium. Because it contains calcium, the zeolite of this embodiment exhibits excellent hydrothermal durability. In the zeolite of this embodiment, the molar ratio of calcium to aluminum (hereinafter also referred to as the "Ca / Al ratio") is not particularly limited, but from the viewpoint of further improving hydrothermal durability, it is preferably 0.01 or more, more preferably 0.015 or more, and even more preferably 0.02 or more. Furthermore, from the viewpoint of further improving hydrothermal durability, the Ca / Al ratio in the zeolite of this embodiment is preferably 0.3 or less, more preferably 0.25 or less, and even more preferably 0.15 or less. The upper and lower limits of the Ca / Al ratio can be any combination of the above-mentioned upper and lower limits, preferably 0.01 or more and 0.3 or less, more preferably 0.015 or more and 0.25 or less, and even more preferably 0.02 or more and 0.15 or less.

[0042] The zeolite of this embodiment contains copper. In the zeolite of this embodiment, the molar ratio of copper to aluminum (hereinafter also referred to as the "Cu / Al ratio") is not particularly limited, but from the viewpoint of further improving hydrothermal durability, it is preferably 0.05 or more, more preferably 0.10 or more, and even more preferably 0.12 or more. Furthermore, from the viewpoint of further improving hydrothermal durability, the Cu / Al ratio in the zeolite of this embodiment is preferably 0.4 or less, more preferably 0.35 or less, and even more preferably 0.30 or less. The upper and lower limits of the Cu / Al ratio can be any combination of the above-mentioned upper and lower limits, but from the viewpoint of further improving hydrothermal durability, it is preferably 0.05 or more and 0.4 or less, more preferably 0.10 or more and 0.35 or less, even more preferably 0.10 or more and 0.30 or less, and particularly preferably 0.12 or more and 0.30 or less.

[0043] In this embodiment, the zeolite only needs to contain calcium and copper, and their composition is not particularly limited. However, from the viewpoint of further improving hydrothermal durability, it is preferable that at least one of calcium and copper is loaded onto the zeolite. It should be noted that in this embodiment, "containing a specified element" means that the zeolite contains the specified element, which can be contained in any state or at any location. On the other hand, "loading a specified element" means that the specified element is included as a component of the zeolite other than T atoms. Examples of loading the specified element include loading it onto at least one of the outer surface of the zeolite (the surface of the zeolite other than the inner surface of the pores) and the inner surface of the pores.

[0044] The calcium and copper contained in the zeolite of this embodiment are not particularly limited in state, as long as the XPS area ratio described later is less than 34%. Examples include compounds (e.g., oxides), metals, ions, alloys, or two or more of these states. It should be noted that the calcium and copper can be in the same or different states.

[0045] In addition to calcium and copper, the zeolite of this embodiment may also contain other substances. Examples of such other substances include alkali metals, alkaline earth metals, and transition metals.

[0046] In this embodiment, the zeolite's XPS spectrum shows that the area of ​​the spectrum in the range of 930.0 eV and above to 933.0 eV is less than 34% relative to the area of ​​the spectrum in the range of 930.0 eV and above to 940.0 eV (XPS area ratio). From the viewpoint of further improving hydrothermal durability, the XPS area ratio of the zeolite in this embodiment is preferably 10% or more and less than 34%, more preferably 15% or more and less than 33%, and even more preferably 25% or more and less than 33%. It should be noted that the XPS area ratio is a value expressed as a percentage, obtained by dividing the area of ​​the spectrum in the range of 930.0 eV and above to 933.0 eV by the area of ​​the spectrum in the range of 930.0 eV and above to 940.0 eV.

[0047] X-ray photoelectron spectroscopy (XPS) is a method for analyzing the chemical state of metals contained in a sample. In XPS spectra obtained by analyzing zeolites containing calcium and copper, peaks representing 0-valent, 1-valent, and 2-valent copper appear above 930.0 eV and below 940.0 eV, while peaks representing 0-valent copper appear above 930.0 eV and below 933.0 eV. Therefore, the aforementioned XPS area ratio functions as an indicator of the ratio of 0-valent copper to all copper (0-valent, 1-valent, and 2-valent copper) in zeolites containing calcium and copper.

[0048] In this embodiment, the XPS spectrum can be measured using a conventional X-ray photoelectron spectroscopy analyzer (e.g., PHI5000VersaProbeII, manufactured by ULVAC-PHI). The following conditions can be cited as examples of measurement conditions.

[0049] X-ray source: Monochromatic Al-K α ray X-ray beam diameter: 100 μm f Energy resolution: Wide-scan spectrum 117.40 eV High-resolution spectrum 46.95 eV (Cu2p 3 / 2 ) Charge correction: Al2p main peak (74.4 eV) No sputtering treatment The peak area of ​​an XPS spectrum can be calculated by summing the areas of the trapezoids between data points. More specifically, the measured XPS spectrum is segmented using multiple imaginary lines spaced at 0.10 eV intervals. Each segmented XPS spectrum is assumed to be a trapezoid (a right-angled trapezoid formed by two adjacent imaginary lines, a straight line connecting the intersection of these two lines with the XPS spectrum curve, and the horizontal axis). The area of ​​each trapezoid is calculated, and then the areas of all trapezoids are added together to determine the peak area of ​​the XPS spectrum.

[0050] In the zeolite of this embodiment, the molar ratio of silica to alumina (hereinafter also referred to as the "SiO2 / Al2O3 ratio") is not particularly limited. From the viewpoint of further improving the SCR catalytic activity across the low-temperature (e.g., 150°C) region to the high-temperature (e.g., 600°C) region, it is preferably 5.0 or more, more preferably 5.5 or more, and even more preferably 6.0 or more. Furthermore, in the zeolite of this embodiment, from the viewpoint of further improving the SCR catalytic activity across the low-temperature (e.g., 150°C) region to the high-temperature (e.g., 600°C) region, the SiO2 / Al2O3 ratio is preferably 15 or less, more preferably 10 or less, and even more preferably 9.5 or less. The upper and lower limits of the SiO2 / Al2O3 ratio can be any combination of the upper and lower limits mentioned above. From the viewpoint of further improving the SCR catalytic activity from the low temperature (e.g., 150°C) region to the high temperature (e.g., 600°C) region, it is preferably 5.0 or more and 15 or less, more preferably 5.5 or more and 10 or less, and even more preferably 6.0 or more and 9.5 or less.

[0051] In the zeolite of this embodiment, the T atoms constituting the framework structure can be composed of at least one of metal atoms and half-metal atoms, without particular limitation. From the viewpoint of further improving hydrothermal durability, it is preferable to be composed of aluminum (Al) and silicon (Si). In other words, the zeolite of this embodiment is preferably a crystalline aluminosilicate having a symbiotic crystal structure including CHA and GME structures.

[0052] The zeolite of this embodiment described above can be used as a selective reduction catalyst (SCR catalyst) for the reduction and removal of nitrogen oxides. The method for removing nitrogen oxides using the zeolite of this embodiment includes a contact step (hereinafter also simply referred to as the "contact step") in which a fluid containing nitrogen oxides and a reducing agent (hereinafter also referred to as "nitrogen oxide-containing fluid") is brought into contact with the zeolite of this embodiment. In the contact step, by bringing the nitrogen oxide-containing fluid into contact with the zeolite of this embodiment, the nitrogen oxides are reduced and removed.

[0053] Nitrogen oxides contained in a fluid containing nitrogen oxides include, for example, nitric oxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetroxide, and nitrous oxide, and two or more of them may also be used.

[0054] Examples of reducing agents that can be used in fluids containing nitrogen oxides include ammonia, urea, alcohols, ketones, carbon monoxide, and hydrogen, and two or more of them may be used.

[0055] Fluids containing nitrogen oxides may consist solely of nitrogen oxides and a reducing agent, but may further include one or more other components such as carbon dioxide, nitrogen, oxygen, sulfur oxides, and water. Examples of specific fluids that can be used as nitrogen oxide-containing fluids include exhaust gases from diesel vehicles, gasoline vehicles, boilers, and gas turbines.

