JP7444674B2 - Manufacturing method of chabazite type zeolite - Google Patents

Description

The present invention relates to a method for producing chabazite-type zeolite with high yield.

Zeolite is a general term for aluminosilicates that have relatively large voids in their crystal structure, and has a basic skeleton made of silicon dioxide, with some of the silicon replaced by aluminum, which becomes negatively charged and contained within micropores. It has a structure in which the charge balance is maintained by cations such as alkali metals. Zeolites are typically represented by the general formula xM ₂ O・yAl ₂ O ₃ zSiO ₂・nH ₂ O (M is a cationic metal such as an alkali metal), and there are various types of zeolites depending on the type of cation contained in the crystal. It has properties.

Chabazite is a typical zeolite having a three-dimensional pore structure (chabazite skeleton) consisting of an eight-membered oxygen ring. Zeolites having a chabazite skeleton are called chabazite-type zeolites. Zeolites are classified based on structural codes by the International Zeolite Society, and chabazite-type zeolites are classified according to the structural code of CHA.

Patent Document 1 describes that chabazite-type zeolite is used for gas separation, selective reduction of nitrogen oxides contained in automobile exhaust gas, conversion of oxygen-containing hydrocarbons such as lower alcohols into liquid fuel, and production of dimethylamine. It is disclosed that it can be used for catalysts, separation membranes, etc.

There are two methods for producing chabazite-type zeolite: a method using a structure-directing agent (also referred to as SDA or template) (template method), and a method using faujasite-type zeolite (hereinafter also referred to as "FAU-type zeolite") as a starting material. (FAU conversion method) is known.

The template method is a method for synthesizing chabazite-type zeolite by hydrothermally treating a slurry or aqueous solution containing a structure-directing agent together with a Si source, an Al source, and an alkali source. , is a method in which chabazite-type zeolite is crystallized by hydrothermal treatment with an alkali source in the presence of SDA, which serves as a template for the chabazite structure.

The FAU conversion method is a method in which a slurry containing an alkali source and FAU type zeolite is hydrothermally treated to convert it into chabazite type zeolite. This method is disclosed in, for example, Patent Documents 2 and 3. In this method, FAU type zeolite serves as a Si source and an Al source. When FAU type zeolite is hydrothermally treated in the presence of an alkali source, the basic skeleton of FAU type zeolite is rearranged to produce chabazite type zeolite. Therefore, the FAU conversion method does not require SDA like the template method. Therefore, the FAU conversion method is highly economical because it does not use expensive SDA, and has a low environmental impact because it does not produce organic waste liquid, and has great advantages in industrial production. However, the FAU conversion method has a problem in that the yield tends to be low because chabazite-type zeolite is synthesized through a complicated process of recombining the FAU-type zeolite skeleton into a chabazite-type skeleton.

US Patent No. 6,709,644 Japanese Patent Application Publication No. 2015-101506 Patent No. 6320658

The present invention provides a method for producing chabazite-type zeolite that solves the problem of low yield in the conventional method for producing chabazite-type zeolite based on the FAU conversion method.

The production method of the present invention is a method of converting FAU type zeolite to produce chabazite type zeolite, which comprises: mixing FAU type zeolite and a solvent to prepare a raw material slurry; and wet-pulverizing the raw material slurry. The process includes a step of preparing a pulverized slurry, a step of adding a potassium source to the pulverized slurry to prepare a blended slurry, and a step of hydrothermally treating the blended slurry to form a chabazite-type zeolite, wherein the alkali metal of the raw material slurry is The amount is 0.30 mol or less per 1 mol of Si in the slurry, and the amount of potassium in the prepared slurry is 0.320 mol or more and 0.380 mol or less per 1 mol of Si in the prepared slurry. This is a method for producing chabazite-type zeolite, which is characterized by adding a potassium source and performing hydrothermal treatment so that the following results are obtained.

