JPH01208314A - Mordenite-type zeolite having particular crystal form and production thereof - Google Patents

Abstract

PURPOSE:To obtain the above rod-shaped zeolite having spherically grown parts at both ends and useful as a catalyst, etc., by reacting an aqueous solution of an alkali metal silicate with an Al-containing aqueous solution under specific condition, contacting the obtained compound with NaBr or Na3BO3 and crystallizing in an aqueous solution of an alkali metal hydroxide. CONSTITUTION:An aqueous solution of an alkali metal silicate (e.g., Na2SiO3) is made to continuously react with an Al-containing aqueous solution [e.g., Al2(SO4)3 solution] at pH 5-9 and a definite ratio selected according to the SiO2/Al2O3 molar ratio of the objective zeolite. The produced slurry is retained in a reaction vessel preferably for >=3min and then separated to obtain a homogeneous phase compound of a granular amorphous aluminosilicate having an Al2O3 content of 3-14wt.% (in terms of anhydrous state). The obtained compound is mixed with an aqueous solution of NaBr or Na3BO3 at a molar ratio of 0.1-20 based on the Al2O3 in the aluminosilicate compound. After homogenizing the mixture, it is crystallized in an aqueous solution of an alkali metal hydroxide having a concentration of 0.5-3.0wt.% e.g., at 130-250 deg.C and the obtained crystal is separated and dried.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a zeolite having a unique crystal morphology, and
The manufacturing method is explained below. When zeolite is used as a catalyst or adsorbent, its performance is affected by its composition, crystal shape, crystal size, etc. Therefore, the present invention provides a mordenite-type zeolite having a novel crystalline form that can be effectively used as a catalyst, an adsorbent, etc., and an economical method for producing the same.

[Prior Art] Mordenite used in catalysts, adsorbents, etc. is usually a plate-like crystal of 0.5 to 2 μm or a prismatic crystal with a width of 1 μm or less, and the crystals stick together and form secondary particles. is forming. However, mordenite with controlled crystal shape has also been synthesized.

JP-A No. 62-52121 discloses that large crystal mordenite of 30 to 50 μm can be obtained by the presence of an amino alcohol in the reaction mixture! ! The method of leaving is disclosed. Furthermore, this method is non-industrial because it uses expensive organic materials.

Furthermore, a method for synthesis by adding an inorganic mineralizing agent to the reaction mixture is also disclosed.

The method disclosed in Japanese Patent Application Laid-Open No. 46-4369 is as follows:
The purpose is to obtain high-quality crystals at a temperature of 160°C or lower, and a pK of 10 or more when measured at 18°C for the highest dissociation stage.
A polybasic acid having a value is present in the reaction mixture. Then, the polybasic acid is expressed as Na2O, and the molar ratio (m) of Na2O/A or 203 in the reaction mixture is m=8.3-0.06 (t-100)±2.3 and t is 160 ℃ or below). However, in the embodiments of this invention, only sodium orthophosphate is used.

[Problems to be Solved by the Invention] The present invention provides a mordenite-type zeolite that has a novel crystalline form that can be effectively used as an adsorbent, a catalyst, etc., which has not been previously available, and an economical method for producing the same. It is.

[Means for Solving the Problems] The novel substance of the present invention is a mordenite-type zeolite having a rod-like crystal morphology with both ends grown into spherical shapes.

The method for producing this new substance will be explained below.

A granular amorphous aluminosilicate homogeneous phase compound obtained by simultaneously and continuously reacting an alkali metal silicate aqueous solution and an aluminum-containing aqueous solution at a fixed ratio is brought into contact with sodium bromide or sodium borate to form an alkali metal hydroxide. Manufactured by crystallization in an aqueous solution.

As the aqueous alkali metal silicate solution, aqueous solutions of lithium silicate, sodium silicate, potassium silicate, etc. can be suitably used, and as the aluminum-containing aqueous solution, aluminum sulfate, aluminum nitrate, aluminum chloride, sodium aluminate, potassium aluminate, etc. can be suitably used. . Also,
If necessary, a caustic alkali or a mineral acid may be added to these aqueous solutions to adjust the amount of alkali or acid. Both aqueous solutions may be commercially available aqueous alkali metal silicate solutions, aqueous aluminum mineral salt solutions, or alkali aluminate solutions. Aqueous solutions may be used, or aqueous solutions may be prepared by dissolving silica sources such as silica sand and hydrated solid silicic acid in caustic alkali, and dissolving aluminum sources such as aluminum hydroxide and activated alumina in caustic alkali or mineral acids. It can also be used.

