KR20240076928A - Preparation method for zeolite having both micropores and mesopores - Google Patents

Abstract

The present invention relates to a method for producing zeolite having both micropores and mesopores, and has the effect of significantly improving the mesopore formation rate compared to the conventional method.

Description

Method for producing zeolite having both micropores and mesopores {Preparation method for zeolite having both micropores and mesopores}

The present invention relates to a method for producing zeolite having both micropores and mesopores.

Zeolite is a microporous crystalline aluminosilicate with a variety of skeletal structures in which silicon and aluminum atoms are bonded to each other in a tetrahedral structure. Zeolites are used in a variety of fields due to their high porosity, high specific surface area, and low cost.

The main uses of zeolites are as heterogeneous catalysts, ion exchangers, and adsorbents in petrochemical processes. In particular, it is mainly used in petrochemical processes. Zeolite, obtained by exchanging the cations of zeolite with protons, is a solid acid with a strong acidity similar to that of 98% sulfuric acid, and is used in reactions to obtain light oil by decomposing heavy oil contained in crude oil and in various catalytic reactions.

One of the unique characteristics of zeolite is that it has micropores of regular and uniform size. Only molecules smaller than the micropores selectively enter the pores and react, and only molecules smaller than the micropores can be obtained as products. It can cause size-selective catalytic reactions. However, in the case of a reaction that decomposes large molecules into small molecules, such as a fluid catalytic decomposition reaction, if the size of the reactant is larger than or equal to the size of the micropores of the zeolite, the active site of the zeolite cannot be fully utilized due to strong diffusion limitations, so a zeolite catalyst is used. Makes it less effective.

Research is being conducted on the production of zeolite that has both micropores and mesopores for catalytic reaction, adsorption, and separation of molecules larger than the micropore size of zeolite. Bottom up and top down approaches are used to introduce mesopores into zeolite with micropores. In the case of the bottom-up approach, surfactants or templates that induce mesopore formation during the zeolite synthesis process are used, but it is disadvantageous for mass production due to the use of expensive mesopore-forming materials and changes in zeolite synthesis conditions. On the other hand, the top-down approach has the advantage of mass production because it forms mesopores through chemical treatment using acids and bases in zeolite.

Y zeolite is a microporous crystalline aluminosilicate belonging to the Faujasite (FAU) group of zeolites, and is widely used as a catalyst material in oil refining and petrochemical processes. Y zeolite has circular micropores with vertices made of 12 silicon and aluminum atoms. The size of the micropores is about 7.4 Å, and it has a structure in which oxygen atoms are bonded between each vertex.

It is known in the art that micropores have a diameter of less than 2 nm, and mesopores have a diameter of 2 to 20 nm.

Zeolites with regular micropores are used in many catalytic conversion processes because of their high surface area, strong acid sites, and excellent thermal stability, but effective mass transfer within the zeolites is limited due to their very small pore sizes.

Therefore, there is a need to develop zeolite in which both micropores and mesopores are formed simultaneously.

Public Patent Publication No. 10-2022-7001696

The purpose of the present invention is to provide a method for producing zeolite having both micropores and mesopores.

Another object of the present invention is to provide a zeolite having both micropores and mesopores prepared by the above production method.

Another object of the present invention is to provide a heterogeneous catalyst, ion exchanger, and adsorbent containing zeolite.

In order to achieve the above purpose,

The present invention includes the steps of dealuminizing zeolite by treating it with acid (step 1);

Desiliconization by base treatment (step 2);

Mixing with an aqueous ammonium chloride solution and subjecting it to ion exchange to prepare NH ₄ ⁺ -zeolite (step 3); and

Including a step of producing H ⁺ -zeolite by calcining (step 4);

A method for producing zeolite having both micropores and mesopores is provided.

The zeolite treated in step 1 may further include washing with distilled water or an organic solvent and then drying.

The zeolite treated in step 2 may further include washing with distilled water or an organic solvent and then drying.

The zeolite treated in step 3 may further include washing with distilled water or an organic solvent and then drying.

The zeolite treated in step 4 may further include washing with distilled water or an organic solvent and then drying.

