KR20220102462A - Method for synthesizing high-crystalline CHA zeolite by addition of organic acid - Google Patents

Abstract

The present invention relates to a preparation method of CHA zeolite, and more specifically, to a synthesis method of highly crystalline CHA zeolite using an organic acid in which an organic acid is added during the synthesis of CHA zeolite to prepare CHA zeolite having excellent crystallinity in a pure state without any impurities regardless of the properties of USY zeolite, which is a raw material for silica and alumina.

Description

Method for synthesizing high-crystalline CHA zeolite by addition of organic acid

The present invention relates to a method for producing CHA zeolite, and more specifically, CHA zeolite having excellent crystallinity in a pure state without impurities regardless of the characteristics of USY zeolite, which is a raw material of silica and alumina, by adding an organic acid during the synthesis of CHA zeolite. It relates to a method for synthesizing highly crystalline CHA zeolite using an organic acid capable of producing

Zeolites are crystalline hydrated aluminosilicates that may further contain other elements deposited on and/or on the crystalline backbone. The term "zeolite" includes not only aluminosilicates, but also materials in which aluminum is replaced by another trivalent element and silicon in which another tetravalent element is replaced. In general, zeolites are TO4 tetrahedral structures, forming a three-dimensional network structure sharing oxygen atoms, where T represents a tetravalent element such as silicon and a trivalent element such as aluminum.

As such, zeolite is a crystalline material with regular channels of a unique shape and size, has cation exchange ability, and can control acidity widely, so it is used as a catalyst in various fields. Recently, as strict environmental regulations on automobile exhaust gas are continuously strengthened, interest in CHA zeolite used as an SCR catalyst for NOx removal is increasing.

In general, zeolite is manufactured by a hydrothermal synthesis method in which a synthetic mother solution obtained by mixing silica and alumina raw materials, structure directing agents (SDA), and complexing materials, which are structural materials of the skeleton, in water is placed in a sealed high-pressure container and heated. In particular, zeolites with unique structures are synthesized using various types of organic structure-inducing materials, or zeolites having a large Si/Al molar ratio are synthesized. When N,N,N -tri-methyl-1-adamantammonium hydroxide (TMAdaOH), which is well known for inducing CHA structure, is used as an organic structure-inducing material, SSZ-13 zeolite with a Si/Al molar ratio of 10 or more is produced, from this The prepared Cu-SSZ-13 catalyst has excellent hydrothermal stability due to its low aluminum content and is widely used as a catalyst for automobiles. However, TMAdaOH, which is a structure-inducing material of SSZ-13 zeolite, is quite expensive, so the unit cost of a catalyst prepared therefrom is inevitably high. Therefore, research to synthesize SSZ-13 zeolite using an inexpensive organic structure-inducing material to replace expensive TMAdaOH is being actively conducted.

Recently, the results of synthesizing CHA zeolite with excellent hydrothermal stability from USY zeolite using relatively inexpensive benzyltrimethylammonium ion as an organic structure inducing material were published. The CHA zeolite catalyst prepared by this method showed excellent performance in maintaining the zeolite structure and SCR reaction activity of the catalyst considerably even after hydrothermal treatment at 900 °C. However, this preparation method used benzyltrimethylammonium hydroxide (BTMAOH) or benzyltrimethylammonium chloride (BTMACl) as a structure-inducing material, and the product distribution according to the composition of the synthetic mother liquor and the order of mixing the raw materials was significantly different. In addition, CHA was generated only in a limited area according to various synthesis conditions such as the Si/Al molar ratio, moisture content, components and amounts of impurities, composition of the synthetic mother liquor, raw material mixing sequence, and stirring speed of USY zeolite, a source of silica and alumina, in a limited area. .

Therefore, it is necessary to improve the synthesis method that can purely obtain CHA zeolite with excellent crystallinity regardless of the characteristics or synthesis conditions of the raw material USY.

Republic of Korea Patent No. 10-1795354

Accordingly, it is an object of the present invention to provide a method for producing a CHA zeolite having excellent crystallinity regardless of the characteristics or synthesis conditions of a USY zeolite precursor, which is a raw material of silica and alumina, when synthesizing CHA zeolite.

