JP7113821B2 - Method for producing CHA-type aluminosilicate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a CHA-type aluminosilicate, a method for producing the same, an exhaust gas purification catalyst, an exhaust gas purification apparatus, and an exhaust gas purification method using the same.

Synthetic zeolite has a crystal structure with regular and constant-sized pores, and is used as a desiccant, a dehydrating agent, and an adsorbent or separator for various inorganic or organic molecules using differences in polarity and molecular diameter. , ion exchangers, petroleum refining catalysts, petrochemical catalysts, and solid acid catalysts.

The skeletal structures of various zeolites are compiled into a database by the International Zeolite Association (hereinafter sometimes abbreviated as "IZA"), and at present, there are over 200 types of zeolite skeletal structures. However, there are only about 10 kinds of zeolites that are industrially used.

In recent years, attention has been focused on chabazite-type zeolites. The chabazite-type zeolite is an aluminosilicate having a crystal structure equivalent to that of a natural product, Chabazite, and has a three-dimensional pore structure with a pore size of 0.38 nm×0.38 nm. In IZA, chabazite is named and classified under the structure code CHA as a natural zeolite whose crystal structure has been identified in detail (Non-Patent Document 1).

As such a CHA-type zeolite, for example, Patent Document 1 discloses a so-called high-silica chabazite-type zeolite (that is, a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ molar ratio) of 5 or more) and a method for producing the same. ing. Further, Patent Documents 2 to 8 also disclose various high-silica CHA-type zeolites and methods for producing the same. These high-silica CHA-type zeolites are made from Y-type zeolite, amorphous silica, aluminosilicate gel, colloidal silica, etc., and N,N,N-trialkyl-adamantammonium cations and N,N,N-trialkyl - are produced by hydrothermal reactions using organic structure-directing agents such as benzylammonium cations;

Further, for example, Patent Documents 9 and 10 disclose nitrogen oxides (hereinafter sometimes referred to as "NOx") contained in a gas flow using a catalyst in which high silica CHA-type zeolite contains metals or metal ions. is disclosed. Further, in Patent Document 11, a CHA-type zeolite having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ molar ratio) of greater than about 15 and containing a predetermined amount of copper is used to selectively convert an exhaust gas stream containing NOx. A method for the catalytic reduction of is disclosed. These use CHA-type zeolite as a catalyst carrier, and metal is supported on the surface of the catalyst carrier, and are expected to be used as catalysts for selective reduction of NOx in exhaust gas from automobiles and the like.

On the other hand, in Patent Document 12, CHA-type zeolite having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ molar ratio) of 15 to 50 and an average particle size of 1.5 μm or more is used as a heat-resistant catalyst carrier. It is disclosed that it is excellent in

Further, Patent Document 13 discloses a CHA-type zeolite having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ molar ratio) of less than about 15 disposed on a substrate, and an alkali content of less than about 3% by weight. A catalyst product for NOx mitigation is disclosed comprising:

U.S. Pat. No. 4,544,538 U.S. Patent Application Publication No. 2003/0176751 U.S. Patent Application Publication No. 2007/0100185 U.S. Patent Application Publication No. 2008/0075656 U.S. Patent Application Publication No. 2008/0159950 WO2010/074040 JP 2010-163349 A JP 2011-102209 A U.S. Pat. No. 6,709,644 Japanese Patent Publication No. 2008-521744 Japanese Patent Publication No. 2010-519038 JP 2010-168269 A U.S. Patent Application Publication No. 2011/0020204

ATLAS OF ZEOLITE FRAMEWORK TYPES, Fifth Revised Edition, p.102(2001)

Thus, CHA-type zeolite is expected to be used in various applications, and various research and development are being conducted. However, for industrial use in applications such as adsorbents, separating agents, ion exchangers, catalysts, catalyst carriers, etc., in addition to excellent basic performance such as solid acidity and ion exchange capacity, Alternatively, it is required to be able to maintain high adsorption performance, catalytic performance, etc. even after exposure to high temperatures.

The present invention has been made in view of the above problems, and its purpose is to maintain relatively high adsorption performance, catalyst performance, etc. even in a high temperature environment or after high temperature exposure, and to have excellent thermal durability. An object of the present invention is to provide a CHA-type aluminosilicate and a method for producing the same at low cost and with good reproducibility. Another object of the present invention is to provide an exhaust gas purifying catalyst having excellent exhaust gas purifying performance, and an exhaust gas purifying apparatus and exhaust gas purifying method using the same.

It is to be noted that the present invention is not limited to the purpose described here, and that it is a function and effect derived from each configuration shown in the mode for carrying out the invention described later, and a function and effect that cannot be obtained by the conventional technology can be achieved. It can be positioned as another purpose.

As a result of intensive studies to solve the above problems, the present inventors have found that in hydrothermal synthesis, a Si element source and a Si—Al element source containing at least an aluminosilicate having a relatively low silica-alumina ratio are used in combination. By doing so, it was found that a CHA-type aluminosilicate having excellent thermal durability can be obtained, leading to the completion of the present invention. That is, the present invention provides various specific aspects shown below.

<1> A Si—Al element source containing at least an aluminosilicate having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 2 or more and less than 12; ), preparing a mixture containing an alkali metal source, an organic structure-directing agent and water, and hydrothermally treating the mixture.

<2> The method for producing a CHA-type aluminosilicate according to <1>, wherein the aluminosilicate is a solid powdery aluminosilicate at normal temperature and normal pressure.
<3> The method for producing a CHA-type aluminosilicate according to <1> or <2>, wherein the aluminosilicate substantially does not contain Si-3Al and Si-4Al.
<4> Any one of <1> to <3>, wherein the Si element source is at least one selected from the group consisting of precipitated silica, colloidal silica, fumed silica, silica gel, sodium silicate, and alkoxysilane. A method for producing the CHA-type aluminosilicate according to item 1.
<5> The method for producing a CHA-type aluminosilicate according to any one of <1> to <4>, wherein a CHA-type aluminosilicate having a silica-alumina ratio of 14 or more and 40 or less is synthesized.

<6> The method for producing a CHA-type aluminosilicate according to any one of <1> to <5>, wherein in the step of hydrothermally treating, heat treatment is performed at 100 to 200° C. for 1 to 480 hours.
<7> The CHA according to any one of <1> to <6>, further comprising a firing step of heat-treating the obtained CHA-type aluminosilicate at 300 to 1000° C. after the hydrothermal reaction step. A method for producing a type aluminosilicate.
<8> The method for producing a CHA-type aluminosilicate according to <7>, further comprising the step of ion-exchanging the obtained CHA-type aluminosilicate into NH ₄ ⁺ type and/or H ⁺ type.
<9> The method for producing a CHA-type aluminosilicate according to any one of <1> to <8>, wherein the mixture further contains seed crystals of the CHA-type aluminosilicate.

<10> Synthesizing a CHA-type aluminosilicate having a cobalt divalent ion adsorption capacity to all Al atoms ratio (Co ²⁺ /Al) of 0.2 or more <1> to <9> A method for producing the described CHA-type aluminosilicate.
<11> Any one of <1> to <10>, wherein the organic structure-directing agent is at least one selected from the group consisting of primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. A method for producing the CHA-type aluminosilicate according to the item.
<12> The method for producing a CHA-type aluminosilicate according to any one of <1> to <11>, wherein the alkali metal source contains an alkali metal hydroxide.
<13> The method for producing a CHA-type aluminosilicate according to any one of <1> to <12>, wherein the mixture has a water-silica ratio (H ₂ O/SiO ₂ ) of 5 or more and less than 100.

