JP2022008141A - Afx-type zeolite and production method thereof - Google Patents

Abstract

To provide an AFX-type zeolite of a novel shape which is expected to have high catalytic activity and durability.SOLUTION: There is provided an AFX-type zeolite. The AFX-type zeolite particle which is crystallized has a macropore on its surface. There is also provided a production method thereof.SELECTED DRAWING: Figure 4

Description

The present invention relates to a novel form of AFX-type zeolite.

Zeolites include adsorbents that adsorb water, heat pump materials that use the property of generating heat when adsorbing water, zeolite membranes that are used for dehydration from alcohol, and catalyst materials that use pores and cation sites. Widely used in industrial applications, it is a functional material whose existence has been known for a long time.

The action of zeolite as such a functional material is contributed by various physical characteristics of zeolite, and one of them is the state of pores. In the action of the catalytic reaction or the like in zeolite, the action of the pores exerts the diffusibility of a substance such as gas, and the action of the catalytic reaction or the like is promoted.

Zeolites have micropores of several nanometers derived from the crystal structure, but it is preferable that as many larger pores as possible are formed in order to improve the diffusivity of substances such as gas. Zeolites having mesopores formed in crystal particles have also been proposed for the purpose of improving the diffusivity of substances such as gas (Patent Document 1). In particular, in the case of a catalyst for purifying automobile exhaust gas as described later, it is necessary to purify harmful components and environmentally hazardous substances with high efficiency while the flow velocity of exhaust gas is high, and zeolite having a large number of large pores is a catalyst component. It can be said that it is a highly valuable material.

In addition, its durability as a functional material for industrial use is also an important factor. Zeolites are functional materials that are used under a variety of harsh conditions, but the durability of crystalline substances such as zeolites is high because of their high crystal strength. That is, high durability can be expected if the zeolite has crystals having a geometrically arranged shape. The AFX-type zeolite described later is also disclosed in Patent Document 2 (FIG. 2) and Patent Document 3.

On the other hand, having a geometrically arranged shape also means that the geometrically composed surface of the crystal is smooth. The fact that the surface constituting the crystal is smooth does not mean that many large pores that can contribute to the improvement of gas diffusivity are formed on the crystal surface. In other words, a highly crystallized, geometrically well-shaped zeolite can be expected to have high durability, but may be inferior in the diffusivity of substances such as gas.

Further, in the catalytic reaction, the reactants are converted into products by contacting with the catalyst, but when the contact surface is composed only of smooth surfaces, the region of the particles that is easily used for the reaction is on the surface of the catalyst particles. As a result, access to the inside of the catalyst particles of the reactants tends to be poor. Regarding this point, if the zeolite has poor crystallinity, it is easy to access the reactant to the inside of the zeolite particles starting from the place where the crystal is broken, but in that case, the durability is lowered due to the above reason. I am concerned.

The industrial usefulness of zeolite is as described above, and one of its important uses is its function as an environmental catalyst. Applications of environmental catalysts include purification of harmful substances and environmentally hazardous substances contained in exhaust gas discharged from internal combustion engines such as automobiles and adsorbents for harmful substances.

An SCR (Selective Catalytic Reduction) catalyst is known as a catalyst for purifying exhaust gas discharged from an internal combustion engine such as an automobile by using a catalyst using zeolite. SCR uses ammonia or an aqueous urea solution that is an ammonia precursor as a reducing component, and selectively reduces the reducing component and NOx in the exhaust gas by contacting them with the SCR catalyst. It is widely used for purification and is one of the important technologies for exhaust gas purification.

The activity of zeolite in such SCR is also contributed by the action of the above-mentioned cationic site. Then, for the purpose of further improving the activity, it is widely practiced to introduce a copper atom or an iron atom into a cation site by ion exchange (Patent Document 4).

As a zeolite used for an SCR catalyst, it is known that a zeolite having small pores due to an 8-membered ring in a crystal structure exhibits high performance (Patent Document 5). Among such zeolites having small pores with an 8-membered ring, AFX-type zeolite is expected as one of particularly highly active zeolites, which is also studied in Patent Document 5 and also in Patent Document 1. It is an invention concerning the improvement of this AFX type zeolite. Also in AFX-type zeolite, copper atoms and iron atoms are introduced into the cation site by ion exchange as in Patent Document 4 when it is carried out as a catalyst component.

As described above, zeolites are recognized for their high value for industrial use and are widely used. However, with the increasing interest in the environment in the future, higher activity is required as an environmental catalyst material.

Japanese Unexamined Patent Publication No. 2017-128457 Japanese Patent No. 6430303 Japanese Unexamined Patent Publication No. 2018-1408887 Patent No. 2904862 Special Table 2010-524677

An object of the present invention is to provide an AFX-type zeolite having a novel shape, which is expected to have high catalytic activity and durability.

As a result of diligent research to solve the above problems, the present inventors have found that an AFX-type zeolite having a novel shape can be obtained by using a specific organic structure defining agent (OSDA), and complete the present invention. I let you.

That is, the present invention is an AFX-type zeolite characterized by having macropores on the surface of crystallized AFX-type zeolite particles.

（式（１）中、Ｒ^１～Ｒ^４はそれぞれ独立してアルキル基、Ｘはアンモニウムカチオンと塩を形成するカウンターアニオンを示す）で表される有機構造規定剤を含有する水溶液を、加圧加熱条件下で攪拌することを特徴とする上記のＡＦＸ型ゼオライトの製造方法である。 Further, the present invention relates to a silica source, an alumina source, an alkali metal hydroxide, and the following general formula (1).

(In the formula (1), R ¹ to R ⁴ each independently represent an alkyl group, and X represents a counter anion forming a salt with an ammonium cation), and the aqueous solution containing the organic structure defining agent is pressurized. The above-mentioned method for producing an AFX-type zeolite, which comprises stirring under heating conditions.

Further, the present invention is a catalyst characterized by containing the above-mentioned AFX-type zeolite as an active ingredient.

The AFX-type zeolite of the present invention is crystallized and has macropores on its surface, so that it has excellent diffusivity to substances such as gas. In addition, high durability can be expected by providing high crystallinity. Due to these actions, when used for purifying exhaust gas discharged from an internal combustion engine, it can exhibit high purification performance for a long period of time even as an _NH3 -SCR catalyst component.

It is a figure which shows the ¹ HNMR spectral data of the D2O solution of N, N, N', N'-tetraethylbicyclo [2.2.2] octane- _2,3 : 5,6-dipyrrolidinium diiodide. * In the figure is the peak of the internal standard (4,4-dimethyl-4-silappentan-1-sulfonic acid). It is a figure which shows the ¹³ CNMR spectral data of the D2O solution of N, N, N', N'-tetraethylbicyclo [2.2.2] octane- _2,3 : 5,6-dipyrrolidinium diiodide. * In the figure is the peak of the internal standard (4,4-dimethyl-4-silappentan-1-sulfonic acid). AFX type zeolite of Example 1 synthesized using N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium dihydroxide as OSDA. It is a scanning electron microscope (SEM) photograph of. It is a partially enlarged photograph of FIG. It is an X-ray diffraction (XRD) pattern of the zeolite produced in Example 1. The AFX-type zeolite of Example 2 synthesized using N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium diiodide as OSDA. It is a scanning electron micrograph. It is a partially enlarged photograph of FIG. AFX type of Example 3 synthesized using N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium dihydrate and chloride. It is a scanning electron micrograph of zeolite. It is a partially enlarged photograph of FIG. It is a scanning electron micrograph of the cross section of the AFX type zeolite of Example 3. FIG. AFX type of Example 4 synthesized using N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium dihydroxide and fluoride. It is a scanning electron micrograph of zeolite. It is a partially enlarged photograph of FIG. It is a scanning electron micrograph of the cross section of the AFX type zeolite of Example 4. FIG. It is a scanning transmission electron microscope (STEM) image of the AFX type zeolite particle of Example 1. FIG. FIG. 14 is a computed tomography (CT) image of the particles of FIG. It is the figure which plotted the fractal dimension corresponding to the pore volume of the pore diameter region smaller than the mode radius on the horizontal axis, and the fractal dimension corresponding to the pore diameter region smaller than the mode radius on the vertical axis.

