JP5657458B2 - Mordenite-type zeolite having flaky crystal shape and method for producing the same - Google Patents

Description

  The present invention relates to a mordenite-type zeolite having a flaky crystal shape resulting from a silicate skeleton of a mesoporous silicate precursor, and a hydrothermal synthesis reaction of a mesoporous silicate precursor in the presence of a template agent, an alkali agent, and an aluminum compound. The present invention relates to a production method for producing a mordenite-type zeolite having a flaky crystal shape.

Aluminosilicates, particularly crystalline aluminosilicates (zeolites) are widely used in industry as catalysts, adsorbents, ion exchangers and the like. Various structures of zeolite are known. For example, MFI type zeolite (ZSM-5 type zeolite) is known to be effective as a catalyst for isomerization of metaxylene, reforming of toluene, synthesis of ethylbenzene, and the like.
As-synthesized Na-mordenite has an effective pore diameter of only 4 angstroms because Na ions block the pores of oxygen 12-membered rings. Therefore, the diffusion of paraffin and aromatic into the pores is hindered and cannot be applied to adsorption / catalyst applications. Similarly, diffusion of oxygen and nitrogen into the pores is inhibited, and the pore volume and specific surface area cannot be measured by a commonly used nitrogen adsorption method. For adsorption / catalyst use, H-mordenite in which Na ions are substituted with protons is used. Moreover, the evaluation of the pore characteristics of the mordenite-type zeolite in the present invention uses an argon gas adsorption method that is less susceptible to diffusion inhibition.
H-mordenite is used for isomerization of paraffins and aromatics that require high acidity, and has a larger pore size than ZSM-5 type zeolite, and is used for adsorption / catalysis of larger chemical species. Since all zeolites often exhibit catalytic action only on the crystal surface, and it is desired to increase the reaction activity as a catalyst and accelerate molecular diffusion, the crystallinity is increased and the crystal size is increased. It is necessary to make it smaller. This often means conflicting synthesis conditions, and subtle synthesis conditions are selected, causing problems in product quality. In the flaky crystal shape, the contact surface with the chemical species becomes large, and therefore, zeolite having the flaky crystal shape is expected as a means for solving the above problems.

  The mordenite type zeolite is a naturally produced zeolite, and its basic technology is described in Patent Document 1 for its synthesis. This zeolite is referred to by the applicant as “Zeolon”. Since then, numerous related reports, patent applications, etc. have been made. In these, synthesis | combination is generally performed by the autoclave at the temperature of about 150 degreeC under the high temperature / high pressure of about 0.5 MPa without using a template agent. However, as described in Patent Document 2, a template agent such as tetraethylammonium is used for the synthesis of a mordenite type zeolite having a high silica / alumina ratio. Further, the fluorine ion functions as an accelerator for the synthesis reaction.

On the other hand, in the synthesis of mesoporous silicate, the basic synthesis technique of mesoporous silica is essentially a process of firing a reaction complex of a silica source and alkyltrimethylammonium (hereinafter referred to as “ATMA”) which is a cationic surfactant. There are two methods according to the type of silica source. The first method uses a layered silicate as a silica source. Specifically, for example, as described in a report by T. Yanagisawa et al. This is a method in which a complex of certain kanemite (NaHSi ₂ O ₅ .3H ₂ O) and ATMA is formed and then baked to remove organic substances. The second method uses amorphous silica powder or an aqueous alkali silicate solution as a silica source, and JSBeck et al. (Non-patent Document 2) describes synthesis examples from various silica sources. Patent Document 3 also describes the basic technique, and is referred to as “MCM-41” by the applicant. In the synthesis, a silica source or a silica source and an aluminum source and a cationic surfactant are used. As developments from the second method, new industrially feasible manufacturing methods have been proposed one after another. For example, Patent Document 4 discloses a third method in which a sodium silicate aqueous solution is brought into contact with a cation exchange resin to prepare an active silica, and the active silica obtained in the first step and the cationic surfactant are made alkaline. In the process of mixing and reacting in the region, a second step of adding a water-soluble aluminum salt to form a composite of silica / alumina / cationic surfactant and a third step of firing the composite are sequentially performed. A featured mesoporous aluminosilicate production method is described. Alternatively, as a fourth method, Patent Document 5 discloses that sodium silicate and a cationic surfactant are dissolved in an alkaline region, adjusted to pH 7 to 12 with an acid, precipitated silica, and then reacted under heating. A first step of forming a composite of the silica and the cationic surfactant, a second step of washing and removing the complex, and a third step of firing the removed Na complex The method for producing mesoporous silica, characterized in that is sequentially applied, is described. In this production method, mesoporous aluminosilicate can be produced by adding and dissolving an aluminum salt in an acid.
Separately, a method for producing mesoporous silica using a nonionic surfactant such as polyoxyethylene / polyoxypropylene copolymer has also been proposed.