[0056] The fluid containing nitrogen oxides can be one or more selected from liquids, gases, and mixtures of liquids and gases, and from the viewpoint of further improving the reduction rate of nitrogen oxides, gases are preferred.

[0057] The zeolite of this embodiment, which comes into contact with a fluid containing nitrogen oxides, can be molded into a predetermined shape. Examples of methods for molding the zeolite of this embodiment include roll forming, compression molding, extrusion molding, injection molding, casting, and sheet forming. Examples of the shapes of the molded zeolite include spherical, substantially spherical, elliptical, plate-like, cylindrical, polyhedral, irregular, and petal-shaped. It should be noted that the zeolite of this embodiment can be molded together with a binder to form a molded body containing both the binder and the zeolite. Examples of binders include those selected from silica, etc. c - One or more of the following: alumina other than alumina, kaolin, palygorskite, montmorillonite, bentonite, and sepiolite.

[0058] The reduction reaction of nitrogen oxides in the contact process is carried out by contacting the zeolite of this embodiment with a fluid containing nitrogen oxides. Therefore, there are no particular limitations on the contact conditions for contacting the zeolite of this embodiment with the fluid containing nitrogen oxides. The following conditions are preferred contact conditions.

[0059] From the viewpoint of further improving the reduction rate of nitrogen oxides, the contact temperature between the zeolite and the nitrogen oxide-containing fluid in this embodiment is preferably 100°C or higher and 700°C or lower, more preferably 150°C or higher and 600°C or lower.

[0060] From the viewpoint of further improving the reduction rate of nitrogen oxides, the space velocity (SV) of the nitrogen oxide-containing fluid in contact with the zeolite of this embodiment is preferably 500 hr. -1 Above and 500,000 hr -1 The following is more preferably 2000hr-1 Above and 300,000 hours -1 The following should be noted: SV of the nitrogen oxide-containing fluid is a parameter representing the supply rate of nitrogen oxide-containing fluid per unit volume of zeolite per hour ([L(zeolite)] / [L(nitrogen oxide-containing fluid) / h] = [hr] -1 ])).

[0061] Taking into account the concentration of nitrogen oxides contained in exhaust gases from automobiles, etc., the concentration of nitrogen oxides in the nitrogen oxide-containing fluid in contact with the zeolite of this embodiment is preferably 3 ppm or more and 600 ppm or less, more preferably 100 ppm or more and 550 ppm or less. It should be noted that ppm in this specification refers to volume ppm.

[0062] From the viewpoint of further improving the reduction rate of nitrogen oxides, the volume of the reducing agent in the nitrogen oxide-containing fluid that comes into contact with the zeolite of this embodiment is preferably 100 parts or more and 200 parts or less, more preferably 100 parts or more and 150 parts or less, relative to 100 parts by volume of nitrogen oxides in the nitrogen oxide-containing fluid.

[0063] The contact time between the zeolite and the nitrogen oxide-containing fluid in this embodiment can be appropriately set according to the amount of nitrogen oxides to be reduced. The zeolite in this embodiment has excellent hydrothermal durability, so it can maintain SCR catalytic activity even when exposed to a high-temperature nitrogen oxide-containing fluid containing moisture for a long time.

[0064] Next, the method for manufacturing zeolite according to this embodiment will be described.

[0065] The zeolite manufacturing method of this embodiment includes a copper-containing step of making calcium-containing zeolite (hereinafter referred to as "calcium-containing zeolite") contain copper. It should be noted that, as shown in the comparative example described later, if the copper-containing zeolite (hereinafter also referred to as "copper-containing zeolite") contains calcium, the XPS area ratio of the obtained zeolite is likely to be more than 34%, making it difficult to manufacture the zeolite of this embodiment.

[0066] In the copper-containing process, there is no particular limitation on the method for containing copper in calcium-containing zeolite. For example, a treatment that brings a copper source into contact with calcium-containing zeolite (hereinafter also referred to as "copper contact treatment") can be used. It should be noted that as a method for containing copper by copper contact treatment, examples include ion exchange, impregnation loading, evaporation drying, precipitation loading, and physical mixing. Ion exchange or impregnation loading is preferred.

[0067] The copper source in contact with the calcium-containing zeolite is a copper-containing substance, such as copper nitrate, copper sulfate, copper acetate, copper chloride, copper complex salts, copper oxide, copper-containing complex oxides, or two or more thereof. To make the calcium-containing zeolite more likely to contain copper, the copper source in contact with the calcium-containing zeolite is preferably selected from one or more of copper nitrate, copper sulfate, and copper oxide.

[0068] To facilitate the inclusion of copper in calcium-containing zeolite, the contact between the copper source and the calcium-containing zeolite is preferably carried out by contacting a solution containing the copper source (hereinafter also referred to as "copper solution") with the calcium-containing zeolite. Examples of solvents included in the copper solution include at least one of water and alcohol, with water being preferred.

[0069] The copper concentration in the copper solution is not particularly limited, as long as the Cu / Al ratio and other factors are appropriately adjusted to enable the manufacture of the zeolite of this embodiment. From the viewpoint of making it easier to manufacture the zeolite of this embodiment, the copper concentration in the copper solution is preferably such that the Cu / Al ratio of the calcium-containing zeolite (the zeolite of this embodiment) that has undergone copper contact treatment is 0.10 or more and 0.30 or less.

[0070] The contact conditions between the copper source and the calcium-containing zeolite are not particularly limited, as long as the Cu / Al ratio and other factors are appropriately adjusted to enable the manufacture of the zeolite of this embodiment. From the viewpoint of making it easier to manufacture the zeolite of this embodiment, the contact conditions between the copper source and the calcium-containing zeolite are preferably such that the Cu / Al ratio of the calcium-containing zeolite (the zeolite of this embodiment) that has undergone copper contact treatment is 0.10 or more and 0.30 or less. For example, the contact time between the calcium-containing zeolite and the copper source can be 10 minutes or more and 24 hours or less. In addition, the contact temperature between the calcium-containing zeolite and the copper source can be 20°C or more and 110°C or less. In addition, the contact pressure between the calcium-containing zeolite and the copper source can be 0.0 MPa or more and 1.0 MPa or less (gauge pressure).

[0071] The calcium-containing zeolite is brought into contact with a copper source through a copper contact treatment, thereby incorporating copper into the calcium-containing zeolite. The copper-containing calcium-containing zeolite can be used directly as the zeolite of this embodiment, or it can be used as the zeolite of this embodiment after undergoing one or more treatments selected from cleaning treatment, drying treatment, calcination treatment, and ion exchange treatment. It should be noted that the order of these treatments can be appropriately set.

[0072] The cleaning process involves rinsing the zeolite. For example, rinsing the zeolite with pure water is sufficient.

[0073] Drying is the process of removing moisture adsorbed on zeolite. The drying conditions are arbitrary as long as moisture can be removed from the zeolite. As an example of drying conditions, drying the zeolite in air at a temperature of 50°C to 150°C for 2 to 12 hours is recommended. Drying can be carried out under static or agitated conditions. Alternatively, a spray dryer can be used, for example.

[0074] Firing is a process that immobilizes metallic elements (copper, calcium) within zeolite by firing it. The firing conditions are arbitrary as long as they enable the immobilization of these elements. For example, firing the zeolite in air at a temperature between 400°C and 800°C for at least 1 hour and no more than 5 hours can be considered. Firing can be performed while the zeolite is stationary or while it is being stirred in a kiln or similar environment.

[0075] Ion exchange treatment is a process that changes the cationic form of zeolite to any other cationic form. Ion exchange treatment can be performed using conventionally known methods, for example, by setting the cationic form of the zeolite to ammonium (NH4) + In the case of a cationic zeolite (e.g., a protonated zeolite), a method can be used to contact the zeolite with an aqueous solution containing ammonium ions (e.g., an aqueous solution of ammonium chloride). Alternatively, for example, when the cationic form of the zeolite is set to the protonated form (H... + In the case of (type), it can be set as ammonium (NH4) + A method for firing type zeolite at a temperature above 400°C and below 700°C for more than 1 hour and less than 5 hours.