The AFX-type zeolite of the present invention has macropores on the surface of the crystallized particles.

(Crystalization of zeolite)
Whether or not the zeolite is crystallized can be determined from the position of the main peak obtained by the analysis by XRD and the shape of the chart, and the degree of crystallization is estimated by using the half width at half maximum for the sharpness of the diffraction peak. You can also do that. However, the diffraction peak is easily affected by the measurement conditions such as the shape of the sample at the time of measurement and other components such as household objects, and the peak shift and peak width are likely to change. It is difficult to judge whether the degree is good or bad. In particular, the AFX-type zeolite of the present invention has macropores, and the presence of these macropores may also be a factor that affects the position and shape of the XRD peak.

On the other hand, if it is visually confirmed using an electron microscope such as SEM, it is possible to directly confirm the shape of the crystal particles, and if it is a well-organized crystal shape, the regular arrangement of the constituent elements is possible. It can be said that it is certain to determine whether or not crystallization is progressing due to the geometrical shape resulting from. As will be described later, as for the confirmation of the macropores of the AFX-type zeolite of the present invention, the confirmation by the SEM image is one of the reliable methods. Therefore, the observation by the SEM is the crystal shape in the practice of the present invention. It can be said that this is an efficient and desirable method for observing macropores at the same time.

(Background that requires a high degree of crystallization)
As mentioned above, one of the main uses of zeolites these days is the NH ₃ -SCR catalyst for purifying automobile exhaust gas. NH ₃ -SCR uses ammonia as a reducing agent or an aqueous urea solution as an ammonia precursor. Ammonia reacts with NO, N2O, which _are the main components of NOx, to generate nitrogen and water. Further, an aqueous urea solution as an ammonia precursor is widely used in the market as an aqueous solution having a concentration of 32.5 wt% as [AdBlue (registered trademark)]. In this way, the NH ₃ -SCR catalyst is derived from the reducing component and comes into contact with a large amount of water, but water generated by combustion of fuel is also added to this.

It goes without saying that water itself is not a harmful component and there is no problem even if it is discharged into the atmosphere, but when water and heat are supplied to zeolite at the same time, dealumination is induced and the zeolite structure deteriorates due to hydrothermal deterioration. Is known (Special Publication No. 2004-536756). However, automobile exhaust gas is rich in factors that induce such water heat deterioration. Therefore, it is desirable to use zeolite having excellent hydrothermal durability for the NH ₃ -SCR catalyst.

As a zeolite having such high hydrothermal durability, a zeolite having a low aluminum content, that is, a zeolite having a high silica / alumina ratio (SAR) in the zeolite, may be selected because dealumination is unlikely to occur. (Patent Document 2: Japanese Patent Application Laid-Open No. 2010-524677 [0043]). However, the aluminum atom in zeolite forms a cation site, and the cation site is also a transition metal exchange site, which is an important factor for the high activity of zeolite. Especially for NH ₃ -SCR catalysts, it may not be possible to easily select a zeolite having a large SAR.

The fact that zeolites used in NH ₃ -SCR catalysts require ion exchange with a predetermined amount of transition metals such as copper and iron is disclosed in many of the applications relating to NH ₃ -SCR catalysts using zeolites. For this reason, the zeolite used in the NH ₃ -SCR catalyst requires that the SAR is not too large and that it has high hydrothermal durability. Such a SAR is appropriately set according to the environment in which the catalyst is used, but is preferably 5 to 100, more preferably 10 to 50, and most preferably 10 to 20. Further, it is preferable that the zeolite is a high-strength zeolite having a well-organized particle shape with advanced crystallization that can obtain high hydrothermal stability.

(Shape of zeolite)
The shape of the AFX-type zeolite of the present invention is not particularly limited as long as it has macropores on the surface of the crystallized AFX-type zeolite particles. A shape in which one equatorial plane is shared and connected, or a bipolyhedral pyramid is preferable. Examples of the shape in which two polyhedra share one equatorial plane and are connected to each other include a bale shape in which two parallel bottom surfaces of a hexagonal column are substantially hemispherical. Further, as the bi-polygonal pyramid, a bi-hexagonal pyramid or the like can be mentioned, but a bi-hexagonal pyramid is preferable.

The shape of the primary particles of the AFX-type zeolite in the examples of the present invention was a bihexagonal pyramid, but this shape itself (without macropores) is also the AFX-type zeolite in FIG. 2 of Patent Document 3. It is disclosed as an SEM photograph of.

(Macro pores)
The AFX-type zeolite of the present invention can be said to be primary particles, but has macropores on the surface of the particles. The size of this macrohole is as defined by IUPAC. The definition in IUPAC is that pores with a pore diameter of less than 2 nm are micropores, pores with a pore diameter of 2 nm or more and 50 nm or less are mesopores, and pores with a pore diameter of more than 50 nm are macropores. be. As described above, the macropores of the AFX-type zeolite in the present invention refer to those having a macropore of more than 50 nm according to the definition of the macropores, and are preferably 50 nm to 500 nm. The geometric mean radius of the macropores is 25 nm to 250 nm, preferably 50 nm to 200 nm, and more preferably 75 nm to 150 nm. Here, the geometric mean radius of the macropores is calculated from the average of the long and short diameters of 50 arbitrary macropores measured from the SEM photograph as described in the examples. .. The size of such macropores can also be expressed as a ratio of the size of macropores to the grain shape, and is 5 to 30% with respect to the length between the vertices of the vertices constituting the double horn. It is preferably 10 to 20%, and more preferably 10 to 20%. The moderately large macropores make it easy to access the reactants and adsorbents inside the particles, as will be described later, and the not too large, the strength of the particles, that is, the durability when used as a catalyst or adsorbent. It will be highly sexual.

When the AFX-type zeolite of the present invention is used as a catalyst, it goes without saying that the diffusivity of the reactant is improved by having macropores, but other effective utilization of the zeolite can be expected. When zeolite is used in a catalytic reaction, the zeolite itself is used as a heterogeneous catalyst. In general, it is the active site present on the surface of the catalyst particles that contributes most to the reaction of the heterogeneous catalyst. The fact that the active site on the surface of the catalyst easily contributes to the reaction is because the contact with the reactant is easy, and this point does not need to be explained in particular. However, it can be said that this is a state in which the components on the center side of the catalyst are not sufficiently utilized for the catalytic reaction on the particle surface side and the particle center side portion. However, since macropores are formed in the AFX-type zeolite of the present invention, the reactant can easily access the central portion of the zeolite particles, and the central portion is effectively used for the catalytic reaction.

When such a zeolite having a well-organized crystal shape, that is, a zeolite particle which is highly crystallized and has only a flat surface with a smooth crystal particle surface, is used as a catalyst, the action of such macropores is described above. It will be possible to solve the problem that it was difficult to access the reactant to the central part. The action of the macropores in the AFX-type zeolite of the present invention is not limited to the use as a catalyst, and the same applies to the zeolite used with the expectation of adsorption performance.

(Internal space)
It is desirable that the AFX-type zeolite of the present invention not only has macropores as described above, but also has a space inside. This space is a cavity, a sparse state filled with fine primary particles of several nm to 100 nm, a state where such a cavity and a sparse state are combined, or a macropore on the surface of the particle and the inside of the particle. The spaces are connected, and the macropores are connected inside the particle via the space inside the particle. This space may or may not be connected to the pores, but it is preferable that the space is connected, and the presence of the space causes the AFX-type zeolite to become hollow particles, so that the space itself is in the form of a film. It will have a zeolite shell (hereinafter, this may be referred to as "zeolite membrane hollow particles").