Chabazite-type zeolite has a basic skeleton consisting of SiO ₂ , and some of the Si is replaced with Al, which makes it negatively charged, and the charge balance is maintained by cations such as alkali metals contained within the micropores of the basic skeleton. It has a sagging structure. In the synthesis of chabazite-type zeolite by the template method, the amount of alkali metal added is generally adjusted based on the amount of Al added.

On the other hand, the method for producing chabazite-type zeolite of the present invention (hereinafter also referred to as "the production method of the present invention") is a production method based on the FAU conversion method. As mentioned above, the FAU conversion method has a problem in that the yield of chabazite-type zeolite produced is low. When this problem was investigated, it was thought that this low yield was caused by excessive destruction of the FAU skeleton due to the elution of Si from the FAU type zeolite.

Based on this knowledge, the production method of the present invention is based on the idea of minimizing the elution of Si from the FAU type zeolite. Specifically, when FAU type zeolite is exposed to conditions with a large amount of alkali metals, Si is easily eluted from FAU type zeolite. In the production method of the present invention, by limiting the amount to the minimum amount required to produce chabazite-type zeolite, the elution of Si from FAU-type zeolite is reduced and a decrease in yield is avoided. Note that the template method is a method of hydrothermally synthesizing raw materials Si and Al in the presence of SDA, and since Si is in a dissolved state, the template method does not have a technical concept of reducing the elution of Si.

The manufacturing method of the present invention will be specifically explained below.
[Raw material slurry preparation process]
The production method of the present invention includes a step of mixing FAU type zeolite and a solvent to prepare a raw material slurry. As this FAU type zeolite, a general FAU type zeolite can be used as long as it is a zeolite having an FAU skeleton. For example, conventionally known X-type zeolite, Y-type zeolite, etc. can be used as the FAU-type zeolite. Among these, Y-type zeolite is preferred. NaY-type zeolite (NaY), ultra-stable Y-type zeolite (USY), rare earth ion exchange type Y-type zeolite (ReY), etc. can be used as the Y-type zeolite. Such FAU type zeolite can be prepared, for example, by the method described in Patent Document 3. The SiO ₂ /Al ₂ O ₃ molar ratio of the FAU type zeolite that can be used in the production method of the present invention may be less than 100, may be less than 30, or may be less than 15, It may be in the range of 2 to 10.

As the solvent to be mixed with the FAU type zeolite, common solvents such as water and ethanol can be used. For example, water is preferred. The water is more preferably water with few impurities, such as pure water or ion-exchanged water.

In the process of preparing the raw material slurry, seed crystals may be added together with the FAU zeolite and the solvent. By wet-pulverizing the raw material slurry containing seed crystals in the grinding slurry preparation process described below, the chabazite-type zeolite finally obtained contains a different phase (crystalline phase different from the chabazite-type zeolite derived from by-products, etc.). This makes it difficult to break down and increases the yield. A conventionally known chabazite type zeolite can be used as a seed crystal. Specifically, for example, the homepage of the International Zeolite Society (http://www.iza-online.org・synthesis/) or "VERIFIED SYNTHESES OF ZEOLITIC MATERIALS" edited by H. Robson, K. P. Lillerud XRD diagram: 2001 Chabazite-type zeolite synthesized by the chabazite synthesis method described in 2006, 2nd edition, pages 123 to 125 can be used.

The amount of seed crystals added to the raw material slurry is preferably in the range of 0.1% by mass or more and 50% by mass or less, based on the total mass of the seed crystals and FAU type zeolite in this raw material slurry. The range is more preferably from 5% by mass to 30% by mass. If the content of seed crystals in the raw material slurry is too large, the substantial yield of chabazite-type zeolite tends to decrease. In order to maximize the effect of the seed crystal while maintaining a high substantial yield, the content of the seed crystal in the raw material slurry is more preferably in the range of 1% by mass or more and 15% by mass or less.

