JP6759596B2 - AFX type zeolite and its manufacturing method - Google Patents

Description

The present invention relates to AFX-type zeolite and a method for producing the same. Furthermore, the present invention relates to an AFX-type zeolite having mesopores and a method for synthesizing an AFX-type zeolite without using an organic structure-directing agent.

AFX type zeolite is S.I. I. It is the first synthetic zeolite synthesized by Zones (Patent Document 1) and has an oxygen double six-membered ring (hereinafter referred to as "D6R") in its crystal structure. Zeolites having D6R in their crystal structure are expected as catalysts for olefin production and selective catalytic reduction catalysts (so-called SCR catalysts).

However, the methods for producing AFX-type zeolite reported so far are limited, and the following methods for producing AFX-type zeolite are widely known.

One of the methods for producing AFX-type zeolite is a method for crystallizing a composition containing a quinuclidine derivative as an organic structure-directing agent (hereinafter, also referred to as “OSDA”) (Patent Document 1, Non-Patent Document 1). However, since the quinuclidine derivative is a very expensive compound, the production method of Patent Document 1 and the AFX-type zeolite produced by the method cannot be industrially applied, and of course, it should be a practical production method. I couldn't.

The other method for producing AFX-type zeolite is the production of crystallizing a composition containing 1,4-diazabicyclo [2.2.2] -octane-C4-diquat dibromid (hereinafter referred to as "DC4Br"). This is a method (Patent Documents 2 and 3, Non-Patent Documents 2 to 4). DC4Br is cheaper than quinuclidine derivatives. Therefore, these manufacturing methods using DC4Br as OSDA may be industrially applicable. On the other hand, in the production method using DC4Br, Y-type zeolite, which is a zeolite containing D6R in the crystal structure, is used as a raw material, and D6R facilitates AFX structure formation to produce AFX-type zeolite from Y-type zeolite. It was a thing.

U.S. Pat. No. 4,508,837 U.S. Pat. No. 5,194,235 International release 2010/118377

Chem Matter 8 (1996) 2409-2411 The Journal of Physical Chemistry C 114 (2010) 1633-1640 Applied Catalysis B: Environmental 102 (2011) 441-448 ACS Catalysis 2 (2012) 2490-2495

A method for producing an AFX-type zeolite that crystallizes a composition containing DC4Br and an AFX-type zeolite obtained by this method are expected to have industrial application. On the other hand, in applications with catalysts, especially SCR catalysts, it is necessary to further improve the catalyst properties.

In view of these problems, an object of the present invention is to provide an AFX-type zeolite that can be applied as an industrial catalyst. Furthermore, another object is to provide an industrial production method for producing such an AFX-type zeolite.

The present inventor investigated AFX type zeolite. As a result, the AFX-type zeolite obtained by crystallizing the composition containing DC4Br does not sufficiently diffuse the substance, and by controlling the pore state of the AFX-type zeolite, the substance diffusion is excellent and the catalyst is used. We have found that the characteristics are improved. Furthermore, we have found an inexpensive method for producing AFX-type zeolite, which can industrially produce AFX-type zeolite having excellent material diffusion.

That is, the present invention is an AFX-type zeolite having mesopores.

Hereinafter, the AFX-type zeolite of the present invention will be described.

The present invention relates to AFX type zeolite. The AFX-type zeolite is a zeolite having an AFX structure, and is particularly an aluminosilicate having an AFX structure.

The AFX structure is an IUPAC structure code (hereinafter, simply referred to as “structure code”) defined by the Structure Communication of the International Union of Pure and Applied Zeolite Association, and is an AFX type structure.

The molar ratio of silica to alumina of the AFX-type zeolite of the present invention (hereinafter, also referred to as “SiO ₂ / Al ₂ O ₃ ratio”) is preferably 4 or more. The SiO ₂ / Al ₂ O ₃ ratio may be a value suitable for each application such as a catalyst. When the SiO ₂ / Al ₂ O ₃ ratio is 4 or more, further 5 or more, and further 6 or more, it has catalytic properties and heat resistance applicable to catalysts and the like. The heat resistance tends to increase as the SiO ₂ / Al ₂ O ₃ ratio increases, but in order to achieve both catalytic properties and heat resistance, the SiO ₂ / Al ₂ O ₃ ratio of the AFX-type zeolite of the present invention is It is preferably 50 or less, more preferably 30 or less, and even more preferably 15 or less.