Another object of the present invention is to provide a Cu/CHA zeolite catalyst with very high NOx removal activity in the SCR reaction using ammonia because the zeolite structure does not collapse even after high-temperature hydrothermal treatment at 900 ° C. will provide

The object of the present invention is not limited to the above-mentioned object, and even if not explicitly mentioned, the object of the invention that can be recognized by a person of ordinary skill in the art from the description of the detailed description of the invention to be described later may also be included. .

In order to achieve the object of the present invention described above, the present invention comprises the steps of preparing a precursor suspension by treating a USY zeolite dispersion with an organic acid; preparing a structure-inducing material solution by dissolving the structure-inducing material and the basic material in water; preparing a synthetic mother solution by adding a structure-inducing material solution to the precursor suspension; It provides a method for synthesizing CHA zeolite comprising; synthesizing CHA zeolite by hydrothermal reaction of the synthetic mother liquor.

In a preferred embodiment, the organic acid is at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, and citric acid.

In a preferred embodiment, the precursor suspension contains 0.1 to 10 parts by weight of the organic acid per 100 parts by weight of the USY zeolite.

In a preferred embodiment, the USY zeolite has a Si/Al molar ratio of 10 to 30.

In a preferred embodiment, the USY zeolite further comprises at least one of an alkali metal, an alkaline earth metal, and a transition metal.

In a preferred embodiment, the structure-inducing material is at least one selected from the group consisting of hydroxides, halides, carbonates and sulfates having an ion of the following formula (1) as a cation.

[Formula 1]

여기서, R은 C₁ 내지 C₂₀ 인 알킬기이다.

Here, R is a C ₁ to C ₂₀ alkyl group.

In a preferred embodiment, in Formula 1, R is any one of a methyl group, an ethyl group, a propyl group, or a butyl group.

In a preferred embodiment, when R is a C ₈ to C ₂₀ alkyl group in Formula 1, mesopores are formed in the synthesized CHA zeolite.

In a preferred embodiment, the basic substance is a hydroxide of an alkali metal.

In a preferred embodiment, the hydrothermal reaction is carried out for 2 to 6 days while putting the synthetic mother liquor in a sealed autoclave and rotating it at 60 rpm or less at a temperature of 120 to 160 °C.

In a preferred embodiment, the step of drying the synthesized CHA zeolite at 70 to 100 ° C. for 9 hours or more after washing, and calcining the dried CHA zeolite for 4 hours or more while flowing air in a kiln heated to 500 ° C. or more It further comprises a step of recovering the synthesized zeolite.

In addition, the present invention provides a Cu/CHA zeolite catalyst, characterized in that copper is supported on the CHA zeolite prepared by any one of the above-described manufacturing methods.

In a preferred embodiment, the catalyst has a NOx removal activity of 25% or more at a low temperature of 150 °C to 200 °C even after hydrothermal treatment at 900 °C.

According to the CHA zeolite synthesis method of the present invention described above, CHA zeolite having excellent crystallinity can be prepared in a pure state without impurities, regardless of the characteristics of silica used as a starting material and USY zeolite, a raw material of alumina.

In addition, according to the Cu/CHA zeolite catalyst of the present invention, the zeolite structure did not collapse and was well maintained even after high-temperature hydrothermal treatment at 900° C., so the NOx removal activity of the SCR reaction using ammonia was very high.

These technical effects of the present invention are not limited only to the range mentioned above, and even if not explicitly mentioned, the effect of the invention that can be recognized by those of ordinary skill in the art from the description of the specific content for the implementation of the invention to be described later is also of course included