<14> Obtained by the production method according to any one of <1> to <13>, having a silica-alumina ratio of 14 or more and 40 or less, and a ratio of the cobalt divalent ion adsorption capacity to the total Al atoms (Co ² A CHA-type aluminosilicate characterized in that ⁺ /Al) is 0.2 or more.

<15> A Si—Al element source containing at least an aluminosilicate having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 2 or more and less than 12, a Si element source (provided that the above Si—Al element source ), preparing a mixture containing an alkali metal source, an organic structure-directing agent and water, hydrothermally treating the mixture, converting the obtained CHA-type aluminosilicate into NH ₄ ⁺ type and/or H ⁺ A method for producing a transition metal-supported CHA-type aluminosilicate, comprising at least a step of ion-exchanging a mold and a step of supporting a transition metal on the obtained CHA-type aluminosilicate.

<16> A CHA-type aluminosilicate characterized by having a silica-alumina ratio of 14 or more and 40 or less and a ratio (Co ²⁺ /Al) of cobalt divalent ion adsorption capacity to all Al atoms of 0.2 or more. salt.
<17> An exhaust gas purifying catalyst comprising at least the CHA-type aluminosilicate according to <16> and a transition metal supported on the CHA-type aluminosilicate.
<18> An exhaust gas purifying device comprising at least a catalyst carrier and a catalyst layer, wherein the catalyst layer contains at least the exhaust gas purifying catalyst according to <17>.
<19> A method for purifying exhaust gas, comprising contacting exhaust gas containing at least one selected from the group consisting of HC, CO, and NOx with the exhaust gas purifying catalyst according to <17>.

According to the present invention, a CHA-type aluminosilicate that can maintain relatively high adsorption performance, catalytic performance, etc. even in a high-temperature environment or after high-temperature exposure, and has excellent thermal durability, and its low cost and reproducibility A manufacturing method or the like that can be manufactured well can be realized. By using this CHA-type aluminosilicate, it is possible to realize an exhaust gas purifying catalyst having excellent exhaust gas purifying performance, an exhaust gas purifying apparatus and an exhaust gas purifying method using the same.

4 is a graph showing measurement results of NOx purification rates of honeycomb catalysts of Example 1 and Comparative Example 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. The following embodiments are examples (representative examples) of embodiments of the present invention, and the present invention is not limited to these. In addition, the present invention can be arbitrarily changed and implemented without departing from the gist thereof. In this specification, when a numerical value or a physical property value is sandwiched before and after the "~", it is used to include the values before and after it. For example, the notation of a numerical range of "1 to 100" includes both the upper limit of "100" and the lower limit of "1". The same applies to the notation of other numerical ranges.

[Method for producing CHA-type aluminosilicate]
As described above, the method for producing a CHA-type aluminosilicate of the present embodiment is an aluminosilicate having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ , hereinafter sometimes referred to as “SAR”) of 2 or more and less than 12. a step of preparing a mixture comprising at least a salt-containing Si—Al element source, a Si element source (excluding those corresponding to the Si—Al element source), an alkali metal source, an organic structure directing agent, and water; It is characterized by having at least a step of hydrothermally treating the mixture.

<Mixture preparation process>
In this preparation step, a mixture containing a Si—Al element source, a Si element source, an alkali metal source, an organic structure directing agent (hereinafter sometimes abbreviated as “SDA”), and water is prepared. .

(Si—Al element source)
As the Si—Al element source used as a raw material, any known source can be used without particular limitation as long as it contains at least an aluminosilicate having a silica-alumina ratio of 2 or more and less than 12. The type is not particularly limited. Here, the aluminosilicate has a structure in which some of the silicon atoms in the silicate are replaced with aluminum atoms. The silica-alumina ratio is preferably 5 or more and less than 12, more preferably 7 or more and less than 11. In addition, in this specification, a silica-alumina ratio means the value calculated|required from a fluorescent X-ray analysis. Specifically, using Axios (Spectricis Inc.), about 5 g of the sample was subjected to pressure molding at 20 t for measurement, and the SAR was calculated from the results of the obtained mass% of Al ₂ O ₃ and SiO ₂ . did.

As such an aluminosilicate, an aluminosilicate represented by the following general formula (I) is preferably used.
_{xM2O.Al2O3.mSiO2.nH2O ( I ) _}
(In formula (I) above, M represents an alkali metal element, x is a number that satisfies 0≦x≦1.0, m is 2≦m<12, and n is a number that satisfies 5≦n≦15.)

In the general formula (I), the alkali metal element includes Li, Na, Ka, Rb, Cs, etc. Among them, Na and K are preferable, and Na is more preferable. In addition to Si and Al, the above-mentioned aluminosilicate may contain other elements such as Ga, Fe, B, Ti, Zr, Sn, and Zn.
Further, in the general formula (I), 0≦x≦0.6 is preferable, and 0.2≦x≦0.5 is more preferable.
On the other hand, in the general formula (I), m preferably satisfies 5≦m<12, more preferably 7≦m<11.
In the general formula (I), n is preferably 6≦n≦15, more preferably 7≦n≦15.

Among aluminosilicates having an SAR of 2 or more and less than 12, solid powdery aluminosilicates at normal temperature and normal pressure (25° C., 1 atm) are preferably used from the viewpoint of handleability, diffusibility, and the like. Here, in this specification, the term "powder" includes powder (powder containing primary particles and/or aggregates (secondary particles) in which primary particles are aggregated), and granules obtained by granulating primary particles to secondary particles. It is a concept. The shape of each particle of the powdery aluminosilicate is not particularly limited, and may be, for example, spherical, ellipsoidal, crushed, flat, irregular, or the like.

Although the average particle size (D ₅₀ ) of the powdery aluminosilicate is not particularly limited, it is preferably 1 to 500 μm, more preferably 20 to 350 μm. In the present specification, the average particle diameter D ₅₀ means the median diameter measured by a laser diffraction particle size distribution analyzer (for example, laser diffraction particle size distribution analyzer SALD-3100 manufactured by Shimadzu Corporation). .

As the aluminosilicate having an SAR of 2 or more and less than 12, an aluminosilicate having an amorphous crystal structure as determined by a powder X-ray diffraction method is preferably used. Here, the fact that the crystal structure by powder X-ray diffraction method is amorphous means that there is no clear peak indicating a specific plane index in the X-ray diffraction diagram. Commercially available synthetic aluminum silicate can be used as such an amorphous aluminosilicate.

Among these, in addition to its low impurity concentration and high quality, it conforms to the synthetic aluminum silicate standard of the 17th revision of the Japanese Pharmacopoeia from the viewpoint of the catalytic activity and durability of the resulting CHA-type aluminosilicate. is particularly preferably used.