The AFX-type zeolite of the present invention has mesopores. The mesopores and micropores in the present invention follow the definition of IUPAC. That is, pores having a pore diameter of less than 2 nm are micropores, pores having a pore diameter of 2 nm or more and 50 nm or less are mesopores, and pores having a pore diameter of more than 50 nm are macropores.

The fact that the AFX-type zeolite of the present invention has mesopores can be confirmed by measuring the adsorption and desorption of nitrogen. In the nitrogen adsorption / desorption measurement, the adsorption isotherm and the desorption isotherm of a substance having no mesopores show almost the same behavior. On the other hand, in a substance having mesopores, desorption of nitrogen is unlikely to occur, so that there is a portion where the adsorption isotherm and the desorption isotherm do not match in a specific pressure range. The AFX-type zeolite of the present invention has a discrepancy between the adsorption isotherm and the desorption isotherm (hereinafter, also referred to as “hysteresis loop”) in the nitrogen adsorption / desorption measurement at the measurement temperature of 77K, and further, the relative pressure (hereinafter, also referred to as “hysteresis loop”). it has a hysteresis loop in the P _/ P 0) 0.4~0.9, also be mentioned that even with H4, type hysteresis loop in the relative pressure _(P / P 0) 0.4~0.9. The H4 type hysteresis loop is based on the definition of IUPAC.

AFX-type zeolite of the present invention, the cation type of the AFX type zeolite in a case where the NH ₄ form, it is preferable that the nitrogen adsorption amount at the nitrogen adsorption-desorption measurements under liquid nitrogen temperature satisfies the following relationship.

V _P1- V _P2 ≧ 0.7
In the above formula, _VP1 is a value (mL / g) obtained by converting the amount of nitrogen adsorbed at a relative pressure (P / P ₀ ) of 0.9 in the desorption process of saturated nitrogen at 0 ° C. and 1 atm. On the other hand, _VP2 is a value (mL / g) obtained by converting the amount of nitrogen adsorbed at a relative pressure (P / P ₀ ) of 0.4 in the desorption process of saturated nitrogen at 0 ° C. and 1 atm. Moreover, 77K can be mentioned as a liquid nitrogen temperature.

In the nitrogen adsorption / desorption measurement, when the amount of nitrogen adsorption at relative pressures (P / P ₀ ) 0.9 and 0.4 is not directly measured, it is measured within the range of each relative pressure (P / P ₀ ) ± 0.05. It was a nitrogen adsorption amount, corresponding plots of the nitrogen adsorption amount from a line connecting a straight line at a relative pressure of the nearest two points to each relative pressure (P / P _0), each relative pressure (P / P ₀₎ The value obtained by converting the amount of nitrogen adsorbed at 0 ° C. and 1 atm is defined as _VP1 and _VP2 .

Additional V _{P1 -V} P2 _{(hereinafter,} referred to as "mesopore adsorption".) Is indicative that reflects the pore volume of the mesopores. The larger the amount of mesopores adsorbed, the larger the mesopore volume of the AFX-type zeolite of the present invention. Since the diffusion of substances in the crystal structure is further promoted, the amount of mesopores adsorbed is preferably 7 (mL / g) or more, more preferably 9 (mL / g). On the other hand, it can be confirmed that the AFX-type zeolite having no mesopores does not have an H4 type hysteresis loop or the amount of mesopores adsorbed is 5 (mL / g) or less.

From the viewpoint of promoting substance diffusion and packing of particles, the amount of mesopores adsorbed is preferably 20 mL / g or less, more preferably 16 mL / g or less, and further preferably 14 mL / g or less.