[0076] The calcium-containing zeolite (calcium-containing zeolite to be copper-containing) used in the copper-containing process (copper contact treatment) is not particularly limited as long as it is obtained by containing copper, but preferably is a calcium-containing zeolite manufactured by at least one of the first manufacturing method (hereinafter also referred to as "manufacturing method (1)") and the second manufacturing method (hereinafter also referred to as "manufacturing method (2)"). It should be noted that the calcium-containing zeolite used in the copper-containing process (copper contact treatment) can be a mixture of calcium-containing zeolite manufactured by manufacturing method (1) and calcium-containing zeolite manufactured by manufacturing method (2).

[0077] First, the method (1) for manufacturing calcium-containing zeolite will be explained. Method (1) is a method of synthesizing zeolite from a raw material composition and then making the zeolite contain calcium.

[0078] The manufacturing method (1) comprises: a crystallization step (hereinafter also referred to as "crystallization step (1)") in which a raw material composition comprising at least an alumina source, a silica source, an alkali source and water is crystallized in the presence of a seed crystal; and a calcium-containing step (hereinafter also referred to as "calcium-containing step (1)") in which the raw material zeolite obtained in the crystallization step (1) contains calcium. By manufacturing method (1) including these steps, calcium-containing zeolite can be obtained.

[0079] In the crystallization step (1), the alumina source included in the raw material composition is at least one of alumina (Al2O3) and its precursors, such as one or more selected from alumina, aluminum sulfate, aluminum nitrate, sodium aluminate, aluminum hydroxide, aluminum chloride, amorphous aluminum silicate, metallic aluminum, crystalline aluminum silicate, and aluminum alkoxide. Preferably, it is an amorphous aluminum compound, more preferably at least one of aluminum hydroxide and amorphous aluminum silicate, and even more preferably, it is an amorphous aluminum silicate. It should be noted that substances containing aluminum (Al) and silicon (Si), such as amorphous aluminum silicate, can be used not only as an alumina source but also as a silicon dioxide source as described later.

[0080] In the crystallization process (1), the silica source contained in the raw material composition is at least one of silica (SiO2) or its precursor, for example, one or more selected from colloidal silica, amorphous silica, sodium silicate, tetraethoxysilane, tetraethyl orthosilicate, precipitated silica, fumed silica, amorphous aluminosilicate and crystalline aluminosilicate, preferably an amorphous silicon compound, more preferably an amorphous aluminosilicate.

[0081] The alumina and silica sources included in the raw material composition can be manufactured at a lower cost without the presence of crystalline aluminosilicates, which is advantageous for industry.

[0082] In the crystallization step (1), the alkali source included in the raw material composition is a compound containing an alkali metal element or an alkali metal. Examples include one or more selected from alkali metal hydroxides, carbonates, sulfates, chlorides, bromides, and iodides. Preferably, it is selected from one or more selected from alkali metal hydroxides, chlorides, bromides, and iodides, and more preferably, it is an alkali metal hydroxide. As the alkali metal (alkali metal element) included in the alkali source, examples include one or more selected from sodium, potassium, rubidium, and cesium, and more preferably, at least one selected from sodium and potassium. Particularly preferred alkali sources are at least one selected from sodium hydroxide and potassium hydroxide.

[0083] In the crystallization process (1), the water contained in the raw material composition can be deionized water or pure water. It should be noted that when the raw materials other than the water contained in the raw material composition are hydrates, structural water, solvents, or other water-containing substances, the water in them can be regarded as the water (H2O) contained in the raw material composition.

[0084] In the crystallization step (1), the raw material composition does not contain calcium. The method for preparing the raw material composition containing calcium belongs to the method (2) described later. In addition, in the crystallization step (1), in order to facilitate the formation of a symbiotic crystal structure containing CHA and GME structures in the raw material zeolite obtained by crystallization, the raw material composition preferably does not contain organic structure directing agents. In addition, in the crystallization step (1), in order to facilitate the application of manufacturing equipment made of common materials, the raw material composition preferably does not contain fluorine (F) and phosphorus (P).

[0085] It should be noted that, in this specification, "not containing the specified substance" means that the content determined by conventional composition analysis such as ICP determination is less than 100 ppm by mass, preferably less than 10 ppm by mass, and more preferably less than the detection limit.

[0086] In the crystallization step (1), the SiO2 / Al2O3 ratio in the raw material composition is preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. Furthermore, in the crystallization step (1), the SiO2 / Al2O3 ratio in the raw material composition is preferably 8 or more, more preferably 10 or more, and even more preferably 13 or more. The upper and lower limits of the SiO2 / Al2O3 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 8 or more and 24 or less, more preferably 10 or more and 22 or less, and even more preferably 13 or more and 20 or less. The SiO2 / Al2O3 ratio in the raw material zeolite obtained by crystallizing the raw material composition tends to be lower than that in the raw material composition. Therefore, by making the SiO2 / Al2O3 ratio in the raw material composition less than 24, it is easy to obtain calcium-containing zeolite with the SiO2 / Al2O3 ratio described later, and it is easy to obtain zeolite with better SCR catalytic activity from the low temperature (e.g., 150°C) region to the high temperature (e.g., 600°C) region.

[0087] In the crystallization step (1), the molar ratio of alkali metal to silicon dioxide in the raw material composition (hereinafter also referred to as "M / SiO2 ratio") is preferably 0.30 or more, more preferably 0.35 or more, and even more preferably 0.40 or more. Furthermore, in the crystallization step (1), the M / SiO2 ratio in the raw material composition is preferably 0.70 or less, more preferably 0.65 or less, and even more preferably 0.60 or less. The upper and lower limits of the M / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 0.30 or more and 0.70 or less, more preferably 0.35 or more and 0.65 or less, and even more preferably 0.40 or more and 0.60 or less. By keeping the M / SiO2 ratio in the raw material composition within the above range, the XRD pattern of the raw material zeolite obtained by crystallization more easily includes the peaks in Table 3, making it easier to manufacture the zeolite of this embodiment.

[0088] In the crystallization step (1), the molar ratio of water to silicon dioxide in the raw material composition (hereinafter also referred to as "H2O / SiO2 ratio") is preferably 3 or more, more preferably 5 or more, and even more preferably 8 or more. Furthermore, in the crystallization step (1), the H2O / SiO2 ratio in the raw material composition is preferably 50 or less, more preferably 30 or less, and even more preferably 25 or less. The upper and lower limits of the H2O / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 3 or more and 50 or less, more preferably 5 or more and 30 or less, and even more preferably 8 or more and 25 or less. By keeping the H2O / SiO2 ratio in the raw material composition within the above range, the XRD pattern of the raw material zeolite obtained by crystallization more easily includes the peaks in Table 3, making it easier to manufacture the zeolite of this embodiment.

[0089] In the crystallization step (1), the molar ratio of hydroxide ions to silicon dioxide in the raw material composition (hereinafter also referred to as "OH / SiO2 ratio") is preferably 0.30 or more, more preferably 0.35 or more, and even more preferably 0.40 or more. Furthermore, in the crystallization step (1), the OH / SiO2 ratio in the raw material composition is preferably 0.70 or less, more preferably 0.65 or less, and even more preferably 0.60 or less. The upper and lower limits of the OH / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 0.30 or more and 0.70 or less, more preferably 0.35 or more and 0.65 or less, and even more preferably 0.40 or more and 0.60 or less. By keeping the OH / SiO2 ratio in the raw material composition within the above range, the XRD pattern of the raw material zeolite obtained by crystallization more easily includes the peaks in Table 3, making it easier to manufacture the zeolite of this embodiment.

[0090] The raw material composition in the crystallization process (1) is preferably any combination of the following molar compositions. In the following molar compositions, M represents the molar amount of an alkali metal. When the raw material composition contains only one alkali metal, it represents the molar amount of that alkali metal. When the raw material composition contains two or more alkali metals, it represents the total molar amount of those two or more alkali metals. For example, when the raw material composition contains sodium and potassium as alkali metals, the M / SiO2 ratio is (Na+K) / SiO2 ratio.

