JPH0142887B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel synthetic materials related to crystalline silica. More particularly, the present invention relates to a synthetic material made of oxides of silicon and boron and having a porous crystal structure, a process for making the synthetic material, and a use of the synthetic material. According to various literatures, dense natural borosilicates (which are non-porous materials) are known, in which boron can have planar or tetrahedral coordination. Porous glasses are also known, and such glasses are obtained by chemically acting on glass-like substances. Depending on their source, these materials can include silica, alkali, _alumina and _B2O3 . Although the literature teaches that the coordination of boron is a zeolite-type structure, i.e. an ordered porous crystal structure, so far such a structure has not been obtained (Break Zeolite Molecular Sieves). Molecular Sieves) J. Wiley and
Sons, New York, 1974, p. 322). The only known method is to impregnate a zeolite of aluminum and silicon oxides with boron, as described in US Pat. No. 4,049,573. In this case, the boron does not enter the crystal lattice to form part of it. The inventors have developed crystalline silica modified by introducing boron into the crystal lattice as a substitute for silicon. Furthermore, the inventors have found that boron, in addition to being a replacement element for silicon, can produce new materials that are porous, well-controlled, and have a crystalline structure similar to that of a zeolite. This led to the present invention. The substance (hereinafter referred to as "Boralite A" for the sake of brevity)
is characterized as the molar ratio of oxides and in the anhydrous state by the following formula: (0-1) _R2O・(0-1)C2 _/ oO・_B2O3・( _8-30 ) _SiO2 (wherein, R is tetramethylammonium cation (TMA) and C is H ⁺ , NH ₄ ⁺ or valence n
It is a cation such as a metal. ) The thermal stability of Volarit A is determined by the molar ratio
This is related to the fact that SiO ₂ /B ₂ O ₃ is large. In particular, it is desirable (but not necessarily in a strict sense) that R ₂ O be absent after calcination. Volatile A, which corresponds to the above formula, has a specific crystal structure, and the X-ray diffraction spectrum of the H ⁺ form calcined at high temperatures (450°C to 750°C) has the characteristic peaks listed in Table 1. shows.