Here, the synthetic aluminum silicate standards of the Japanese Pharmacopoeia 17th Edition are as follows.
[1] Properties White powder, odorless and tasteless.
Practically insoluble in water, ethanol (95) or diethyl ether.
Dissolves in heated NaOH solution leaving a small insoluble fraction.
[2] Confirmation test Aluminum salt, silicate → both compatible [3] Purity test Neutral Chloride 0.021% or less Sulfate 0.480% or less Heavy metal 30 ppm or less Arsenic 2 ppm or less [4] Loss on drying Drying Weight loss is 20.0% or less [5] Antacid power 50.0 mL or more

The aluminosilicate has the following five types of skeletons, namely Si-0Al, Si-1Al, Si-2Al, Si-3Al, Si- 4Al is known to exist. It is also known that there are Si atoms in which some of the bonding sites are OH, that is, Si-1OH. These chemical bonding states can be analyzed in detail by solid-state ²⁹ Si NMR measurements, and since these 6 types of skeletons exhibit different chemical shifts, their respective abundances can be quantitatively detected from solid-state ²⁹ Si NMR spectra. be. In addition, Si-2Al and Si-1OH appear at almost the same position and are often detected as a sum in the solid-state ²⁹ Si NMR spectrum.

From the viewpoint of the catalytic activity and durability of the obtained CHA-type aluminosilicate, the aluminosilicate having an SAR of 2 or more and less than 12 is most preferably substantially free of Si-3Al and Si-4Al. Used. In this specification, "substantially free" means less than 5% by mass, preferably less than 3% by mass, more preferably less than 1% by mass, relative to the total amount of aluminosilicate. Since these Si-3Al and Si-4Al are inferior in heat resistance, the CHA-type aluminosilicate synthesized using the aluminosilicate containing a large amount of Si-3Al and Si-4Al as a raw material cannot be used in a high-temperature environment or at a high temperature. The three-dimensional pore structure cannot be maintained due to, for example, thermal decomposition after exposure, and the performance tends to be relatively inferior. In other words, from the viewpoint of heat resistance, it is preferable to use an aluminosilicate having a large proportion of Si-1Al, which is excellent in thermal stability. Specifically, an aluminosilicate containing Si-1Al in an amount of 50% by mass or more is preferable, more preferably 55% by mass or more, relative to the total amount. Similarly, an aluminosilicate containing Si-0Al, Si-1Al, Si-2Al and Si-1OH in total of 95% by mass or more is preferable, more preferably 97% by mass or more, and still more preferably 99% by mass. % or more.

Various grades of aluminosilicates conforming to the synthetic aluminum silicate standards of the Japanese Pharmacopoeia 17th Edition are commercially available, and corresponding grades from these commercial products can be used. Commercially available products include synthetic aluminum silicate "Yoshida" manufactured by Yoshida Pharmaceutical Co., Ltd., synthetic aluminum silicate bulk powder "Maruishi" manufactured by Maruishi Pharmaceutical Co., Ltd., synthetic aluminum silicate manufactured by Tomita Pharmaceutical Co., Ltd., and "Yoshida" manufactured by Kyowa Chemical Industry Co., Ltd. Kyoward (registered trademark) 700", Synthetic aluminum silicate "Pfizer" bulk powder manufactured by Pfizer, Synthetic aluminum silicate "Sankei" manufactured by Sankei Pharmaceutical Co., Ltd., Synthetic aluminum silicate "Shioe" manufactured by Shioe Pharmaceutical Co., Ltd., Junsei "Junsei" synthetic aluminum silicate manufactured by Yakuhin Kogyo Co., Ltd., synthetic aluminum silicate "Tokai" manufactured by Tokai Pharmaceutical Co., Ltd., and synthetic aluminum silicate "Yamazen" M manufactured by Yamazen Pharmaceutical Co., Ltd., but are not particularly limited thereto. .

Further, an aluminosilicate having an SAR of 2 or more and less than 12 can be synthesized by a method known in the art, and the synthesized product can be used as the Si—Al element source. For example, a water-soluble silicate and a water-soluble aluminum salt are mixed so that the ratio of silicon atoms in the water-soluble silicate to aluminum atoms in the water-soluble aluminum salt (Si/Al) is 1.0 to 5.5 (preferably 2.5 to 5.4), liquid temperature 20 to 90°C (preferably 40 to 70°C), pH 3.8 to 5.0 (preferably 4.0 to 4.7), reaction solution concentration (SiO ₂ +Al ₂ O ₃ ) is 70 to 250 g/L (preferably 100 to 180 g/L), and the reaction method is a continuous reaction. Aluminum silicate is solid-liquid separated from the resulting reaction solution, washed and By drying, an aluminosilicate having an SAR of 2 or more and less than 12 can be obtained. At this time, as the water-soluble aluminum salt, aluminum chloride, aluminum nitrate, aluminum sulfate, sodium aluminate and the like are preferably used. As the water-soluble silicate, an alkali metal silicate such as sodium silicate or potassium silicate is preferably used. Sodium silicate No. 1, No. 2, No. 3, No. 4, sodium metasilicate, sodium orthosilicate and the like are preferably used as sodium silicate.

The aluminosilicate having a silica-alumina ratio of 2 or more and less than 12, which serves as the Si—Al element source, can be used singly or in any combination and ratio of two or more.

(Si element source)
The Si element source used as a raw material is used in combination with the above-mentioned Si—Al element source, so that high silica (i.e., silica-alumina ratio is 14 or more and 40 or less). Si element sources include precipitated silica, colloidal silica, fumed silica, silica gel, sodium silicate (sodium metasilicate, sodium orthosilicate, sodium silicate No. 1, 2, 3, 4, etc.), tetraethoxysilane. alkoxysilanes such as (TEOS) and trimethylethoxysilane (TMEOS), but not limited thereto. However, in this specification, an aluminosilicate having an SAR of 2 or more and less than 12 corresponds to the above-mentioned Si—Al element source and is not included in this Si element source.

In addition, Si element source can be used individually by 1 type or in arbitrary combinations and ratios of 2 or more types.

(alkali metal source)
Examples of alkali metal sources include alkali metal hydroxides such as LiOH, NaOH, KOH, CsOH, and RbOH, aluminates of these alkali metals, and alkali components contained in the Si—Al element sources and Si element sources described above. etc. Among these, NaOH and KOH are preferably used. Since the alkali metal in the mixture can also function as an inorganic structure-directing agent, there is a tendency to easily obtain a CHA-type aluminosilicate with excellent crystallinity.

In addition, an alkali metal source can be used individually by 1 type or in arbitrary combinations and ratios of 2 or more types.

(organic structure directing agent)
At least one selected from the group consisting of primary amines, secondary amines, tertiary amines and quaternary ammonium salts is used as the organic structure directing agent. Specifically, hydroxide salts, halides, carbonates, sulfates, methyl carbonate salts and sulfates with adamantane amine derivatives such as N,N,N-trialkyladamantammonium as cations; , N-trialkylbenzylammonium ions and other benzylamine derivatives, N,N,N-trialkylcyclohexylammonium ions and N,N,N-methyldiethylcyclohexylammonium ions and other cyclohexylamine derivatives, N-alkyl-3-quinine Quinuclidinol derivatives such as clidinol ion, or aminonorbornane derivatives such as N,N,N-trialkylexoaminonorbornane, tetramethylammonium ion, ethyltrimethylammonium ion, diethyldimethylammonium ion, triethylmethylammonium ion, tetraethylammonium ion Hydroxide salts, halides, carbonates, methyl carbonate salts and sulfates having C 1-2 alkylamine derivatives as cations; but not limited to these.

