JP3767041B2 - Method for synthesizing zeolite β - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing zeolite β useful as a catalyst or an adsorbent.
[0002]
[Prior art]
Zeolite β is a zeolite having 12-membered ring pores first disclosed in US Pat. No. 3,308,069. The synthesis methods proposed so far have been based on an aqueous reaction slurry using tetraethylammonium ions as a template agent. That is, in a typical example, an aqueous slurry having a H ₂ O / SiO ₂ ratio of 20 and capable of uniform stirring and mixing is used. When the ratio of H ₂ O / SiO ₂ is 10 or less, uniform mixing becomes impossible.
[0003]
Therefore, in the prior art, zeolite β is crystallized by preparing a homogeneous mixed slurry of raw material components and heating it.
[0004]
However, in the conventional method described above, a part of the raw material components are dissolved in water during heating, so that the proportion of components converted into crystals inevitably decreases and the alkali components are diluted, so that the crystallization time becomes longer. Further, since the aqueous slurry is heated, there is a drawback that a closed container having a relatively large volume with respect to the weight of the produced crystal is required.
[0005]
[Problems to be solved by the invention]
The object of the present invention is to reduce the water content to reduce the volume of the raw material composition to increase the efficiency of the reaction, to shorten the crystallization time, and at the same time to increase the yield of the raw material components. It is to propose.
[0006]
[Means for Solving the Problems]
In the present invention, the chemical composition is expressed by the molar ratio of oxide
SiO ₂ / Al ₂ O ₃ = 10 to 1000
M ₂ O _/ SiO ₂ = 0.0~0.4
TEA ₂ O / SiO ₂ = 0.1 to 1.0
(Here, M represents an alkali metal and TEA represents tetraethylammonium) A powdery raw material composition having a low water content dried at a temperature of 50 ° C. or higher is brought into contact only with water vapor grown at 80 to 200 ° C. Thus, the volume of the raw material composition is reduced, and the ratio of the raw material composition substantially occupied in the reaction vessel is increased to increase the reaction efficiency. At the same time, by reducing the water content, the raw material components dissolved in water during heating are reduced to improve the yield.
[0007]
Details of the present invention will be described below.
[0008]
The powder raw material composition of the present invention comprises alumina, silica, an alkali component and tetraethylammonium ions, and does not need to contain a large amount of moisture.
[0009]
Aluminum sulfate, sodium aluminate, aluminum hydroxide, aluminosilicate gel, etc. are used as the alumina component, and colloidal silica, amorphous silica, sodium silicate, aluminosilicate gel, etc. are used as the silica source. It is desirable to have a form that can be mixed. As the alkali source, caustic soda, sodium aluminate, and alkali components in sodium silicate, or alkali components in aluminosilicate gel are preferably used. Further, potassium hydroxide, potassium aluminate or the like may be used. The tetraethylammonium ion may be a compound containing tetraethylammonium ion, and tetraethylammonium hydroxide is usually used.
[0010]
These raw material compositions are first thoroughly mixed in the presence of water to form a uniform slurry. The amount of water in this case is not particularly limited. Next, this uniform slurry is dried at a temperature of 50 ° C. or higher while stirring to obtain a powdery raw material composition. The upper limit of the drying temperature is not particularly limited, but a temperature range in which moisture does not boil is preferable, and drying is performed uniformly until the equilibrium moisture content at that temperature is reached. When the drying temperature is less than 50 ° C., the water content of the powdery raw material composition increases, and the raw material components are eluted during crystallization, resulting in a decrease in yield. The drying method is not particularly limited, but it is desirable to dry the aqueous slurry of the raw material mixture with stirring.
[0011]
The chemical composition of the obtained powdery raw material composition is expressed in terms of the molar ratio of oxide, and SiO ₂ / Al ₂ O ₃ = 10 to 1000.
M ₂ O / SiO ₂ = 0.0 to 0.4
TEA ₂ O / SiO ₂ = 0.1-10
Must. (Where M represents an alkali metal and TEA represents tetraethylammonium)
A more preferred range is
SiO ₂ / Al ₂ O ₃ = 30 to 600
M ₂ O / SiO ₂ = 0.0 to 0.1
TEA ₂ O / SiO ₂ = 0.15 to 0.25
It is.