The AFX type zeolite of the present invention has micropores. Since the micropores serve as a reaction field in a catalytic reaction or an adsorption field in an adsorption reaction, the AFX-type zeolite of the present invention preferably contains a large number of micropores, and is also referred to as the pore volume of the micropores (hereinafter, also referred to as “micropore volume”). ) Is preferably 0.20 mL / g or more, further 0.22 mL / g or more, further 0.24 mL / g or more, and further preferably 0.25 mL / g or more. Since the micropores are derived from the crystal structure of AFX-type zeolite, there is an upper limit to the micropore volume of AFX-type zeolite. Therefore, the micropore volume of the AFX-type zeolite of the present invention is 0.40 mL / g or less, further 0.35 mL / g or less, and further 0.30 mL / g or less.

Here, the micropore volume in the present invention is a value measured by the t-plot method.

As described above, the AFX-type zeolite of the present invention has a structure having micropores and mesopores. Such a hierarchical pore structure promotes the diffusion of the reactant in the reaction in which the diffusion in the micropores is rate-determining. This enhances the catalytic properties of the AFX-type zeolite of the present invention.

The AFX-type zeolite of the present invention preferably has a BET specific surface area of 400 m ² / g or more, more preferably 450 m ² / g or more, further 500 m ² / g or more, and further preferably 550 m ² / g or more. When the BET specific surface area is appropriately high, a reaction or adsorption using the surface as a reaction field is likely to occur. The specific surface area may be 700 m ² / g or less, further 650 m ² / g or less, and further 600 m ² / g or less.

Next, the method for producing the AFX-type zeolite of the present invention will be described.

As described above, the method for producing AFX-type zeolite using the quinuclidine derivative is not a realistic production method because the production cost is too high. On the other hand, a method for producing an AFX-type zeolite that crystallizes a composition containing DC4Br as OSDA may be industrially applicable, but the material diffusibility of the obtained AFX-type zeolite is low. Further, although DC4Br is cheaper than the quinuclidine derivative, DC4Br is still an expensive compound when used as an industrial raw material. As described above, since OSDA is indispensable for all the manufacturing methods, these manufacturing methods increase the manufacturing cost. On the other hand, the production method of the present invention can produce AFX-type zeolite without requiring OSDA.

That is, the method for producing an AFX-type zeolite of the present invention crystallizes a composition containing a silica source, an alumina source, a sodium source and a seed crystal, and the molar ratio of the quaternary ammonium cation to silica is less than 0.01. It is a method for producing an AFX-type zeolite having a crystallization step of allowing it to be formed.

In the production method of the present invention, a composition containing a silica source, an alumina source, a sodium source and a seed crystal (hereinafter, also referred to as “raw material composition”) is crystallized. As the raw material composition in the production method of the present invention, AFX-type zeolite having mesopores and further AFX-type zeolite having mesopores and micropores can be obtained without using OSDA as an essential component.

The molar ratio of quaternary ammonium cations to silica in the raw material composition is less than 0.01. The raw material composition in the production method of the present invention can obtain AFX-type zeolite without containing OSDA. Therefore, the raw material composition does not contain OSDA, especially quaternary ammonium cations. However, a very small amount of quaternary ammonium cation may be contained as an impurity or the like. Therefore, the molar ratio of the quaternary ammonium cation to silica in the raw material composition of the present invention is preferably less than 0.01, more preferably 0.005 or less. It is preferable that the molar ratio of the quaternary ammonium cation to silica is substantially 0 in the raw material composition, but the molar ratio of the quaternary ammonium cation to silica in the raw material composition is 0 in consideration of errors in composition analysis and the like. It may be .002 or less, and further 0.001 or less.

The silica source contained in the raw material composition is silica (SiO ₂ ) or a silicon compound as a precursor thereof, for example, colloidal silica, atypical silica, sodium silicate, tetraethyl orthosilicate, precipitation method silica, fumed silica, and the like. At least one of the group consisting of zeolite and aluminosilicate gel can be mentioned, and at least one of the group consisting of colloidal silica, atypical silica, sodium silicate, tetraethyl orthosilicate, precipitation method silica, fumed silica and aluminosilicate gel. Is preferable.