By the way, membrane-like zeolite is called a zeolite membrane and is a membrane separation technology that has been attracting attention in recent years. In the zeolite membrane, the target product can be selectively filtered out from a liquid or a gas by utilizing the pores derived from the skeleton structure of zeolite. Since the AFX zeolite particles of the present invention are hollow particles of a zeolite membrane, a specific component is selectively supplied to the inside of the zeolite particles from a liquid or gas containing a reactant or an adsorbent supplied from the particle surface, and the reactant may be. For example, it is expected that the selectivity of the catalytic reaction inside the particle will be improved, and if it is an adsorbent, the components will be concentrated and stored inside the particle. Expected to function as an occlusion release material that maintains the equilibrium of the component concentration in the adsorption system by releasing the component stored inside the particle when the balance of the component concentration in the adsorption system is disturbed by concentrating and storing the component inside the particle. can. Here, the presence of macropores on the surface of the particles can be expected to promote access to the internal space of the adsorbents and reactants. Further, since the component stored in the particle internal space needs to pass through the shell of the hollow particle in order to be released to the outside of the particle, it can be expected to delay the release of the occluded component. The expected action of such zeolite membrane hollow particles can be expected to be particularly promoted in a state where the particle internal space and the particle surface macropores are not connected.

On the other hand, when the internal space of the AFX-type zeolite particles of the present invention and the macropores on the particle surface are connected, pores derived from the zeolite skeleton structure are formed from the inside of the internal space in the catalytic reaction or adsorption. It can be used effectively and quickly.

The AFX-type zeolite of the present invention can be used as an NH ₃ -SCR catalyst, but as an NH ₃ -SCR catalyst mounted on a vehicle as an exhaust gas purification system, it is used as a composition with other components. Such other components are not particularly limited, but the particle size of the other components, the particle internal space of the AFX-type zeolite of the present invention, and the particle surface macropores correlate with each other as follows. Can be obtained.

The NH ₃ -SCR catalyst mounted for purifying automobile exhaust gas is a catalyst composition obtained by mixing zeolite and other components, which is coated on a honeycomb structure by using a wash coat method or the like, and is the AFX type of the present invention. The same applies to zeolite. Other such components include oxides such as titanium, tungsten, cerium, and zirconium used to decompose urea, which is a reducing component, or composite oxides containing at least one of them. Oxides such as barium, cerium, zirconium, etc. used for temporary occlusion of NOx, or composite oxides containing at least one of them. Examples thereof include binder particles such as silica, alumina, and zirconia that are blended between such oxide particles or for the purpose of fixing the honeycomb structure and the catalyst composition.

Conventionally, such other particle components have been used by appropriately selecting the particle size, but when the AFX-type zeolite of the present invention has macropores, the particle size of the other particles is larger than that of the macropores. It can be expected to work in both large and small cases.

When the particle size of the other particles is larger than the macropores, the internal space of the pores is not blocked. Therefore, NOx in the exhaust gas and urea supplied in the exhaust gas or ammonia obtained by decomposing urea are the present invention. The inside of the AFX-type zeolite particles can be easily accessed. Therefore, the purification reaction as an NH ₃ -SCR catalytic system becomes rapid. Such an action is effective when the particle internal space and the particle surface macropores are connected as shown in FIGS. 13, 14, and 15.

On the other hand, when the particle size of the other particles is smaller than the macropores, the other particles invade the macropores on the surface of the particles, and a flow path of a smaller reaction component is formed in the macropores. The formation of such a flow path can improve the gas diffusivity in the macropores as a reaction field, and improve the conversion rate of the reactants and the purification rate of the NH ₃ -SCR catalyst system. Can be done. Further, when urea is supplied to the SCR catalyst as a reducing component, the diffusivity of the urea component is increased by the flow path formed in the macropores, and the decomposition into ammonia becomes more complete. Is expected to improve. Further, since the reactants access into the skeleton structure of the AFX-type zeolite through the flow path in the macropores, the flow path can be designed to be long by adjusting the particle size of the particles penetrating into the macropores. It is possible to increase the time required for the reaction with respect to the amount of the reactants and improve the conversion rate (purification rate) of the reactants (NOx). Such an action is also effective when the particle internal space and the particle surface macropores are connected as shown in FIGS. 13, 14, and 15.

Particles in which such other particles are larger than the macropores and particles in which the particles are smaller may be used in combination. This makes it possible to optimize the _NH3 -SCR catalyst system for various combustion controls and urea spraying systems that differ from vehicle to vehicle.

The catalyst for mounting on an automobile is usually produced as a honeycomb catalyst obtained by coating a honeycomb structure with a slurryed catalyst composition by a wash coat method, but the AFX type zeolite of the present invention is produced. In order to effectively utilize the effects of the particle internal space and the particle surface macropores when mounting the catalyst as an SCR catalyst in an automobile, a crushing and mixing treatment using a ball mill or the like is performed when the catalyst composition is adjusted and made into a slurry. It is desirable to adjust by non-crushing and mixing treatment using a stirring blade or the like so that the grain shape is maintained.

Whether or not the zeolite has an internal space can be confirmed according to a known method. For example, after the zeolite is hardened with a resin such as epoxy, the cross section of the zeolite obtained by polishing may be confirmed by SEM or the like. ..

(Particle size)
When the AFX-type zeolite of the present invention is used as particles like a catalyst or an adsorbent, the shape is preferably particulate, but the size of the particles is not particularly limited and depends on the usage environment. It is selected as appropriate. For example, when used in an NH ₃ -SCR catalyst, the average particle size is preferably 0.1 to 500 μm, more preferably 0.5 to 200 μm. If the crystal size is large to some extent, it can be expected to improve the durability in the environment of use as a catalyst. Such an average particle size may be a value when the average particle size based on the volume by the laser diffraction method is D50, but the actual measurement of the particles in an arbitrary viewing range in the SEM image of the AFX type zeolite of the present invention. It may be the average of the values.

The size of the crystals and particles of the AFX-type zeolite of the present invention can also be adjusted by changing the conditions for synthesizing the zeolite. Zeolites, for example, generally crystallize nuclei, such as lowering the concentration of raw materials during synthesis, lowering the stirring speed, lowering the temperature at the time of nucleation as crystals, and lowering the pressure during synthesis. Since it is possible to increase the diameter of zeolite crystals and particles by synthesizing under conditions in which it is difficult to generate zeolite, the synthesis conditions may be changed accordingly in the present invention.

(AFX type skeletal structure)
The AFX-type zeolite of the present invention has a skeletal structure specified by AFX among those code-registered by type by IZA (international Zeolite Association (International Zeolite Society)). The composition of the AFX-type zeolite other than water of the AFX-type zeolite is represented by the following formula.

In the formula, M is a metal cation, a is preferably 1 to 10, b is a valence of M, Q is a cation derived from the compound represented by (1) and / or a salt thereof, and c is 0. .5-2 preferably 0.9-2, d represents 4-12 preferably 5-8. M in the above composition formula is usually a Na cation. Further, the above composition represents the composition per unit cell of the AFX type zeolite.

Further, the AFX-type zeolite having the above composition has a 2θ value (°) in the table below according to the XRD chart obtained by powder X-ray diffraction analysis. Further, 2θ = 21.77 ° ± 0.15 ° is the strongest line.

AFX-type zeolite is a zeolite having a structure that has been attracting attention in recent years as a catalyst material for purifying automobile exhaust gas, especially as a material for _NH3 -SCR catalyst, and has been actively filed by those skilled in the art. (Special Publication No. 2017-519627, Special Publication No. 2017-512630, and many others).

(Method for confirming AFX-type zeolite of the present invention)
In the present invention, it is confirmed by analysis by XRD that the zeolite has an AFX type structure, and it is confirmed by observing the image by SEM that the zeolite has a high crystallinity, and it is confirmed that the shape of the primary particles is in order. The presence of holes is confirmed by observing the image with SEM. It has been confirmed that the AFX-type zeolite of the present invention was obtained in this way also in the examples described later.

(Manufacturing method of AFX type zeolite of the present invention)
In the AFX type zeolite of the present invention, an aqueous solution containing a silica source, an alumina source, an alkali metal hydroxide and an organic structure defining agent (OSDA) represented by the following general formula (1) is stirred under pressurized heating conditions. It can be manufactured by (hydrothermal synthesis).