Several syntheses of plate-like or flaky crystalline zeolites have been proposed. For example, Patent Document 6 describes a plate-like or flaky crystal-like COD-type zeolite (zeolite CDS-1).
Patent Document 7 describes MFI-type zeolite having a plate-like or flaky crystal shape.
Patent Document 8 describes K-type zeolite having a hexagonal plate-like crystal shape.

  However, there is no case of synthesizing flaky crystalline mordenite.

British Patent 983756 JP 2003-313026 A Japanese National Patent Publication No. 5-503499 JP-A-8-259220 JP 11-49511 A JP 2007-77006 A JP 2004-307296 A JP-A-7-206425

Bulletin of the Chemical Society of Japan, Vol.63,988-992 (1990) Journal of the American Chemical Society, Vol. 114, 10834-10843 (1992)

An object of the present invention is to provide a mordenite-type zeolite having a flaky crystal shape and having a nitrogen gas adsorption capacity of 50 to 150 cc / g at −196 ° C. and 76 torr and a process for producing the same.

  As a result of diligent studies to solve the above problems, the inventors of the present invention have developed a flaky shape resulting from a silicate skeleton of a composite of silica or aluminosilicate and a surfactant (hereinafter referred to as “mesoporous silicate precursor”). A mordenite-type zeolite having the following crystal shape could be obtained. That is, it has been found that a mordenite-type zeolite having a flaky crystal shape can be produced by hydrothermal synthesis reaction of a mesoporous silicate precursor containing a surfactant in the presence of a template agent, an alkali agent and an aluminum compound. The present invention has been made.

  Further, the present invention creates a mesoporous silicate precursor using a raw material composition comprising a silica source or a silica source and an aluminum source, and a surfactant, and mixes the precursor, the template agent, the alkali agent, and the aluminum compound. There is provided a production method for producing a mordenite-type zeolite having a flaky crystal shape by hydrothermal treatment.

The mordenite-type zeolite having the flaky crystal shape of the present invention has a wide reaction field called the surface of the flaky crystal, and this part becomes a contact field of the adsorbate, so that it is more than the conventional mordenite-type zeolite. The contact area with the object to be adsorbed is remarkably large, and the progress of the catalytic reaction is remarkably accelerated. In addition, while conventional Na-mordenite shows inhibition of nitrogen gas diffusion into the pores by Na ions and the amount of adsorption is low, flaky mordenite has good nitrogen gas adsorption performance while containing Na. It was confirmed to show.
The mordenite-type zeolite having a flaky crystal shape of the present invention can be used not only for a catalyst but also in the cosmetics, resin filler, and electronic / information fields by utilizing the characteristics having a flaky crystal shape.

FIG. 3 is a powder X-ray diffraction pattern of a mordenite-type zeolite having a flaky crystal shape obtained in Example 1. FIG. 4 is a powder X-ray diffraction pattern of a comparative mordenite-type zeolite obtained in Comparative Example 1. FIG. (A) is an argon gas adsorption isotherm of the mordenite type zeolite having the flaky crystal shape obtained in Example 1, and (b) is an argon gas adsorption of the comparative mordenite type zeolite obtained in Comparative Example 1. Isotherm. (A), (b) and (c) are TEM photographs of three views of the mordenite type zeolite having the flaky crystal shape obtained in Example 1. FIG. (A) is a SEM photograph example of a mordenite-type zeolite having a flaky crystal shape obtained in Example 1. (B) is a SEM photograph of the comparative mordenite zeolite obtained in Comparative Example 1. (C) is a reference example, which is a SEM photograph example of mordenite-type zeolite distributed by the Catalysis Society of Japan. (A) is a nitrogen adsorption isotherm of the mordenite type zeolite having the flaky crystal shape obtained in Example 1, and (b) is a nitrogen adsorption isotherm of Na-mordenite.