In this step, the raw material slurry may contain a predetermined amount or less of an alkali metal. When the raw material slurry containing alkali metal is pulverized in the pulverization process described below, Si easily elutes from the FAU type zeolite due to the heat and energy during pulverization, but if the amount of alkali metal is small, the effect of Si elution is small. Therefore, the alkali metal can be added in a predetermined amount or less. In this step, the amount of alkali metal contained in the raw material slurry is preferably 0.30 mol or less, more preferably 0.03 mol or more and 0.15 mol or less, per 1 mol of Si in the raw material slurry.

If the amount of alkali metal contained in the raw material slurry is higher than the above range, the heat and energy generated during wet grinding will easily cause Si to be eluted from the FAU type zeolite, resulting in the formation of different phases and the final product. The yield of chabazite-type zeolite produced decreases (for example, Comparative Example 4). If the alkali metal amount is within the above range, the yield of the finally obtained chabazite type zeolite can be maintained high (for example, Examples 1 and 4).

In this step, since the raw material slurry may contain a predetermined amount or less of alkali metal, it is possible to allow the presence of a predetermined amount or less of alkali metal derived from the FAU type zeolite as the raw material. Furthermore, by adding a predetermined amount or less of alkali metal in this step, the amount of potassium added in the next step can be adjusted. As the alkali metal used in this step, for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide can be used.

[Crushed slurry preparation process]
The manufacturing method of the present invention includes the step of wet-pulverizing the raw material slurry to prepare a pulverized slurry. The wet pulverization in this step may be any method that can pulverize the raw material slurry as it is, and any conventionally known method can be used. For example, a ball mill, a bead mill, etc. can be used.

In this step, it is preferable to perform wet pulverization in a state where FAU type zeolite and seed crystals coexist in the raw material slurry. When wet pulverization is performed in a state where FAU type zeolite and seed crystals coexist, aggregates are generated in which the crushed FAU type zeolite and seed crystal particles aggregate in the pulverized slurry, so a different phase is generated in the hydrothermal treatment process described later. It becomes difficult to do.

The wet grinding process reduces the total intensity (Ha ), wet pulverization is preferably carried out so that the total strength (Hb) of the FAU type zeolite contained in the pulverized slurry is less than half (0.5Ha≧Hb).

In this wet pulverization, it is preferable to maintain the temperature of the raw material slurry during pulverization at 50° C. or lower (for example, Examples 1 and 5). The temperature of the raw material slurry during wet pulverization easily rises due to the heat generated by the pulverization. At this time, if the temperature of the raw material slurry during wet pulverization exceeds 50° C., the yield of the chabazite-type zeolite that is finally obtained tends to decrease. In particular, when this temperature exceeds 65° C., the yield of chabazite-type zeolite decreases and a different phase is generated (for example, Comparative Example 3). Note that the lower limit of the temperature of the raw material slurry depends on the melting point of the solvent. For example, when water is used as a solvent, the temperature is 0°C or higher. The temperature of the raw material slurry during this wet grinding is controlled by the temperature of the raw material slurry discharged from the mill outlet when using a circulation type mill, and by the temperature of the raw material slurry discharged from the mill outlet when using a batch type mill. For example, it is preferable to control the temperature using a temperature measured by Fritsch's GTM system.

The temperature of the raw material slurry during wet pulverization can be adjusted by changing the wet pulverization conditions. For example, when using a circulating mill, there are methods such as lowering the temperature of the raw material slurry before it enters the mill using a chiller, lowering the rotation speed of the mill to reduce the amount of grinding work, and cooling the mill itself. It can be adjusted using In addition, when using a batch type mill, adjustments can be made by lowering the rotational speed of the mill to reduce the amount of grinding work, or by cooling the mill itself.

[Mixed slurry preparation process]
The production method of the present invention includes the step of adding a potassium source to the pulverized slurry to prepare a blended slurry. The molar amount of potassium contained in the prepared slurry is in a molar ratio of 0.320 mol or more to 0.380 mol or less with respect to 1 mol of Si contained in the prepared slurry. A potassium source is added to the milled slurry to achieve this potassium molar ratio . Note that the molar amount of Si and the molar amount of potassium are the molar amount of Si and the molar amount of potassium derived from all substances contained in the prepared slurry.