The concentrations of both aqueous solutions are not particularly limited, as long as the reaction solution becomes a slurry, but if the slurry concentration is too high, it becomes uneconomical.

The most preferred embodiment for preparing a homogeneous phase compound using this method is a method in which both aqueous solutions are simultaneously and continuously fed into an overflow type reaction tank equipped with a stirrer and reacted under stirring.

According to this method, the homogeneous phase compound produced is approximately spherical, and most of the particle diameters are distributed in the range of 1 to 500μ.
The amount of fine particles smaller than μ is extremely small.

The supply ratio of both aqueous solutions is set depending on the S i O2/A120a molar ratio of the target mordenite-type zeolite and can be arbitrarily determined.

At that time, the reaction solution suspends the generated particulate homogeneous phase compound and becomes a slurry, but the pH of the slurry is controlled by the amount of alkali or acid added to both aqueous solutions, and the pH of the slurry is usually adjusted.
The pH is adjusted to a range of 5 to 9, more preferably a pH of 6 to 8. When the pH becomes low, aluminum dissolves in the mother liquor, and when the pH increases, silicon dissolves in the mother liquor, both of which are uneconomical. Further, the time that the slurry stays in the reaction species is preferably 3 minutes or more. The residence time is expressed as (inner volume of reaction vessel)/(sum of supply amounts of both aqueous solutions per unit time). If the residence time is shorter than 3 minutes, the proportion of fine particles of 1 μm or less in size increases, which puts an undesirable burden on the filtration and separation process of the produced homogeneous phase compound. On the other hand, when the residence time is 3 minutes or more, most of the product becomes spherical, and the presence of fine particles becomes extremely small. Further, as the residence time becomes longer, the particle diameter becomes larger and at the same time the hardness of the spherical particles increases. Therefore, by controlling the residence time, the size and hardness of the generated spherical particles can be changed, so it is possible to adjust the reactivity of the homogeneous phase compound itself depending on the purpose.

The reaction temperature during the preparation of the homogeneous phase compound is not particularly limited, and may be from room temperature to 100°C, which is commonly used.

If the temperature is lower than room temperature, cooling is required, and 1
If the temperature is higher than 00℃, a pressure-resistant container is required to prevent the water from evaporating, which is undesirable.Also, in both low and high temperatures, the homogeneous phase compound becomes almost spherical, and there is no significant difference in the reactivity of the homogeneous phase compound formed. do not have.

The characteristic feature of the present invention is that by reacting both aqueous solutions simultaneously and continuously at a fixed ratio, a nearly spherical homogeneous phase compound is used, which always precipitates in a uniform state with a constant composition. There is no non-uniformity in the phase compound, and the coexistence of impurities caused by non-uniformity of composition during crystallization can be completely prevented.

On the other hand, in a conventional method, for example, a method in which one aqueous solution is added to another aqueous solution, non-uniform portions occur in the precipitate. Furthermore, since the particle size of the precipitate has a very wide distribution, solid-liquid separation and cleaning become extremely difficult. Furthermore, since the precipitate has a high water absorption rate, slurrying the reaction mixture for crystallization requires a very low slurry concentration, which is uneconomical.

However, since the homogeneous phase compound obtained by the method of the present invention is obtained in the form of spheres of appropriate size, solid-liquid separation and washing are extremely easy. Furthermore, since it is well dehydrated, even if it is used as it is in a wet state, it is possible to increase the slurry concentration when preparing a homogeneous phase compound slurry for crystallization. This point is also one of the features of the present invention. The homogeneous phase compound after washing can be used in a wet or dry state.