[Table] The above values change slightly with changes in the molar ratio SiO ₂ /B ₂ O ₃ , calcination temperature, and cation properties. The presence of other cations instead of H ⁺ produces slight changes in the spectra similar to those of normal zeolites. The infrared absorption spectrum shows characteristic absorption in the region of 910 to 925 cm ^-1 as a function of the amount of boron introduced. The manufacturing method for Volarit A involves reacting a silicon derivative, a boron derivative, and an clathrating agent (tetramethylammonium compound) under hydrothermal reaction conditions at a pH of 9 to 14, a temperature of 110 to 220°C, and a period of 1 to 30 days. Features. Organic derivatives of boron and silicon (e.g., trialkyl borates and tetraalkyl orthosilicate esters) are used to remove impurities from the crystallization vessel, such as in Teflon vessels or vessels of polypropylene, platinum, or other materials. In order to prevent extraction), high purity volatile A can be obtained by carrying out a hydrothermal reaction. The absence of impurities guarantees the unique properties of volatile A, such as its hydrophobic nature and therefore no dehydrating power. If very high purity is not required, inexpensive raw materials can be used for each component. For example, for boron, boric acid, sodium borate, and borax can be used, and for silicon, colloidal silica, silica gel, sodium silicate, Aerosil, etc. can be used. Additionally, containers made of glass, stainless steel, etc. can be used for crystallization. In such cases, Borirat A may contain impurities originating from the reactants or the crystallization vessel. For example, commercially available silica contains less than 2000 ppm Al ₂ O ₃ , but at alumina contents of around 10 000 ppm, structural and crystallographic It does not change the characteristics. Mineralizing agents such as alkali metal or alkaline earth metal hydroxides or halides can also be added. Volarit A is very stable both when heat treated at high temperatures and in the presence of water vapor. Volarit A according to the invention is used in catalytic reactions or absorption treatments as such or dispersedly supported on an inert support, preferably chosen from silica, alumina and clay-like materials. It is commonly utilized in a number of reactions described below. 1 Reaction of alkylating toluene with methanol to produce xylene, mainly para-xylene 2 Reaction of disproportionation of toluene to produce mainly para-xylene 3 Olefins and aromatics of dimethyl ether and/or methanol or other lower alcohols 4. Cracking and hydrogenolysis 5. Isomerization of normal-paraffins and naphthenes 6. Polymerization of compounds with olefin or acetylene bonds 7. Modification reactions 8. Polyalkyl-substituted aromatics such as ortho-xylene Isomerization of Compounds 9 Disproportionation of Aromatics, Especially Toluene 10 Conversion of Aliphatic Carbonyl Compounds to At least Partial Aromatic Hydrocarbons 11 Separation of Ethylbenzene from Other C ₈ Aromatic Hydrocarbons 12 Hydrogen of Hydrocarbons Addition and dehydrogenation 13 Methanation 14 Oxidation, especially the formulation of internal combustion engine emissions 15 Dehydration of oxygenated aliphatic compounds 16 Conversion of olefins to high octane fuels In particular, Volarit A of the present invention can be prepared from methyl tertiary butyl ether. Effectively used as a catalyst in reactions that produce methanol and isobutylene. In order to explain the above-mentioned object of the present invention, some examples will be described next, but the present invention is not limited thereto. Example 1 Into a Pyrex glass vessel maintained in a CO ₂ -free atmosphere, 132 g of a 25% (by weight) solution of tetramethylammonium hydroxide was introduced, followed by the addition of 18.6 g of boric acid with stirring. After dissolution, 187.5 g of orthosilicate tetraethyl ester was added while stirring was continued. The reaction mixture was heated to 60°C with stirring. The reaction gradually produced a white milky precipitate, and during the reaction, ethanol produced by hydrolysis of the orthosilicate ester was simultaneously distilled off. After 12 hours, alcohol is completely removed,
Add 0.18g of KOH and distilled water to bring the total volume to about 300ml
And so. At this stage, the reaction mixture was transferred to a Teflon-lined static autoclave and a hydrothermal reaction at 145°C was initiated and continued for 12 days. Then,
The reaction product thus obtained was allowed to cool to room temperature, collected on a filter, carefully washed with distilled water and dried at 120°C. The product consisted of crystals with a particle size of about 0.1 to 0.5 μm. A portion of the product was calcined at 750°C. Such a product has a molar ratio SiO ₂ /B ₂ O ₃ =11.
The X-ray diffraction spectrum for the H ⁺ form was consistent with the data in Table 1. In the infrared absorption spectrum, 921 related to boron
It showed a characteristic absorption band in cm ^-1 (which cannot be seen in conventional zeolites). Example 2 This example describes the preparation of Volatile A using colloidal silica. Working as in Example 1 and in the same order, 210 g of a 25% (by weight) solution of tetramethylammonium hydroxide, 27 g of H ₃ BO ₃ and 240 g of Ludox colloidal silica (40% concentration) are placed in a Pyrex glass container. After charging, stirring and heating to 80°C for 1 hour, the reaction mixture was transferred to a titanium autoclave (1 hour) with a stirrer.
), and a hydrothermal reaction was carried out at 150°C for 10 days under autogenous pressure. The crystalline product from the reaction is passed through a filter,
Washed, dried and calcined at 750°C for 6 hours.
The product, in its H ⁺ form, had the X-ray diffraction spectrum shown in Table 1 and an infrared absorption band at 917 cm ^-1 . Furthermore, the reaction product exhibited the following properties. Measured density (Helium method): 2.19 g/cm ³ Acidity (CsCl method): PH2.4 Molar ratio SiO ₂ /B ₂ O ₃ : 12.3 Reference example Example 1 was placed in an electrically heated tubular reactor with an inner diameter of 8 mm.
Volarit A catalyst 3 with particle size 14 to 30 mesh (ASTM, US series) prepared according to
Filled with ml. Methyl tert-butyl ether, which had been preheated in a preheating tube, was introduced into the reactor by means of a metering pump. A pressure check valve set at 6 bar was installed downstream of the reactor. The check valve was equipped with a suitably heated sample collection device so that when the pressure was reduced, the reactor effluent was introduced into the gas chromatography. It was heated to the temperature shown in Table 2 and methyl tert-butyl ether was introduced at a flow rate of 6 cm ³ per hour (ie liquid hourly space velocity (LHSV)=2). The results obtained are also shown in Table 2.

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Claims (1)

[Scope of Claims] 1 Crystalline modified silica in which boron is introduced as a substitutional element in place of silicon into the crystal lattice of crystalline silica, which in an anhydrous state has the formula (0-1)
R ₂ O・(0-1)C _2/o O・B ₂ O ₃・(8-30)SiO ₂
(wherein R is a tetramethylammonium cation and C is a cation such as H ⁺ , NH ₄ ⁺ or a metal of valence n), in the H ⁺ form,
A crystalline modified silica characterized by having an X-ray diffraction spectrum corresponding to the following data. [Table] [Table] [Table] 2 Crystalline modified silica in which boron is introduced as a substitutional element in place of silicon into the crystal lattice of crystalline silica, which has the formula (0-1) in an anhydrous state.
R ₂ O・(0-1)C _2/o O・B ₂ O ₃・(8-30)SiO ₂
(wherein R is a tetramethylammonium cation and C is a cation such as H ⁺ , NH ₄ ⁺ or a metal of valence n), in the H ⁺ form,
In a method for producing crystalline modified silica having an X-ray diffraction spectrum corresponding to the data below, a silicon derivative, a boron derivative, and a tetramethylammonium compound are heated under hydrothermal conditions at a pH of 9 to 14 and a temperature of 110.
A method for producing crystalline modified silica, which is characterized by reacting at a temperature of 1 to 220°C for 1 to 30 days. [Table] 3 In the manufacturing method described in claim 2,
the silicon derivative is an organic derivative of silicon;
Method for producing crystalline modified silica. 4 In the manufacturing method described in claim 3,
A method for producing crystalline modified silica, wherein the organic derivative of silicon is an orthosilicate tetraalkyl ester. 5. In the manufacturing method described in claim 2,
A method for producing crystalline modified silica, wherein the boron derivative is boric acid.