If the molar ratio of the amount of potassium contained in the prepared slurry is less than 0.320 mol, the basic skeleton of FAU zeolite will be insufficiently recombined, and the yield of chabazite zeolite will decrease. On the other hand, if the molar ratio of the amount of potassium contained in the prepared slurry is more than 0.380 mol, the yield of chabazite-type zeolite will decrease. When the molar ratio of the amount of potassium contained in the prepared slurry is within the above range, less Si is eluted from the FAU type zeolite, and the yield of the chabazite type zeolite finally obtained is increased (for example, in Examples 1 to 3). 6).

The molar ratio of the amount of potassium contained in the prepared slurry is more preferably in the range of 0.320 mol or more and 0.360 mol or less, and 0.325 mol or more and 0.345 mol or less, per 1 mol of Si in the prepared slurry. The following ranges are more preferable. By setting the molar ratio of the amount of potassium contained in the prepared slurry in the range of 0.320 mol or more to 0.360 mol or less, the yield of the chabazite type zeolite finally obtained becomes higher (for example, in Example 1, 2). Furthermore, by setting the molar ratio of the amount of potassium contained in the prepared slurry in the range of 0.325 mol or more to 0.345 mol or less, the yield of the chabazite type zeolite finally obtained is further increased (for example, in Examples 1).

Potassium -containing salts or hydroxides can be used as a source of potassium in the formulation slurry. Specifically, potassium hydroxide or the like can be used.

Preferably, the blended slurry contains water. The water content of the prepared slurry is preferably in the range of 100 to 800 in H ₂ O/Al ₂ O ₃ molar ratio. When the water content is within the above range, chabazite-type zeolite can be obtained in high yield with less foreign phases. If the water content is less than 100% (that is, if the raw material concentration is high), by-products will be produced during hydrothermal treatment and the yield of chabazite-type zeolite will tend to decrease, which is not preferable. On the other hand, if the water content is more than 800%, the raw material concentration becomes low, the yield of chabazite type zeolite is low, and productivity is decreased, which is not preferable.

[Hydrothermal treatment process]
In this step, the pulverized slurry is hydrothermally treated to produce chabazite-type zeolite. In this hydrothermal treatment, the pulverized slurry is filled into a closed container such as an autoclave and heated at a predetermined temperature. The temperature of the hydrothermal treatment is preferably in the range of 130°C or higher and 190°C or lower. If the temperature of the hydrothermal treatment is lower than 130° C., it is not preferable because it takes too much time to crystallize the chabazite type zeolite. If the temperature of the hydrothermal treatment exceeds 190° C., it is not preferable because foreign phases are likely to be generated.

The hydrothermal treatment time may be approximately 12 to 96 hours. Note that the hydrothermal treatment time is the time during which the temperature is maintained within the range of 130° C. to 190° C. after reaching ±10° C. of the set temperature.

Since the slurry after hydrothermal treatment contains the produced chabazite type zeolite, the solvent is removed by filtration, centrifugation, spray drying, etc. Since unreacted raw materials may remain in the chabazite-type zeolite obtained here, these may be removed by washing with warm water or the like, if necessary.

After the hydrothermal treatment step, it is preferable to perform solid-liquid separation to recover chabazite-type zeolite, which is then calcined at a temperature of 300°C to 500°C.

After the hydrothermal treatment step, if necessary, potassium and the like contained in the chabazite-type zeolite may be ion-exchanged with transition metals and the like. In order to efficiently ion-exchange potassium, etc. with transition metals, etc., chabazite-type zeolite is first immersed in an aqueous solution containing ammonium sulfate, etc., and potassium, etc. is ion-exchanged with ammonium ions. It is preferable to immerse chabazite-type zeolite, which has been previously ammonium ion-exchanged, in an aqueous solution to exchange ammonium ions with transition metals and the like.