The zeolite can be applied to various zeolite types, but is preferably applicable to Y zeolite, beta zeolite, ZSM-5, etc., and in the present invention, Y zeolite was used as an example.

The Y zeolite may have a silica to alumina ratio (SiO ₂ /Al ₂ O ₃ ) of 1-10, but is not limited thereto.

The acid in step 1 can be organic acids such as acetic acid, oxalic acid, formic acid, and ethylenediaminetetraacetic acid, and inorganic acids such as hydrochloric acid and nitric acid, either alone or in a mixture of two or more.

The acid treatment in step 1 is,

Using 100-400 ml of acid solution based on 10g of zeolite,

The concentration of the acid solution is 0.05-1 M,

It can be carried out at 80-120℃ for 2-24 hours.

Preferably,

The acid treatment in step 1 is,

Using 140-160 ml of acid solution based on 10g of zeolite,

The concentration of the acid solution is 0.09-0.13 M,

It can be carried out at 95-105℃ for 5-7 hours.

The base in step 2 may be sodium hydroxide, potassium hydroxide, etc., used alone or in a mixture of two or more types.

The base treatment in step 2 is,

Using 100-500 ml of base solution based on 10 g of zeolite,

The concentration of the base solution is 0.05-0.5 M,

It can be carried out at 50-80℃ for 10-600 minutes.

Preferably,

The base treatment in step 2 is,

Using 290-310 ml of base solution based on 10 g of zeolite,

The concentration of the base solution is 0.18-0.22 M,

It can be carried out at 60-70℃ for 20-40 minutes.

The ion exchange treatment in step 3 is,

Using 80-120 parts by weight of ammonium chloride aqueous solution based on 10 parts by weight of zeolite,

The concentration of the ammonium chloride aqueous solution is 0.5-1.5M,

It can be carried out at 70-110℃ for 1-24 hours.

Preferably,

The ion exchange treatment in step 3 is,

Using 90-110 parts by weight of ammonium chloride aqueous solution based on 10 parts by weight of zeolite,

The concentration of the ammonium chloride aqueous solution is 0.9-1.1M,

It can be carried out at 85-95℃ for 2-4 hours.

The baking treatment of step 4 is,

After drying the zeolite obtained in step 3,

It can be fired at 500-600℃ for 2-4 hours.

Preferably,

The baking treatment of step 4 is,

After drying the zeolite obtained in step 3,

It can be fired at 530-570℃ for 2.5-3.5 hours.

In addition, the present invention provides a zeolite having both micropores and mesopores prepared by a manufacturing method.

Furthermore, the present invention provides a heterogeneous catalyst, ion exchanger, and adsorbent including the zeolite.

The method for producing zeolite having both micropores and mesopores according to the present invention has the effect of significantly improving the mesopore formation rate compared to the conventional method.

Figure 1 is a diagram showing the nitrogen adsorption/desorption isotherm results of Y zeolite having both micropores and mesopores prepared in the present invention.
Figure 2 is a diagram showing the pore size distribution results of Y zeolite having both micropores and mesopores prepared in the present invention.
Figure 3 is a diagram showing the X-ray diffraction pattern of Y zeolite having both micropores and mesopores prepared in the present invention.
Figure 4 is a conceptual diagram showing the mesopore formation principle of Y zeolite prepared in Example 3.

Hereinafter, the present invention will be described in more detail through the following examples. However, the following examples are merely illustrative of the present invention, and the content of the present invention is not limited by the following examples.

<Example 1> Production of Y zeolite having both micropores and mesopores through dealuminization, ion exchange, and sintering processes (HY-AT)

Y zeolite was Na ⁺ -Y zeolite provided by Cosmo Catalyst Co., Ltd., and the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) was 5.

Step 1: Dealuminization (acid treatment)

A suspension was prepared by mixing 10 g of Y zeolite with 150 ml of a 0.11 M aqueous solution of ethylenediaminetetraacetic acid (EDTA). The prepared suspension was stirred at 100 °C for 6 hours. After 6 hours, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 2: Ion exchange treatment

Afterwards, 10 g of Y zeolite that had undergone the acid treatment process was dispersed in 100 g of 1 M aqueous ammonium chloride solution to prepare a suspension. The prepared suspension was stirred at 90°C for 3 hours, and Y zeolite in the form of NH ₄ ⁺ -Y zeolite was recovered through a centrifuge. The recovered Y zeolite was washed with distilled water and dried.