Homogeneous phase compounds having various compositions can be prepared by the method described above, but in order to carry out the present invention, the homogeneous phase compound has an aluminum content of A1203 on an anhydrous basis.
It is essential to contain 14 wt% (anhydrous standard)*
A! ; When crystallization is performed using a homogeneous phase compound in which the 1203 content is lower than 3 wt% and the homogeneous phase compound in which the Af20a content is higher than 14 wt%, impurities are generated. A homogeneous phase compound with an Al203 content of 3 to 14 wt% (anhydrous basis) is composed of SiO2 and Al2 of both raw material aqueous solutions.
This can be obtained by adjusting the flow rate ratio of both aqueous solutions in consideration of the O3 concentration. For example, by increasing the Yamata 203 concentration of the aluminum-containing aqueous solution and its flow rate ratio, a homogeneous phase compound with a high An203 content can be obtained.
In order to increase the molar ratio, it is desirable to use a homogeneous phase compound with a low AlzOa content within the above range, and S
In order to obtain a mordenite type zeolite with a low iO2/Al2O3 molar ratio, it is desirable to use a homogeneous phase compound with a high Al2O3 content within the above range. As mentioned above, in the present invention, the SiO? /Al2O3 molar ratio can be adjusted freely.

The homogeneous phase compound obtained in this way is a porous amorphous aluminosilicate with many fine pores, so a large amount of inorganic or organic neutral salts can be selectively adsorbed into the pores. I can do things.

Therefore, these inorganic or organic neutral salts act very effectively on changing the structure and crystal form of the crystallized product.

The resulting homogeneous phase compound is contacted with sodium bromide or sodium borate. As the sodium borate, sodium tetraborate, sodium metaborate, sodium pentaborate, etc. can be used. When sodium chloride, sodium sulfate, sodium tripolyphosphate, and sodium nitrate are used, plate-shaped mordenite is obtained. The contacting method is not particularly limited, but it is usually immersed in an aqueous solution containing sodium bromide or sodium borate. Although the amount of sodium bromide or sodium borate added is not particularly limited,
It is essential that the molar ratio to O3 is 0.1 to 20. When the amount added is less than 0.1, plate-like mordenite is obtained. Moreover, even if it exceeds 20, it is uneconomical and the same improvement cannot be achieved.

Crystallization is then carried out by heating the homogeneous phase compound in contact with sodium bromide or sodium borate in an aqueous alkali metal hydroxide solution. As the aqueous alkali metal hydroxide solution, an aqueous solution of sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. is suitable. Moreover, a mixed aqueous solution of two or more of these may be used.

The concentration of the alkali metal hydroxide aqueous solution is the MO in the crystallization solution.
It is essential that the H (M is an alkali metal) concentration be 0.3 to 5 wt%. If 0M0Hi1 degree exceeds 5 wt%, impurities will coexist, and if it is lower than 0.3 wt%, it will be difficult to crystallize. The amount of the alkali metal hydroxide aqueous solution is not particularly limited, and it is sufficient that the reaction mixture for crystallization becomes a slurry, but if the amount of the alkali metal hydroxide aqueous solution is too large, the slurry concentration will decrease and the It becomes economical.

Crystallization is carried out using a closed container made of stainless steel or the like at a temperature of 130 to 250°C, which is usually used for zeolite synthesis.

If the temperature is lower than 130℃, the crystallization time will be very long.
When the temperature exceeds 250°C, impurities coexist. The time required for crystallization depends on the temperature, but is usually 1 to 200 hours.

After crystallization is completed, the generated crystals undergo solid-liquid separation, washing,
It is then recovered by drying.

In the manner described above, a mordenite-type zeolite having a rod-like crystal form with both ends grown into spherical shapes can be obtained.

[Action and Effect of the Invention When cozeolite is used as a catalyst, adsorbent, etc.
In particular, the crystal shape greatly affects the catalyst performance, thermal stability, lifespan, etc.

In the present invention, a granular amorphous aluminosilicate homogeneous phase compound obtained by simultaneously and continuously reacting an aqueous alkali metal silicate solution and an aqueous aluminum-containing solution is brought into contact with sodium bromide or sodium borate, and an alkali hydroxide By crystallizing it in an aqueous metal solution, it has become possible to economically obtain mordenite-type zeolite, which has a unique crystalline form that can be effectively used as a catalyst, adsorbent, etc.

As explained above, according to the present invention, mordenite-type zeolite having a unique crystal form can be obtained economically and can be effectively used as a catalyst, an adsorbent, etc.

Usually, mordenite-type zeolite is obtained in the form of secondary agglomerated particles by prismatic or flat crystals sticking together and agglomerating. For this reason, when used as a catalyst, adsorbent, etc., most of the pore population on the crystal surface becomes unusable. However, since the mordenite-type zeolite obtained in the present invention has spherical bulges at both ends, the crystals do not stick together and form an aggregated state, and the entire surface of the crystals can be effectively used as a catalyst, adsorbent, etc.