The chabazite type zeolite obtained by the production method of the present invention has a chabazite skeleton with Si, Al, and O as basic skeleton elements, and the FAU type zeolite used as the raw material of the present invention has a chabazite skeleton with Si, Al, and O as the basic skeleton elements. It has a faujasite skeleton as the basic skeleton element. Whether the obtained zeolite has these skeletons can be confirmed according to the general rules for X-ray diffraction analysis of JIS K 0131. In addition, the measurement patterns of the X-ray diffraction of the obtained zeolite were compared to the CHA type zeolite and FAU described in "Collection of Simulated When compared with the X-ray diffraction pattern of type zeolite, if there is a peak in addition to the peaks of chabazite type zeolite and FAU type zeolite, it is determined that a different phase is generated.

According to the production method of the present invention, chabazite-type zeolite can be produced in high yield. Specifically, chabazite-type zeolite can be produced with high yield over a wide range of SiO ₂ /Al ₂ O ₃ molar ratio, and furthermore, when the SiO ₂ /Al ₂ O ₃ molar ratio is 2 or more and less than 15. It can be produced with a higher yield when the SiO ₂ /Al ₂ O ₃ molar ratio is in the range of 2 or more and 10 or less.

Examples of the manufacturing method of the present invention are shown below along with comparative examples. Note that the manufacturing method of the present invention is not limited to the following examples.

[Example 1]
Raw material slurry preparation process
846 g of pure water and 104 g of FAU type zeolite (SiO ₂ /Al ₂ O ₃ molar ratio = 8.8) were mixed. Next, a chabazite type obtained by the synthesis method of Chabazite described in "VERIFIED SYNTHESES OF ZEOLITIC MATERIALS" edited by H. Robson, KPLillerud XRD diagram: published in 2001, 2nd edition, pages 123 to 125. 11.2 g of zeolite (SiO ₂ /Al ₂ O ₃ molar ratio = 4.5, Na ₂ O / Al ₂ O ₃ molar ratio = 0.02, K ₂ O / Al ₂ O ₃ molar ratio = 0.98) It was added as a seed crystal to obtain a raw material slurry. At this time, the molar ratio of Si to Al in the raw material slurry is 8.3 in terms of SiO ₂ /Al ₂ O ₃ (hereinafter also referred to as "SAR"), and the alkali metal The molar amount of was 0.03 mol. Further, the content of the seed crystals contained in the raw material slurry was 9.7% by mass with respect to the sum of the masses of the seed crystals and FAU type zeolite contained in the raw material slurry.

Pulverized Slurry Preparation Step The raw material slurry prepared in the above step was wet-pulverized using a circulating bead mill (manufactured by Ashizawa Finetech Co., Ltd.: LMZ015) while cooling the bead mill container and the raw material slurry container with a chiller. At this time, the total intensity (H _a ) of three peaks [peaks attributed to the Miller indices of (111), (331), and (533)] appearing in the X-ray diffraction pattern of FAU type zeolite contained in the raw material slurry In contrast, the raw material slurry was wet-pulverized until the total strength (H _b ) of the FAU type zeolite became less than half (0.5H _a ≧H _b ) to obtain a pulverized slurry.
The X-ray diffraction pattern of the FAU type zeolite contained in the raw material slurry was obtained by measuring the powder obtained by removing the solvent from the raw material slurry under the following conditions.
<X-ray diffraction measurement conditions>
Device: MiniFlex (manufactured by Rigaku Co., Ltd.)
Operation axis: 2θ/θ
Radiation source: CuKα
Measurement method: Continuous voltage: 40kV
Current: 15mA
Starting angle: 2θ=5°
End angle: 2θ=50°
Sampling width: 0.020°
Scan speed: 10.000°/min

The wet pulverization conditions were as follows: zirconia beads were 0.5 mm, peripheral speed was 10 m/s, and the amount of beads filled was 85% of the container volume in terms of volume. Furthermore, when the temperature of the raw material slurry during wet pulverization exceeded 20°C, the peripheral speed was reduced. When wet pulverization was performed under these conditions, the temperature of the raw material slurry during wet pulverization was 25° C. at maximum.