  Hereinafter, the present invention will be described in more detail.

The first feature of the mordenite-type zeolite of the present invention is that the crystal shape is flaky. More specifically, the crystal shape has a thickness measured by SEM observation of 10 to 200 nm, a plane long-axis length of 0.2 to 1.0 μm, and a short-axis length of 0. It is a flaky crystal shape of 0.1 to 0.3 μm.
The thickness and the length of one side of the plane in the present invention are arithmetic average values measured for 50 randomly selected mordenite zeolite particles by applying a scale to the SEM photograph of the obtained mordenite zeolite.

  The second feature of the mordenite-type zeolite of the present invention is that the nitrogen gas adsorption ability at -196 ° C. and 76 torr is 50 to 150 cc / g.

The third feature of the mordenite zeolite of the present invention is that the specific surface area determined by the BET method determined by the argon gas adsorption method is in the range of 450 to 700 m ² / g.

The fourth feature of the mordenite-type zeolite of the present invention is that the specific surface area by the Langmuir method determined by the argon gas adsorption method is in the range of 600 to 800 m ² / g.

  The fifth feature of the mordenite-type zeolite of the present invention is that the pore volume determined by the argon gas adsorption method is in the range of 0.4 to 1.0 cc / g.

  The sixth feature of the mordenite-type zeolite of the present invention is that the pore diameter determined by the SF (Saito-Foley) method from the argon gas adsorption isotherm is in the range of 0.45 to 0.55 nm.

The mordenite-type zeolite production method of the present invention is characterized by a first step of synthesizing a mesoporous silicate precursor using a silicate material and a surfactant, and a template agent without firing the mesoporous silicate precursor obtained in the first step. A second step of synthesizing a mordenite-type zeolite by adding a hydrothermal synthesis reaction by adding an alkali agent and an aluminum compound, and a third step of removing the surfactant and the template agent by baking the mordenite-type zeolite It is a manufacturing method to be applied. In the second step, it is preferable to further add a fluorine compound.
The silicate material is silica or aluminosilicate.

  Examples of the surfactant include nonionic surfactants such as polyoxyethylene / polyoxypropylene copolymers, and cationic surfactants such as alkylamine salts and quaternary long chain alkyltrimethylammonium salts. A quaternary long chain alkyltrimethylammonium salt is preferred.

  The mesoporous silicate precursor is mesoporous silica or mesoporous aluminosilicate.

<First step: Method for producing mesoporous silicate precursor>
As described in the background art, there are two methods for synthesizing mesoporous silicate. Although any method can be used in the present invention, it is important not to perform a baking step for removing the surfactant, and a mesoporous silicate precursor containing the surfactant is obtained. However, in the first method, it is necessary to prepare kanemite as a silica source, and since a large amount of Na is present in the reaction system, the Na component destroys the silica structure and lowers the surface area of the porous body when firing the composite. There are drawbacks. As the production method used in the present invention, the third method or the fourth method described in the background art is preferable. Moreover, the method using said nonionic surfactant is also employable. When a nonionic surfactant is used, a mesoporous silicate precursor having a d-interval greater than 5.0 nm can be obtained.

Although it does not restrict | limit especially as a cationic surfactant, A quaternary ammonium salt or an alkylamine salt etc. are mentioned. As a quaternary ammonium salt, the following general formula (1)
[R ¹ _n (CH ₃ ) _4-n N] ⁺ [X] ^- (1)
(Wherein, R ¹ represents a long-chain alkyl group, n represents an integer of 1 to 3, and X represents a halogen atom or a hydroxyl group). Since the halide or hydroxide of the quaternary long-chain alkyltrimethylammonium represented by the general formula [R ¹ (CH ₃ ) ₃ N] ⁺ [X] ^{− in} which n is 1 forms a uniform mesopore structure of silica preferable. In general formula (1), the carbon number of the long-chain alkyl group R ¹ is preferably 8 to 24, and particularly preferably 8 to 17. When the number of carbon atoms is 25 or more, it is insoluble and difficult to handle. Moreover, as a halogen atom of X, a chlorine atom and a bromine atom are preferable since they can be easily obtained as industrial products. In the general formula (1), those in which X is a hydroxyl group are more preferably used since the subsequent Na removal washing treatment is advantageously performed.

