JPS6327056B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a chlorosilane disproportionation catalyst, and more particularly to a catalyst based on a hybrid tertiary amine that disproportions chlorosilane such as trichlorosilane (SiHCl ₃ ) and dichlorosilane (SiH ₂ Cl ₂ ). Recently, in the semiconductor industry, silanes (silicon hydride compounds) such as SiH ₂ Cl ₂ and SiH ₄ are used in large quantities for various purposes such as high-purity silicon epitaxy and amorphous silicon raw materials for solar cells, so it is important. It is a substance. It is known that silane can be obtained by the disproportionation reaction of SiHCl ₃ in the presence of a catalyst according to the equilibrium reaction described below. (1) 2SiHCl ₃ SiH ₂ Cl ₂ +SiCl ₄ (2) 2SiH ₂ Cl ₂ SiHCl ₃ +SiH ₃ Cl (3) 2SiH ₃ ClSiH ₄ +SiH ₂ Cl ₂ In total, (4) 4SiHCl ₃ SiH ₄ +3SiCl ₄ Equalization catalysts have been studied for a long time, and various proposals have been made. For example, (1) the method using nitriles (USP 2732282) requires the reaction temperature to be operated at 150°C or higher, and (2) the method using aliphatic cyanamide (USP 2732280) requires pretreatment with a Lewis acid. (3) Methods using dimethylformamide or dimethylbutyramide (USP3222511) tend to cause catalyst deterioration; (4) Methods using tertiary amines containing hydrocarbons consisting of alkyl groups having 1 to 2 carbon atoms ( USP2834648) is similar to method (1) using nitriles as a catalyst, in addition to operating at a temperature of 150°C or higher, the equipment must be equipped with a pressure-resistant container, and its equilibrium conversion rate (calculated value) is
Although it is 18% in the case of °C, it is actually 10%.
However, there were drawbacks such as the need to increase the size of the equipment in order to obtain the desired production volume. The present inventor conducted various studies on tertiary amines which are catalysts for the method (4) above. For example, trimethylamine is known to form a 1:1 adduct with SiHCl ₃ , and this adduct, N(CH ₃ ) ₃ H ⁺ SiCl ₃ ^- , is a white solid, which is different from chlorosilane. It does not dissolve and becomes cloudy, so if this is used as a catalyst, even if sufficient stirring is done to ensure uniform dispersion, it will cause agglomeration in various parts of the device, causing various operational problems. I understood. Furthermore, when the present inventor used a hybrid tertiary amine, which had not been previously known as a disproportionation catalyst for chlorosilane, he discovered that it was an excellent catalyst with a high conversion rate at low temperatures and in a short time. It has been reached. The purpose of the present invention is to solve these drawbacks, and by using a specific hybrid tertiary amine as a disproportionation catalyst for chlorosilane, the disproportionation reaction can be carried out in a short time at a low temperature. The present invention aims to provide a chlorosilane disproportionation catalyst with a high conversion rate. That is, the present invention is a chlorosilane disproportionation catalyst containing as a main component a hybrid tertiary amine represented by the following general formula. general formula (However, R ₁ , R ₂ , and R ₃ are hydrocarbon groups having 4 to 12 carbon atoms, and all of R ₁ , R ₂ , and R ₃ represent saturated hydrocarbon groups that are not of the same type.) The following The present invention will be further explained in detail. The present invention is a chlorosilane disproportionation catalyst containing a specific hybrid tertiary amine as a main component. In the present invention, chlorosilane refers to SiHCl ₃ ,
Refers to at least one or two or more selected from SiH ₂ Cl ₂ and SiH ₃ Cl. The disproportionation catalyst of the present invention is mainly represented by the following general formula. general formula (However, R ₁ , R ₂ , and R ₃ are hydrocarbon groups having 4 to 12 carbon atoms, and all of R ₁ , R ₂ , and R ₃ represent saturated hydrocarbon groups that are not of the same type.) The reason why a specific hybrid tertiary amine was selected as the chlorosilane disproportionation catalyst of the invention is as follows. (1) Since the hybrid tertiary amine completely dissolves in chlorosilane, chlorosilane becomes a solvent in the reaction system, lowering the vapor pressure, and the disproportionation reaction rate is high even at low temperatures below about 150°C, and the conversion rate is high. This is because it is high. (2) Mixed tertiary amine forms a white solid addition compound with chlorosilane, which is also completely soluble in chlorosilane and does not adhere to the inside of the reactor, making it easy to operate. This is because the disproportionation reaction can be carried out in a continuous manner. Specific examples of hybrid tertiary amines with such structures include octyldibutylamine, butyldioctylamine, dibutyloctylamine, butyldidodecylamine, hexyldioctylamine, butyldihexylamine, octyldihexylamine, and tert-butyldioctylamine. , butyldiisopentylamine, etc. Since all of these have boiling points of 150°C or higher, they can be easily separated from the disproportionation reaction product. The amount of disproportionation catalyst added to chlorosilane is 2
~50 mol%, preferably 5-40 mol%. The disproportionation reaction is carried out at room temperature to 150℃, preferably 50 to 100℃.
The disproportionation reaction is preferably carried out at a temperature below the boiling point of the catalyst. To explain further, in order to produce SiH ₂ Cl ₂ and SiH ₄ by disproportionation reaction of chlorosilane using the catalyst of the present invention, a known method is used, for example, by mixing chlorosilane and a catalyst, carrying out a disproportionation reaction to produce SiH 2 Cl 2 and SiH 4 . did
A series of operations for condensing and separating, distilling, and separating SiH ₂ Cl ₂ and SiH ₄ may be performed, or these operations may be performed simultaneously. As explained above, the chlorosilane disproportionation catalyst of the present invention has a specific hybrid tertiary amine as its main component, and by using the disproportionation catalyst of the present invention, the following effects can be achieved. There is. (1) Temperature 150℃ compared to conventional tertiary amine catalyst
The following low-temperature disproportionation reaction is performed to obtain a conversion close to the equilibrium conversion. (2) The time required to reach equilibrium conversion is short and the disproportionation rate is high, so the equipment can be made smaller. (3) It completely dissolves in the raw material chlorosilane, and its boiling point is 150°C or higher, which lowers the vapor pressure of the reaction solution, making it highly safe. (4) Products such as SiH ₂ Cl ₂ and SiH ₄ can be easily separated. (5) Since it is a homogeneous liquid phase system, operations such as stirring are not required, and handling such as transporting the catalyst is easy. The present invention will be described in more detail below using examples. Example 1 A SUS304 autoclave (equipped with a jacket and stirrer) having an internal volume of 500 c.c. was filled with 1 mol of trichlorosilane and 0.1 mol of a catalyst, and a disproportionation reaction was carried out by changing the reaction temperature. The type of catalyst and reaction temperature are
Shown in the table. The amount of chlorosilane in the gas phase was determined over time using gas chromatography in a closed state. The change in the amount of trichlorosilane in the gas phase corresponds to the conversion rate, and Table 1 shows the time required for the concentration of trichlorosilane to reach a constant value and the concentration of trichlorosilane at that time. In Table 1, it can be seen that the shorter the time, the faster the conversion rate, and the lower the concentration value, the better the conversion rate, indicating that the catalyst of the present invention is superior. Table 1 shows the equilibrium trichlorosilane concentration determined by calculation for reference. Comparative Example 1 Using trimethylamine, triethylamine, and dimethylcetylamine as catalysts, the reaction temperature was set at 25
The same procedure as in Example 1 was carried out except that the temperatures were changed to 100°C, 50°C, and 100°C. However, since the catalyst was present as a solid substance, the experiment was conducted with a stirrer in order to improve dispersion.