The alumina source contained in the raw material composition is alumina (Al ₂ O ₃ ) or an aluminum compound as a precursor thereof, for example, aluminum sulfate, sodium aluminate, aluminum hydroxide, aluminum chloride, aluminosilicate gel, zeolite, and the like. At least one of the group consisting of metallic aluminum can be used, and at least one of the group consisting of aluminum sulfate, sodium aluminate, aluminum hydroxide, aluminum chloride, metallic aluminum and aluminosilicate gel is preferable.

The sodium source contained in the raw material composition may be a compound containing sodium, and sodium hydroxide or a halide of sodium, more preferably sodium hydroxide. Also. Sodium contained in other raw materials such as a silica source and an alumina source may be used as a sodium source.

The raw material composition contains seed crystals. The seed crystal is preferably AFX type zeolite. In the crystallization of zeolite without OSDA, the seed crystal has a great influence on the crystal phase of the produced zeolite. There are various modes of action of seed crystals. In particular, when the seed crystal does not completely dissolve and functions as a new crystal growth field, it is considered that the crystal structure of the seed crystal and the exposed crystal plane directly affect the product. By using AFX-type zeolite as a seed crystal, it is easiest to obtain AFX-type zeolite.

The seed crystal is preferably mixed with the raw material composition so that the weight ratio of the seed crystal to the solid content weight of the raw material composition is 1% or more, further 5% or more, further 10% or more, and further. Is 20% or more, further 30% or more, further 40% or more, and further 50% or more. Here, the solid content weight of the raw material composition is the sum of the weights of Si and Al in the raw material composition converted into SiO ₂ and Al ₂ O ₃ , respectively, and the Si in the seed crystal mixed with the raw material composition. And the weight of Al are not included.

The SiO ₂ / Al ₂ O ₃ ratio of the raw material composition is preferably 20 or more, more preferably 25 or more, further 30 or more, further 35 or more, and further preferably 40 or more. This promotes dissolution and accelerates crystal growth. The SiO ₂ / Al ₂ O ₃ is preferably 100 or less, more preferably 80 or less, and further preferably 65 or less. As a result, the yield of AFX-type zeolite tends to increase.

The molar ratio of water to silica in the raw material composition (hereinafter, also referred to as “H ₂ O / SiO ₂ ratio”) is preferably 5 or more and 60 or less. When H ₂ O / SiO ₂ is in this range, a mixture having a viscosity capable of being appropriately stirred during crystallization is obtained. Further, H ₂ O / SiO ₂ is preferably 50 or less, more preferably 40 or less, and further preferably 25 or less. This tends to increase the yield.

The molar ratio of hydroxide ions to silica in the raw material composition (hereinafter, also referred to as “OH / SiO ₂ ratio”) is 0.40 or more, further 0.50 or more, further 0.55 or more, and further. Is preferably 0.60 or more. This promotes the dissolution of the raw material and accelerates the crystal growth. OH / SiO ₂ is preferably 1.00 or less, further 0.80 or less, further 0.70 or less, and further preferably 0.65 or less. As a result, the yield of AFX-type zeolite tends to increase.

Since the formation of impurities is easily suppressed, the crystallization temperature is preferably 110 ° C. or higher and 180 ° C. or lower, more preferably 120 ° C. or higher and 160 ° C. or lower, and further preferably 120 ° C. or higher and 150 ° C. or lower. If the conditions are met, any crystallization method can be used, and crystallization by hydrothermal treatment is preferable. For hydrothermal treatment, the mixture may be placed in a closed pressure-resistant container and heated. The following can be mentioned as hydroheat treatment conditions.
Treatment time: 2 hours or more and 500 hours or less, preferably 5 hours or more and 240 hours or less Treatment pressure: Self-sustaining pressure

During the hydrothermal treatment, the raw material composition may be in a stationary state or in a stirred state. Crystallization is preferably carried out with the mixture agitated in order to suppress the formation of impurities.

The production method of the present invention may include any of a washing step, a drying step, an ammonium treatment step, and a protonation step after the crystallization step. On the other hand, in the production method of the present invention, AFX-type zeolite can be obtained from a raw material composition containing no OSDA. Therefore, the firing step required for the step of removing the OSDA and other OSDA removing steps may not be included.