(Silica and alumina sources)
As the silica source and alumina source used as raw materials, an aluminosilicate (Si—Al element source) having a silica-alumina ratio (SiO ₂ / Al ₂ O ₃ , hereinafter sometimes referred to as “SAR”) of 2 or more and less than 50. ) Is included at least, and known substances can be used without particular limitation. The type is not particularly limited. Here, the aluminosilicate has a structure in which a part of silicon atoms in the silicate is replaced with aluminum atoms. The crystal morphology of the aluminosilicate is not particularly limited, but may be amorphous or may have a zeolite structure such as FAU. The silica-alumina ratio of the aluminosilicate is preferably 5 or more and less than 40, more preferably 10 or more and 30 or less. In the present specification, the silica-alumina ratio of the aluminosilicate means a value obtained from fluorescent X-ray analysis. Specifically, using Axios (Spectrisis), a sample obtained by pressure-molding about 5 g of a sample at 20 tons was subjected to measurement, and SAR was calculated from the results of mass% of Al ₂ O ₃ and SiO ₂ obtained. did.

As the silica source and the alumina source used as raw materials, the above-mentioned Si—Al element source can be used alone, but the Si source (however, the one corresponding to the Si—Al element source is excluded) and the Al element source. (However, those corresponding to the Si—Al element source are excluded), and a mixture of the Si element source and the Al element source can also be used as the silica source and the alumina source. For example, as a silica source and an alumina source, a Si-Al element source, a Si element source (excluding those corresponding to the Si-Al element source) and / or an Al element source (however, the Si-Al element source). It may be a mode in which (excluding those corresponding to element sources) are used in combination. Among these raw materials, it is preferable to use the Si—Al element source alone.

Examples of the Si element source include precipitated silica, colloidal silica, fumed silica, silica gel, sodium silicate (sodium metasilicate, sodium orthosilicate, sodium silicate No. 1, 2, 3, 4, etc.), tetraethoxy. Examples thereof include alkoxysilanes such as silane (TEOS) and trimethylethoxysilane (TMEOS), but the present invention is not particularly limited thereto. However, in the present specification, the aluminosilicate having a SAR of 2 or more and less than 20 corresponds to the above-mentioned Si—Al element source, and is not included in this Si element source.

As the Si element source, one type can be used alone, or two or more types can be used in any combination and ratio.

Examples of the Al element source include, but are not limited to, aluminum hydroxide, sodium aluminate, aluminum hydroxide, aluminum oxide and the like. However, in the present specification, the aluminosilicate having a SAR of 2 or more and less than 20 corresponds to the above-mentioned Si—Al element source, and is not included in this Al element source.

As for both the Si element source and the Al element source, one type can be used alone, or two or more types can be used in any combination and ratio.

Also in the AFX-type zeolite of the present invention, the SAR is preferably 2 or more and less than 50, and more preferably 10 or more and less than 20. As described above, the SAR of the AFX-type zeolite can be adjusted to the above range by using an aluminosilicate (Si—Al element source) having a SAR of 2 or more and less than 50 in the production of the AFX-type zeolite. can.

Zeolites have Si and Al as the T element, and have a continuous structure with the TO4 _tetrahedral structure centered on the T element as a unit. In this continuous structure of TO ₄ , trivalent Al ³⁺ forms cation sites and contributes to the improvement of the reactivity and adsorptivity of zeolite, while it reduces the structural strength of the tetrahedron and disturbs the crystal shape. There is a risk of making it a thing. Considering the macropores of the AFX-type zeolite of the present invention as disorder of crystal shape, low SAR may be one of the macropore-forming elements. However, it is desirable that the SAR is large in terms of the stability (durability) of the zeolite structure, but if the SAR is too large, the crystal shape may be stabilized and it may be difficult to form macropores. In the AFX-type zeolite of the present invention, it is preferable that macropores are formed and the SAR value is such that both high activity and durability can be expected.

(Alkali metal hydroxide)
The alkali metal hydroxide is not particularly limited as long as it is an alkali metal hydroxide, and examples thereof include LiOH, NaOH, KOH, CsOH, and RbOH. Among these, NaOH and KOH are preferable. Since the alkali metal can also function as an inorganic structure-directing agent, it tends to be easy to obtain an AFX-type zeolite having excellent crystallinity.

The alkali metal hydroxide may be used alone or in any combination and ratio of two or more. Further, if necessary, one or more alkali metal salts such as NaCl, KCl, LiCl, and Na ₂ CO ₃ may be used in combination with one or more of the alkali metal hydroxides.

(Organic structure regulator)
The organic structure defining agent is represented by the following general formula (1).

In the general formula (1), R ¹ to R ⁴ independently represent an alkyl group, and X represents a counter anion forming a salt with an ammonium cation. As the alkyl group, a linear or branched alkyl group having 1 to 4 carbon atoms can be preferably mentioned, and specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group and an n-butyl group. , Isobutyl group, sec-butyl group, tert-butyl group and the like. Among these alkyl groups, an alkyl group having 1 to 3 carbon atoms is preferable, and an alkyl group having 1 to 2 carbon atoms is more preferable. Specifically, the alkyl group is preferably a methyl group, an ethyl group, an n-propyl group or an isopropyl group, more preferably a methyl group or an ethyl group, and further preferably an ethyl group.

The counter anion forming a salt with the ammonium cation in the general formula (1) is not particularly limited, and may be an inorganic anion or an organic anion. Examples of the counter anion include hydroxide ion, nitrate ion, sulfate ion, carbonate ion, hydrogen carbonate ion, halide ion (fluorine, chlorine, bromine, iodine), formate ion, acetate ion, citrate ion, and tartrate acid. Examples thereof include an ion, a oxalate ion, a fumarate ion, and an anion of a saturated or unsaturated chain fatty acid having 3 to 20 carbon atoms. Among these, hydroxide ion and halide ion are preferable. As the organic structure defining agent, one or a mixture of two or more kinds represented by the general formula (1) may be used.

Specific examples of the compound represented by the general formula (1) include N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium dihydrate. Oxide, N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium diiodide, N'-tetraethylbicyclo [2.2.2] octane -2,3: 5,6-dipyrrolidinium difluoride, N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium dichloride, N'-tetraethylbicyclo [2.2] .2] Octane-2,3: 5,6-dipyrrolidinium dibromide and the like.

The above-mentioned silica source, alumina source, alkali metal hydroxide and organic structure defining agent represented by the general formula (1) are dissolved in water to prepare an aqueous solution. This aqueous solution becomes a slurry.

(water)
The water used above may be tap water, RO water, deionized water, distilled water, industrial water, pure water, ultrapure water or the like according to the desired performance.

As for the method of blending each component into water when preparing the above aqueous solution, one in which each component is separately dissolved or dispersed in water may be mixed, or all the components may be dissolved or dispersed in water. ..

At the time of the above dissolution or dispersion, a known mixer or stirrer, for example, a ball mill, a bead mill, a medium stirring mill, a homogenizer or the like may be used for wet mixing. In addition, when stirring is usually performed at a rotation speed of about 30 to 2000 rpm, more preferably 50 to 1000 rpm.

The content of each component in the aqueous solution can be appropriately set in consideration of reactivity, handleability, etc., and is not particularly limited, but the overall water-silica ratio (H ₂ O / SiO ₂ mol) at the time of zeolite synthesis. The ratio) is usually 5 or more and 100 or less, preferably 6 or more and 50 or less, and more preferably 7 or more and 40 or less. When the water-silica ratio is within the above-mentioned preferable range, stirring is facilitated at the time of preparing the aqueous solution or under the subsequent pressurized heating conditions, the handleability is improved, and the formation of by-products and impurity crystals is suppressed. It tends to be easy to obtain a high yield.

On the other hand, the hydroxide ion / silica ratio (OH ⁻ / SiO ₂ molar ratio) in the aqueous solution can also be appropriately set and is not particularly limited, but is usually 0.10 or more and 0.90 or less, preferably 0.10 or more. 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 AFX-type zeolite having excellent thermal durability tends to be easily obtained in a high temperature environment or after high temperature exposure. ..