Among these, as the organic structure directing agent, N,N,N-trimethyladamantane ammonium hydroxide (hereinafter sometimes abbreviated as "TMAdaOH"), N,N,N-trimethyladamantane ammonium halide , N,N,N-trimethyladamantane ammonium carbonate, N,N,N-trimethyladamantane ammonium methyl carbonate salt, N,N,N-trimethyladamantane ammonium hydrochloride, and N,N,N-trimethyladamantane ammonium sulfate At least one selected from the group consisting of is preferable.

Such cations may be accompanied by anions which are generally not detrimental to the formation of CHA-type aluminosilicates. Examples of such anions include halogen ions such as Cl ⁻ , Br ⁻ and I ⁻ , hydroxide ions, acetates, sulfates, carboxylates and the like, but are not particularly limited thereto. Among these, hydroxide ions are preferably used.

The organic structure-directing agent can be used singly or in any combination and ratio of two or more.

(Preparation of mixture)
Then, in this mixture preparation step, a mixture (slurry) containing the aforementioned Si—Al element source, Si element source, alkali metal source, organic structure directing agent and water is prepared. At this time, if necessary, wet mixing can be performed using a known mixer or stirrer such as a ball mill, bead mill, medium stirring mill, homogenizer, or the like. When stirring is carried out, it is usually preferably carried out at a rotational speed of about 30 to 2000 rpm, more preferably 50 to 1000 rpm.

_At this time, the content of water in the mixture can be appropriately set in consideration of reactivity, _{handleability} , etc., and is not particularly limited. , usually 5 or more and 100 or less, preferably 6 or more and 50 or less, more preferably 7 or more and 40 or less. When the water-silica ratio is within the above preferable range, stirring during preparation of the mixture or during crystallization by hydrothermal synthesis is facilitated, handleability is improved, and formation of by-products and impurity crystals is suppressed, resulting in high Yield tends to be easily obtained. The water used here may be tap water, RO water, deionized water, distilled water, industrial water, pure water, ultrapure water, etc., depending on the desired performance. As for the method of blending water into the mixture, water may be blended separately from each component described above, or it may be blended with each component in advance and blended as an aqueous solution or dispersion of each component.

In addition, the silica-alumina ratio (SiO ₂ /Al ₂ O ₃ molar ratio) in the mixture can also be set as appropriate and is not particularly limited, but is usually 5 or more and 50 or less, preferably 8 or more and less than 45, more preferably 8 or more and less than 45. is 10 or more and less than 40. When the silica-alumina ratio is within the above preferable range, dense crystals are likely to be obtained, and a CHA-type aluminosilicate having excellent thermal durability in a high-temperature environment or after high-temperature exposure tends to be easily obtained.

On the other hand, the hydroxide ion/silica ratio (OH ⁻ /SiO ₂ molar ratio) in the mixture can also be set as appropriate and is not particularly limited, but is usually 0.10 or more and 0.90 or less, preferably It is 0.15 or more and 0.50 or less, more preferably 0.20 or more and 0.40 or less. When the hydroxide ion/silica ratio is within the above preferable range, crystallization tends to proceed easily, and a CHA-type aluminosilicate having excellent thermal durability in a high-temperature environment or after high-temperature exposure tends to be easily obtained. It is in.

_The content of the alkali metal in the mixture can also be set as appropriate and is not particularly limited. /SiO ₂ molar ratio) is usually 0.01 or more and 0.50 or less, preferably 0.05 or more and 0.30 or less. When the alkali metal oxide/silica ratio is within the above preferable range, crystallization due to mineralization is promoted, and the formation of by-products and impurity crystals is suppressed, so that a high yield tends to be easily obtained. be.

On the other hand, the organic structure-directing agent/silica ratio (organic structure-directing agent/SiO ₂ molar ratio) in the mixture can also be set appropriately and is not particularly limited, but is usually 0.05 or more and 0.40 or less, It is preferably 0.07 or more and 0.30 or less, more preferably 0.09 or more and 0.25 or less. When the organic structure-directing agent/silica ratio is within the above preferred range, crystallization is facilitated, and a CHA-type aluminosilicate having excellent thermal durability in a high-temperature environment or after high-temperature exposure can be obtained at low cost. tend to be easily stolen.

(Seed crystal of CHA-type aluminosilicate)
The mixture described above may further contain seed crystals (seed crystals) of CHA-type aluminosilicate from the viewpoint of promoting crystallization. Addition of seed crystals tends to promote the crystallization of the CHA-type crystal structure, making it easier to obtain a high-quality CHA-type aluminosilicate. The seed crystal used here is not particularly limited as long as it is a crystal of CHA-type aluminosilicate. Although the silica-alumina ratio of the seed crystal is arbitrary, it is preferably the same as or approximately the same as the silica-alumina ratio of the mixture. From this point of view, the silica-alumina ratio of the seed crystal is preferably 5 or more and 50 or less. More preferably 8 or more and less than 40, still more preferably 10 or more and less than 19.

The seed crystal used here can be a commercially available CHA-type aluminosilicate as well as a separately synthesized CHA-type aluminosilicate. Naturally produced CHA-type aluminosilicates can of course be used, and CHA-type aluminosilicates synthesized according to the present invention can also be used as seed crystals. The cation type of the seed crystal is not particularly limited, and for example, sodium type, potassium type, ammonium type, proton type, etc. can be used.

The particle size (D ₅₀ ) of the seed crystal used here is not particularly limited, but from the viewpoint of promoting the crystallization of the CHA type crystal structure, it is preferably relatively small, usually 0.5 nm or more and 5 μm or less, preferably. is 1 nm or more and 3 μm or less, more preferably 2 nm or more and 1 μm or less. _The amount of seed crystals to be blended can be appropriately set according to the desired crystallinity, and is not particularly limited. It is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass.

<Hydrothermal treatment process of mixture>
In this step, a crystallized CHA-type aluminosilicate is obtained by heating the above-described mixture in a reaction vessel for hydrothermal synthesis.

As the reaction vessel used in this hydrothermal synthesis, a known closed pressure-resistant vessel that can be used in hydrothermal synthesis can be appropriately used, and the type thereof is not particularly limited. For example, a sealed heat-resistant and pressure-resistant container such as an autoclave equipped with a stirrer, heat source, pressure gauge, and safety valve is preferably used. The crystallization of the CHA-type aluminosilicate may be carried out while the above-described mixture (raw material composition) is left standing. (Raw material composition) is preferably stirred and mixed. At this time, the number of revolutions is preferably about 30 to 2000 rpm, more preferably 50 to 1000 rpm.

The treatment temperature (reaction temperature) of the hydrothermal synthesis is not particularly limited, but from the viewpoint of the crystallinity of the obtained aluminosilicate and economic efficiency, it is usually 100° C. or higher and 200° C. or lower, preferably 120° C. or higher and 190° C. or lower. More preferably, it is 150°C or higher and 180°C or lower.

The treatment time (reaction time) of hydrothermal synthesis is not particularly limited as long as it takes a sufficient time for crystallization. hours to 20 days, preferably 4 hours to 10 days, more preferably 12 hours to 8 days.

The processing pressure for hydrothermal synthesis is not particularly limited, and the autogenous pressure generated when the mixture put into the reaction vessel is heated to the above temperature range is sufficient. At this time, if necessary, an inert gas such as nitrogen or argon may be introduced into the container.