In the washing step, the AFX zeolite and the liquid phase are solid-liquid separated from the product after the crystallization step. In the washing step, solid-liquid separation may be performed by a known method, and the AFX-type zeolite obtained as a solid phase may be washed with pure water. Specific examples thereof include a method in which the product obtained by hydrothermal treatment is filtered and washed, and separated into a liquid phase and a solid phase to obtain an AFX-type zeolite.

The drying step removes water from the AFX-type zeolite after the crystallization step or the washing step. The conditions of the drying step are arbitrary, but the mixture after the crystallization step or the AFX-type zeolite obtained after the washing step is treated in the air under the conditions of 100 ° C. or higher and 150 ° C. or lower for 2 hours or longer. Can be exemplified. Examples of the drying method include standing and spraying dryers.

The ammonium treatment step is carried out to exchange the alkali metal cation contained in the AFX type zeolite to form an ammonium type. The ammonium treatment step is performed, for example, by bringing an aqueous solution containing ammonium ions into contact with AFX-type zeolite.

The protonation step is carried out to exchange the protons of the AFX-type zeolite to form a protonation type. Protonation can be carried out by heat treatment or acid treatment. Specific heat treatment conditions include using ammonium-type AFX-type zeolite for treatment in the air at 500 ° C. for 1 to 2 hours. Examples of the acid treatment condition include contacting an aqueous solution containing hydrochloric acid, nitric acid or sulfuric acid with AFX-type zeolite at room temperature.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an AFX-type zeolite that can be applied as an industrial catalyst. It is possible to provide an AFX-type zeolite which is superior in substance diffusion as compared with the conventional AFX-type zeolite and whose catalytic reaction and adsorption reaction are promoted. Furthermore, it is possible to provide an industrial production method for producing such an AFX-type zeolite. Since the production method of the present invention is a method for producing AFX-type zeolite without using an organic structure-directing agent, AFX-type zeolite can be obtained at a lower cost.

XRD pattern of the product of Example 1 Nitrogen desorption isotherm of AFX type zeolite of Example 1 XRD pattern of the product of Example 2 XRD pattern of the product of Comparative Example 1 Nitrogen desorption isotherm of AFX type zeolite of Comparative Example 2

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

(Powder X-ray diffraction)
The XRD measurement of the sample was performed using a general X-ray diffractometer (trade name: manufactured by Ultima IV Rigaku). The measurement conditions are as follows.

Source: CuKα ray (λ = 1.5405Å)
Measurement mode: Step scan
Scan conditions: 0.02 ° / s
Divergence slit: 1.00 deg
Scattering slit: 1.00 deg
Light receiving slit: 0.30 mm
Measurement range: 2θ = 3.0 ° to 43.0 °
From the obtained XRD pattern, the crystal phase of the product obtained in the crystallization step, the lattice spacing d, and the XRD peak intensity ratio were confirmed.

(Composition analysis)
The composition of the sample was analyzed using a general inductively coupled plasma emission spectrometer (device name: OPTIMA3300DV, manufactured by PERKIN ELMER). The sample was dissolved in a mixed solution of hydrofluoric acid and nitric acid to prepare a measurement solution. The obtained measurement solution was put into an apparatus and the composition of the sample was analyzed.
SiO ₂ / Al ₂ O ₃ was calculated from the obtained molar concentrations of silicon (Si) and aluminum (Al).

(BET specific surface area)
A general gas adsorption amount measuring device (device name: BELSORP-max, manufactured by MicrotracBEL) was used to obtain a nitrogen adsorption / desorption isotherm of the sample. Prior to the measurement, the sample was ion-exchanged with an aqueous ammonium chloride solution and then heat-treated at 350 ° C. for 2 hours under vacuum to prepare a pretreatment. The nitrogen adsorption conditions are as follows.
Measurement method: Constant volume method
Adsorbed gas: Nitrogen
Measurement temperature: 77K
The BET specific surface area was determined from the obtained adsorption isotherm by the BET multipoint method. The relative pressure P / P ₀ was in the range of 0.05 to 0.15.