Further, the content of the alkali metal in the aqueous solution can be appropriately set and is not particularly limited, but is not particularly limited, but is the molar ratio of the alkali metal (M) in terms of oxide, that is, the alkali metal oxide / silica ratio (M ₂ O). / 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-mentioned preferable range, crystallization by 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-determining agent / silica ratio (organic structure-determining agent / SiO ₂ molar ratio) in the aqueous solution can also be appropriately set 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, and more preferably 0.09 or more and 0.25 or less. When the organic structure-defining agent / silica ratio is within the above-mentioned preferable range, crystallization is likely to proceed, and AFX-type zeolite having excellent thermal durability in a high-temperature environment or after high-temperature exposure can be easily obtained at low cost. There is a tendency.

(Seed crystal)
Further, the aqueous solution may further contain seed crystals (seed crystals) of aluminosilicate having a desired skeletal structure from the viewpoint of promoting crystallization and the like. By blending seed crystals, crystallization of a desired skeletal structure is promoted, and high-quality aluminosilicates tend to be easily obtained. The seed crystal used here is not particularly limited as long as it has a desired skeletal structure. As the seed crystal, for example, a seed crystal of aluminosilicate having at least one skeletal structure of CHA, AEI, ERI, and AFX can be used. Needless to say, the seed crystal referred to here may be different from the AFX type, which is the object of the present invention, because it is disintegrated by the action of alkali and reconstructed by OSDA.

As the seed crystal used here, not only a separately synthesized aluminosilicate but also a commercially available aluminosilicate can be used. Of course, a natural aluminosilicate can also be used, and the AFX-type zeolite synthesized according to the present invention can also be used as a seed crystal. The cation type of the seed crystal is not particularly limited, and for example, sodium type, potassium type, ammonium type, proton type and the like can be used.

The particle size (D ₅₀ ) of the seed crystal used here is not particularly limited, but is preferably relatively small from the viewpoint of promoting crystallization of a desired crystal structure, and is 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 blending amount of the seed crystal can be appropriately set according to the desired crystallinity, and is not particularly limited, but is preferably 0.05 to 30% by mass based on the mass of SiO ₂ in the aqueous solution. It is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass.

The silica-alumina ratio of the seed crystal is arbitrary, but it is preferably the same as or about the same as the silica-alumina ratio of the mixture. From this viewpoint, the silica-alumina ratio of the seed crystal is preferably 5 or more and 50 or less. It is more preferably 8 or more and less than 40, and further preferably 10 or more and less than 30.

(Hydrothermal synthesis)
The aqueous solution obtained as described above is then stirred under pressurized heating conditions (hydrothermal synthesis).

As the reaction vessel used for this hydrothermal synthesis, a known one can be appropriately used as long as it is a closed pressure-resistant vessel that can be used for hydrothermal synthesis, and the type thereof is not particularly limited. For example, a closed heat resistant pressure resistant container such as an autoclave equipped with a stirrer, a heat source, a pressure gauge, and a safety valve is preferably used. The crystallization of the AFX-type zeolite may be carried out in a state where the above-mentioned mixture (raw material composition) is allowed to stand, but from the viewpoint of improving the uniformity of the obtained AFX-type zeolite, the above-mentioned mixture (raw material composition) is used. ) May be performed in a state of stirring and mixing. At this time, it is usually preferable to carry out the rotation at a rotation speed of about 30 to 2000 rpm, and more preferably 50 to 1000 rpm. Further, stirring may be performed intermittently for the purpose of controlling the crystal grain size and the like.

The heating temperature for hydrothermal synthesis is not particularly limited, but is usually 100 ° C. or higher and 200 ° C. or lower, preferably 120 ° C. or higher and 190 ° C. or lower, more preferably 150, from the viewpoint of crystallinity and economic efficiency of the obtained AFX-type zeolite. ° C or higher and 180 ° C or lower.

The treatment time for hydrothermal synthesis may be crystallization over a sufficient period of time and is not particularly limited, but is usually 1 hour or more and 20 days or less from the viewpoint of crystallization and economic efficiency of the obtained aluminosilicate. It is preferably 4 hours or more and 15 days or less, and more preferably 12 hours or more and 10 days or less.

The pressurizing pressure for hydrothermal synthesis is not particularly limited, and the spontaneous pressure generated when the mixture charged in 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.

By performing such hydrothermal treatment, crystallized AFX-type zeolite can be obtained. At this time, if necessary, a solid-liquid separation treatment, a water washing treatment, for example, a drying treatment for removing water at a temperature of about 50 to 150 ° C. in the air may be performed according to a conventional method.

(Post-processing)
The AFX-type zeolite thus obtained may contain an organic structure-regulating agent, an alkali metal, or the like in the macropores or the like. Therefore, it is preferable to perform a removal step for removing these, if necessary. The removal of the organic structure defining agent, the alkali metal 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 a decomposition component of an organic structure defining agent, exchange treatment using a resin or the like, It is possible to perform a firing process or the like. These processes can be performed in any combination. Among these, a firing treatment is preferably used for removing the organic structure defining agent, the alkali metal, and the like from the viewpoint of production efficiency and the like.

The processing temperature (calcination temperature) in the firing process can be appropriately set according to the raw materials used, etc., and is not particularly limited, but from the viewpoint of maintaining crystallinity and reducing the residual ratio of the structural regulator, alkali metal, etc. It 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 further 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 atmospheric atmosphere.

The treatment time (baking time) in the firing 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, more preferably. Is 3 hours or more and 40 hours or less.

(Use)
The application of the AFX-type zeolite of the present invention is not limited, and various catalyst applications can be mentioned. For example, an automobile catalyst application such as purification of exhaust gas discharged from an internal combustion engine is preferable. In addition to the NH ₃ -SCR catalyst described above, such automobile catalyst applications include a filter catalyst (SCRoF) for filtering out fine particles such as soot from the exhaust gas of a diesel engine while purifying NOx like SCR. (There is also), NH ₃ -SCR post-stage oxidation catalyst (sometimes called AMOX or Slip-DOC) for oxidizing NH ₃ that could not be used for NOx purification with NH ₃ -SCR catalyst, etc. Can also be used. It should be noted that these SCR catalysts are not limited to those used for diesel engines, and may be used for gasoline engines. In addition to the SCR catalyst, a three-way catalyst (TWC) for purifying NOx, hydrocarbons (HC), and carbon monoxide (CO) in the exhaust gas emitted from gasoline vehicles, such TWC. GPF (Gasoline Particulate Filter) that collects and purifies soot in gasoline engine exhaust gas, and HC used to temporarily adsorb HC in exhaust gas regardless of whether it is a gasoline engine or diesel engine. -May be used as a trap (Hydro Carbon Trap) catalyst.

In the above-mentioned automobile catalyst applications, the catalyst component coats the surface of a structural carrier formed into a honeycomb shape by a heat-resistant inorganic oxide such as a metal plate or cordierite, or invades the inside of a partition wall constituting the honeycomb structure. By doing so, it is used as a structural catalyst (sometimes called a monolith catalyst or a honeycomb catalyst). Needless to say, the zeolite of the present invention can also be used in such a honeycomb structure as one of the catalyst components. Further, the zeolite of the present invention is combined with other catalyst components to form a catalyst composition, and this catalyst composition is combined with another catalyst composition to form a part of the front portion or the rear portion of the honeycomb structure in the exhaust gas flow direction. , In the case of laminated coating, it may be used for a part of the upper layer or the lower layer thereof.

Further, with respect to the AFX-type zeolite of the present invention, if necessary, a transition metal such as iron or copper or a noble metal such as platinum, palladium or rhodium is added by a known method for the purpose of improving the reactivity as a catalyst. Is also good.

The AFX-type zeolite to which such a transition metal or a noble metal is added can be used for the above-mentioned _NH3 -SCR, SCRoF, Slip-DOC and the like as long as it is to which a transition metal such as copper or iron is added. If it is added with a noble metal, it can be used for applications such as TWC, GPF, and HC-trap.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

= Manufacture of organic structure directional agents =
The OSDA used in the examples of the present invention hydrogenates N, N'-diethylbicyclo [2.2.2] octo-7-en-2, 3: 5,6-dipyrrolidine (molecular weight 246.39). , N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium diiodide, obtained by ion exchange of this iodide, N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium dihydroxide.