Mixed Slurry Preparation Step 27.9 g of potassium hydroxide (KOH concentration: 95.5% by mass) was added to the pulverized slurry obtained in the above step to prepare a mixed slurry. At this time, the molar amount of potassium contained in the prepared slurry was 0.335 per mole of Si in the prepared slurry.

Hydrothermal treatment process This prepared slurry was placed in an autoclave and hydrothermally treated at 150°C for 48 hours. Thereafter, the prepared slurry after the hydrothermal treatment was taken out, filtered, washed, and dried to obtain chabazite-type zeolite.

[Example 2]
Chabazite-type zeolite was produced in the same manner as in Example 1, except that the molar amount of potassium contained in the prepared slurry was 0.350 mol per 1 mol of Si contained in the prepared slurry.

[Example 3]
Chabazite-type zeolite was produced in the same manner as in Example 1, except that the molar amount of potassium contained in the prepared slurry was 0.365 mol per 1 mol of Si contained in the prepared slurry.

[Example 4]
Chabazite-type zeolite was produced in the same manner as in Example 1, except that potassium hydroxide was added to the raw material slurry so that the amount of potassium was 0.12 molar ratio to 1 mole of Si contained in the raw material slurry. did.

[Example 5]
Example 1 except that the temperature of the chiller that cools the bead mill container and the raw material slurry container was changed, and the raw material slurry was wet-pulverized so that the temperature of the raw material slurry during wet-pulverization was 45° C. at maximum. Chabazite type zeolite was produced in the same manner.

[Example 6]
The amount of FAU type zeolite added was 80.4 g, the amount of seed crystal added was 34.8 g, the molar ratio of Si to Al in the raw material slurry was 7.2 in terms of SiO ₂ / Al ₂ O ₃ , and the amount of the seed crystal added was 80.4 g. A chabazite-type zeolite was obtained in the same manner as in Example 1, except that the molar amount of the alkali metal was set to 0.10 with respect to 1 mole of Si contained.

[Comparative example 1]
The same process as in Example 1 was carried out, except that potassium hydroxide was added to the pulverized slurry so that the molar amount of potassium contained in the mixed slurry was 0.310 mol per 1 mol of Si contained in the mixed slurry. Chabazite type zeolite was produced by the method.

[Comparative example 2]
The same process as in Example 1 was carried out, except that potassium hydroxide was added to the pulverized slurry so that the molar amount of potassium contained in the mixed slurry was 0.400 mol per 1 mol of Si contained in the mixed slurry. Chabazite type zeolite was produced by the method.

[Comparative example 3]
Comparative Example 2 except that the temperature of the chiller that cools the bead mill container and the raw material slurry container was changed, and the raw material slurry was wet-pulverized so that the temperature of the raw material slurry during wet-pulverization was 65°C at maximum. Chabazite type zeolite was produced in a similar manner.

[Comparative example 4]
Example 1 except that potassium hydroxide was added so that the molar amount of potassium was 0.40 with respect to 1 mole of Si contained in the raw material slurry, and on the other hand, no potassium source was added to the pulverized slurry. Chabazite-type zeolite was produced in the same manner.

The skeleton (X-ray diffraction measurement) of the produced zeolite was measured and calculated using the following method. Furthermore, the SAR and yield of the produced chabazite-type zeolite were measured or calculated using the following methods.