1 is a flowchart for explaining a method of synthesizing CHA zeolite from a zeolite precursor USY by adding an organic acid according to an embodiment of the present invention.
2 is an XRD pattern of a comparative example synthesized by a conventional hydrothermal synthesis method according to the type of USY zeolite, which is a zeolite precursor.
3 is an SEM photograph of Comparative Example 1 and Comparative Example 2 prepared by the conventional hydrothermal synthesis method.
4 is an XRD pattern of a CHA zeolite prepared by adding oxalic acid through a manufacturing method according to an embodiment of the present invention.
5 is an SEM photograph of a CHA zeolite prepared by adding oxalic acid through a manufacturing method according to an embodiment of the present invention.
6 is an XRD pattern of CHA zeolite prepared by adding various types of organic acids through a manufacturing method according to another embodiment of the present invention.
7 is an XRD pattern after hydrothermal treatment of a Cu/CHA zeolite catalyst prepared by ion-exchanging copper to CHA zeolite synthesized by adding oxalic acid according to another embodiment of the present invention.
8 is a nitrogen adsorption isotherm before and after hydrothermal treatment of a Cu/CHA zeolite catalyst prepared by ion-exchanging copper to CHA zeolite synthesized by adding oxalic acid according to another embodiment of the present invention.
9 is a graph showing the ammonia SCR reaction activity after hydrothermal treatment of a Cu/CHA zeolite catalyst prepared by ion-exchanging copper to CHA zeolite synthesized by adding oxalic acid according to another embodiment of the present invention; to be.

The terms used in the present invention are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the description of the invention is present, but one or more other It should be understood that this does not preclude the possibility of addition or presence of features or numbers, steps, operations, components, parts, or combinations thereof.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present invention. does not

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description. In particular, when the terms "about", "substantially", etc. of degree are used, they may be construed as being used in a sense at or close to the numerical value when manufacturing and material tolerances inherent in the stated meaning are presented. . Also, where the description discloses numerical ranges, such ranges are continuous and inclusive of all values from the minimum to the maximum inclusive of the range, unless otherwise indicated. Furthermore, when such ranges refer to integers, all integers inclusive from the minimum to the maximum inclusive are included, unless otherwise indicated.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described as 'after', 'following', 'after', 'before', etc., 'immediately' or 'directly' This includes cases that are not continuous unless ' is used.

Hereinafter, the technical configuration of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein, and like reference numerals indicate like elements in different forms.

The technical feature of the present invention is a method for producing a CHA zeolite having excellent crystallinity regardless of the characteristics or synthesis conditions of a USY zeolite precursor, which is a raw material of silica and alumina, by adding an organic acid during the synthesis of CHA zeolite, and CHA prepared by the method in a catalyst comprising a zeolite.

That is, according to the conventionally known CHA zeolite synthesis method, the Si/Al molar ratio, moisture content, components and amounts of impurities, composition of the synthetic mother liquor, raw material mixing order, stirring speed, etc. This is because the CHA zeolite was not formed and showed a tendency to generate CHA only in a limited area that had to meet certain conditions.

Accordingly, the method for synthesizing CHA zeolite of the present invention comprises the steps of preparing a precursor suspension by treating an organic acid in a USY zeolite dispersion; preparing a structure-inducing material solution by dissolving the structure-inducing material and the basic material in water; preparing a synthetic mother solution by adding a structure-inducing material solution to the precursor suspension; and synthesizing CHA zeolite by hydrothermal reaction of the synthetic mother liquor.

The step of preparing the precursor suspension may be performed by dispersing the USY zeolite in an appropriate amount of water, adding an organic acid, and treating with an organic acid while stirring at room temperature to 80°C.

Here, as the organic acid, all known organic acids may be used, but in one embodiment, it may be one or more selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, citric acid, and the like.

The USY zeolite may include various types of sources having different chemical compositions and physicochemical properties. As an embodiment, USY zeolite having a Si/Al molar ratio of 10 to 30 may be used. In addition, the USY zeolite may further contain one or more of an alkali metal, an alkaline earth metal, and a transition metal as an impurity.

The precursor suspension may contain 0.1 to 10 parts by weight of an organic acid per 100 parts by weight of USY zeolite.

The step of preparing the structure-directing material solution may be performed by dissolving structure directing agents (SDA) and a basic material in water, and may be performed before or simultaneously with the step of preparing the precursor suspension.

As the structure-inducing material, hydroxides, halides, carbonates and sulfates containing quaternary ammonium ions may be used, and in one embodiment, from the group consisting of hydroxides, halides, carbonates and sulfates having ions of Formula 1 as a cation It may be one or more selected.

[Formula 1]

여기서, R은 C₁ 내지 C₂₀ 인 알킬기이다.