【table】

[Table] Example 2 Experiments were carried out in the same manner as in Example 1 except that the catalyst amounts in Experiment No. 1 and No. 2 of Example 1 were changed as shown in Table 2. The conditions and results are shown in Table 3.

[Table] Example 3 1 mol of raw material trichlorosilane was added to dichlorosilane
The same procedure as in Example 1 was carried out, except that the monosilane concentration in the gas phase was determined by gas chromatography, and the time at which the concentration became constant and the concentration at that time were measured. These conditions and results are shown in Table 3. For reference, the gas phase concentration of monosilane determined by calculation is also shown. Comparative Example 2 The same procedure as in Example 3 was carried out except that the catalyst and reaction temperature were changed as shown in Table 3. The results are shown in Table 3. Note that, as in Comparative Example 1, the experiment was conducted by operating the stirrer.

【table】

[Table] Example 4 The same procedure as in Example 1 was carried out except that butyl-hexyl-octylamine and butyloctyldodecylamine were used as the catalyst. The results are shown in Table 4.

【table】

【table】

Claims (1)

[Scope of Claims] 1. A chlorosilane disproportionation catalyst whose main component is a hybrid tertiary amine represented by the following general formula. general formula (However, R ₁ , R ₂ , and R ₃ are hydrocarbon groups having 4 to 12 carbon atoms, and all of R ₁ , R ₂ , and R ₃ represent saturated hydrocarbon groups that are not of the same type.)