[0091] The SiO2 / Al2O3 ratio is 8 or higher, 10 or higher, or 13 or higher, and 24 or below, 22 or below, or 20 or below M / SiO2 ratio = 0.30 or higher, or 0.35 or higher, or 0.40 or higher, and Below 0.70, below 0.65, or below 0.60 H2O / SiO2 ratio = 3 or higher, 5 or higher, or 8 or higher, and Under 50, Under 30, or Under 25 OH / SiO2 ratio = 0.30 or higher, 0.35 or higher, or 0.40 or higher, and Below 0.70, below 0.65, or below 0.60 In the crystallization process (1), the raw material composition is crystallized in the presence of seed crystals. As a method for crystallizing the raw material composition in the presence of seed crystals, for example, a method of adding seed crystals to the raw material composition and crystallizing the raw material composition with added seed crystals can be cited.

[0092] In order to make it easier for the raw material zeolite obtained by crystallization to include the peaks in Table 3 in the XRD pattern, the seed crystal is preferably selected from one or more of CHA type zeolite, AFX type zeolite, GME type zeolite, LEV type zeolite and OFF type zeolite, and more preferably CHA type zeolite.

[0093] The ratio of the total mass of silicon (Si) and aluminum (Al) in the seed crystal, converted to SiO2 and Al2O3 respectively, to the total mass of silicon (Si) and aluminum (Al) in the raw material composition (excluding the seed crystal), converted to SiO2 and Al2O3 respectively (hereinafter also referred to as "seed content") is preferably more than 0% by mass, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more. Furthermore, the seed content is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. The upper and lower limits of the seed content can be any combination of the above-mentioned upper and lower limits, preferably more than 0% by mass and less than 10% by mass, more preferably 0.5% by mass and less than 5% by mass, and even more preferably 1% by mass and less than 3% by mass. By keeping the seed content within the above range, the XRD pattern of the raw material zeolite obtained by crystallization more likely to include the peaks shown in Table 3, making it easier to manufacture the zeolite of this embodiment.

[0094] The crystallization method for the raw material composition can be any method for crystallizing the raw material composition, such as hydrothermal synthesis by hydrothermal treatment of the raw material composition. Examples of hydrothermal treatment conditions include the following.

[0095] Crystallization temperature: above 120℃, above 130℃, or above 135℃, and Below 200℃, below 180℃, or below 160℃ Crystallization time: more than 1 hour, more than 5 hours, or more than 10 hours, and Less than 7 days, less than 5 days, less than 3 days, or less than 2 days Crystallization state: at least one of the following: stirring state and standing state, or stirring state. Crystallization pressure: self-generated pressure The raw material zeolite obtained in the crystallization process (1) described above is used in the calcium-containing process described later. It should be noted that the raw material zeolite obtained in the crystallization process (1) can be used directly in the calcium-containing process (1), or it can be further treated by one or more of the following methods: washing, drying, and ion exchange before being used in the calcium-containing process (1). When the raw material zeolite obtained in the crystallization process (1) is subjected to ion exchange treatment, this ion exchange treatment preferably sets the cation type of the raw material zeolite to proton (H+). + ) type or ammonium (NH4) + Ion exchange treatment of type 1. When the cationic form of the raw material zeolite is proton (H2O) + ) type or ammonium (NH4) + When the cation is of the cation type, it is easier to contain calcium in the calcium-containing process described later compared to other cationic types.

[0096] It should be noted that the cleaning, drying and ion exchange treatments have already been described (as they are the same as those that can be performed on calcium-containing zeolites containing copper), so detailed descriptions are omitted.

[0097] In the calcium-containing process (1), the raw material zeolite obtained in the crystallization process (1) is made to contain calcium. The method for making the raw material zeolite obtained in the crystallization process (1) contain calcium in the calcium-containing process (1) is not particularly limited; for example, a treatment that brings a calcium source into contact with the raw material zeolite (hereinafter also referred to as "calcium contact treatment") can be used. It should be noted that methods for containing calcium through calcium contact treatment include ion exchange, impregnation loading, evaporation drying, precipitation loading, and physical mixing, etc., with ion exchange or impregnation loading being preferred.

[0098] The calcium source in contact with the raw material zeolite is a calcium-containing substance, such as calcium salts or compounds. To make it easier for the raw material zeolite to contain calcium, the calcium source in contact with the raw material zeolite is preferably selected from one or more of calcium chloride, calcium iodide, calcium bromide, calcium hydroxide, calcium oxide, and calcium nitrate, more preferably selected from one or more of calcium chloride, calcium bromide, and calcium nitrate, and even more preferably calcium nitrate.

[0099] To facilitate the incorporation of calcium into the raw material zeolite, the contact between the calcium source and the raw material zeolite is preferably carried out by contacting the raw material zeolite with a solution containing the calcium source (hereinafter also referred to as "calcium solution"). Examples of solvents included in the calcium solution include at least one of water and alcohol, with water being preferred.

[0100] The calcium concentration in the calcium solution is not particularly limited, as long as the Ca / Al ratio and other factors are appropriately adjusted to enable the manufacture of the zeolite of this embodiment. From the viewpoint of making it easier to manufacture the zeolite of this embodiment, the calcium concentration in the calcium solution is preferably such that the Ca / Al ratio in the calcium-containing zeolite obtained by calcium contact treatment is 0.01 or more and 0.3 or less.

[0101] The contact conditions between the calcium source and the raw material zeolite are not particularly limited, as long as the Ca / Al ratio and other factors are appropriately adjusted to enable the manufacture of the zeolite of this embodiment. From the viewpoint of facilitating the manufacture of the zeolite of this embodiment, the contact conditions between the calcium source and the raw material zeolite are preferably performed when the Ca / Al ratio of the calcium-containing zeolite obtained by calcium contact treatment is 0.01 or higher and 0.3 or lower. For example, the contact time between the raw material zeolite and the calcium source can be 10 minutes or more and 24 hours or less. In addition, the contact temperature between the raw material zeolite and the calcium source can be 20°C or higher and 110°C or lower. In addition, the contact pressure between the raw material zeolite and the calcium source can be 0.0 MPa or higher and 1.0 MPa or lower (gauge pressure).

[0102] In the calcium-containing process (1), calcium-containing zeolite (calcium-containing zeolite obtained by method (1)) can be manufactured by containing calcium in the raw material zeolite. The calcium-containing zeolite obtained by method (1) can be used directly in the copper-containing process described above, or it can be used in the copper-containing process described above after performing one or more treatments selected from cleaning treatment, drying treatment, calcination treatment and ion exchange treatment. When the calcium-containing zeolite obtained by method (1) is subjected to ion exchange treatment, the ion exchange treatment is preferably performed to set the cation type of the calcium-containing zeolite to proton (H) + ) type or ammonium (NH4) + Ion exchange treatment of type ) . When the cation of calcium-containing zeolite is proton (H) + ) type or ammonium (NH4) + When it is of the cation type, it is more likely to contain copper in copper-containing processes compared to other cation types.

[0103] It should be noted that the cleaning, drying, firing, and ion exchange treatments have already been described (as they are the same as those that can be performed on calcium-containing zeolites containing copper), so detailed descriptions are omitted.

[0104] Next, the method (2) for manufacturing calcium-containing zeolite will be described. Method (2) is a method for synthesizing calcium-containing zeolite from a raw material composition. Compared with method (1), method (2) can suppress the generation of by-products and can also produce calcium-containing zeolite with a higher yield.

[0105] Method (2) includes a crystallization step (hereinafter also referred to as "crystallization step (2)") in which a raw material composition comprising at least an alumina source, a silicon dioxide source, an alkali source, a calcium source and water is crystallized in the presence of a seed crystal. Crystallization step (2) is the same as crystallization step (1) except for the raw material composition to be crystallized, so detailed descriptions are omitted except for the raw material composition to be crystallized.

[0106] In the crystallization process (2), the alumina source, silicon dioxide source, alkali source and water contained in the raw material composition can be the alumina source, silicon dioxide source, alkali source and water contained in the raw material composition of the crystallization process (1), respectively.

[0107] In the crystallization process (2), the calcium source contained in the raw material composition may be the same as the calcium source used in the calcium-containing process (1) (calcium contact treatment).