Here, R is a C ₁ to C ₂₀ alkyl group.

Here, in Formula 1, R may be any one of a methyl group, an ethyl group, a propyl group, or a butyl group. In this case, the cation is benzyltrimethylammonium ion, benzyltriethylammonium ion, benzyltripropylammonium ion or benzyltributylammonium ion can In particular, when R is a C ₈ to C ₂₀ alkyl group in Formula 1, mesopores may be formed in the synthesized CHA zeolite.

The basic material is a material for making a basic aqueous solution by mixing with distilled water, and is not limited as long as it is a basic material having no problem in compatibility with the precursor suspension.

The step of preparing the synthetic mother liquor may be carried out by slowly adding the precursor suspension to a well-mixed structure-inducing material solution while stirring it at a high speed.

The step of synthesizing CHA zeolite is a step of producing CHA zeolite by aging the synthetic mother liquor and then hydrothermal reaction. Rotating at 60 rpm or less at 160 ° C. can be performed for 2 to 6 days.

Thereafter, the step of recovering the synthesized zeolite may be further performed, and the recovery step may be performed by separating the solids through centrifugation or filtration and then washing. More specifically, the steps of drying the synthesized CHA zeolite at 70 to 100° C. for 9 hours or more after washing and calcining the dried CHA zeolite in a kiln heated to 500° C. or more while flowing air for 4 hours or more may include.

Example 1

As shown in FIG. 1, CHA zeolite was prepared.

1. Preparing a precursor suspension

Si/Al molar ratio is 21.5, surface area is 785 m ² /g, and 1 g of USY1 containing 10.2 wt% of water is dispersed in 3 g of water, and 0.012 g of oxalic acid ((COOH) ₂ ㅇ2H ₂ O) is added. and stirred at 60° C. for 2 hours to prepare a zeolite suspension.

2. Preparing a structure-inducing material solution

The structure-inducing material solution was prepared by dissolving 0.21 g of sodium hydroxide and 0.94 g of the structure-inducing material in 6.0 g of water, followed by sufficient stirring. Here, benzyltrimethyl ammonium chloride (BTMACl) was used as a structure-inducing material.

3. Preparation of synthetic mother liquor

A synthetic mother solution was prepared by slowly adding the structure-inducing material solution while vigorously stirring the suspension. The final composition of the synthetic mother liquor was 1.0 SiO ₂ : 0.3 SDA: 0.3 NaOH: 30.0 H ₂ O.

4. Synthesis of CHA zeolite

The synthetic mother liquor was aged at room temperature for 4 hours, and then hydrothermal reaction was performed for 4 days while rotating at 140° C. at 40 rpm to prepare CHA zeolite 1.

5. Synthesized CHA Zeolite Recovery Step

After the hydrothermal reaction was completed, the solid was separated through filtration, washed with a sufficient amount of distilled water, and dried at 90° C. for 12 hours. After that, it was fired for 6 hours while flowing air in a kiln heated to 550 °C.

6. Preparation of Cu/CHA Zeolite Catalyst

After the synthesized CHA zeolite 1 was made into NH ₄ -form through NH ₄ ⁺ ion exchange, Cu/CHA zeolite catalyst 1 was prepared by further ion-exchanging Cu.

Example 2

CHA zeolite 2 and Cu/CHA zeolite catalyst 2 were prepared in the same manner as in Example 1, except that the Si/Al molar ratio was 18.0, the surface area was 758 m ² /g, and USY2 containing 9.6 wt% of moisture was used. got it

Example 3

CHA zeolite 3 and Cu/CHA zeolite catalyst 3 were prepared in the same manner as in Example 1 except that USY3 having a Si/Al molar ratio of 17.2, a surface area of 769 m ² /g and containing 8.8 wt% of moisture was used. got it

Example 4

CHA zeolite 4 and Cu/CHA zeolite catalyst 4 were prepared in the same manner as in Example 1 except that USY4 having a Si/Al molar ratio of 18.5, a surface area of 744 m ² /g and containing 11.0 wt% of moisture was used. got it