Step 3: Firing treatment

The dried Y zeolite was calcined at 550°C for 3 hours to prepare Y zeolite in the form of H ⁺ -zeolite.

<Example 2> Preparation of Y zeolite having both micropores and mesopores through desiliconization, ion exchange, and sintering processes (HY-BT)

Y zeolite was Na ⁺ -Y zeolite provided by Cosmo Catalyst Co., Ltd., and the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) was 5.

Step 1: Desiliconization (base treatment)

A suspension was prepared by mixing 10 g of Y zeolite with 300 ml of a 0.2 M sodium hydroxide aqueous solution. The prepared suspension was stirred at 65°C for 30 minutes. After 30 minutes, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 2: Ion exchange treatment

Afterwards, 10 g of Y zeolite that had undergone the base treatment process was dispersed in 100 g of 1 M aqueous ammonium chloride solution to prepare a suspension. The prepared suspension was stirred at 90°C for 3 hours, and Y zeolite in the form of NH ₄ ⁺ -Y zeolite was recovered through a centrifuge. The recovered Y zeolite was washed with distilled water and dried.

Step 3: Firing treatment

The dried Y zeolite was calcined at 550°C for 3 hours to prepare Y zeolite in the form of H ⁺ -zeolite.

<Example 3> Preparation of Y zeolite having both micropores and mesopores through sequential dealuminium, desiliconization, ion exchange, and calcination processes (HY-AT-BT)

Y zeolite was Na ⁺ -Y zeolite provided by Cosmo Catalyst Co., Ltd., and the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) was 5.

Step 1: Dealuminization (acid treatment)

A suspension was prepared by mixing 10 g of Y zeolite with 150 ml of a 0.11 M aqueous solution of ethylenediaminetetraacetic acid (EDTA). The prepared suspension was stirred at 100 °C for 6 hours. After 6 hours, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 2: Desiliconization (base treatment)

Afterwards, a suspension was prepared by mixing 10 g of Y zeolite that had undergone the acid treatment process with 300 ml of a 0.2 M sodium hydroxide aqueous solution. The prepared suspension was stirred at 65°C for 30 minutes. After 30 minutes, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 3: Ion exchange treatment

Thereafter, 10 g of Y zeolite that had undergone the acid treatment and base treatment was dispersed in 100 g of 1 M aqueous ammonium chloride solution to prepare a suspension. The prepared suspension was stirred at 90°C for 3 hours, and Y zeolite in the form of NH ₄ ⁺ -Y zeolite was recovered through a centrifuge. The recovered Y zeolite was washed with distilled water and dried.

Step 4: Firing treatment

The dried Y zeolite was calcined at 550°C for 3 hours to prepare Y zeolite in the form of H ⁺ -zeolite.

<Example 4> Preparation of Y zeolite having both micropores and mesopores through sequential desiliconization, dealuminium, ion exchange, and calcination processes (HY-BT-AT)

Y zeolite was Na ⁺ -Y zeolite provided by Cosmo Catalyst Co., Ltd., and the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) was 5.

Step 1: Desiliconization (base treatment)

A suspension was prepared by mixing 10 g of Y zeolite with 300 ml of a 0.2 M sodium hydroxide aqueous solution. The prepared suspension was stirred at 65°C for 30 minutes. After 30 minutes, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 2: Dealuminization (acid treatment)

Thereafter, a suspension was prepared by mixing 150 ml of 0.11 M aqueous solution of ethylenediaminetetraacetic acid (EDTA) with 10 g of Y zeolite that had undergone the base treatment process. The prepared suspension was stirred at 100 °C for 6 hours. After 6 hours, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 3: Ion exchange treatment

Thereafter, 10 g of Y zeolite that had undergone the base and acid treatment processes was dispersed in 100 g of 1 M aqueous ammonium chloride solution to prepare a suspension. The prepared suspension was stirred at 90°C for 3 hours, and Y zeolite in the form of NH ₄ ⁺ -Y zeolite was recovered through a centrifuge. The recovered Y zeolite was washed with distilled water and dried.