<Post-process>
By performing such a hydrothermal treatment, a crystallized CHA-type aluminosilicate can be obtained. At this time, if necessary, solid-liquid separation treatment, water washing treatment, drying treatment for removing moisture at a temperature of about 50 to 150° C. in air, etc. may be carried out according to conventional methods.

The CHA-type aluminosilicate thus obtained may contain a structure-directing agent, an alkali metal, or the like in pores or the like. Therefore, it is preferable to perform a removal step for removing these as necessary. The removal of organic structure-directing agents, alkali metals and the like can be carried out according to a conventional method, and the method is not particularly limited. For example, liquid phase treatment using an acidic aqueous solution, liquid phase treatment using an aqueous solution containing ammonium ions, liquid phase treatment using a chemical solution containing decomposition components of an organic structure directing agent, exchange treatment using a resin, etc. Firing treatment or the like can be performed. These treatments can be performed in any combination. Among these, the removal of organic structure-directing agents, alkali metals, and the like is preferably performed by calcination from the viewpoint of production efficiency and the like.

<Baking treatment>
The treatment temperature (firing temperature) in the firing treatment can be appropriately set according to the raw material used, etc., and is not particularly limited. The temperature is usually 300°C or higher and 1000°C or lower, preferably 400°C or higher and 900°C or lower, more preferably 430°C or higher and 800°C or lower, and still more preferably 480°C or higher and 750°C or lower. The firing treatment is preferably performed in an oxygen-containing atmosphere, for example, in an air atmosphere.

The treatment time (calcination time) in the baking treatment can be appropriately set according to the treatment temperature, economic efficiency, etc., and is not particularly limited, but is usually 0.5 hours or more and 72 hours or less, preferably 1 hour or more and 48 hours or less, and more preferably. is 3 hours or more and 40 hours or less.

<Ion exchange treatment>
The CHA-type aluminosilicate after crystallization may have metal ions such as alkali metal ions on its ion exchange sites. Depending on the performance desired here, an ion exchange step for ion exchange can be carried out. In this ion exchange step, ions can be exchanged with non-metal cations such as ammonium ions (NH ₄ ⁺ ) and protons (H ⁺ ) according to a conventional method. For example, CHA-type aluminosilicate can be subjected to liquid-phase treatment using an aqueous solution containing ammonium ions, such as an aqueous solution of ammonium nitrate or an aqueous solution of ammonium chloride, so that it can be ion-exchanged to an ammonium type. In addition, ion-exchange to a proton type can be performed by subjecting the CHA-type aluminosilicate to ion-exchange with ammonia and then performing a calcination treatment.

If necessary, the CHA-type aluminosilicate thus obtained may be subjected to further treatments such as reducing the acid content and supporting a transition metal. The acid amount reduction treatment may be performed by, for example, silylation, steam treatment, dicarboxylic acid treatment, or the like. These acid amount reduction treatments and composition changes may be carried out in accordance with conventional methods.

<Transition metal supporting treatment>
Moreover, the treatment for supporting the transition metal may also be carried out according to a conventional method. Any transition metal can be supported on the above-described CHA-type aluminosilicate, thereby functioning as a catalyst in various applications. Examples of catalyst applications include, but are not limited to, exhaust gas purification catalysts, catalysts for producing lower olefins from alcohols and ketones, cracking catalysts, dewaxing catalysts, and isomerization catalysts. The transition metal element to be supported can be appropriately selected according to the required performance, and the type is not particularly limited. For example, when the above-mentioned CHA-type aluminosilicate is used as an ethanol conversion catalyst, iron (Fe) and tungsten (W) are preferably used as transition metals.

Further, for example, when the above-described CHA-type aluminosilicate is used as an exhaust gas purification catalyst, copper (Cu) and iron (Fe) are preferably used as transition metals. In particular, a transition metal-supported CHA-type aluminosilicate has a high utility value as a nitrogen oxide reduction catalyst. That is, the above-described transition metal-supported CHA-type aluminosilicate has a relatively higher nitrogen oxide reduction rate than conventional metal-supported zeolites, and in particular, exhibits adsorption performance, catalytic performance, etc. even in a high-temperature environment or after high-temperature exposure. relatively high and maintainable.

The treatment for supporting the transition metal may be carried out according to a conventional method. For example, the CHA-type aluminosilicate described above may be brought into contact with a simple substance or compound of a transition metal, transition metal ions, or the like. The method for supporting the transition metal may be any method as long as the transition metal is retained in at least one of the ion exchange sites and pores of the CHA-type aluminosilicate. The transition metals can be supplied as transition metal inorganic acid salts, such as transition metal sulfates, nitrates, acetates, chlorides, oxides, composite oxides, complex salts, and the like. Specific methods include, but are not limited to, ion exchange method, evaporation to dryness method, precipitation support method, physical mixing method, skeleton replacement method, and impregnation support method. After the transition metal supporting treatment, if necessary, a solid-liquid separation treatment, a water washing treatment, a drying treatment for removing moisture at a temperature of about 50 to 150° C. in the atmosphere, etc. can be performed according to a conventional method. .

If necessary, a platinum group metal (PGM) such as platinum, palladium, rhodium and iridium may be supported on the CHA-type aluminosilicate. A known method can be applied to the method for supporting the noble metal element or the platinum group element, and there is no particular limitation. For example, a noble metal element or a platinum group element can be supported by preparing a salt solution containing a noble metal element or a platinum group element, impregnating a CHA-type aluminosilicate with this salt-containing solution, and then calcining the solution. can. Although the salt-containing solution is not particularly limited, nitrate aqueous solution, dinitrodiammine nitrate solution, chloride aqueous solution and the like are preferable. The firing treatment is also not particularly limited, but is preferably performed at 350° C. to 1000° C. for about 1 to 12 hours. Prior to high-temperature firing, it is preferable to perform drying under reduced pressure using a vacuum dryer or the like, and to perform drying treatment at about 50° C. to 200° C. for about 1 to 48 hours.

[CHA-type aluminosilicate, transition metal-supporting CHA-type aluminosilicate]
Next, the CHA-type aluminosilicate obtained by the production method described above will be described. This CHA-type aluminosilicate is a crystalline aluminosilicate having a crystal structure equivalent to that of chabazite, which is classified by the structure code of CHA in IZA. This CHA-type aluminosilicate has aluminum (Al) and silicon (Si) as main skeleton metal atoms, and has a structure consisting of a network of these and oxygen (O). The structure is then characterized by X-ray diffraction data.

The particle size of the CHA-type aluminosilicate and transition metal-supporting CHA-type aluminosilicate is not particularly limited because it may vary depending on the conditions for synthesizing the CHA-type aluminosilicate. The average particle diameter (D ₅₀ ) is preferably 0.01 μm to 500 μm, more preferably 0.02 to 20 μm.

The silica-alumina ratio (SiO ₂ /Al ₂ O ₃ molar ratio) of the CHA-type aluminosilicate and the transition metal-supporting CHA-type aluminosilicate can be set as appropriate and is not particularly limited. From the viewpoint of thermal durability, catalytic activity, etc., it is preferably 14 or more and 40 or less, more preferably 15 or more and 30 or less, and still more preferably 15 or more and 28 or less. By using a CHA-type aluminosilicate having a silica-alumina ratio within the above preferred numerical range, there is a tendency to easily obtain a catalyst or catalyst carrier in which thermal durability and catalytic activity are highly balanced.