Further, the mordenite having a unique crystal form obtained by the present invention can be further ion-exchanged with other ions to control the pore size and adsorption characteristics, and can be used as various adsorption/separation agents. In addition, it can be catalyzed by converting it into H type and used as a solid acid catalyst for various reactions. Furthermore, P
By supporting metal ions such as t, it can be effectively used as various catalysts.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1゜An aqueous aluminum sulfate solution (Ai20a=
5.97w/v%, H2S04=24°5w/v%) and sodium silicate aqueous solution (S i 02=15.Ow/v
%, Na20=4.78w/v%) respectively at 21/H
The reactants were fed simultaneously and continuously at a constant feed rate of r and 81/Hr, and the reaction was carried out at 60° C. for a residence time of 30 minutes.

The pH of the reaction solution was 7.0. The product overflowing from the reaction tank was separated into solid and liquid using a centrifuge and thoroughly washed to obtain a homogeneous phase compound. The composition of this homogeneous phase compound is: Na2O (anhydrous basis) 5.23 wt% A or 20
3 (anhydrous standard) 8.60wt%SiO2 (anhydrous standard) 8B, 2wt%H20 (as-formed standard)
It was 53.4 wt%, and the particles had an average of 40μ and a distribution of lO to 100μ.

64.5 g of this homogeneous phase compound was mixed with an aqueous solution prepared by adding 13.3 g of sodium bromide to 120 g of pure water with stirring to make the mixture homogeneous. The amount of sodium bromide added was 6.1 expressed as a molar ratio of the homogeneous phase compound to Al2O2. Next, 2.32 g of sodium hydroxide was added to prepare a reaction mixture. The concentration of sodium hydroxide in the crystallization solution was 1.45 wt%. This reaction mixture was thoroughly stirred until each component became homogeneous, and then placed in a stainless steel sealed container and reacted at 175° C. under autogenous pressure for 72 hours.

The obtained product slurry was separated into solid and liquid, washed, and heated to 110°C.
It was dried with.

The X-ray diffraction pattern of this product is shown in Figure 1, and the electron micrograph is shown in Figure 2. This crystal has a width of approximately 0.3μ and a length of approximately 2.5μ.
It had grown into a spherical shape at both ends.

Example 2 133 g of the homogeneous phase compound used in Example 1 was added to 226 g of pure water.
g and 32.6 g of sodium tetraborate decahydrate were added thereto and mixed with stirring to homogenize. The amount of sodium tetraborate added, expressed as a molar ratio to AJ120s of the homogeneous phase compound, was 1.7.0 Next, 8.3 g of sodium hydroxide was added to prepare a reaction mixture. The concentration of sodium hydroxide in the crystallization solution was 2.66 wt%.

This reaction mixture was thoroughly stirred until each component became uniform, and then placed in a stainless steel sealed container and allowed to react at 175°C under autogenous pressure for 84 hours.

The obtained product slurry was separated into solid and liquid, washed, and heated to 110°C.
It was dried with.

This product showed an X-ray diffraction pattern substantially the same as in FIG. An electron micrograph of this product is shown in FIG.

This crystal had a width of 0.2 to 0.4 μm, a length of 3 to 5 μm, and had grown into a spherical shape at both ends.

Comparative Example 1 173 g of the homogeneous phase compound used in Example 1 was added to 321 g of pure water.
To an aqueous solution in which 8.22 g of sodium hydroxide was added to g,
Mix while stirring and reduce the reaction mixture to 1! ! The concentration of sodium hydroxide in the crystallization solution was 1.45 wt%. This reaction mixture was thoroughly stirred until each component became homogeneous, and then placed in a stainless steel sealed container and reacted at 175° C. under autogenous pressure for 72 hours.

The obtained product slurry was separated into solid and liquid, washed, and heated to 110°C.
It was dried with.

This product showed an X-ray diffraction pattern substantially the same as in FIG. An electron micrograph of this product is shown in FIG.

This crystal was plate-shaped with a width of 0.3 to 0.5 μm and a length of about 1 μm.

Comparative Example 2゜White carbon (manufactured by Nippon Shirikanigyo, 5i02;
87.7wt%+AfzOa; 0.5wt%.