[0012]
The powdery raw material composition thus prepared is placed in a closed container and crystallized by contacting only with water vapor which is spontaneously generated at the reaction temperature without directly contacting with water.
[0013]
The temperature for crystallization is in the range of 80-200 ° C. At temperatures below 80 ° C., the crystallization rate is very slow and lacks economic rationality. Further, at a temperature of 200 ° C. or higher, the decomposition of tetraethylammonium ions becomes severe, and it is difficult to obtain zeolite β having a high degree of crystallinity.
[0014]
The method and apparatus for heating the powdery raw material composition by bringing it into contact with water vapor is not particularly limited. Although the apparatus used in the Example is shown in FIG. 1, an embodiment is not limited to this. You may use the airtight container which put powdery raw material composition in the container and put water in the outer side. Moreover, the method of moving a powdery raw material composition continuously, making it contact with water vapor | steam may be sufficient.
[0015]
【The invention's effect】
According to the method of the present invention, since the volume of the raw material composition can be reduced by using the powdery raw material composition, the reaction efficiency per volume can be increased.
[0016]
Further, since the raw material components are not dissolved in water and most of them are transferred to crystals, the reaction yield can be increased and the crystallization time can be greatly shortened. Therefore, if a method of continuously moving the powdery raw material composition in contact with water vapor is employed, continuous synthesis of zeolite β is possible. In addition, since almost no waste liquid is generated, there is no need for recovery and waste liquid treatment, which is economical.
[0017]
【Example】
The present invention is specifically described by the following examples, but the present invention is not limited to these examples.
[0018]
Example 1
To 10 g of colloidal silica (SiO ₂ , 30 wt%), 0.9 ml of a 4 molar aqueous sodium hydroxide solution and 13.6 g of an aqueous tetraethylammonium hydroxide solution (concentration 20%) were added with stirring. Thereafter, an aqueous solution in which 0.57 g of aluminum sulfate was dissolved in 10 ml of water was added to the mixed slurry. The aqueous raw material mixture was stirred for 1 hour and then stirred and dried until the water content reached an equilibrium amount while maintaining the temperature at 80 ° C. to obtain a raw material composition. The chemical composition of this raw material composition was as follows in anhydrous terms.
[0019]
_{1.09Na 2 O · Al 2 O 3} · 30.3SiO 2 · 5.6TEA 2 O
This raw material composition was pulverized to obtain a powdery raw material composition. This was placed on a support plate in an airtight container shown in FIG. 1, water was added to the bottom of the container and heated at 180 ° C. for 120 hours. The product was simply washed with water and dried at 80 ° C. As a result of X-ray diffraction measurement of the product, it was zeolite β as shown in FIG. Its chemical composition _{0.02Na 2 O · Al 2 O 3} · 33.7SiO 2 · 1.05TEA 2 O · 9.5H 2 O
Met.
[0020]
Example 2
The aqueous raw material mixture was prepared using the same raw material as in the Example 1, this stirring dried at a temperature of 80 ° C., and _{pulverized, 1.52Na 2 O · Al 2 O} 3 · 30.3SiO 2 · 5 in anhydrous basis .6 TEA ₂ O
A powdery raw material composition having the following composition was obtained.
[0021]
This was heated at 180 ° C. for 3 hours in the same manner as in Example 1. The product was simply washed with water and dried at 80 ° C. Its X-ray diffraction pattern was essentially the same as FIG.
[0022]
The composition of the organic substance and the component not containing water is 0.11 Na ₂ O.Al ₂ O ₃ .30.2 SiO ₂
Met.
[0023]
Example 3
An aqueous raw material mixture was prepared using the same raw materials as in Example 1, and this was stirred, dried and pulverized at a temperature of 80 ° C., and was converted into 2.18Na ₂ O · Al ₂ O ₃ · 60.6SiO ₂ · 11 in anhydrous terms. .2TEA ₂ O
A powdery raw material composition having the following composition was obtained.
[0024]
This was heated at 180 ° C. for 120 hours in the same manner as in Example 1. The product was simply washed with water and dried at 80 ° C. Its X-ray diffraction pattern was essentially the same as FIG.
The composition of the organic substance and the component not containing moisture is 0.23 Na ₂ O.Al ₂ O ₃ .66.7 SiO ₂
Met.