In addition, from the viewpoint of realizing a high-performance catalyst or catalyst carrier with excellent catalytic activity, the CHA-type aluminosilicate has a ratio of cobalt divalent ion adsorption capacity to all Al atoms (Co ²⁺ /Al) of 0.2 or more. is preferably Cobalt divalent ions have the property of adsorbing Co ²⁺ to the highly active sites in the CHA-type aluminosilicate, so by measuring the cobalt divalent ion adsorption capacity (saturation amount), the superiority or inferiority of catalytic activity can be determined. can do. Here, 1500 g of 0.25 M aqueous solution of cobalt (II) nitrate is used for 10 g of CHA-type aluminosilicate, and Co ²⁺ is adsorbed on CHA-type aluminosilicate under stirring. Since cobalt (II) hydroxide precipitates when the pH exceeds 7.5, the mixture is stirred at room temperature for 4 hours while adding dilute nitric acid so as to keep the pH between 3 and 6. After filtration, saturated adsorption is carried out using 1500 g of 0.5 M cobalt (II) nitrate aqueous solution. A sample is prepared by washing with 700 ml of pure water four times and drying, and subjected to fluorescent X-ray analysis. Specifically, using Axios (Spectricis Inc.), about 5 g of the sample was pressure-molded at 20 t, and the sample was used for the measurement. The ratio of the cobalt divalent ion adsorption capacity to the total Al atoms (Co ²⁺ /Al) was calculated from the obtained mass % of Al and Co.

On the other hand, the transition metal content in the transition metal-supporting CHA-type aluminosilicate is not particularly limited, but is preferably 0.1 to 10% by mass, more preferably 0.5 to 8% by mass relative to the total amount. .

In addition, the atomic ratio of the transition metal to aluminum in the transition metal-supporting CHA-type aluminosilicate (transition metal/aluminum) is not particularly limited, but is preferably 0.01 to 1.0, more preferably 0.05 to 0.7, more preferably 0.1 to 0.5.

[Use]
As detailed above, the CHA-type aluminosilicate and transition metal-supported CHA-type aluminosilicate of the present embodiment can be suitably used in applications such as adsorbents, separating agents, ion exchangers, catalysts, and catalyst carriers. . In particular, the CHA-type aluminosilicate and transition metal-supported CHA-type aluminosilicate of the present embodiment are excellent in thermal durability, and maintain relatively high adsorption performance, catalytic performance, etc. even in a high temperature environment or after high temperature exposure. Since it is possible, it can be used particularly preferably in applications where it is used in a high temperature environment or exposed to high temperatures. Adsorbents used in a high-temperature atmosphere include, but are not limited to, water adsorbents, hydrocarbon adsorbents, nitrogen oxide adsorbents, and the like. Catalysts used in high-temperature and high-humidity atmospheres include, for example, exhaust gas purifying catalysts for purifying exhaust gases from diesel automobiles, gasoline automobiles, jet engines, boilers, gas turbines, etc., catalyst carriers thereof, nitrogen oxide catalysts or catalysts thereof. Carriers (nitrogen oxide direct decomposition catalysts, nitrogen oxide reduction catalysts, catalyst carriers thereof, etc.) may be mentioned, but are not particularly limited to these.

In addition, transition metal-supported CHA-type aluminosilicates, especially Cu and/or Fe-supported CHA-type aluminosilicates, are particularly useful as exhaust gas purification catalysts, and in particular ammonia, urea, organic amines, etc. are used as reducing agents. It is particularly suitably used as a selective catalytic reduction catalyst (SCR catalyst). That is, the transition metal-supporting CHA-type aluminosilicate has excellent thermal durability, and can maintain a high reduction rate of nitrogen oxides even in a high temperature range of 400° C. or higher and 600° C. or lower after hydrothermal durability treatment. In contrast, conventionally known copper-supporting chabazite-type zeolites have a significantly reduced rate of reduction of nitrogen oxides in the same high temperature range. As is clear from these comparisons, the Cu and/or Fe-supporting CHA-type aluminosilicate described above has a particularly remarkable effect in that it exhibits a high reduction rate in a high temperature range when used as an SCR catalyst.

Note that the hot water durability treatment means aging treatment of the catalyst, which is performed in order to exhibit stable catalyst performance in actual use. Time processing shall be performed. After such hot water durability treatment, the reduction rate of nitrogen oxides at 450° C. is preferably 70% or more, more preferably 75% or more, still more preferably 80% or more, and particularly preferably 85%. % or more. Similarly, at 500° C., it is preferably 65% or more, more preferably 70% or more, preferably 75% or more, more preferably 80% or more.

In a preferred embodiment, the transition metal-supporting CHA-type aluminosilicate described above has a nitrogen oxide reduction rate equivalent to that of a conventionally known copper-supporting chabazite-type zeolite even in a low temperature range of 150° C. or more and less than 400° C. demonstrate. That is, after the hot water durability treatment described above, the reduction rate of nitrogen oxides at 200° C. is preferably 55% or more, more preferably 60% or more, still more preferably 65% or more, and particularly Preferably it is 70% or more. Similarly, at 300° C., it is preferably 70% or more, more preferably 75% or more, even more preferably 80% or more, and particularly preferably 85% or more.

[Exhaust gas purification catalyst, exhaust gas purification device, exhaust gas purification method]
When used as an exhaust gas purifying catalyst or a catalyst carrier thereof, the CHA-type aluminosilicate or the transition metal-supporting CHA-type aluminosilicate of the present embodiment can be used in powder form. Further, for example, by molding the powder into an arbitrary shape, it can be used as a granular or pellet-shaped compact. Various known dispersing devices, kneading devices, and molding devices can be used when producing the molded body. Furthermore, the CHA-type aluminosilicate or transition metal-supported CHA-type aluminosilicate of the present embodiment may be used as a ceramic monolith carrier such as cordierite, silicon carbide, or silicon nitride, or a metal honeycomb carrier such as stainless steel, or a wire. It can also be held (carried) on a catalyst carrier such as a mesh carrier or a steel wool-like knit wire carrier. In addition, these can be used individually by 1 type, or in arbitrary combinations and ratios of 2 or more types. When the CHA-type aluminosilicate or transition metal-supported CHA-type aluminosilicate is held on the catalyst carrier, various known coating methods, wash coating methods, and zone coating methods can be applied.

The CHA-type aluminosilicate and the transition metal-supporting CHA-type aluminosilicate of the present embodiment can be used by blending in a catalyst layer of a catalytic converter for exhaust gas purification. For example, it can be carried out by providing a catalyst layer containing the CHA-type aluminosilicate of the present embodiment or a transition metal-supporting CHA-type aluminosilicate on a catalyst support such as a monolithic support. Further, the catalyst area of the exhaust gas purifying catalytic converter may be a single layer having only one catalyst layer, or may be a laminate having two or more catalyst layers. Additionally, any laminate that combines one or more catalyst layers with one or more other layers known in the art. For example, in the case where the catalytic converter for purifying exhaust gas has a multi-layer structure having at least an oxygen storage layer and a catalyst layer on a catalyst carrier, at least the CHA-type aluminosilicate or transition metal-supporting CHA-type aluminosilicate of the present embodiment is used in the catalyst layer. By containing salt, it is possible to obtain a catalytic converter for exhaust gas purification that is excellent in heat resistance and three-way purification performance. Considering the trend toward stricter exhaust gas regulations, the layer structure is preferably two or more layers.