[Synthesis Example 1]
Synthesis of N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium diiodide: N, synthesized according to JP-A-2016-169139. 370.0 g of N'-diethylbicyclo [2.2.2] octo-7-en-2,3: 5,6-dipyrrolidine (molecular weight 246.39) was dissolved in 1,200 mL of isopropyl alcohol (IPA) modified alcohol. Add 31.08 g (equivalent to 1.0 mol% of the substrate as palladium) in terms of dry mass to a 5% palladium carbon catalyst (K-type water-containing product manufactured by N.E. Chemcat), and hydrogen at 50 ° C. and normal pressure for 190 hours. It was reacted. The conversion rate of the substrate by gas chromatography (GC) was 99% or more. This was separated by filtration to remove the catalyst, and then 516.0 g of ethyl iodide (molecular weight 155.11, 2.2 eq) was added dropwise with stirring. After gently refluxing for 16 hours in a nitrogen atmosphere, the mixture is allowed to cool, filtered, washed with acetone and dried to obtain the desired product N, N, N', N'-tetraethylbicyclo [2.2.2]. ] Octane-2,3: 5,6-dipyrrolidinium diiodide white powder 703.0 g (yield 90%) was obtained. The ¹ H-NMR and ¹³ C-NMR of the obtained white powder are shown below. In addition, ¹ H _- NMR spectral data of a D2O solution of N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium diiodide is shown in FIG. ¹³ C-NMR spectrum data is shown in FIG.

^{1 1} H-NMR (400MHz, D ₂ O) δ: 3.82 (dd, 4H), 3.49 (q4, 4H), 3.38 (q4, 4H), 3.33 (d, 4H), 2 .69 (m, 4H), 1.80 (s, 2H), 1.64 (s, 4H), 1.36 (t, 6H), 1.31 (t, 6H). ¹³ C-NMR (100Hz, D2O) δ: 65.00 (× 4), 58.51 (× ₂ ), 54.41 (× 2), 40.11 (× 4), 28.33 (×) 2), 14.86 (x2), 11.01 (x2), 10.17 (x2)

The conditions for the gas chromatography were as follows.
Device name: GCMS-QP2010 (manufactured by Shimadzu Corporation)
Column: SH-Rtx-200MS manufactured by SHIMADZU
Carrier gas: Total helium flow rate: 98.9 mL / min
Column flow rate: 2.56 mL / min
Temperature: The column oven was heated from 40 ° C to 300 ° C in increments of 10 ° C / min. After that, it was held at 300 ° C. for 10 minutes.

Moreover, the measurement conditions of the above NMR were as follows.
Device name: Ascend4000 (manufactured by BRUKER)
Measuring method: ^{1 1} H-NMR and ¹³ C-NMR were measured by dissolving the sample in heavy water.

[Synthesis Example 2]
N, N'-diethylbicyclo [2.2.2] Oct-7-en-2, 3: 5,6-Dipyrrolidine synthesis:
The N, N'-diethylbicyclo [2.2.2] octo-7-en-2,3: 5,6-dipyrrolidin in Synthesis Example 1 can also be synthesized by the following method.

(1) Preparation of catalyst: Pt-V / HAP
To 90 mL of acetone, add Pt (acac) ₂ (platinum acetylacetonate, 0.4 mmol) manufactured by N.E. Chemcat and VO (acac) ₂ (vanadyl acetylacetonate, 0.4 mmol) manufactured by Sigma-Aldrich, and at room temperature. The mixture was stirred for 30 minutes. Further, 1.0 g of HAP (trade name "tricalcium phosphate") manufactured by Wako Pure Chemical Industries, Ltd. was added, and the mixture was stirred at room temperature for 4 hours. The solvent was removed from the resulting mixture with a rotary evaporator to give a pale green powder. The obtained powder was dried at 110 ° C. overnight. Further, the dried powder was pulverized in an agate pot and calcined in the air at 300 ° C. for 3 hours to obtain a dark gray powder (Pt-V / HAP).

(2) Synthesis of N, N'-diethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidin 0.3 g of Pt-V / HAP thus obtained, JP-A-2016. N, N'-diethylbicyclo [2.2.2] octo-7-en-2,3: 5,6-tetracarbonyldiimide 0.3 mmol synthesized according to the method described in -169139, Wako Pure Chemical Industries, Ltd. Add 0.1 g of Molecular Sieves 4 Å to 50 mL of stainless steel autoclave, add 5 mL of the solvent 1,2-dimethoxyethane (DME), and hydrogenate at a reaction temperature of 150 ° C. and a hydrogen pressure of 5 MPa for 48 hours. Was done. After the reaction, the yield of N, N'-diethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidin was measured using GC-MS, and the yield was 77%. It was confirmed by NMR measurement of the isolated component that the product of Synthesis Example 2 was the same compound that became the OSDA precursor as Synthesis Example 1.

[Synthesis Example 3]
N, N'-diethylbicyclo [2.2.2] Oct-7-en-2, 3: 5,6-Dipyrrolidine synthesis:
In addition to Synthesis Example 2, N, N'-diethylbicyclo [2.2.2] Oct-7-en-2, 3: 5,6-dipyrrolidine can also be synthesized by the following method.

(1) Preparation of catalyst: Rh-Mo / HAP
To a 100 ml eggplant flask containing 80 ml of distilled water, 0.2 mmol of _{3H 2 Oaq} manufactured by N.E. 1.0 g of HAP (trade name "tricalcium phosphate") manufactured by Kojun Yakuhin Co., Ltd. was added and heated to 80 ° C., and the mixture was stirred in this state for 15 hours and then allowed to stand for 1.5 hours to cool to room temperature. 25 ml (Mo content: 1.0 mmol) of (NH ₄ ) ₆ Mo ₇ O _{24.4H 2} Oaq (40 mM) was added dropwise to the allowed to cool solution, and the mixture was heated to 50 ° C. and then stirred for 3 hours. After stirring, the mixture was filtered, and the mixture was filtered and washed using about 1 L of distilled water. The filtered and washed filtrate was dried at 120 ° C. for 8 hours or more to obtain Rh-Mo / HAP (Rh: 0.2 mmol / g, Mo: 0.017 mmol / g).

(2) OSDA precursor: N, N'-diethylbicyclo [2.2.2] Octane-2, 3: 5,6-Dipyrrolidine synthesis:
0.3 g of Rh-Mo / HAP thus obtained was synthesized according to the method described in JP-A-2016-169139. N, N'-diethylbicyclo [2.2.2] Oct-7- En-2,3: 5,6-tetracarbonyldiimide 0.3 mmol, Wako Pure Chemical Industries, Ltd. Molecular Sieves 4Å 0.1 g was added to a 50 mL stainless steel autoclave, and the solvent 1,2-dimethoxyethane (DME) 5 mL. Was added, and a hydrogenation reaction was carried out for 48 hours under a reaction temperature of 160 ° C. and a hydrogen pressure of 5 MPa. After the reaction, the yield of N, N'-diethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidin was measured using GC-MS, and the yield was 60%. It was confirmed by NMR measurement of the isolated component that the product of Synthesis Example 3 was the same OSDA precursor compound as the target Synthesis Example 1 as in Synthesis Example 1.

[Synthesis Example 4]
OSDA: N, N, N', N'-Tetraethylbicyclo [2.2.2] Octane-2, 3: 5,6-Dipyrrolidinium Dihydride Synthesis:
120.0 g of N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium diiodide (molecular weight 558.62) obtained in Synthesis Example 1 was added. Ion exchange was performed by dissolving in 800 mL of water, adding 800.0 g of iodide SA10AOH (manufactured by Mitsubishi Chemical Corporation), and stirring at room temperature for 48 hours. After filtration and washing, the filtrate and washing liquid are combined and concentrated to a mass of 379.9 g, and 19.26% by mass of N, N, N', N'-tetraethylbicyclo [2.2.2] octane- 2,3: 5,6-dipyrrolidinium dihydroxide (molecular weight 340.55) was obtained.

