JPH0353250B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention aims to provide a novel synthetic crystalline aluminosilicate zeolite and a method for producing the same. Crystalline aluminosilicate zeolites exist in large numbers naturally, and can also be produced artificially. Each crystalline aluminosilicate zeolite forms a certain skeletal structure and has a large number of voids and tunnels within the structure, which can cause the adsorption of molecules of a certain size, but larger expresses the function of exclusion,
Also known as molecular sieve. The size and shape of pores due to voids and tunnels are determined by SiO ₄ and
It is determined by the form in which AlO ₄ covalently bonds oxygen. The electronegative nature of aluminum-containing tetrahedra is kept electroneutral by cations, usually alkali metal ions. Therefore, in general, aluminosilicate zeolite can be expressed in terms of the molar ratio of oxides in a dehydrated state as follows. M ₂ /nO.Al _{2 O} 3.xSiO ₂ (M is a cation of valence n) Zeolites occur naturally and are also produced synthetically. In recent years, when synthesizing zeolite, there have been many reports on the use of organic ammonium cations such as tetramethylammonium, tetraethylammonium, and tetrapropylammonium in addition to using alkali metals such as sodium as cations. When tetramethylammonium is used, TMA offretite (MKRubin Ger. Offen 1806154 (1969), ZSM-
4 (Mobil Oil corp., Brit.Pat, 1117568 (1968)
etc. These zeolites have different X-ray diffraction patterns and seem to belong to different structural classes. It is well known that even if the same starting materials are used, different zeolites can be synthesized due to differences in raw material composition ratio, hydrothermal treatment, and other conditions. As a result of intensive research, the present inventors completed a new aluminosilicate zeolite whose X-ray diffraction pattern is completely different from existing ones by hydrothermally treating an aqueous gel containing tetramethylammonium. The crystalline aluminosilicate zeolite (hereinafter referred to as CHC-2) of the present invention will be explained in detail. The chemical composition of the synthetic form of CHC-2 of the present invention is expressed as the oxide molar ratio in the dehydrated state: aNa ₂ O・b(TMA) ₂ O・Al ₂ O ₃・cSiO ₂ (where
(TMA is tetramethylammonium) where 0<a<2.0 0<b<10.0 30<c<300. Furthermore, the lattice spacing determined by X-ray diffraction is shown in Table 1. Note that these X-ray diffraction patterns were obtained using standard X-ray techniques by irradiating copper with K-alpha rays, and the height I of the peak representing reflection is at the Black angle corresponding to the lattice spacing d. 2
times, recorded on the recorder as a function of 2θ. The relative intensity 100I/Io is relative to the highest peak height Io. Furthermore, the chemical composition of CHC-2 of the present invention after firing is as follows:
The molar ratio of oxides in a dehydrated state is aNa ₂ O.Al ₂ O _{3.cSiO 2} where 0<a<2.0 30<c<300. Further, the lattice spacing determined by X-ray diffraction is shown in Table 2. As mentioned above, the crystalline aluminosilicate zeolite of the present invention, CHC-2, has an X-ray diffraction pattern that is completely different from that of existing zeolites in both the synthesized form and the calcined form, and is a new crystalline aluminosilicate zeolite. be.