Specific examples of the quaternary long chain alkyltrimethylammonium salt include octyltrimethylammonium chloride, octyltrimethylammonium bromide, octyltrimethylammonium hydroxide, decyltrimethylammonium chloride, decyltrimethylammonium bromide, decyltrimethylammonium hydroxide. , Dodecyltrimethylammonium chloride, dodecyltrimethylammonium bromide, dodecyltrimethylammonium hydroxide, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium hydroxide, octadecyltrimethylammonium chloride, octadecyltrimethylammonium bromide, Include oxidation octadecyl trimethyl ammonium, etc., may be used singly or in combination of two or more of these fourth head of class-chain alkyl trimethyl ammonium salts.
Products made from natural fats and oils are generally used for industrial use, and the long chain alkyl group is coconut oil, beef tallow, hardened beef tallow or vegetable stearyl, and a plurality of quaternary long chain alkyltrimethylammonium salts. Since it is often a mixture and can be obtained relatively inexpensively, it can be preferably used. Furthermore, dialkyldimethylammonium salts having a substitution number n of 2 made from these natural fats and oils are also frequently used and can be used preferably because they can be obtained at a relatively low cost.

Moreover, as an alkylamine salt, general formula (2);
[R ² NH ₂ ] ⁺ [X] ^- (2)
(Wherein, R ² represents a long-chain alkyl group, and X represents a halogen atom or a hydroxyl group). In the general formula (2), the carbon number of the long-chain alkyl group R ¹ is preferably 8 to 24, and particularly preferably 8 to 17. When the number of carbon atoms is 25 or more, it is insoluble and difficult to handle. Moreover, a chlorine atom and a bromine atom are mentioned as a halogen atom of X.
Similarly to the above, products made from natural fats and oils are generally used for industrial use, and the long chain alkyl group is coconut oil, beef tallow, hardened beef tallow or vegetable stearyl, and a plurality of long chain alkylamines. Often a mixture of salts. Since it can be obtained relatively inexpensively, it can be preferably used.

  In the present invention, the quaternary long-chain alkyltrimethylammonium salt is preferably used because it has a higher basicity than an alkylamine salt and is excellent in reactivity.

In the first step of the method of the present invention, first, sodium silicate and a cationic surfactant are dissolved in water in an alkaline region to form a transparent uniform solution. The amount of water in this system is preferably 50 to 300 mol, preferably 70 to 150 mol, relative to 1 mol of SiO ₂ . Further, the addition amount of the cationic surfactant, at a molar ratio of SiO ₂ / surfactants, usually 2-10, preferably 4-5.

<Second step; production method of mordenite type zeolite>
As the mordenite-type zeolite of the present invention, an aluminum amount, that is, a SiO ₂ / Al ₂ O ₃ molar ratio of 30 or less is easy to synthesize, but 30 or more can also be obtained by dealumination after synthesis.

In the second step, the hydrothermal synthesis reaction is performed by adding the mesoporous silicate precursor obtained in the first step, the template agent, the alkali agent and the aluminum compound.
The synthesis conditions of the hydrothermal synthesis reaction may be any method as long as the synthesis conditions enable the synthesis of the mordenite zeolite, and are not limited. In the presence of an alkaline agent, hydrothermal synthesis is usually performed at a temperature of 150 to 170 ° C. for about 24 to 72 hours using an autoclave.

Further, nitrogen-containing compounds such as tetraethylammonium, tributylamine, cyclohexylamine, and trimethylbenzylammonium hydroxide are known as template agents, and among them, tetraethylammonium is preferable because it is easily available and less harmful.
Further, the synthesis reaction can be promoted by adding a fluorine compound.

<Third step: Method for producing mordenite-type zeolite having flaky crystal shape>
In the third step, the mordenite zeolite obtained in the second step is calcined to remove the surfactant and the template agent to obtain a mordenite zeolite having a desired flaky crystal shape. The firing temperature is not particularly limited, and depends on the type of the surfactant and the template agent to be used, but is not less than the temperature at which both components of the surfactant and the template agent disappear, usually 500 ° C. or more.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these.