[0108] In the crystallization process (2), in order to facilitate the formation of a symbiotic crystal structure containing CHA and GME structures in the calcium-containing zeolite obtained by crystallization, the raw material composition preferably does not contain organic structure directing agents. In addition, in the crystallization process (2), in order to facilitate the application of manufacturing equipment made of common materials, the raw material composition preferably does not contain fluorine (F) and phosphorus (P).

[0109] In the crystallization step (2), the SiO2 / Al2O3 ratio in the raw material composition is preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. Furthermore, in the crystallization step (2), the SiO2 / Al2O3 ratio in the raw material composition is preferably 8 or more, more preferably 10 or more, and even more preferably 13 or more. The upper and lower limits of the SiO2 / Al2O3 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 8 or more and 24 or less, more preferably 10 or more and 22 or less, and even more preferably 13 or more and 20 or less. The SiO2 / Al2O3 ratio in the zeolite obtained by crystallizing the raw material composition tends to be lower than that in the raw material composition. Therefore, by making the SiO2 / Al2O3 ratio in the raw material composition less than 24, it is easy to obtain calcium-containing zeolite with the SiO2 / Al2O3 ratio described later, and it is easy to obtain zeolite with better SCR catalytic activity from the low temperature (e.g., 150°C) region to the high temperature (e.g., 600°C) region.

[0110] In the crystallization step (2), the M / SiO2 ratio in the raw material composition is preferably 0.30 or more, more preferably 0.35 or more, and even more preferably 0.40 or more. Furthermore, in the crystallization step (2), the M / SiO2 ratio in the raw material composition is preferably 0.70 or less, more preferably 0.65 or less, and even more preferably 0.60 or less. The upper and lower limits of the M / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 0.30 or more and 0.70 or less, more preferably 0.35 or more and 0.65 or less, and even more preferably 0.40 or more and 0.60 or less. By keeping the M / SiO2 ratio in the raw material composition within the above range, the peaks in Table 3 are more likely to be included in the XRD pattern of the calcium-containing zeolite obtained by crystallization, making it easier to manufacture the zeolite of this embodiment.

[0111] In the crystallization step (2), the H2O / SiO2 ratio in the raw material composition is preferably 3 or more, more preferably 5 or more, and even more preferably 8 or more. Furthermore, in the crystallization step (2), the H2O / SiO2 ratio in the raw material composition is preferably 50 or less, more preferably 30 or less, and even more preferably 25 or less. The upper and lower limits of the H2O / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 3 or more and 50 or less, more preferably 5 or more and 30 or less, and even more preferably 8 or more and 25 or less. By keeping the H2O / SiO2 ratio in the raw material composition within the above range, the peaks in Table 3 are more likely to be included in the XRD pattern of the calcium-containing zeolite obtained by crystallization, making it easier to manufacture the zeolite of this embodiment.

[0112] In the crystallization step (2), the molar ratio of calcium to silicon dioxide in the raw material composition (hereinafter also referred to as "Ca / SiO2 ratio") is preferably 0.001 or more, more preferably 0.003 or more. Furthermore, in the crystallization step (2), the Ca / SiO2 ratio in the raw material composition is preferably 0.030 or less, more preferably 0.020 or less. The upper and lower limits of the Ca / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 0.001 or more and 0.030 or less, more preferably 0.001 or more and 0.020 or less, and even more preferably 0.003 or more and 0.020 or less. By keeping the Ca / SiO2 ratio in the raw material composition within the above range, the peaks in Table 3 are more likely to be included in the XRD pattern of the calcium-containing zeolite obtained by crystallization, making it easier to manufacture the zeolite of this embodiment.

[0113] In the crystallization step (2), the OH / SiO2 ratio in the raw material composition is preferably 0.30 or more, more preferably 0.35 or more, and even more preferably 0.40 or more. Furthermore, in the crystallization step (2), the OH / SiO2 ratio in the raw material composition is preferably 0.70 or less, more preferably 0.65 or less, and even more preferably 0.60 or less. The upper and lower limits of the OH / SiO2 ratio in the raw material composition can be any combination of the above-mentioned upper and lower limits, preferably 0.30 or more and 0.70 or less, more preferably 0.35 or more and 0.65 or less, and even more preferably 0.40 or more and 0.60 or less. By keeping the OH / SiO2 ratio in the raw material composition within the above range, the peaks in Table 3 are more likely to be included in the XRD pattern of the calcium-containing zeolite obtained by crystallization, making it easier to manufacture the zeolite of this embodiment.

[0114] The raw material composition in the crystallization process (2) is preferably any combination of the following molar compositions.

[0115] The SiO2 / Al2O3 ratio is 8 or higher, 10 or higher, or 13 or higher, and 24 or below, 22 or below, or 20 or below M / SiO2 ratio = 0.30 or higher, or 0.35 or higher, or 0.40 or higher, and Below 0.70, below 0.65, or below 0.60 H2O / SiO2 ratio = 3 or higher, 5 or higher, or 8 or higher, and Under 50, Under 30, or Under 25 The Ca / SiO2 ratio is 0.001 or higher, or 0.003 or higher, and Below 0.030 or below 0.020 OH / SiO2 ratio = 0.30 or higher, 0.35 or higher, or 0.40 or higher, and Below 0.70, below 0.65, or below 0.60 In the crystallization step (2), calcium-containing zeolite (calcium-containing zeolite obtained by method (2)) can be manufactured by crystallizing the above-mentioned raw material composition in the presence of seed crystals. The calcium-containing zeolite obtained by method (2) can be used directly in the above-mentioned copper-containing process, or it can be used in the above-mentioned copper-containing process after performing one or more treatments selected from cleaning treatment, drying treatment, calcination treatment and ion exchange treatment. When performing ion exchange treatment on the calcium-containing zeolite obtained in method (2), the ion exchange treatment is preferably performed by setting the cation type of the zeolite to proton (H) + ) type or ammonium (NH4) + Ion exchange treatment of type ) . When the cation of calcium-containing zeolite is proton (H) + ) type or ammonium (NH4) + When it is of the cation type, it is more likely to contain copper in copper-containing processes compared to other cation types.

[0116] It should be noted that since the cleaning, drying, firing, and ion exchange treatments have already been described (and are the same as those that can be performed on calcium-containing zeolites containing copper), detailed descriptions are omitted.

[0117] The calcium-containing zeolite obtained by methods (1) and (2) can be used as a calcium-containing zeolite containing copper in the copper-containing process (copper contact treatment) described above. In the copper-containing process (copper contact treatment), by containing copper in the calcium-containing zeolite, the zeolite of this embodiment can be manufactured.

[0118] From the viewpoint that it is easier to manufacture the zeolite of this embodiment, the calcium-containing zeolite obtained by method (1) and method (2) is preferably a calcium-containing zeolite having a symbiotic crystal structure including CHA structure and GME structure, and more preferably a calcium-containing zeolite having a symbiotic crystal structure including CHA structure and GME structure and having at least the peaks in Table 3 above in its powder X-ray diffraction pattern.

[0119] In order to easily obtain zeolites with superior SCR catalytic activity from the low temperature (e.g., 150°C) region to the high temperature (e.g., 600°C) region, the SiO2 / Al2O3 ratio in the calcium-containing zeolite obtained by preparation method (1) and preparation method (2) is preferably 5.0 or more and 15 or less, more preferably 5.5 or more and 10 or less, and even more preferably 6.0 or more and 9.5 or less.

[0120] Furthermore, from the viewpoint that it is easier to manufacture the zeolite of this embodiment, the Ca / Al ratio in the calcium-containing zeolite obtained by method (1) and method (2) is preferably 0.01 or more and 0.3 or less, more preferably 0.015 or more and 0.25 or less, and even more preferably 0.02 or more and 0.15 or less.

[0121] The zeolite of this embodiment described above exhibits excellent hydrothermal durability, displaying excellent SCR catalytic activity even after hydrothermal durability treatment. The reason for the excellent hydrothermal durability of the zeolite of this embodiment is not yet clear, but it is speculated that: by having copper and calcium coexist, the 0-valent copper reaches a specified ratio below, making it less prone to deactivation even after hydrothermal durability treatment. As a result, it displays excellent SCR catalytic activity even after hydrothermal durability treatment.