Example 5

The Si/Al molar ratio is 16.9, the surface area is 700 m ² /g, the water content is 7.9 wt%, and as shown in Table 1 below, USY5 in which a significant amount of metal ions are mixed as impurities was used, except that USY5 was used. The same method was followed to obtain CHA zeolite 5 and Cu/CHA zeolite catalyst 5.

division Si/Al surface area
(m ² /g) pore volume
(cm ³ /g) moisture content
(wt%) Impurities (ppm) Na Fe Zr Ce Ti La USY1 21.5 785 0.52 10.2 270 90 490 20 130 < 10 USY2 18.0 758 0.53 9.6 〃 〃 〃 〃 〃 〃 USY3 17.2 769 0.52 8.8 〃 〃 〃 〃 〃 〃 USY4 18.5 744 0.49 11.0 〃 〃 〃 〃 〃 〃 USY5 16.9 700 0.51 7.9 530 180 370 210 210 240

Example 6

CHA zeolite 6 and Cu/CHA zeolite catalyst 6 were obtained in the same manner as in Example 4 except that 0.010 g of malonic acid, not oxalic acid, was added.

Example 7

CHA zeolite 7 and Cu/CHA zeolite catalyst 7 were obtained in the same manner as in Example 4 except that 0.011 g of succinic acid instead of oxalic acid was added.

Example 8

CHA zeolite 8 and Cu/CHA zeolite catalyst 8 were obtained in the same manner as in Example 4 except that 0.013 g of glutaric acid, not oxalic acid, was added.

Example 9

CHA zeolite 9 and Cu/CHA zeolite catalyst 9 were obtained in the same manner as in Example 4 except that 0.018 g of citric acid instead of oxalic acid was added.

Comparative Example 1

For comparison between the present invention and the conventional synthesis method, CHA zeolite was synthesized by the conventional method without any organic acid treatment.

1. Hydration gel preparation step

After dissolving NaOH and benzyltrimethylammonium chloride (BTMACl) in 9 g of water and sufficiently stirring, add 1 g of USY1 having a Si/Al molar ratio of 21.5, a surface area of 785 m ² /g and 10.2 wt% of moisture, and mix. Thus, a hydrogel having the following molar ratio composition was prepared.

SiO2 : SDA(BTMACl) : NaOH : H ₂ 0 = 1.0 : 0.3 : 0.3 : 30.0

2. Hydrothermal synthesis step

After hydrothermal synthesis was performed for 4 days while rotating the hydrogel at 140° C. at 40 rpm, the sample was recovered through centrifugation to prepare CHA zeolite 1 of Comparative Example.

3. Preparation of Comparative Example Cu/CHA Zeolite Catalyst 1

Comparative Example CHA zeolite 1 was made into NH ₄ -form through NH ₄ ⁺ ion exchange, and then Cu was further ion-exchanged to prepare Comparative Example Cu/CHA zeolite catalyst 1.

Comparative Example 2

Comparative Example CHA Zeolite 2 and Comparative Example Cu/CHA were performed in the same manner as in Comparative Example 1 except that USY2 having a Si/Al molar ratio of 18.0, a surface area of 758 m ² /g, and a moisture content of 9.6 wt% was used. A zeolite catalyst 2 was obtained.

Comparative Example 3

The same method as in Comparative Example 1 was performed except that USY3 having a Si/Al molar ratio of 17.2, a surface area of 769 m ² /g and containing 8.8 wt% of moisture was used, but CHA zeolite 3 of Comparative Example was hardly formed.

Comparative Example 4

The same method as in Comparative Example 1 was performed except that USY4 having a Si/Al molar ratio of 18.5, a surface area of 744 m ² /g and containing 11.0 wt% of moisture was used, but Comparative Example CHA zeolite 4 was hardly formed.

Comparative Example 5

The Si/Al molar ratio is 16.9, the surface area is 700 m ² /g, the moisture content is 7.9 wt%, and as shown in Table 1 above, USY5 in which a significant amount of metal ions are mixed as impurities was used, except that USY5 was used as compared to Comparative Example 1 Although the same method was performed, comparative example CHA zeolite 5 was hardly formed.

Experimental Example 1

The XRD patterns were observed for Comparative Examples CHA zeolites 1 to 5 obtained in Comparative Examples 1 to 5, and the results are shown in FIG. 2 .