<Evaluation equipment>
X-ray diffraction: Bruker D8 Advance
TEM: Hitachi, Ltd. H-7500 type SEM: Hitachi, Ltd. S-4800 type Nitrogen gas adsorption and argon gas adsorption: Measured at -196 ° C and -186 ° C, respectively, using Autosorb-1 of Quantachrome.

<Materials used>
No. 3 sodium silicate: manufactured by Nippon Chemical Industry Co., Ltd. (SiO ₂ : 28.96 wt%, Na ₂ O: 9.37 wt%, H ₂ O: 61.67 wt%).
Colloidal silica: Silica Dole-30 (SiO ₂ : 30% by weight) manufactured by Nippon Chemical Industry Co., Ltd.
Surfactant: Stearyl trimethylammonium chloride (manufactured by Sanyo Chemical Industries, solid content: 68% by weight, solvent: 32% by weight).
Caustic soda: 25% sodium hydroxide for industrial (NaOH 25 _wt%, H 2 O: 75 wt%).
Template: Tetraethylammonium hydroxide (TEAH-40W manufactured by Lion Corporation, solid content: 40% by weight, H ₂ O: 60% by weight).
Aluminum chloride: Reagent _{(AlCl 3 · 6H 2 O,} 97 wt%).
Sodium aluminate: Showa Denko SA-2019
Diluted hydrochloric acid: Reagent, 35 wt% hydrochloric acid was diluted with pure water to prepare 7 wt% hydrochloric acid.
Sodium fluoride: Reagent

[Example 1]
<Production of mesoporous silica precursor>
No. 3 sodium silicate 86.1 g, surfactant 36.8 g, caustic soda 28.4 g and pure water 463.2 g were mixed and heated to 70 ° C. with stirring, and stirring was continued until the mixture became transparent. . Next, dilute hydrochloric acid was added to the mixture over 10 minutes while maintaining the liquid temperature at 70 ° C. with stirring, and the pH was adjusted to 8.0. Silica / surfactant complex was precipitated by the addition of diluted hydrochloric acid. The silica / surfactant composite was filtered, washed with water, and dried at 110 ° C. to obtain 39.1 g of a mesoporous silica precursor.
<Production of mordenite-type zeolite having flaky crystal shape>
To 84.5 g of pure water, 26.0 g of template, 10.1 g of caustic soda and 5.1 g of aluminum chloride were added and dissolved. To this solution, 30.0 g of mesoporous silica precursor was gradually added and dispersed. When sufficiently dispersed, 10.5 g of sodium fluoride was added and dissolved. After adding sodium fluoride, stirring was performed for 1 hour or more. This was charged into a 200 ml autoclave, subjected to crystallization reaction at 170 ° C. for 48 hours, and allowed to cool. After cooling, the crystallization reaction liquid was filtered, washed with water, and dried at 110 ° C. This dried product was calcined at 700 ° C. for 5 hours to obtain a mordenite-type zeolite having a flaky crystal shape. Hereinafter, this may be abbreviated as “flaky mordenite”.
<Characteristics of mordenite zeolite having flaky crystal shape>
The analytical composition of the flaky mordenite obtained above is shown in Table 1. The raw material composition of the flaky mordenite was a molar ratio SiO ₂ / Al ₂ O ₃ = 30, but the molar ratio of the obtained flaky mordenite was SiO ₂ / Al ₂ O ₃ = 24.47.
FIG. 1 shows a powder X-ray diffraction pattern of flaky mordenite. FIG. 2 shows a powder X-ray diffraction pattern of comparative mordenite produced in Comparative Example 1 described later. The peak positions in FIG. 1 coincide with those in FIG. 2, and it was confirmed that mordenite can be synthesized even when the whole mesoporous silica is used as a silica source. FIG. 3A shows an argon gas adsorption isotherm of the mordenite zeolite having the flaky crystal shape obtained in Example 1. FIG. 3 (b) shows an argon gas adsorption isotherm of the comparative mordenite zeolite obtained in Comparative Example 1.
FIGS. 4A, 4B, and 4C are examples of TEM photographs of three fields of flaky mordenite obtained above. From the TEM photograph, it was confirmed that the crystal shape was flaky.
FIG. 5A is an SEM photograph example of the flaky mordenite obtained above. From the SEM photograph, the thickness of the flake was about 100 nm, the length in the major axis direction was 0.6 μm, the width was 0.2 μm, and it was confirmed to be a thin flake.