[0122] It should be noted that hydrothermal durability treatment involves exposing zeolite to a high-temperature atmosphere containing moisture. Specifically, this could involve exposing zeolite to an atmosphere containing 5% to 15% by volume of moisture at a temperature between 600°C and 700°C. The duration of the hydrothermal durability treatment is not particularly limited; for example, it could be 1 hour to 150 hours. In hydrothermal durability treatment, the atmosphere in which the zeolite is exposed can consist of any gas containing moisture; exhaust gas or air can also be used.

[0123] The SCR catalytic activity (SCR catalytic activity after hydrothermal durability treatment) of the zeolite of this embodiment is excellent from the low temperature (e.g., 150°C) region to the high temperature (e.g., 600°C) region. In particular, as shown in the examples described later, compared with zeolites with the same composition as the zeolite of this embodiment except that they do not contain calcium, and zeolites with the same composition as the zeolite of this embodiment except that their XPS area ratio is 34% or more, the SCR catalytic activity (SCR catalytic activity after hydrothermal durability treatment) of the zeolite of this embodiment is more excellent at temperatures below 200°C, and even more excellent at temperatures above 150°C and below 200°C.

[0124] Example The following describes this embodiment through examples. However, this embodiment is not limited thereto.

[0125] (Identification of crystal structure) XRD measurements of the samples were performed using a powder X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation). The measurement conditions are as follows.

[0126] Accelerating current and voltage: 40mA·40kV X-ray source: CuK αray( l =1.5405Å) Measurement mode: Continuous scanning Scanning conditions: 40° / minute Measurement range: 2 i =3° to 43° Longitudinal diverging slit: 10mm Diverging / Incident Slit: 1° Light-receiving slit: open Light-receiving Soler slit: 5° Detector: Semiconductor detector (D / teX Ultra) Filter: Ni filter The XRD patterns obtained were analyzed using the analysis software included with the device (Software name: Smart Lab Studio II, manufactured by Rigaku Co., Ltd.) under the following conditions.

[0127] Fitting conditions: Automatic, refine background Dispersed pseudo-Voigt function (peak shape) Background removal method: Fitting method K α 2. Removal method: K α 1 / K α 2 = 0.497 Smoothing methods: B-Spline-based smoothing Smoothing conditions: Quadratic differentiation method, σ cutoff value = 3, χ threshold = 1.5 (Composition Analysis) Compositional analysis of the samples was performed using a standard inductively coupled plasma optical emission spectrometry (ICP-OES) system (OPTIMA 7300DV, manufactured by PerkinElmer). The samples were dissolved in a mixture of hydrofluoric acid and nitric acid to prepare the assay solution. The resulting assay solution was used to analyze the sample composition (SiO2 / Al2O3 ratio, Ca / Al ratio, Cu / Al ratio).

[0128] (Chemical state analysis of copper) The chemical state of copper in the sample was analyzed using a standard X-ray photoelectron spectroscopy (XPS) system (PHI5000 VersaProbeII, manufactured by ULVAC-PHI). The measurement conditions are as follows.

[0129] X-ray source: Monochromatic Al-K α ray X-ray beam diameter: 100 μm f Energy resolution: Wide-scan spectrum 117.40 eV High-resolution spectrum 46.95 eV (Cu2p 3 / 2 ) Charge correction: Al2p main peak (74.4 eV) No sputtering treatment The peak area of ​​the XPS spectrum is calculated as follows: The measured XPS spectrum is divided by multiple imaginary lines spaced at 0.10 eV intervals. Each segmented XPS spectrum is assumed to be a trapezoid (a right trapezoid formed by two adjacent imaginary lines, a straight line connecting the intersection of the two imaginary lines and the XPS spectrum curve, and the horizontal axis). The area of ​​this trapezoid is calculated, and then the areas of each trapezoid are added together to calculate the peak area of ​​the XPS spectrum.

[0130] Example 1 A raw material composition having the following molar composition is obtained by mixing 50% by mass of sodium hydroxide aqueous solution, 50% by mass of calcium nitrate aqueous solution, amorphous aluminosilicate (SiO2 / Al2O3 ratio = 15), and pure water.

[0131] SiO2 / Al2O3 ratio = 15 Na / SiO2 ratio = 0.48 Ca / SiO2 ratio = 0.008 H2O / SiO2 ratio = 12 OH / SiO2 ratio = 0.48 Seed crystals (CHA type zeolite; SiO2 / Al2O3 ratio = 24) were mixed into the raw material composition at a seed crystal content of 1.0% by mass, and then filled into a sealed 80 mL container. After filling the mixture of seed crystals and raw material composition, the container was hydrothermally treated at 140 °C under autogenous pressure for 20 hours while being stirred at 55 rpm. The solid product obtained by hydrothermal treatment was subjected to solid-liquid separation and washed with deionized water. The washed solid product was then contacted with 100 mL of a 20% by mass ammonium chloride aqueous solution and dried overnight at 110 °C under atmospheric atmosphere, thereby recovering the crystals.

[0132] The crystalline substance is a calcium-containing zeolite with a SiO2 / Al2O3 ratio of 7.0 and a Ca / Al ratio of 0.02. Table 5 below shows the peaks with a relative intensity of over 10% relative to the interplanar spacing d = 4.99 in the XRD pattern of this crystalline substance. The XRD pattern confirms that the obtained crystalline substance is a calcium-containing zeolite (calcium-containing crystalline aluminosilicate) with a symbiotic crystal structure including CHA and GME structures.

[0133] [Table 5]

[0134] (Contains copper) Copper nitrate solution was added dropwise at a rate of 4% by mass relative to the copper content of the obtained calcium-containing zeolite, and the mixture was stirred in a mortar for 10 minutes. The zeolite was dried overnight at 110°C under atmospheric conditions, and then calcined at 550°C under atmospheric conditions for 1 hour to obtain the calcium- and copper-containing zeolite of this embodiment (hereinafter also referred to as "Ca-Cu zeolite").

[0135] The SiO2 / Al2O3 ratio of the Ca-Cu zeolite in this embodiment is 7.0, the Ca / Al ratio is 0.02, and the Cu / Al ratio is 0.18. Table 6 below shows the peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.95 among the peaks in the XRD pattern of the Ca-Cu zeolite of this embodiment. The XRD pattern confirms that the Ca-Cu zeolite of this embodiment is a Ca-Cu zeolite (a crystalline aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0136] [Table 6]

[0137] The Ca-Cu zeolite in this embodiment has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 31%.

[0138] Example 2 By varying the amount of raw materials added in Example 1, a raw material composition having the following molar composition was obtained. Crystals were obtained using the same method as in Example 1, except that the obtained raw material composition was not used.

[0139] SiO2 / Al2O3 ratio = 15 Na / SiO2 ratio = 0.48 Ca / SiO2 ratio = 0.012 H2O / SiO2 ratio = 12 OH / SiO2 ratio = 0.48 The crystal is a calcium-containing zeolite with a SiO2 / Al2O3 ratio of 7.7 and a Ca / Al ratio of 0.05. Furthermore, the XRD pattern of the crystal confirms that it is a calcium-containing zeolite (calcium-containing crystalline aluminosilicate) with a symbiotic crystal structure including CHA and GME structures.

[0140] The Ca-Cu zeolite of this embodiment was obtained by containing copper in the crystals obtained using the same method as in Example 1. The SiO2 / Al2O3 ratio of the Ca-Cu zeolite of this embodiment is 7.7, the Ca / Al ratio is 0.05, and the Cu / Al ratio is 0.19. The XRD peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.95 in the XRD pattern of the Ca-Cu zeolite of this embodiment are shown in Table 7 below. The XRD pattern confirms that the Ca-Cu zeolite of this embodiment is a Ca-Cu zeolite (a crystalline aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0141] [Table 7]

[0142] The Ca-Cu zeolite in this embodiment has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 28%.