<skeleton>
The manufactured zeolite was subjected to X-ray diffraction measurement to confirm the presence or absence of chabazite skeleton (CHA), faujasite skeleton (FAU), and heterophase.
<X-ray diffraction measurement conditions>
Device: MiniFlex (manufactured by Rigaku Co., Ltd.)
Operation axis: 2θ/θ
Radiation source: CuKα
Measurement method: Continuous voltage: 40kV
Current: 15mA
Starting angle: 2θ=5°
End angle: 2θ=50°
Sampling width: 0.020°
Scan speed: 10.000°/min

<Presence or absence of chabazite skeleton and faujasite skeleton>
Using the X-ray diffraction pattern obtained from the above measurement, confirm whether the obtained zeolite has a chabazite skeleton (CHA) and a faujasite skeleton (FAU) according to the general rules for X-ray diffraction analysis of JIS K 0131. did.
<Presence or absence of abnormality>
The measurement patterns of the X-ray diffraction of the obtained zeolites were compared to the X-ray diffraction patterns of CHA type zeolites and FAU type zeolites described in "Collection of Simulated If the sample had a peak in addition to the peaks of CHA-type zeolite and FAU-type zeolite when compared with the line diffraction pattern, it was determined that a different phase was generated.

<SAR>
The Si and Al contents of the produced zeolite were measured under the following conditions. The content of each component was calculated as mass % in terms of oxide.
<Si, Al content measurement>
Measurement method: ICP emission spectrometer: ICPS-8100 (Shimadzu Corporation)
Sample melting: Al is acid dissolved, Si is alkali melted.

<Yield>
Regarding the produced chabazite-type zeolite, the yield of chabazite-type zeolite was calculated under the following conditions. Specifically, the Si and Al contents (respectively, in oxide terms) contained in the chabazite-type zeolite obtained in the example were measured, and this was calculated as the Si and Al contents (respectively, in terms of oxide) contained in the prepared slurry. , oxide equivalent) to calculate the yield. The calculation formula is as follows.
Yield [%] = (sum of the mass of SiO ₂ and mass of Al ₂ O ₃ contained in the produced zeolite) / (sum of the mass of SiO ₂ and mass of Al ₂ O ₃ contained in the prepared slurry) ×100

The results of Examples 1 to 6 and Comparative Examples 1 to 4 are shown in Table 1. The molar amount of alkali metal in the column of prepared slurry in Table 1 is the molar amount of potassium. In Examples 1 to 6, chabazite-type zeolites are obtained in high yields (91% to 94%). On the other hand, in Comparative Example 1, FAU zeolite was mixed with chabazite-type zeolite, and in Comparative Examples 3 and 4, zeolite of a different phase was mixed with chabazite-type zeolite, and chabazite-type zeolite could not be selectively produced. In Comparative Example 2, the yield of chabazite type zeolite is low (80%).

Claims (5)

A method for converting FAU type zeolite to produce chabazite type zeolite, the method comprising:
A step of mixing FAU type zeolite and a solvent to prepare a raw material slurry,
wet-pulverizing the raw material slurry to prepare a pulverized slurry;
adding a potassium source to the pulverized slurry to prepare a blended slurry;
and a step of hydrothermally treating the blended slurry to form chabazite-type zeolite,
The amount of alkali metal in the raw material slurry is 0.30 mol or less with respect to 1 mol of Si in the slurry, and the amount of potassium in the blended slurry is 0.320 mol or more with respect to 1 mol of Si in the blended slurry. A method for producing chabazite-type zeolite, which comprises adding a potassium source and hydrothermally treating the potassium to a concentration of 0.380 mol or less. 2. The method for producing chabazite -type zeolite according to claim 1, wherein in the step of preparing the raw material slurry, chabazite-type zeolite is added to the raw material slurry as a seed crystal . The chabazite type according to claim 2, wherein the amount of seed crystals contained in the raw material slurry is in the range of 0.1% by mass or more and 50% by mass or less based on the total mass of the seed crystals and FAU type zeolite. Method of manufacturing zeolite. The method for producing chabazite-type zeolite according to any one of claims 1 to 3, wherein in the step of preparing the pulverized slurry, the slurry temperature during pulverization is controlled to 50° C. or less. The method for producing a chabazite-type zeolite according to any one of claims 1 to 4, which includes a step of ion-exchanging the produced chabazite-type zeolite with a transition metal ion or a rare earth metal ion.