[Comparative Example 1]
<Manufacture of mordenite type zeolite for comparison>
A crystallization reaction was carried out at 170 ° C. for 48 hours without using a mesoporous silica precursor and aluminum chloride, using colloidal silica as a silica source and sodium aluminate as an aluminum source to obtain a Na-mordenite type zeolite. Since this Na-mordenite type zeolite hardly adsorbs even argon gas, ion exchange of Na to ammonia was performed with ammonium chloride, and then calcined at 400 ° C. to obtain H-mordenite in which Na was replaced with protons. Hereinafter, this may be abbreviated as “comparative mordenite”. The analytical composition of the comparative mordenite is shown in Table 1. FIG. 2 shows a powder X-ray diffraction pattern of the comparative mordenite.
FIG. 5B is an SEM photograph example of the comparative mordenite obtained above. From this SEM photograph, it was mainly a massive crystal.
FIG. 5 (c) is a reference example, which is an SEM photograph example of mordenite type zeolite distributed by the Catalysis Society of Japan, which was mainly in the form of massive crystals.

<Characteristic measurement and comparison between flaky mordenite and comparative mordenite>
FIG. 3A is an argon gas adsorption isotherm of flaky mordenite obtained above, and FIG. 3B is an argon gas adsorption isotherm of comparative mordenite. The results of (1) and (2) in Table 2 were obtained by analyzing the adsorption isotherm. In Table 2, (1) is a characteristic value of the flaky mordenite obtained in Example 1, and (2) is a characteristic value of the comparative mordenite obtained in Comparative Example 1. (3) is reference data, which is a characteristic value of mesoporous silica prepared by the production method described in Patent Document 4.
The flaky mordenite has a larger specific surface area and pore volume than the comparative mordenite (conventional product). The mordenite for comparison is H-mordenite, whereas the flaky mordenite is Na-mordenite, and the good gas adsorption performance while containing Na is due to the crystal shape of flaky. Guessed.

<Measurement and comparison of nitrogen adsorption between flaky mordenite and Na-mordenite>
FIG. 6A is a nitrogen adsorption isotherm of the flaky mordenite (Na type) obtained above, and FIG. 6B is a nitrogen adsorption isotherm of Na-mordenite. The nitrogen gas adsorption capacity of flaky mordenite (Na type) at −196 ° C. and 76 torr was about 100 cc / g. Na-mordenite shows inhibition of nitrogen gas diffusion into pores by Na ions and the adsorption amount is low, whereas flaky mordenite shows good nitrogen gas adsorption performance while containing Na. It is presumed to be caused by the crystal shape of flaky shape. In addition, the Na-mordenite used here is the Na-mordenite type zeolite as synthesized in the comparative example 1 before proton substitution.

[Example 2]
<Production of mesoporous aluminosilicate precursor>
No. 3 sodium silicate 86.1g, cationic surfactant 36.8g, caustic soda 28.4g and pure water 463.2g were mixed and heated to 70 ° C under stirring, and stirring was continued until the mixture became transparent It was. Separately, 2.49 g of aluminum chloride was added to 172.2 g of diluted hydrochloric acid and dissolved by stirring. This is called neutralizing hydrochloric acid.
Next, while maintaining the liquid temperature at 70 ° C. with stirring, neutralizing hydrochloric acid was added to the mixture over 10 minutes to adjust the pH to 8.0. The aluminosilicate / surfactant complex was precipitated by the addition of neutralizing hydrochloric acid. The molar ratio of SiO ₂ / Al ₂ O _{3 in} the precipitated aluminosilicate / surfactant complex is 80. The precipitated aluminosilicate / surfactant complex was filtered, washed with water, and dried at 110 ° C. to obtain a mesoporous aluminosilicate precursor.
<Production of mordenite-type zeolite having flaky crystal shape>
To 84.5 g of pure water, 26.0 g of template, 10.1 g of caustic soda and 5.1 g of aluminum chloride were added and dissolved. To this solution, 30.0 g of a mesoporous aluminosilicate precursor was gradually added and dispersed. When sufficiently dispersed, 10.5 g of sodium fluoride was added and dissolved. After adding sodium fluoride, stirring was performed for 1 hour or more. This was charged into a 200 ml autoclave, subjected to crystallization reaction at 170 ° C. for 48 hours, and allowed to cool. After cooling, the crystallization reaction liquid was filtered, washed with water, and dried at 110 ° C. This dried product was calcined at 700 ° C. for 5 hours to obtain a mordenite-type zeolite having a flaky crystal shape. Hereinafter, this may be abbreviated as “flaky mordenite”.
<Characteristics of mordenite zeolite having flaky crystal shape>
The analytical composition of the flaky mordenite obtained above is shown in Table 3. The raw material composition of flaky mordenite was a molar ratio SiO ₂ / Al ₂ O ₃ = 26, but the molar ratio of the obtained flaky mordenite was SiO ₂ / Al ₂ O ₃ = 20.72.
The powder X-ray diffraction pattern of the obtained flaky mordenite was in agreement with the powder X-ray diffraction pattern of the comparative mordenite, and it was confirmed to be mordenite. Further, from the TEM photograph, it was confirmed that the crystal shape was flaky.
From the SEM photograph, the thickness of the thin piece was about 100 nm, the length in the major axis direction was 0.5 μm, the width was 0.2 μm, and it was confirmed to be a thin thin piece.
The specific surface area determined by the BET method determined by the argon gas adsorption method was 518 m ² / g, the specific surface area determined by the Langmuir method determined by the argon gas adsorption method was 621 m ² / g, and the pore volume determined by the argon gas adsorption method Was 0.73 cc / g, and the pore diameter determined by the SF method from the argon gas adsorption isotherm was 5.0 mm.