[Example 1]
Synthesis of AFX type zeolite:
4 in 20.0 g of an aqueous solution of N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2, 3: 5,6-dipyrrolidinium dihydroxide of Synthesis Example 4 in an amount of 9.43% by mass. 19.0 g of an 0.8% sodium hydroxide solution, 11.0 g of FAU-type zeolite (SAR17), and 70.0 g of water were stirred and held in the reactor for 16 hours. The composition of this aqueous solution is as follows when SiO ₂ is 1. The composition of the following mixture is a weight ratio.

SiO ₂
0.059 Al ₂ O ₃
0.075 OSDA
0.075 Na ₂ O
40.00 H ₂ O

Then, the temperature was raised until the internal pressure of the reactor reached 0.65 MPa, and the mixture was kept stirred in that state for 216 hours. The product after this hydrothermal treatment was solid-liquid separated, the obtained solid phase was washed with a sufficient amount of water, and the product dried at 105 ° C. was calcined at 600 ° C. in the air atmosphere. When SEM observation was performed on this, zeolite was mainly a bihexagonal pyramidal crystal, and there were macropores on the crystal surface, and when particles in 10 μm square of the SEM image were confirmed, the particle size was 1 μm in each case. It was found that the crystal shape and particle size were moderate and well-organized. SEM photographs are shown in FIGS. 3 and 4. Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite. The XRD chart is shown in FIG. 5, and the diffraction peaks are shown in Table 2. Moreover, when the fluorescent X-ray analysis of the obtained AFX-type zeolite was performed, the SAR was 16.1. In addition, the numerical value regarding the radius of the macropore was calculated by using the result of measuring the long diameter and the short diameter of any 50 macropores from the SEM photograph of the product. The average value of the geometric mean radius calculated from the long diameter and the short diameter was 85.2 nm, the maximum value was 118.1 nm, and the minimum value was 56.2 nm.

[Example 2]
Synthesis of AFX type zeolite:
N, N, N', N'-Tetraethylbicyclo [2.2.2] Octane-2, 3: 5,6-dipyrrolidinium diiodide (molecular weight 558.62) 124.0 g, 4.8 mass% hydroxide 524.0 g of sodium solution, 170.0 g of FAU-type zeolite CBV712 (silica-alumina ratio SAR10.9) manufactured by Zeolist, and 134.0 g of water were stirred in a polyethylene beaker for 72 hours. The composition of this aqueous solution is as follows when SiO ₂ is 1. The composition of the following aqueous solution is a weight ratio.

SiO ₂
0.092 Al ₂ O ₃
0.105 OSDA ²⁺
0.302 Na ^+
0.210 I-
0.302 ^OH-
17.78 H ₂ O

Next, this raw material composition (mixture) was divided into four stainless steel airtight pressure-resistant containers of 300 cc inner cylinder Teflon (registered trademark) and kept standing at 170 ° C. for 40 hours. The products after this hydrothermal treatment were collectively solid-liquid separated, and the obtained solid phase was washed with a sufficient amount of water and dried at 105 ° C. to obtain a product. When SEM observation was performed on this, zeolite was mainly a dihexagonal pyramidal crystal, and there were macropores on the crystal surface. It was found that the particle size of each crystallized particle was about 2 μm except for. SEM photographs are shown in FIGS. 6 and 7. Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite as in Example 2. The SAR by fluorescent X-ray analysis was 10.7. In addition, the numerical value regarding the radius of the macropore was calculated by using the result of measuring the long diameter and the short diameter of any 50 macropores from the SEM photograph of the product. The average value of the geometric mean radius calculated from the long diameter and the short diameter was 141.6 nm, the maximum value was 212.3 nm, and the minimum value was 57.8 nm.

[Example 3]
Synthesis of AFX type zeolite (coexistence of chloride):
21.35% by mass N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium dihydroxide (molecular weight 340.55) solution 41.9 g, 4.8% by mass sodium hydroxide solution 43.5 g, sodium chloride 3.0 g, FAU type zeolite HSZ-350HUA (manufactured by Toso Co., Ltd., silica-alumina ratio SAR11.1) 24.6 g, water 87.0 g in a polyethylene beaker. The mixture was stirred for 24 hours. The composition of this aqueous solution is as follows when SiO ₂ is 1. The composition of the following aqueous solution is a weight ratio.

SiO ₂
0.090 Al ₂ O ₃
0.076 OSDA ²⁺
0.298 Na ⁺
0.148 ^Cl-
0.302 ^OH-
26.06 H ₂ O

Next, this raw material composition (mixture) was placed in a stainless steel closed pressure-resistant container with a 300 cc inner cylinder Teflon and kept standing at 170 ° C. for 144 hours. The product after this hydrothermal treatment was separated into solid and liquid, and the obtained solid phase was washed with a sufficient amount of water and dried at 105 ° C. to obtain a product. When SEM observation was performed on this, zeolite was mainly a dihexagonal pyramidal crystal, and there were macropores on the crystal surface. It was found that the particle size of all the crystallized particles was about 1.7 μm except for. SEM photographs are shown in FIGS. 8 and 9. Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite. The SAR by fluorescent X-ray analysis was 10.4.

After the crystals of the AFX-type zeolite were hardened with an epoxy resin, the cross section of the zeolite produced by polishing with an automatic polishing machine (KIRIME Rana-3) manufactured by MIT Co., Ltd. was observed by SEM. An SEM photograph of the cross section is shown in FIG. From this, it was found that the AFX-type zeolite particles of Example 3 had macropores on the surface and cavities inside.

[Example 4]
Synthesis of AFX type zeolite (coexistence of fluoride):
21.35 mass% N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium dihydroxide (molecular weight 340.55) solution 7.5 g, 4.8 mass% sodium hydroxide solution 3.9 g, sodium fluoride 0.4 g, FAU type zeolite HSZ-350HUA (manufactured by Toso Co., Ltd., silica-alumina ratio SAR 11.1) 3.3 g, water 11.2 g in a polyethylene beaker. Was stirred for 24 hours. The composition of this aqueous solution is as follows when SiO ₂ is 1. The composition of the following aqueous solution is a weight ratio.

SiO ₂
0.090 Al ₂ O ₃
0.101 OSDA ²⁺
0.300 Na ⁺
0.200 ^F-
0.302 ^OH-
25.10 H ₂ O

Next, this raw material composition (mixture) was placed in a stainless steel airtight pressure vessel of 50 cc inner cylinder Teflon and kept standing at 170 ° C. for 144 hours. The product after this hydrothermal treatment was separated into solid and liquid, and the obtained solid phase was washed with a sufficient amount of water and dried at 105 ° C. to obtain a product. When SEM observation was performed on this, zeolite was mainly a dihexagonal pyramidal crystal, and there were macropores on the crystal surface. It was found that the particle size of the crystallized particles was about 1.5 μm.
SEM photographs are shown in FIGS. 11 and 12. Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite. The SAR by fluorescent X-ray analysis was 10.6.

After the crystals of the AFX-type zeolite were hardened with an epoxy resin, the cross section of the zeolite produced by polishing with an automatic polishing machine KIRIME Rana-3 manufactured by IMT Co., Ltd. was observed by SEM. An SEM photograph of the cross section is shown in FIG. As a result, it was found that the AFX-type zeolite particles of Example 4 also had macropores on the surface and cavities inside.

Further, FIG. 14 shows an image of different particles observed by STEM in Example 1, and FIG. 15 shows a CT image of a predetermined cross section of the particle. In FIG. 14, it can be seen that macropores are formed on the particle surface, and in FIG. 15, it can be seen that the macropores on the particle surface extend deep inside the particle to the center of the particle where the hollowness is confirmed.

[Reference Example 1]
FAU-type zeolite dealuminum:
FAU type zeolite HSZ-350HUA (manufactured by Tosoh, silica-alumina ratio SAR11.1) 400.0 g, 60 mass% nitric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 84.0 g, 4 L of water in a SUS316 beaker for 24 hours It was stirred. The mixture was solid-liquid separated, the resulting solid phase was washed with a sufficient amount of water and dried at 105 ° C. to give the product. The SAR by X-ray fluorescence analysis was 14.0.