[0143] Example 3 By varying the amount of raw materials added in Example 1, a raw material composition having the following molar composition was obtained. Crystals were obtained using the same method as in Example 1, except that the obtained raw material composition was not used.

[0144] SiO2 / Al2O3 ratio = 15 Na / SiO2 ratio = 0.50 Ca / SiO2 ratio = 0.012 H2O / SiO2=10 OH / SiO2 ratio = 0.50 The crystal is a calcium-containing zeolite with a SiO2 / Al2O3 ratio of 7.4 and a Ca / Al ratio of 0.05. Furthermore, the XRD pattern of the crystal confirms that it is a calcium-containing zeolite (calcium-containing crystalline aluminosilicate) with a symbiotic crystal structure including CHA and GME structures.

[0145] The Ca-Cu zeolite of this embodiment was obtained by containing copper in the crystals obtained using the same method as in Example 1. The SiO2 / Al2O3 ratio of the Ca-Cu zeolite of this embodiment is 7.4, the Ca / Al ratio is 0.05, and the Cu / Al ratio is 0.18. Table 8 below shows the peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.96 among the peaks contained in the XRD pattern of the Ca-Cu zeolite of this embodiment. The XRD pattern confirms that the Ca-Cu zeolite of this embodiment is a Ca-Cu zeolite (a crystalline aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0146] [Table 8]

[0147] The Ca-Cu zeolite in this embodiment has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 31%.

[0148] Example 4 By varying the amount of raw materials added in Example 1, a raw material composition having the following molar composition was obtained. Crystals were obtained using the same method as in Example 1, except that the obtained raw material composition was not used.

[0149] SiO2 / Al2O3=15 Na / SiO2 ratio = 0.48 Ca / SiO2 ratio = 0.017 H2O / SiO2=12 OH / SiO2 ratio = 0.48 The crystal is a calcium-containing zeolite with a SiO2 / Al2O3 ratio of 9.0 and a Ca / Al ratio of 0.10. Furthermore, the XRD pattern of the crystal confirms that it is a calcium-containing zeolite (calcium-containing crystalline aluminosilicate) with a symbiotic crystal structure including CHA and GME structures.

[0150] The Ca-Cu zeolite of this embodiment was obtained by containing copper in the crystals obtained using the same method as in Example 1. The SiO2 / Al2O3 ratio of the Ca-Cu zeolite of this embodiment is 9.0, the Ca / Al ratio is 0.10, and the Cu / Al ratio is 0.20. Table 9 below shows the peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.96 among the peaks contained in the XRD pattern of the Ca-Cu zeolite of this embodiment. The XRD pattern confirms that the Ca-Cu zeolite of this embodiment is a Ca-Cu zeolite (a crystalline aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0151] [Table 9]

[0152] The Ca-Cu zeolite in this embodiment has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 31%.

[0153] Example 5 In Example 1, without using a calcium source, the amount of raw materials added was varied to obtain a raw material composition having the following molar composition. Except for using the obtained raw material composition, crystals were obtained by the same method as in Example 1.

[0154] SiO2 / Al2O3 ratio = 17 Na / SiO2 ratio = 0.50 Ca / SiO2 ratio = 0 H2O / SiO2=12 OH / SiO2 ratio = 0.50 The crystalline substance is a zeolite with a SiO2 / Al2O3 ratio of 6.5 and a Ca / Al ratio of 0. Table 10 below shows the XRD peaks with a relative intensity of over 10% relative to the interplanar spacing d = 4.97. The XRD pattern confirms that the obtained crystalline substance is a zeolite (crystalline aluminosilicate) with a symbiotic crystal structure containing both CHA and GME structures.

[0155] [Table 10]

[0156] (Contains calcium and copper) A 50% by mass aqueous solution of calcium nitrate was added dropwise at a rate of 0.75% by mass relative to the calcium content of the zeolite, and the mixture was impregnated and mixed in a mortar for 10 minutes. After 10 minutes of impregnation and mixing, the zeolite was dried overnight at 110°C under atmospheric conditions. After drying, a 50% by mass aqueous solution of copper nitrate was added dropwise at a rate of 4% by mass relative to the copper content of the zeolite, and the mixture was impregnated and mixed in a mortar for 10 minutes. After 10 minutes of impregnation and mixing, the zeolite was dried overnight at 110°C under atmospheric conditions. The dried zeolite was then calcined at 550°C under atmospheric conditions for 1 hour, thereby obtaining the Ca-Cu zeolite of this embodiment.

[0157] The SiO2 / Al2O3 ratio of the Ca-Cu zeolite in this embodiment is 6.5, the Ca / Al ratio is 0.05, and the Cu / Al ratio is 0.18. Table 11 below shows the XRD peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.95 among the peaks in the XRD pattern of the Ca-Cu zeolite of this embodiment. The XRD pattern confirms that the Ca-Cu zeolite of this embodiment is a Ca-Cu zeolite (a crystalline aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0158] [Table 11]

[0159] The Ca-Cu zeolite in this embodiment has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 25%.

[0160] Comparative Example 1 In Example 1, without using a calcium source, the amount of raw materials added was varied to obtain a raw material composition having the following molar composition. Except for using the obtained raw material composition, crystals were obtained by the same method as in Example 1.

[0161] SiO2 / Al2O3=15 Na / SiO2 ratio = 0.50 Ca / SiO2 ratio = 0 H2O / SiO2=10 OH / SiO2 ratio = 0.50 The crystalline substance is a zeolite with a SiO2 / Al2O3 ratio of 7.3 and a Ca / Al ratio of 0. Table 12 below shows the XRD peaks with a relative intensity of over 10% relative to the interplanar spacing d = 4.99. The XRD pattern confirms that the obtained crystalline substance is a zeolite (crystalline aluminosilicate) with a symbiotic crystal structure containing both CHA and GME structures.

[0162] [Table 12]

[0163] The copper-containing zeolite of this comparative example was obtained by incorporating copper into the zeolite obtained in the same manner as in Example 1. The SiO2 / Al2O3 ratio of the copper-containing zeolite of this comparative example is 7.3, the Ca / Al ratio is 0, and the Cu / Al ratio is 0.19. The peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.96 among the peaks contained in the XRD pattern of the copper-containing zeolite of this comparative example are shown in Table 13 below. The XRD pattern confirms that the copper-containing zeolite of this comparative example is a copper-containing zeolite (copper-containing crystalline aluminosilicate) with a symbiotic crystal structure including CHA and GME structures.

[0164] [Table 13]

[0165] The copper-containing zeolite in this comparative example does not contain calcium, therefore the XPS area ratio, which serves as an indicator for zeolites containing both calcium and copper, could not be determined.

[0166] Comparative Example 2 The crystals were obtained using the same method as in Example 5. These crystals are zeolites with a SiO2 / Al2O3 ratio of 6.5 and a Ca / Al ratio of 0. The peaks in the XRD pattern of these crystals, with a relative intensity of 10% or more relative to the interplanar spacing d = 4.96, are shown in Table 10 above. The XRD pattern confirms that the obtained crystals are zeolites (crystalline aluminosilicates) with a symbiotic crystal structure containing both CHA and GME structures.

[0167] (Contains copper and calcium) A 50% by mass aqueous solution of copper nitrate was added dropwise at a rate of 4% by mass relative to the copper content of the zeolite, and the mixture was impregnated and mixed in a mortar for 10 minutes. After impregnation and mixing for 10 minutes, the zeolite was dried overnight at 110°C under atmospheric atmosphere. After drying, a specified amount of a 50% by mass aqueous solution of calcium nitrate was added dropwise at a rate of 0.75% by mass relative to the calcium content of the zeolite, and the mixture was impregnated and mixed in a mortar for 10 minutes. After impregnation and mixing for 10 minutes, the zeolite was dried overnight at 110°C under atmospheric atmosphere. The dried zeolite was then calcined at 550°C under atmospheric atmosphere for 1 hour, thereby obtaining the Ca-Cu zeolite of this comparative example.