[0025]
Example 4
An aqueous raw material mixture was prepared in the same manner as in Example 1 except that sodium hydroxide and potassium hydroxide were used as the alkali source, and this was stirred and dried at a temperature of 80 ° C., pulverized, and 3.64 Na _{2 in} anhydrous conversion. O ・ 1.82K ₂ O ・ Al ₂ O ₃・ 60.6SiO ₂・ 11.2TEA ₂ O
A powdery raw material composition having the following composition was obtained.
[0026]
This was heated in the same manner as in Example 1 at 180 ° C. for 65 hours. The product was simply washed with water and dried at 80 ° C. Its X-ray diffraction pattern was essentially the same as FIG.
The composition of the organic and moisture-free components is 0.49Na ₂ O.0.18K ₂ O.Al ₂ O ₃ .62.3SiO ₂
Met.
[0027]
Example 5
An aqueous raw material mixture was prepared using the same raw materials as in Example 1, and this was stirred and dried at a temperature of 80 ° C., pulverized, and converted into anhydrous 5.00 Na ₂ O.Al ₂ O ₃ .100SiO ₂ .18.5 TEA. _{2 O}
A powdery raw material composition having the following composition was obtained.
[0028]
This was heated at 180 ° C. for 4 hours in the same manner as in Example 1. The product was simply washed with water and dried at 80 ° C. Its X-ray diffraction pattern was essentially the same as FIG.
[0029]
The product had a SiO ₂ / Al ₂ O ₃ ratio of 78.3.
[0030]
Example 6
The aqueous raw material mixture was prepared using the same raw material as in the Example 1, this stirring dried at a temperature of 80 ° C., and _{pulverized, 21.8Na 2 O · Al 2 O} 3 · 606SiO 2 · 112TEA 2 O in anhydrous basis
A powdery raw material composition having the following composition was obtained.
[0031]
This was heated at 180 ° C. for 72 hours in the same manner as in Example 1. The product was simply washed with water and dried at 80 ° C. Its X-ray diffraction pattern was essentially the same as FIG.
[0032]
The product had a SiO ₂ / Al ₂ O ₃ ratio of 343.
[0033]
Example 7
The aqueous raw material mixture was prepared using the same raw material as in the Example 1, this stirring dried at a temperature of 80 ° C., and _{pulverized, 45.5Na 2 O · Al 2 O} 3 · 909SiO 2 · 168TEA 2 O in anhydrous basis
A powdery raw material composition having the following composition was obtained.
[0034]
This was heated at 180 ° C. for 12 hours in the same manner as in Example 1. The product was simply washed with water and dried at 80 ° C. Its X-ray diffraction pattern was essentially the same as FIG.
[0035]
The product had a SiO ₂ / Al ₂ O ₃ ratio of 463.
[0036]
Comparative Example 1
The aqueous slurry prepared at the same raw material mixing ratio as prepared in Example 1 was filtered to obtain an infiltrated raw material composition. The moisture content was 115% on a dry basis. This was heated at 180 ° C. for 120 hours in the same manner as in Example 1. Most of the raw material mixture on the support fell, and the remaining white powder was almost amorphous.
[Brief description of the drawings]
FIG. 1 shows an apparatus used for contacting a powdery raw material composition and water vapor in an example.
[Explanation of symbols]
(A): Airtight container (b): Thermocouple (c): Teflon container (d): Support plate (e): Powdery raw material composition (f): Water [FIG. 2] CuKαX of the product of Example 1 A line diffraction diagram is shown.

Claims (2)

The chemical composition is expressed as the molar ratio of oxide.
SiO ₂ / Al ₂ O ₃ = 10 to 1000
M ₂ O _/ SiO ₂ = 0.0~0.4
TEA ₂ O / SiO ₂ = 0.1 to 1.0
Zeolite β characterized in that the powdery raw material composition dried at a temperature of 50 ° C. or higher, where M is an alkali metal and TEA is tetraethylammonium, is brought into contact only with water vapor that is spontaneously generated at 80 to 200 ° C. Synthesis method. The method for synthesizing zeolite β according to claim 1, wherein the aqueous raw material composition is dried at a temperature of 50 ° C or higher under stirring to prepare a powdery raw material composition.

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