Claims (12)

Crystal shape, flaky der Ri, -196 ° C., mordenite type zeolite having a flaky crystal form, characterized in that the nitrogen gas adsorption capacity at 76torr is 50~150cc / g. The crystal shape has a thickness measured by SEM observation of 10 to 200 nm, a plane major axis length of 0.2 to 1.0 μm, and a minor axis length of 0.1 to 0. The mordenite-type zeolite having a flaky crystal shape according to claim 1 , which has a flaky crystal shape of 3 μm. The mordenite type having a flaky crystal shape according to any one of claims 1 to 2 , wherein a specific surface area determined by a BET method determined by an argon gas adsorption method is in a range of 450 to 700 m ² / g. Zeolite. Mordenite having a flaky crystal form according to any one of claim 1 to 3, a specific surface area by Langmuir method determined by the argon gas adsorption method is characterized in that in the range of 600~800m ² / g Zeolite. The mordenite having a flaky crystal shape according to any one of claims 1 to 4 , wherein a pore volume determined by an argon gas adsorption method is in a range of 0.4 to 1.0 cc / g. Type zeolite. The flaky shape according to any one of claims 1 to 5 , wherein a pore diameter determined by an SF (Saito-Foley) method from an argon gas adsorption isotherm is in a range of 0.45 to 0.55 nm. Mordenite-type zeolite having the following crystal shape. A first step of synthesizing a mesoporous silicate precursor with a silicate material and a surfactant, and adding a template agent, an alkali agent, and an aluminum compound to the hydrothermal heat without firing the mesoporous silicate precursor obtained in the first step A second step of synthesizing a mordenite-type zeolite by performing a synthesis reaction, and a third step of sequentially removing the surfactant and the template agent by firing the mordenite-type zeolite obtained in the second step, A process for producing a mordenite-type zeolite having a flaky crystal shape according to claim 1 . The method for producing a mordenite-type zeolite having a flaky crystal shape according to claim 7 , wherein, in the second step, a mordenite-type zeolite is synthesized by further adding a fluorine compound to perform a hydrothermal synthesis reaction. The method for producing a mordenite-type zeolite having a flaky crystal shape according to any one of claims 7 and 8 , wherein the silicate material is silica or aluminosilicate. The method for producing a mordenite-type zeolite having a flaky crystal shape according to any one of claims 7 to 9 , wherein the surfactant is a quaternary long-chain alkyltrimethylammonium salt. The method for producing a mordenite-type zeolite having a flaky crystal shape according to any one of claims 7 to 10 , wherein the mesoporous silicate precursor is a mesoporous silica precursor or a mesoporous aluminosilicate precursor. The method for producing a mordenite-type zeolite having a flaky crystal shape according to any one of claims 7 to 11 , wherein the template agent is a tetraethylammonium salt.