As shown in FIG. 2, in Comparative Examples 1 and 2 using USY1 and USY2 as raw materials, CHA zeolite having excellent crystallinity to some extent was produced. However, in Comparative Example 1, only a diffraction peak corresponding to a pure CHA crystal without impurities was observed, but in Comparative Example 2, a diffraction peak of MOR zeolite was mixed, so it can be seen that MOR zeolite was mixed as an impurity. On the other hand, in Comparative Examples 3 to 5, almost no CHA zeolite was produced, and according to the conventional synthesis method, it was confirmed that the product distribution of CHA zeolite was greatly changed according to the characteristics of the raw material USY.

Experimental Example 2

Comparative Examples CHA zeolites 1 and 2 obtained in Comparative Examples 1 and 2 were observed by SEM, and the resulting photograph is shown in FIG. 3 .

As shown in FIG. 3, Comparative Example 1 was produced by mixing a small amount of impurities with large particles of 2 μm or more in cubic CHA zeolite particles of 500 to 700 nm, and Comparative Example 2 was confirmed that much more impurities were generated. .

Experimental Example 3

The XRD patterns were observed for the CHA zeolites 1 to 5 obtained in Examples 1 to 5, and the results are shown in FIG. 4 .

As shown in FIG. 4, CHA zeolites 1 to 5 prepared from a synthetic mother liquor prepared while gradually adding a structure-inducing material solution to a zeolite precursor suspension to which oxalic acid is added by improving the synthesis method according to an embodiment of the present invention are used as raw materials. It can be seen that only pure CHA zeolite without impurities was produced regardless of the characteristics of the USY zeolite.

Experimental Example 4

The CHA zeolites 1 to 4 obtained in Examples 1 to 4 were observed by SEM, and the resulting photograph is shown in FIG. 5 .

As shown in FIG. 5 , in CHA zeolite 1 to 4, although the particle size of the CHA zeolite produced was different depending on the type of USY, only cubic particles without impurities were produced. In particular, when compared with the XRD pattern of Figure 4, it can be seen that only pure CHA zeolite was produced.

Experimental Example 5

The XRD patterns were observed for the CHA zeolites 6 to 9 obtained in Examples 6 to 9, and the results are shown in FIG. 6 .

As shown in FIG. 6 , it can be seen that CHA zeolite having excellent crystallinity was produced even when various types of organic acids were added as well as oxalic acid.

Experimental Example 6

For Cu/CHA zeolite catalysts 1 to 5 obtained in Examples 1 to 5, XRD patterns were observed after hydrothermal treatment at 900° C. as follows, and the results are shown in FIG. 7 . In order to test the hydrothermal stability, the Cu/CHA zeolite catalyst layer heated to 900 °C was hydrothermally treated for 12 hours while flowing air containing 10% water at 100 ml/min.

As shown in FIG. 7, the Cu/CHA zeolite catalysts 1 to 5 prepared through the present invention maintained the characteristic peak of CHA well even after severe hydrothermal treatment at 900°C.

Experimental Example 7

The characteristics of the Cu/CHA zeolite catalysts 1 to 5 obtained in Examples 1 to 5 were observed before and after hydrothermal treatment at 900 ° C. The results are shown in Table 2, and the observation results for the nitrogen adsorption isotherm are shown in FIG. It was.

As shown in Table 2 below, after hydrothermal treatment, the Cu/CHA zeolite catalysts 1 to 5 had slight differences depending on the raw material, but it was found that the micropores were hardly collapsed and were well maintained.

Si/Al Cu content
(wt%) surface area (m ² /g) Pore volume (cm ³ /g) before hydrothermal treatment After hydrothermal treatment before hydrothermal treatment After hydrothermal treatment Example 1 11.2 2.5 580 506 0.35 0.39 Example 2 10.8 3.2 563 506 0.29 0.28 Example 3 11.2 3.2 566 532 0.32 0.30 Example 4 12.1 3.0 575 548 0.27 0.26 Example 5 10.9 1.9 559 569 0.30 0.30

In addition, as shown in FIG. 8 , it can be seen that the Cu/CHA zeolite catalysts 1 to 5 maintained a nitrogen adsorption isotherm similar to that before the hydrothermal treatment even after hydrothermal treatment at 900 ° C. And it can be seen that the structural change of the zeolite is not significant even in the hydrothermal treatment process of 900 °C or higher for the catalyst containing the same.