Step 4: Firing treatment

The dried Y zeolite was calcined at 550°C for 3 hours to prepare Y zeolite in the form of H ⁺ -zeolite.

<Comparative Example 1> H without mesopores ⁺ -Preparation of Y zeolite in zeolite form (HY)

Y zeolite was Na ⁺ -Y zeolite provided by Cosmo Catalyst Co., Ltd., and the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) was 5.

Step 1: Ion exchange treatment

A suspension was prepared by dispersing 10 g of Y zeolite in 100 g of 1 M aqueous ammonium chloride solution. The prepared suspension was stirred at 90°C for 3 hours, and Y zeolite in the form of NH ₄ ⁺ -Y zeolite was recovered through a centrifuge. The recovered Y zeolite was washed with distilled water and dried.

Step 2: Firing treatment

The dried Y zeolite was calcined at 550°C for 3 hours to prepare Y zeolite in the form of H ⁺ -zeolite.

<Comparative Example 2> Production of Y zeolite having both micropores and mesopores through sequential dealuminium and desiliconization processes

Y zeolite was Na ⁺ -Y zeolite provided by Cosmo Catalyst Co., Ltd., and the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) was 5.

Step 1: Dealuminization (acid treatment)

A suspension was prepared by mixing 10 g of Y zeolite with 150 ml of a 0.11 M aqueous solution of ethylenediaminetetraacetic acid (EDTA). The prepared suspension was stirred at 100 °C for 6 hours. After 6 hours, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

Step 2: Desiliconization (base treatment)

Afterwards, a suspension was prepared by mixing 10 g of Y zeolite that had undergone the acid treatment process with 300 ml of a 0.2 M sodium hydroxide aqueous solution. The prepared suspension was stirred at 65°C for 30 minutes. After 30 minutes, Y zeolite was recovered through a centrifuge, and the recovered Y zeolite was washed with distilled water and dried.

<Experimental Example 1> Evaluation of pore characteristics

The nitrogen adsorption/desorption isotherm, pore size distribution, and And, the results of measuring the specific surface area and volume of micropores and mesopores are shown in Table 1.

Figure 1 is a diagram showing the nitrogen adsorption/desorption isotherm results of Y zeolite having both micropores and mesopores prepared in the present invention.

Figure 2 is a diagram showing the pore size distribution results of Y zeolite having both micropores and mesopores prepared in the present invention.

Figure 3 is a diagram showing the X-ray diffraction pattern of Y zeolite having both micropores and mesopores prepared in the present invention.

In Example 1, there was almost no change in microporosity and mesoporosity compared to Comparative Example 1, and in Example 2, the specific surface area of micropores and the specific surface area of mesopores decreased sharply. The pore characteristics of the examples and comparative examples are shown in Table 1.

[Table 1]

In Example 3, the specific surface area of the micropores decreased, but the specific surface area of the mesopores increased significantly, showing a Type 4 adsorption isotherm of a typical material with mesopores. As shown in Figure 2, in Example 3, it can be seen that uniform mesopores of about 4 nm were formed, and mesopores of 4 nm to 20 nm were also formed.

On the other hand, Example 4 was observed to have pore characteristics similar to Example 2.

Figure 3 is a diagram showing the X-ray diffraction pattern of Y zeolite having both micropores and mesopores prepared in the present invention.

In Example 1, the intensity of the diffraction pattern decreased sharply compared to Comparative Example 1. In the X-ray diffraction pattern, the larger and clearer the peak, the higher the crystallinity of the zeolite. This indicates that zeolite crystallinity decreases when going through the dealuminization process.

In Example 2, the intensity of the X-ray diffraction pattern was smaller than Comparative Example 1 and larger than Example 1. This indicates that zeolite crystallinity slightly decreases when going through the desiliconization process, but has higher crystallinity than zeolite that went through the dealuminization process.

In Example 3, the intensity of the X-ray diffraction pattern was greater than that of Example 2. This indicates that the desiliconization process followed by the dealuminium process increased the crystallinity of the zeolite.

Example 4 shows an X-ray diffraction pattern of similar intensity to Example 1.