73.7 g of H2O; 11.8 wt%), 358 g of pure water
33.2 g of sodium bromide was added to the aqueous solution of 33.2 g of sodium bromide.
O; 19.2wt%* H2O; 62.0wt%)
32.4 g and 2.82 g of sodium hydroxide were added to prepare a reaction mixture. The amount of sodium bromide added is Afz
The molar ratio to Oa was 5.1. Also,
The concentration of sodium hydroxide in the crystallization solution was 2.79 wt%.

This reaction mixture was thoroughly stirred until each component became homogeneous, and then placed in a stainless steel sealed container and reacted at 175° C. under autogenous pressure for 900 hours.

The obtained product slurry was separated into solid and liquid, washed, and heated to 110°C.
It was dried with.

This product showed an X-ray diffraction pattern substantially the same as in FIG. An electron micrograph of this product is shown in FIG.

This crystal had a plate shape with a radius of 0.5 to 1.0 μm and a length of about 4 μm.

Comparative example 3゜white carbon (Japanese Silikani Industry iJ, 5i02
; 87.7 wt%, A or 203; 0.5 wt%.

H2O; 11.8wt%) 74.9g, pure water 343g
g and 41.7 g of sodium tetraborate decahydrate were added to the aqueous solution with stirring and homogenized, and then a sodium aluminate aqueous solution (AJ220a; 1B, 8 wt%,
Na2O: 19.2wt%.

H2O; 62. %) and 7.32 g of sodium hydroxide were added to prepare a reaction mixture. The amount of sodium tetraborate added was 1.7 expressed as a molar ratio to A1203. Further, the concentration of sodium hydroxide in the crystallization solution was 3.92 wt%. The reaction mixture was thoroughly stirred until each component became homogeneous, and then placed in a stainless steel sealed container and heated at 175°C and 900°C under autogenous pressure.
Time reacted.

The obtained product slurry was separated into solid and liquid, washed, and heated to 110°C.
It was dried with.

This product showed an X-ray diffraction pattern substantially the same as in FIG. An electron micrograph of this product is shown in FIG.

This crystal had a needle shape with a radius of 0.2 to 0.3 μm and a length of about 3 μm.

Comparative Example 4 160 g of the homogeneous phase compound used in Example 1 was added to 291 g of pure water.
g and 38.8 g of sodium tripolyphosphate were added thereto and mixed with stirring to homogenize. The amount of sodium tripolyphosphate added is the same as that of homogeneous phase compound A J220.
The molar ratio to a was 1.7. Then,
A reaction mixture was prepared by adding 10.0 g of sodium hydroxide. The concentration of sodium hydroxide in the crystallization solution is 2.60w
It was t%. This reaction mixture was thoroughly stirred until each component was homogeneous, and then placed in a stainless steel airtight container.
The reaction was carried out at 175°C under autogenous pressure for 84 hours.

The obtained product slurry was separated into solid and liquid, washed, and heated to 110°C.
It was dried with.

This product showed an X-ray diffraction pattern substantially the same as in FIG. An electron micrograph of this product is shown in FIG.

This crystal has a width of 0.2~0.3μ and a length of 0.5~1.0μ.
It was μ plate-like, and the crystals were tightly adhered to each other.

[Brief explanation of the drawing]

Figure 1 shows the X-ray diffraction pattern of the product obtained in Example 1. Figures 2 and 3 show electron micrographs showing the crystal structure of the product obtained in Example 1 and Example 2, respectively. . Figures 4, 5, 6 and 7 are Comparative Example 1 and Comparative Example 2, respectively.
, shows electron micrographs showing the crystal structure of the products obtained in Comparative Example 3 and Comparative Example 4. Patent applicant: Toyo Soda Kogyo Co., Ltd. Figure 4 “Life゛r'='9-i @51v Figure 611j Figure 71μ

Claims (2)

[Claims] (1) Mordenite-type zeolite that has a rod-like crystal morphology with spherical growth at both ends. (2) A obtained by simultaneously and continuously reacting an alkali metal silicate aqueous solution and an aluminum-containing aqueous solution at a fixed ratio
A granular amorphous aluminosilicate homogeneous phase compound having an l_2O_3 content of 3 to 14 wt% is added with Al of the homogeneous phase compound.
Sodium bromide or sodium borate in a molar ratio of 0.1 to 20 relative to _2O_3 is brought into contact and the concentration is 0.
A method for producing mordenite-type zeolite having a rod-like crystal form with spherical ends grown, the method comprising crystallizing in a 5 to 3.0 wt% aqueous alkali metal hydroxide solution.