(Micro pore volume)
Adsorption isotherms were obtained in the same manner as in the measurement of BET specific surface area. The micropore volume was determined from the obtained adsorption isotherm by the t-plot method.

(Mesopore adsorption amount)
The adsorption isotherm was obtained by the same method as the measurement of the BET specific surface area, and then the desorption isotherm was obtained. From the obtained desorption isotherm, the amount of adsorption of mesopores V _m was determined by the following formula.
V _m = V _P1- V _P2
In the above formula, _VP1 is the amount of nitrogen adsorbed at a relative pressure (P / P ₀ ) of 0.9 (mL / g), and _VP2 is the amount of nitrogen adsorbed at a relative pressure (P / P ₀ ) of 0.4 (mL / g). g).

Synthesis Example 1 (Synthesis of seed crystals)
A solid solution of a gel obtained by mixing No. 3 sodium silicate (SiO ₂ ; 30%, Na ₂ O; 9.1%, Al ₂ O ₃ ; 0.01%), 98% sulfuric acid, water and aluminum sulfate. It was separated and washed with pure water. Water, 1,3-di (1-adamantyl) imidazolium bromide (hereinafter referred to as "DAdIBr") and 48% NaOH were added to the washed gel and thoroughly stirred and mixed to obtain a composition. The obtained composition had the following composition in terms of molar ratio.

SiO ₂ / Al ₂ O ₃ = 19.8
OH / SiO ₂ = 0.20
Na / SiO ₂ = 0.20
DAdIBr / SiO ₂ = 0.05
H ₂ O / SiO ₂ = 40

The obtained composition was sealed in a stainless steel autoclave and heated at 180 ° C. for 48 hours while rotating the autoclave to obtain a product.
The product was filtered, washed and dried in air at 110 ° C. overnight. The dried product was calcined in air at 600 ° C. for 2 hours.

By XRD measurement, it was confirmed that the product after calcination was AFX type zeolite. The SiO ₂ / Al ₂ O ₃ of the AFX type zeolite was 18.4.
The AFX-type zeolite was wet-pulverized using a ball mill to have an average particle size of 1.2 μm. No decrease in crystallinity was observed due to pulverization.

Example 1
A solid solution of a gel obtained by mixing No. 3 sodium silicate (SiO ₂ ; 30%, Na ₂ O; 9.1%, Al ₂ O ₃ ; 0.01%), 98% sulfuric acid, water and aluminum sulfate. It was separated and washed with pure water. The washed gel, water and 48% NaOH were thoroughly stirred and mixed to obtain a raw material composition. The composition of the obtained composition was as follows in terms of molar ratio, and did not contain a quaternary ammonium cation.

SiO ₂ / Al ₂ O ₃ = 43.4
OH / SiO ₂ = 0.65
Na / SiO ₂ = 0.65
H ₂ O / SiO ₂ = 25
The seed crystal obtained in Synthesis Example 1 was added to the raw material composition so that the addition amount was 30%.

The obtained composition was sealed in a stainless steel autoclave and heated at 140 ° C. for 20 hours while rotating the autoclave to obtain a product.

The product was filtered, washed and dried in the air at 110 ° C. overnight to give the zeolite of this example. As a result of XRD measurement, it was confirmed that the product was AFX type zeolite. The weight of the zeolite of this example was 1.4 times the weight of the seed crystal. As a result, it was confirmed that the obtained AFX-type zeolite was not the seed crystal itself, but the AFX-type zeolite was crystallized.

The AFX-type zeolite had SiO ₂ / Al ₂ O ₃ of 11.2, a BET specific surface area of 550 m ² / g, a micropore volume of 0.26 mL / g, and a mesopore adsorption amount of 11.6 mL / g. As a result, it was confirmed that the AFX-type zeolite has a SiO ₂ / Al ₂ O ₃ and BET specific surface area different from that of the seed crystal and has a pore volume of mesopores more than twice that of the seed crystal. The XRD pattern of the AFX-type zeolite of this example is shown in FIG. 1, and the nitrogen desorption isotherm is shown in FIG.