[Example 5]
Synthesis of AFX type zeolite:
21.35% by mass N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium dihydroxide (molecular weight 340.55) solution 35.0 g, 36.0 g of a 4.8 mass% sodium hydroxide solution, 21.0 g of the SAR14.0 FAU-type zeolite obtained in Reference Example 1, and 108.0 g of water were stirred in a SUS316 beaker for 24 hours. The composition of this mixture is as follows when SiO ₂ is 1. The composition of the following aqueous solution is the amount of substance ratio.

SiO ₂
0.071 Al ₂ O ₃
0.080 OSDA ²⁺
0.158 Na ⁺
0.318 ^OH-
35.15 H ₂ O

Next, this raw material composition (mixture) was placed in a stainless steel closed pressure-resistant container with a 300 cc inner cylinder Teflon and kept standing at 170 ° C. for 144 hours. The product after this hydrothermal treatment was separated into solid and liquid, and the obtained solid phase was washed with a sufficient amount of water and dried at 105 ° C. to obtain a product. When SEM observation was performed on this, zeolite was mainly a dihexagonal pyramidal crystal, and there were macropores on the crystal surface. It was found that the particle size of all the crystallized particles was about 0.8 μm except for.
Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite. The SAR by fluorescent X-ray analysis was 13.4. From the SEM photograph of the product, the numerical value regarding the radius of the macropore was calculated by using the result of measuring the long diameter and the short diameter of any 50 macropores. The average value of the geometric mean radius calculated from the long diameter and the short diameter was 77.2 nm, the maximum value was 212.3 nm, and the minimum value was 57.8 nm.

[Comparative Example 1]
Synthesis of AFX type zeolite:
20.0 mass% 1,1'-(1,4-butanjiyl) bis (1-azonia-4-azabicyclo [2.2.2] octane dihydroxide (molecular weight 314.47) solution 310. A mixture of 0 g, 48 mass% sodium hydroxide solution 99.0 g, and FAU type zeolite CBV-720 (Zeolist, silica-alumina ratio SAR30.0) 139.0 g was concentrated to a total mass of 400.0 g.
The composition of the mixture at this time is as follows when SiO ₂ is 1. The composition of the following mixture is the amount of substance ratio.

SiO ₂
0.033 Al ₂ O ₃
0.100 OSDA ²⁺
0.602 Na ^+
0.802 OH-
5.06 H ₂ O

Next, this raw material composition (mixture) was placed in a 300 cc inner cylinder Teflon stainless steel airtight pressure vessel in two portions and kept at 140 ° C. for 96 hours. The product after this hydrothermal treatment was separated into solid and liquid, and the obtained solid phase was washed with a sufficient amount of water and dried at 105 ° C. to obtain a product. When SEM observation was performed on this, no macropores were confirmed in the zeolite particles.
Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite. The SAR by fluorescent X-ray analysis was 7.5.

[Comparative Example 2]
Synthesis of AFX type zeolite:
19.47 mass% N, N, N', N'-tetraethylbicyclo [2.2.2] octane-2,3: 5,6-dipyrrolidinium dihydrate (molecular weight 340.55) solution 580.0 g, 28 g of 48 mass% sodium hydroxide solution, 265.0 g of FAU-type zeolite CBV712 (silica-alumina ratio SAR10.9) manufactured by Zeolist, and 542.0 g of water were stirred in a polyethylene beaker for 24 hours. The composition of the mixture at this time is as follows when SiO ₂ is 1. The composition of the following mixture is the amount of substance ratio.

SiO ₂
0.092 Al ₂ O ₃
0.102 OSDA ²⁺
0.104 Na ⁺
0.308 ^OH-
18.35 H ₂ O

Next, this raw material composition (mixture) was placed in a 1.2 L stainless steel autoclave and kept standing at 160 ° C. for 240 hours while stirring at 300 rpm. The product after this hydrothermal treatment was separated into solid and liquid, and the obtained solid phase was washed with a sufficient amount of water and dried at 105 ° C. to obtain a product. When SEM observation was performed on this, no macropores were confirmed in the zeolite particles.
Further, when powder X-ray diffraction analysis was performed on this, it was confirmed that the product was a single phase of AFX-type zeolite. The SAR by fluorescent X-ray analysis was 10.7.

[Fractal dimension]
The fractal dimension is a concept that expresses coarseness, and it is known that the fractal dimension of a partially sparse plane figure takes a numerical value between one dimension of a straight line and two dimensions of a plane. Similarly, it is known that a sparse solid such as a porous body has a fractal dimension of 2 or more and 3 or less. Regarding the calculation of the fractal dimension of the fractal dimension of an existing porous body, a method of calculating the fractal dimension using the data of the pore distribution measurement by the mercury intrusion method is known (reference: Applied Surface Science 253 (2006) 1349-1355). .. In the mercury press-fitting method, as the pressure of mercury is gradually increased, the volume of mercury press-fitted into the porous body increases accordingly. Assuming that the pressure of mercury in the n-th stage is P _n and the press-fit volume of mercury increased when the pressure of mercury in the n-th stage is changed from the (n-1) stage to the n-th stage is ΔV _n , the work W _n that the mercury has done up to the n-th stage is Is expressed by the following equation.

It is known that the fractal dimension Df corresponds to the slope of the plot of the following equation, _where rn is the pore radius corresponding to P _n .

Further, it is recommended that the calculation of the fractal dimension is performed by dividing the region rather than performing the calculation in the entire region of the pores.
For Example 1, Example 2, Example 5, Comparative Example 1, and Comparative Example 2 in which the pore distribution was measured by the mercury intrusion method, the pore distribution was divided into two parts based on the mode radius of each pore distribution, and the mode radius was used. Table 3 shows the results of obtaining the fractal dimension of the small pore size region.

Further, the fractal dimension corresponding to the pore volume in the pore diameter region smaller than the mode radius is plotted on the horizontal axis and the fractal dimension corresponding to the pore diameter region smaller than the mode radius is plotted on the vertical axis as shown in FIG. Compared with the straight line represented by D _f = 0.5833V _m + 1.8833, the AFX type zeolite having macropores has D _f <0.5833V _m +1.8833, and the AFX type having no macropores. It was suggested that the fractal dimension is smaller than that of zeolite.

The AFX-type zeolite of the present invention can be used for various purposes like the conventional AFX-type zeolite, and can be particularly used for purifying exhaust gas discharged from an internal combustion engine.

Claims (10)

AFX-type zeolite characterized by having macropores on the surface of crystallized AFX-type zeolite particles. The AFX-type zeolite according to claim 1, wherein the crystallized particles have a shape in which two polyhedra are bonded by sharing one equatorial plane. The AFX-type zeolite according to claim 1, wherein the crystallized particles have a bi-polygonal pyramid shape. The AFX-type zeolite according to any one of claims 1 to 3, which has a space inside the particles. The AFX-type zeolite according to any one of claims 1 to 4, wherein the oxide-equivalent silicon and aluminum contained in the AFX-type zeolite particles are 2 or more and less than 50 in terms of the molar ratio of silica / alumina. The AFX-type zeolite according to any one of claims 1 to 5, wherein the geometric mean radius of the macropores is 25 nm to 250 nm. The AFX-type zeolite according to any one of claims 4 to 6, wherein the space inside the particles and the macropores on the surface of the particles are connected. Silica source, alumina source, alkali metal hydroxide and the following general formula (1)

(In the formula (1), R ¹ to R ⁴ each independently represent an alkyl group, and X represents a counter anion forming a salt with an ammonium cation), and the aqueous solution containing the organic structure defining agent is pressurized. The method for producing an AFX-type zeolite according to any one of claims 1 to 7, wherein the mixture is stirred under heating conditions. A catalyst comprising the AFX-type zeolite according to any one of claims 1 to 7 as an active ingredient. The catalyst according to claim 9, which is for an NH ₃ -SCR catalyst.

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