Figure 4 is a conceptual diagram showing the mesopore formation principle of Y zeolite prepared in Example 3.

According to Figures 1, 2, and 3, in the dealuminization process, the aluminum portion that accounts for a relatively low proportion of the zeolite skeleton is selectively removed, and amorphous silica and amorphous aluminosilicate are formed around the removed aluminum, thereby improving the crystallinity of the zeolite. This appears to be decreasing. In addition, the aluminum species removed from the zeolite framework appears to remain inside the pores, thereby reducing the specific surface area of micropores and mesopores.

In the desiliconization process, the silicon portion, which accounts for a relatively high proportion of the zeolite skeleton, is selectively removed, so it appears to have higher crystallinity than zeolite that has gone through the dealuminization process. In addition, the concentration of base is low compared to the dealuminization reaction used and the temperature of the desiliconization process is low, so the amount of silica removed is small, so the pore characteristics do not appear to change significantly compared to Comparative Example 1.

On the other hand, when the dealuminization process is followed by the desiliconization process, the amorphous silica and amorphous aluminosilicate formed inside the zeolite crystal are removed more easily than the crystalline silicon of the zeolite skeleton, making it possible to form mesopores of uniform size. Additionally, the crystallinity of the zeolite appears to increase because the amorphous silica and amorphous aluminosilicate portions formed during the dealuminization process are removed.

When the dealuminization process is performed after the desiliconization process, the amorphous silica and amorphous aluminosilicate formed during the dealuminum process remain inside the zeolite crystals in the zeolite that is finally recovered, causing low crystallinity and low specific surface area.

So far, the present invention has been examined focusing on its preferred embodiments. A person skilled in the art to which the present invention pertains will understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative rather than a restrictive perspective. The scope of the present invention is set forth in particular in the claims rather than the foregoing description, and all differences within the equivalent scope should be construed as being included in the present invention.

Claims (13)

Dealuminizing zeolite by treating it with acid (step 1);
Desiliconization by base treatment (step 2);
Mixing with an aqueous ammonium chloride solution and subjecting it to ion exchange to prepare NH ₄ ⁺ -zeolite (step 3); and
Including a step of producing H ⁺ -zeolite by calcining (step 4),
Method for producing zeolite having both micropores and mesopores.
According to paragraph 1,
A manufacturing method characterized in that the zeolite is Y zeolite, beta zeolite, or ZSM-5.
According to paragraph 2,
The Y zeolite is a manufacturing method characterized in that the ratio of silica and alumina (SiO ₂ /Al ₂ O ₃ ) is 1-10.
According to paragraph 1,
A production method characterized in that the acid in step 1 is at least one of acetic acid, oxalic acid, formic acid, ethylenediaminetetraacetic acid, hydrochloric acid, and nitric acid.
According to paragraph 1,
The acid treatment in step 1 is,
Using 100-400 ml of acid solution based on 10g of zeolite,
The concentration of the acid solution is 0.05-1 M,
A manufacturing method characterized in that it is carried out at 80-120°C for 2-24 hours.
According to paragraph 1,
A production method characterized in that the base in step 2 is at least one of sodium hydroxide and potassium hydroxide.
According to paragraph 1,
The base treatment in step 2 is,
Using 100-500 ml of base solution based on 10 g of zeolite,
The concentration of the base solution is 0.05-0.5 M,
A manufacturing method characterized in that it is carried out at 50-80°C for 10-600 minutes.
According to paragraph 1,
The ion exchange treatment in step 3 is,
Using 80-120 parts by weight of ammonium chloride aqueous solution based on 10 parts by weight of zeolite,
The concentration of the ammonium chloride aqueous solution is 0.5-1.5M,
A manufacturing method characterized in that it is carried out at 70-110°C for 1-24 hours.
According to paragraph 1,
The baking treatment of step 4 is,
After drying the zeolite obtained in step 3,
A manufacturing method characterized by firing at 500-600°C for 2-4 hours.
Zeolite having both micropores and mesopores manufactured by the manufacturing method of claim 1.
A heterogeneous catalyst comprising the zeolite of claim 10.
An ion exchange agent comprising the zeolite of claim 10.
An adsorbent comprising the zeolite of claim 10.