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[Table] Next, the method for producing the crystalline aluminosilicate zeolite of the present invention will be described. The present invention uses the following composition ratio of SiO ₂ source, Al ₂ O ₃ source, Na ⁺ source, tetramethylammonium source, and water in the following molar ratio: SiO ₂ /Al ₂ O ₃ = 30-400 OH ^- /SiO ₂ 0.3- 0.8 NA ⁺ /SiO ₂ 0.3-0.8 TMA ⁺ /SiO ₂ 0.3-4.0 H ₂ O/SiO ₂ A mixture of 30-60 is heated at 100-200℃, preferably 130-180℃ for 10-200 hours. The present invention relates to a method for producing crystalline aluminosilicate zeolite, which is characterized by hydrothermal treatment under autogenous pressure. The method for producing the crystalline aluminosilicate zeolite of the present invention will be specifically described. In this law
SiO ₂ source, Al ₂ O ₃ source, Na ⁺ source, tetramethylammonium source and water are mixed in a predetermined ratio, and this mixture is treated under hydrothermal conditions to obtain zeolite,
The crystalline aluminosilicate zeolite of the present invention can be produced by washing the obtained solid product with water, drying and calcining it. Water glass, silica sol, silica gel, and silica can be used as the SiO ₂ source, and water glass and silica sol are preferably used. As the Al ₂ O ₃ source, aluminum sulfate, aluminum nitrate, aluminum chloride, sodium aluminate, alumina sol, alumina, metal aluminum, etc. can be used, but aluminum nitrate and sodium aluminate are preferable. As the sodium source, in addition to sodium hydroxide, it is also possible to use SiO ₂ sources and Al ₂ O ₃ sources, such as sodium oxide and sodium aluminate contained in water glass. As the tetramethylammonium source, tetramethylammonium bromide, tetramethylammonium iodide, etc. can be used. When mixing the above-mentioned SiO ₂ source, Al ₂ O ₃ source, etc. in a predetermined ratio, the mixing order and mixing method are not particularly limited. This mixture is then hydrothermally treated under conditions such that zeolite is produced. That is, the mixture is hydrothermally treated at 100 to 200° C. (preferably 130 to 180° C.) for 10 to 200 hours in a closed container with stirring under autogenous pressure. After hydrothermal treatment, the reaction product is filtered or centrifuged to separate the solid components, washed with water to remove excess ionic substances, dried at 100℃, and dried at 400-600℃ in an air atmosphere for 2-50 hours. By calcination, the crystalline aluminosilicate zeolite of the present invention, CHC-2, is obtained. Generally, zeolite can be used as an adsorbent or a catalyst for producing petrochemical products, but the crystalline aluminosilicate zeolite of the present invention,
CHC-2 also has ion exchange ability and can be used as an adsorbent or catalyst. When using the crystalline aluminosilicate zeolite of the present invention, CHC-2, as an adsorbent, part or all of the tetramethylammonium contained in the synthetic form is calcined at 400 to 600°C for 2 to 50 hours in an air atmosphere. After removal, it can be used in the usual manner. When used as a catalyst, it can be used in any form such as a gas-solid catalytic reaction after part or all of the tetramethylammonium has been removed by the above method. Generally, catalytic performance can be altered by ion-exchanging at least a portion of the sodium ions in the synthetic form with other ions. Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto unless it exceeds the gist thereof. Example 1 1.60 ammonium sulfate 16-18 hydrate in 116 g of water
g, 3.54 g of sodium hydroxide and 49.3 g of tetramethylammonium bromide were dissolved, and then, while stirring, colloidal silica Cata-loid manufactured by Catalysts Kasei Co., Ltd.
40 g of SI30 was gradually added to form a homogeneous mixture. The composition of this mixture is SiO ₂ /Al ₂ O ₃ expressed in molar ratio.
= 100, OH ^- /SiO ₂ = 0.4, TMA ⁺ /SiO ₂ = 1.6,
H ₂ O/SiO ₂ =40. After this mixture was sealed in a magnetically stirred autoclave with an internal volume of 300 ml, hydrothermal synthesis was carried out at 150° C. for 20 hours while stirring at a rotational speed of 500 rpm under autogenous pressure. After the reaction was completed, solid components were separated from the reaction mixture by centrifugation and thoroughly washed with ion-exchanged water to remove excess ionic substances. this thing
A white powder was obtained by drying at 120°C for 5 hours. The X-ray diffraction pattern of this white powder is shown in Table 4 and FIG. The chemical composition of this powder is
It was _0.84Na2O・4.7(TMA) _{2O ・ Al2O3}・_62SiO2 . In addition, the above white powder was heated at 500℃ for 20 minutes in an air atmosphere.
The X-ray diffraction pattern of the powder obtained by time-calcining is
It is shown in the table and Figure 2. The chemical composition of this powder is
It was 0.84Na ₂ O・Al ₂ O ₃・62SiO ₂ . Examples 2 to 5 As shown in Table 3, the same procedure as in Example 1 was carried out except that the raw materials for the hydrothermal reaction were changed and the reaction conditions were changed. The obtained substances were all white powders, and their X-ray diffraction patterns were as shown in Tables 4 and 1.
It was basically the same as shown in the figure.

[Table] Usage Example 1 g of the calcined white powder obtained in Example 1 was mixed with 50 ml of a 1N aqueous hydrogen chloride solution, and stirred at room temperature for 1 hour to exchange sodium ions with hydrogen ions. Thereafter, it was thoroughly washed, dried at 100°C, and then fired at 500°C for 8 hours. Elemental analysis of the obtained white powder revealed that the chemical composition was 0.07Na ₂ O.Al ₂ O _{3.64SiO 2} . This was compressed into tablets at a pressure of 400 kg/cm ² , then crushed, and 4 ml of 10 to 20 meshes was filled into a reaction tube with an inner diameter of 10 mm. Liquid methanol is sent to the vaporizer at a rate of 4 ml/hr, where it is pumped to 45 ml/hr.
The mixture was mixed with argon gas that was sent at a rate of 15 min, and introduced into a reaction tube, where a reaction was carried out at 400°C. Analysis of the product using gas chromatography revealed that the methanol conversion rate was 39%, and the product was mainly dimethyl ether.

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【table】 [Brief explanation of drawings]

FIG. 1 is an X-ray diffraction pattern of the synthetic form of the material obtained in Example 1. FIG. 2 is an X-ray diffraction pattern of the material obtained in Example 1 after firing.

Claims (1)

[Claims] 1 Expressed in molar ratio of oxides, aNa ₂ O・Al ₂ O ₃・
A crystalline aluminosilicate zeolite having a chemical composition of cSiO ₂ where 0<a<2 30<c<300 and exhibiting the powder X-ray diffraction pattern shown in the following table. [Table] [Table] 2 Using SiO ₂ source, Al ₂ O ₃ source, sodium ion source, tetramethylammonium source and water as raw materials, molar ratio SiO ₂ /Al ₂ O ₃ 30-400 OH ^- /SiO ₂ 0.3 ~0.8 Na ⁺ /SiO ₂ 0.3-0.8 TMA ⁺ /SiO ₂ 0.3-4.0 H ₂ O/SiO ₂ 30-60 is hydrothermally treated, and the obtained crystalline aluminosilicate zeolite is calcined. Expressed as the molar ratio of the oxide obtained by
A method for producing crystalline aluminosilicate zeolite having a chemical composition of aNa ₂ O・Al ₂ O ₃・cSiO ₂ where 0<a<2 30<c<300 and exhibiting a powder X-ray diffraction pattern shown in the following table. 【table】