[0168] The SiO2 / Al2O3 ratio of this comparative example Ca-Cu zeolite is 6.5, the Ca / Al ratio is 0.05, and the Cu / Al ratio is 0.18. Table 14 below shows the peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.96 among the peaks contained in the XRD pattern of this comparative example Ca-Cu zeolite. The XRD pattern confirms that this comparative example Ca-Cu zeolite is a Ca-Cu zeolite (aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0169] [Table 14]

[0170] The Ca-Cu zeolite of this comparative example has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 34%.

[0171] Comparative Example 3 Crystals were obtained using the same method as in Example 2. A 50% by mass aqueous solution of copper nitrate was added dropwise at a copper content of 7% by mass relative to the obtained crystals, and the mixture was impregnated and mixed in a mortar for 10 minutes. After 10 minutes of impregnation and mixing, the zeolite was dried overnight at 110°C under atmospheric conditions. The dried zeolite was then calcined at 550°C under atmospheric conditions for 1 hour, thereby obtaining the Ca-Cu zeolite of this comparative example.

[0172] The SiO2 / Al2O3 ratio of this comparative example Ca-Cu zeolite is 7.7, the Ca / Al ratio is 0.05, and the Cu / Al ratio is 0.34. Table 15 below shows the XRD peaks with a relative intensity of 10% or more relative to the interplanar spacing d = 4.95 among the peaks contained in the XRD pattern of the Ca-Cu zeolite of this example. The XRD pattern confirms that the Ca-Cu zeolite of this comparative example is a Ca-Cu zeolite (a crystalline aluminosilicate containing calcium and copper) with a symbiotic crystal structure including CHA and GME structures.

[0173] [Table 15]

[0174] The Ca-Cu zeolite of this comparative example has a binding energy peak position (eV) in the XPS spectrum ranging from 930.0 eV to 940.0 eV, with an XPS area ratio of 45%.

[0175] (Hydrothermal durability treatment) The zeolites of each embodiment and each comparative example were subjected to hydrothermal durability treatment. The hydrothermal durability treatment was carried out by the following method.

[0176] The zeolites from each embodiment and comparative example were shaped and pulverized to produce aggregated particles with a coagulation diameter of 12–20 mesh. 3 mL of the obtained aggregated particles were filled into a flow-through reactor at atmospheric pressure, and air containing 10% by volume of water was circulated. Hydrothermal durability treatment was then performed under the following conditions.

[0177] Airflow rate: 300 mL / min Processing temperature: 650℃ Processing time: 100 hours (Method for determining nitrogen oxide reduction rate (%)) For the zeolites of each embodiment and comparative example that underwent hydrothermal durability treatment, the nitrogen oxide reduction rate (%) was determined. The nitrogen oxide reduction rate was determined by the following method.

[0178] The zeolites from each of the embodiments and comparative examples that underwent hydrothermal durability treatment were shaped and crushed to produce aggregated particles with a coagulation diameter of 12–20 mesh. 1.5 mL of the aggregated particles were filled into a flow-through fixed-bed reactor at atmospheric pressure and maintained at the following measurement temperature, allowing the flow of nitrogen oxide-containing gas. The nitrogen oxide concentrations at the inlet and outlet of the flow-through fixed-bed reactor were measured, and the nitrogen oxide reduction rate was determined.

[0179] The flow conditions for the nitrogen oxide-containing gas are as follows. It should be noted that the space velocities described below are the flow rates of the nitrogen oxide-containing gas per unit volume of the zeolite-formed catalyst.

[0180] Composition of nitrogen oxide-containing gases: NO 200 ppm (volume) NH3 200 ppm (by volume) O2 10% Volume (Capacity) H2O 3 Volume (capacity) % N2 balance Flow rate of nitrogen oxide-containing gas: 1.5 L / min Space velocity: 60000hr -1 Measurement temperature: 600℃ or 150℃ Gauge pressure: 0.01 MPa The reduction rate of nitrogen oxides is calculated by the following formula (1).

[0181] Nitrogen oxide reduction rate (%) = {([NOx]in-[NOx]out) / [NOx]in}×100···(1) In the above formula (1), [NOx]in is the nitrogen oxide concentration (ppm) of the nitrogen oxide-containing gas at the inlet of the atmospheric pressure fixed bed flow-through reaction tube, and [NOx]out is the nitrogen oxide concentration (ppm) of the nitrogen oxide-containing gas at the outlet of the atmospheric pressure fixed bed flow-through reaction tube.

[0182] For the zeolites of each embodiment and comparative example that underwent hydrothermal durability treatment (hereinafter also referred to as "100h durability treatment samples"), the nitrogen oxide reduction rate at 150°C is shown in Table 16 below.

[0183] [Table 16]

[0184] The results above show that the Ca-Cu zeolite of each embodiment has a higher nitrogen oxide reduction rate at 150°C after hydrothermal durability treatment compared with the zeolite of any comparative example.

[0185] The nitrogen oxide reduction rate of the 100h durability-treated samples at 600℃ is shown in Table 17 below.

[0186] [Table 17]

[0187] Based on the above results, the Ca-Cu zeolites of Examples 1 to 3 exhibited higher nitrogen oxide reduction rates at 600°C after hydrothermal durability treatment compared to any of the comparative examples. This indicates that the Ca-Cu zeolites of Examples 1 to 3, even after hydrothermal durability treatment, not only showed high nitrogen reduction rates at 150°C but also high nitrogen oxide reduction rates at 600°C, demonstrating excellent SCR catalytic activity over a wide temperature range.

[0188] As can be understood from the above results, the Ca-Cu zeolites of Examples 1 to 5 exhibit excellent hydrothermal durability and show superior SCR catalytic activity even after hydrothermal durability treatment, compared with the zeolites of Comparative Examples 1 to 3.

[0189] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2024-49001, filed on March 26, 2024, are incorporated herein by reference and are included as a disclosure of this disclosure.

Claims

1. A zeolite, characterized in that, It has a symbiotic crystal structure containing CHA and GME structures. The powder X-ray diffraction pattern should contain at least the peaks listed in the table below. Contains calcium and copper. In the XPS spectrum of the zeolite, the ratio of the spectral area in the range of 930.0 eV and below to the spectral area in the range of 930.0 eV and below to less than 34% is 。 2. The zeolite according to claim 1, wherein, In the powder X-ray diffraction pattern of the zeolite, the interplanar spacing d = 4.29 ± 0.08 The half-width of the peak relative to the interplanar spacing d = 4.97 ± 0.08 The ratio of the half-width of the peak is greater than 2.0 and less than 7.

0.

3. The zeolite according to claim 1 or 2, wherein, The molar ratio of calcium to aluminum is less than 0.

3.

4. The zeolite according to any one of claims 1 to 3, wherein, The molar ratio of calcium to aluminum is greater than 0.01 and less than 0.

3.

5. The zeolite according to any one of claims 1 to 4, wherein, The molar ratio of copper to aluminum is greater than 0.05 and less than 0.

4.

6. The zeolite according to any one of claims 1 to 5, wherein, The molar ratio of silicon dioxide to aluminum oxide is greater than 5.0 and less than 15.

7. The zeolite according to any one of claims 1 to 6, wherein, In the XPS spectrum of the zeolite, the ratio of the spectral area of ​​the range above 930.0 eV and below 933.0 eV to the spectral area of ​​the range above 930.0 eV and below 940.0 eV is 10% or more and less than 34%.

8. The method for manufacturing zeolite according to any one of claims 1 to 7, characterized in that, include: The copper-containing process involves making calcium-containing zeolite contain copper.

9. The method for manufacturing zeolite according to claim 8, wherein, The manufacturing method further includes a crystallization step, wherein a composition containing an alumina source, a silicon dioxide source, an alkali source, a calcium source and water is crystallized in the presence of a seed crystal to obtain the calcium-containing zeolite.

10. The method for manufacturing zeolite according to claim 8, wherein, The manufacturing method further includes: The crystallization process involves crystallizing a composition containing an alumina source, a silicon dioxide source, an alkali source, and water in the presence of seed crystals to obtain raw material zeolite; and The calcium-containing process involves introducing calcium into the raw material zeolite to obtain the calcium-containing zeolite.

11. A selective reduction catalyst for nitrogen oxides, characterized in that, The zeolite comprising any one of claims 1 to 7.

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