Example 2
The zeolite of this example was obtained by heating, filtering, washing and drying in the same manner as in Example 1 except that the composition having the following molar composition was used and the seed crystal was set to 10%.

SiO ₂ / Al ₂ O ₃ = 60.4
OH / SiO ₂ = 0.65
Na / SiO ₂ = 0.65
H ₂ O / SiO ₂ = 25

As a result of XRD measurement, it was confirmed that the main product was AFX-type zeolite, and further contained by-products having a peak similar to CHA-type zeolite. The weight of the zeolite of this example was 3.6 times the weight of the seed crystal, and it was confirmed that the AFX-type zeolite was crystallized. The XRD pattern of the AFX type zeolite of this example is shown in FIG.

The zeolite of this example has a SiO ₂ / Al ₂ O ₃ ratio of 7.7, a BET specific surface area of 550 m ² / g, a micropore volume of 0.26 mL / g, and a mesopore adsorption amount of 9.1 mL / g. It was.

Comparative Example 1
The composition was prepared in the same manner as in Example 1 except that the composition having the following molar composition was used and the seed crystal was not used.

SiO ₂ / Al ₂ O ₃ = 43.4
OH / SiO ₂ = 0.65
Na / SiO ₂ = 0.65
H ₂ O / SiO ₂ = 25

The obtained composition was sealed in a stainless steel autoclave and heated at 140 ° C. for 72 hours while rotating the autoclave to obtain a product. The product was filtered, washed and dried in the air at 110 ° C. overnight to give the zeolite of this comparative example. As a result of XRD measurement, the zeolite of this comparative example was a mixture of MOR-type zeolite and an amorphous substance. The XRD pattern is shown in FIG.

Comparative Example 2
The AFX-type zeolite obtained in Synthesis Example 1 was used as the zeolite of Comparative Example 2. The zeolite had a BET specific surface area of 580 m ² / g, a micropore volume of 0.25 mL / g, and a mesopore adsorption amount of 4.6 mL / g.

The nitrogen desorption isotherm of the zeolite of this comparative example is shown in FIG. From FIG. 5, it can be confirmed that the zeolite of this comparative example does not have a hysteresis loop at a relative pressure (P / P ₀ ) of 0.4 to 0.9. From the above-mentioned amount of mesopores adsorbed and FIG. 5, it can be confirmed that the AFX-type zeolite of this comparative example does not have mesopores.

The AFX-type zeolite of the present invention can be used as an adsorbent, a catalyst carrier or catalyst, and also as an adsorbent or catalyst incorporated in an exhaust gas treatment system, and nitrogen in the exhaust gas of an automobile, particularly a diesel vehicle, particularly in the presence of a reducing agent. It can be used as an SCR catalyst for reducing and removing oxides.

Claims (4)

In the case where the cation type and NH ₄ form, the nitrogen adsorption amount satisfies the following relationships in the nitrogen adsorption-desorption measurements under liquid nitrogen temperature, AFX type zeolite having mesopores.
VP1-VP2 ≧ 0.7
In the above formula, VP1 is a value (mL / g) obtained by converting the amount of nitrogen adsorbed at a relative pressure (P / P0) of 0.9 in the process of desorbing saturated nitrogen at 0 ° C. and 1 atm. VP2 is a value (mL / g) obtained by converting the amount of nitrogen adsorbed at a relative pressure (P / P0) of 0.4 in the desorption process of saturated nitrogen at 0 ° C. and 1 atm. In addition, liquid nitrogen temperature is Ru 77K der. The AFX-type zeolite according to claim 1, wherein the pore volume of the micropores is 0.20 mL / g or more. Claim 1 or 2 comprising a crystallization step of crystallizing a composition containing a silica source, an alumina source, a sodium source and a seed crystal, and having a molar ratio of quaternary ammonium cations to silica of less than 0.01. The method for producing AFX-type zeolite according to the above method. The method for producing an AFX-type zeolite according to claim 3, wherein the seed crystal is an AFX-type zeolite.

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