Experimental Example 8

Cu/CHA zeolite catalysts 2 to 4 obtained in Examples 2 to 4 and Comparative Example Cu/CHA zeolite catalyst 2 obtained in Comparative Example 2 were subjected to hydrothermal treatment at 900° C. and then the activity of SCR reaction using ammonia was investigated. is shown in FIG. 9 .

As shown in FIG. 9 , the Cu/CHA zeolite catalyst prepared according to the present invention exhibited high NOx removal activity of 70% or more at 200 to 500°C even after hydrothermal treatment at 900°C. In addition, it can be seen that the Cu/CHA zeolite catalysts 2 to 4 of the present invention maintained much higher activity than Comparative Example Catalyst 2 prepared by the conventional method in a low temperature region of 300° C. or less, particularly 150° C. to 200° C., after hydrothermal treatment. .

Although the present invention has been described with reference to preferred embodiments as described above, it is not limited to the above-described embodiments, and various methods can be made by those of ordinary skill in the art to which the present invention pertains without departing from the spirit of the present invention. Changes and modifications will be possible.

Claims (13)

preparing a precursor suspension by treating the USY zeolite dispersion with an organic acid;
preparing a structure-inducing material solution by dissolving the structure-inducing material and the basic material in water;
preparing a synthetic mother solution by adding a structure-inducing material solution to the precursor suspension;
CHA zeolite synthesis method comprising; synthesizing CHA zeolite by hydrothermal reaction of the synthetic mother liquor.
The method of claim 1,
The organic acid is CHA zeolite synthesis method, characterized in that at least one selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, and citric acid.
The method of claim 1,
The precursor suspension is a CHA zeolite synthesis method, characterized in that it contains 0.1 to 10 parts by weight of the organic acid per 100 parts by weight of the USY zeolite.
The method of claim 1,
The USY zeolite is a CHA zeolite synthesis method, characterized in that the Si/Al molar ratio is 10 to 30.
5. The method of claim 4,
The USY zeolite is a CHA zeolite synthesis method, characterized in that it further comprises at least one of an alkali metal, an alkaline earth metal, and a transition metal.
The method of claim 1,
The structure-inducing material is a CHA zeolite synthesis method, characterized in that at least one selected from the group consisting of hydroxides, halides, carbonates and sulfates having an ion of Formula 1 as a cation.
[Formula 1]

Here, R is a C ₁ to C ₂₀ alkyl group.
7. The method of claim 6,
R in Formula 1 is a CHA zeolite synthesis method, characterized in that any one of a methyl group, an ethyl group, a propyl group, or a butyl group.
7. The method of claim 6,
In Formula 1, when R is a C ₈ to C ₂₀ alkyl group, a method for synthesizing CHA zeolite, characterized in that mesopores are formed in the synthesized CHA zeolite.
The method of claim 1,
The basic material is a CHA zeolite synthesis method, characterized in that the hydroxide of an alkali metal.
The method of claim 1,
The hydrothermal reaction is a CHA zeolite synthesis method, characterized in that it is carried out for 2 to 6 days while putting the synthetic mother liquid in a sealed autoclave and rotating it at a temperature of 120 to 160 ° C. at 60 rpm or less. 11. The method according to any one of claims 1 to 10,
After washing the synthesized CHA zeolite, drying the synthesized CHA zeolite at 70 to 100° C. for 9 hours or more, and calcining the dried CHA zeolite in a kiln heated to 500° C. or more while flowing air for 4 hours or more. A synthesized zeolite recovery step CHA zeolite synthesis method, characterized in that it further comprises.
A Cu/CHA zeolite catalyst characterized in that copper is supported on the CHA zeolite prepared by the method of any one of claims 1 to 10.
13. The method of claim 12,
Cu/CHA zeolite catalyst, characterized in that the catalyst has a NOx removal activity of 25% or more at a low temperature of 150°C to 200°C even after hydrothermal treatment at 900°C.

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