The method for forming the catalyst layer is not particularly limited, and may be carried out according to a conventional method. To give an example, the CHA-type aluminosilicate or transition metal-supported CHA-type aluminosilicate of the present embodiment, an aqueous medium, and, if necessary, a binder known in the art, other catalysts, co-catalyst particles, and an OSC material , base material particles, additives and the like are mixed at a desired mixing ratio to prepare a slurry mixture, the obtained slurry mixture is applied to the surface of the catalyst carrier, dried and calcined. At this time, if necessary, an acid or a base may be blended for pH adjustment, or a surfactant, a dispersing resin, or the like may be blended for viscosity adjustment or slurry dispersibility improvement. As a method for mixing the slurry, pulverization and mixing using a ball mill or the like can be applied, but other pulverization or mixing methods can also be applied.

The method of applying the slurry-like mixture to the catalyst carrier is not particularly limited and may be carried out according to a conventional method. Various known coating methods, wash coating methods, and zone coating methods can be applied. After applying the slurry-like mixture, drying and firing are carried out according to conventional methods to purify an exhaust gas having a catalyst layer containing the CHA-type aluminosilicate or transition metal-supporting CHA-type aluminosilicate of the present embodiment. It is possible to obtain a catalytic converter for

The exhaust gas purifying catalytic converter described above can be arranged in the exhaust system of various engines. The number and location of installation of the catalytic converter for purifying exhaust gas can be appropriately designed according to the exhaust gas regulation. For example, if exhaust gas regulations are strict, the number of installation locations may be two or more, and the installation locations may be arranged under the floor behind the catalyst immediately below the exhaust system. According to the catalyst composition and the catalytic converter for purifying exhaust gas containing the CHA-type aluminosilicate and the transition metal-supporting CHA-type aluminosilicate of the present embodiment, CO, HC, and NOx can be purified even in a high-temperature environment. Excellent effect can be exhibited. That is, according to the CHA-type aluminosilicate and transition metal-supported CHA-type aluminosilicate of the present embodiment, by contacting exhaust gas containing at least one selected from the group consisting of HC, CO, and NOx, exhaust gas can be purified.

The features of the present invention will be described in more detail below with reference to test examples, examples and comparative examples, but the present invention is not limited to these. That is, materials, usage amounts, ratios, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the gist of the present invention. In addition, various production conditions and values of evaluation results in the following examples have the meaning of preferable upper limit values or preferable lower limit values in the embodiments of the present invention, and the preferable range is the above-described upper limit value or lower limit value and the values in the following examples or the values between the examples.

(Example 1)
<Preparation of mixture>
1,125.0 g of a 25% aqueous solution of N,N,N-trimethyladamanta ammonium hydroxide (hereinafter sometimes referred to as "TMAdaOH 25% aqueous solution"), 2,990 g of pure water, Si—Al element source 630 g of solid powdery amorphous synthetic aluminum silicate (manufactured by Kyowa Kagaku Co., Ltd., synthetic aluminum silicate, trade name: Kyoward (registered trademark) 700SL, SAR: 9.7), precipitated silica that is a Si element source (manufactured by Tosoh Silica Corporation, trade name: Nipsil (registered trademark) ER) 340.0 g, sodium hydroxide (content of 97% or more) 85.0 g, and chabazite seed crystals (SAR13) 30.0 g are added and thoroughly mixed. to obtain a raw material composition (mixture). The composition of the raw material composition was _SiO2 : _0.059Al2O3 : _0.109TMAdaOH : _0.100Na2O : _18.1H2O in molar ratio.

Table 1 shows the results of solid-state ²⁹ Si NMR measurement of the Si—Al element source used at this time. The solid-state ²⁹ Si NMR measurement was performed by the CPMAS method using Ascend 4000 (manufactured by Bruker Biospin). SAR is a numerical value calculated from XRF.

<Synthesis of CHA-type aluminosilicate>
After putting this raw material composition (mixture) into a 5,000 cc stainless steel autoclave and sealing it, while stirring at 300 rpm, the temperature was raised to 160 ° C. and held for 48 hours, and then further held at 170 ° C. for 48 hours. . The product after this hydrothermal treatment was subjected to solid-liquid separation, and the resulting solid phase was washed with a sufficient amount of water and dried at 105° C. to obtain the product. Powder X-ray diffraction analysis confirmed that the product was a pure CHA-type aluminosilicate, that is, a single phase of chabazite-type synthetic zeolite. Fluorescent X-ray analysis revealed that the obtained CHA-type aluminosilicate had a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 15.1.

<Firing and ion exchange of CHA-type aluminosilicate>
After firing the obtained CHA-type aluminosilicate at 600° C., ion exchange was repeated three times using an aqueous ammonium nitrate solution containing the same amount of ammonium nitrate and 10 times the amount of water, followed by washing with a sufficient amount of pure water. and dried at 120° C. to obtain an NH ₄ ⁺ -type CHA-type aluminosilicate (NH ₄ ⁺ -type CHA-type zeolite).

<Transition metal support>
After impregnating 160 g of NH ₄ ⁺ -type CHA-type aluminosilicate with 84 g of a 25% copper nitrate trihydrate aqueous solution, the mixture was calcined at 500° C. to produce a Cu-supporting CHA-type aluminosilicate (Cu-supporting CHA-type zeolite). Obtained. The atomic ratio (copper/aluminum) to Cu aluminum was 0.27.

<Production of honeycomb catalyst>
The resulting Cu-supported CHA-type aluminosilicate is wet-coated on a honeycomb carrier so that the loading ratio is 180 g per 1 L of the honeycomb carrier, and then fired at 500° C. to contain the Cu-supported CHA-type aluminosilicate. A honeycomb catalyst having a catalyst layer provided on a honeycomb carrier was obtained.

<Laboratory measurement of nitrogen oxide reduction efficiency>
The honeycomb catalyst (a catalyst obtained by applying a Cu-supported CHA-type aluminosilicate to a honeycomb carrier) was cut into a cylindrical shape with a diameter of 25.4 mmφ and a length of 50 mm, and this was subjected to a catalyst evaluation apparatus (trade name: SIGU-2000, HORIBA, Ltd.). (manufactured by Horiba, Ltd.), and the gas composition was analyzed with an automobile exhaust gas analyzer (trade name: MEXA-6000FT, manufactured by Horiba, Ltd.) to measure the nitrogen oxide reduction efficiency in a steady airflow of the model gas. Here, a model gas balanced with 210 ppm NO, 40 ppm NO ₂ , 250 ppm NH ₃ , 4% H ₂ O, 10% O ₂ , balance N ₂ was used and measurements were taken at temperatures between 170°C and 500°C. range and at a space velocity SV=59,000 h ⁻¹ . FIG. 1 shows the measurement results of the NOx purification rate of the honeycomb catalyst.

<Measurement of the ratio (Co ²⁺ /Al) of the Co divalent ion adsorption capacity to the total Al atoms>
Using 1500 g of 0.25 M cobalt (II) nitrate aqueous solution for 10 g of NH ₄ ⁺ -type CHA-type aluminosilicate, stirring was carried out at room temperature for 4 hours while adding dilute nitric acid so as to maintain pH=3-6. . After filtration, saturated adsorption was carried out using 1500 g of 0.5 M cobalt (II) nitrate aqueous solution. After washing with 700 ml of pure water four times, the sample was dried and subjected to fluorescent X-ray analysis. Specifically, using Axios (Spectricis Inc.), about 5 g of the sample was pressure-molded at 20 t, and the sample was used for the measurement. From the results of the obtained mass % of Al and Co, the ratio of the cobalt divalent ion adsorption capacity to the total Al atoms (Co ²⁺ /Al) was calculated. (Co ²⁺ /Al) of the CHA-type aluminosilicate of Example 1 was 0.22.

(Comparative example 1)
To 330.0 g of TMAdaOH 25% aqueous solution, 2,800 g of pure water, 45.0 g of sodium aluminate (manufactured by Wako Pure Chemical Industries, Ltd.) as an Al source and alkali metal source, and precipitated silica (manufactured by Tosoh Silica Co., Ltd.) as a Si element source , trade name: Nipsil (registered trademark) ER) 220.0 g, J Sodium Silicate No. 3 (manufactured by Nippon Kagaku Kogyo Co., Ltd., SiO ₂ content: 29% by mass, Na ₂ O content: 9.0% by mass), which is an Si element source and an alkali metal source. 5% by mass) and 20 g of chabazite seed crystals (SAR13) were added and thoroughly mixed to obtain a raw material composition. The composition of the raw material composition was _SiO2 : _0.065Al2O3 : _0.104TMAdaOH : _0.100Na2O : _44.4H2O in molar ratio.

After this raw material composition was placed in a 5,000 cc stainless steel autoclave and sealed, the temperature was raised to 160° C. and maintained for 48 hours while stirring at 300 rpm. The product after this hydrothermal treatment was subjected to solid-liquid separation, and the resulting solid phase was washed with a sufficient amount of water and dried at 105° C. to obtain the product. Powder X-ray diffraction analysis confirmed that the product was a pure CHA-type aluminosilicate, that is, a single phase of chabazite-type synthetic zeolite. Fluorescent X-ray analysis revealed that the resulting CHA-type aluminosilicate had a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 13.4.

After firing the obtained CHA-type aluminosilicate at 600° C., ion exchange was repeated three times using an aqueous ammonium nitrate solution containing the same amount of ammonium nitrate and 10 times the amount of water, followed by washing with a sufficient amount of pure water. and dried at 120° C. to obtain an NH ₄ ⁺ -type CHA-type aluminosilicate (NH ₄ ⁺ -type CHA-type zeolite).

Then, similarly to Example 1, loading of Cu and formation of a honeycomb catalyst were carried out, and similarly to Example 1, the nitrogen oxide reduction efficiency was measured. The measurement results are shown in FIG. Further, the ratio (Co ²⁺ /Al) of the cobalt divalent ion adsorption capacity to the total Al atoms was measured in the same manner as in Example 1. As a result, the CHA-type aluminosilicate of Comparative Example 1 (Co ²⁺ /Al ) was 0.22.

As is clear from FIG. 1, the catalyst of Example 1 maintains a higher reduction rate than the catalyst of Comparative Example 1 even in a high temperature range of 400° C. or higher and 600° C. or lower. Further, it can be seen that the catalyst of Example 1 exhibits catalytic performance equivalent to that of the catalyst of Comparative Example 1 in the low temperature range of 150°C or more and less than 400°C.

The CHA-type aluminosilicate obtained by the production method of the present invention and the transition metal-supported CHA-type aluminosilicate using the same are excellent in thermal durability, and have adsorption performance and catalytic performance even in a high temperature environment or after high temperature exposure. etc. can be maintained relatively high, it can be widely and effectively used in applications such as adsorbents, separating agents, ion exchangers, catalysts, and catalyst carriers. In particular, as an exhaust gas purifying catalyst or its catalyst carrier, a nitrogen oxide catalyst or its catalyst carrier, etc. for purifying the exhaust gas of diesel automobiles, gasoline automobiles, jet engines, boilers, gas turbines, etc., which are exposed to severe usage environments, these A CHA-type aluminosilicate and a transition metal-supporting CHA-type aluminosilicate using the same can be used particularly effectively.

Claims (14)

A Si—Al element source containing at least an aluminosilicate having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 2 or more and less than 12 (excluding aluminosilicate zeolite) , a Si element source (however, the Si—Al excluding those corresponding to element sources), preparing a mixture containing an alkali metal source, an organic structure-directing agent and water, and hydrothermally treating the mixture,
A method for producing a CHA-type aluminosilicate. 2. The method for producing a CHA-type aluminosilicate according to claim 1, wherein the aluminosilicate is a solid powdery aluminosilicate at normal temperature and pressure. 3. The method for producing a CHA-type aluminosilicate according to claim 1, wherein the aluminosilicate substantially does not contain Si-3Al and Si-4Al. The Si element source according to any one of claims 1 to 3, wherein the Si element source is at least one selected from the group consisting of precipitated silica, colloidal silica, fumed silica, silica gel, sodium silicate, and alkoxysilane. A method for producing a CHA-type aluminosilicate. The method for producing a CHA-type aluminosilicate according to any one of claims 1 to 4, wherein the CHA-type aluminosilicate having a silica-alumina ratio of 14 or more and 40 or less is synthesized. The method for producing a CHA-type aluminosilicate according to any one of claims 1 to 5, wherein in the hydrothermal treatment step, the heat treatment is performed at 100 to 200°C for 1 to 480 hours. The CHA-type aluminosilicate according to any one of claims 1 to 6, further comprising a calcination step of heat-treating the obtained CHA-type aluminosilicate at 300 to 1000°C after the hydrothermal reaction step. Production method. 8. The method for producing a CHA-type aluminosilicate according to claim 7, further comprising the step of ion-exchanging the obtained CHA-type aluminosilicate into NH ₄ ⁺ type and/or H ⁺ type. The method for producing a CHA-type aluminosilicate according to any one of claims 1 to 8, wherein the mixture further contains seed crystals of the CHA-type aluminosilicate. The CHA-type aluminosilicate according to any one of claims 1 to 9, which synthesizes a CHA-type aluminosilicate having a cobalt divalent ion adsorption capacity to all Al atoms ratio (Co ²⁺ /Al) of 0.2 or more. A method for producing a silicate. The CHA according to any one of claims 1 to 10, wherein the organic structure directing agent is at least one selected from the group consisting of primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. A method for producing a type aluminosilicate. The method for producing a CHA-type aluminosilicate according to any one of claims 1 to 11, wherein the alkali metal source contains an alkali metal hydroxide. The method for producing a CHA-type aluminosilicate according to any one of claims 1 to 12, wherein the mixture has a water-silica ratio (H ₂ O/SiO ₂ ) of 5 or more and 100 or less. Si—Al element source (excluding aluminosilicate zeolite) containing at least an aluminosilicate having a silica-alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 2 or more and less than 12; excluding those corresponding to Al element sources), a step of preparing a mixture containing an alkali metal source, an organic structure directing agent and water,
hydrothermally treating the mixture;
characterized by comprising at least a step of ion-exchanging the obtained CHA-type aluminosilicate into NH ₄ ⁺ type and/or H ⁺ type, and a step of supporting a transition metal on the obtained CHA-type aluminosilicate. do,
A method for producing a transition metal-supporting CHA-type aluminosilicate.

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