JPH052379B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a chlorosilane disproportionation catalyst and a continuous method for producing a silane compound. For more details,
Using a mixture or reactant of a nitrogen compound having an electron-donating group other than a tertiary amine and hydrogen chloride as a catalyst, chlorosilane is subjected to a disproportionation reaction in a reaction column, and distillation separation is simultaneously carried out to produce dichlorosilane, monosilane, etc. The present invention relates to a continuous method for producing a silane compound for continuously obtaining a silane compound, and a catalyst used for the production. Demand for dichlorosilane, monosilane, etc. is expected to increase in recent years as raw materials used in semiconductors and solar cell elements, and there is a demand for efficient production of large quantities of these. [Prior art] Silane is produced in the presence of a catalyst according to the following equilibrium reaction.
It is known that it can be obtained by a disproportionation reaction of SiHCl ₃ . (1) 2SiHCl ₃ SiHC ₂ l ₂ +SiCl ₄ (2) 2SiH ₂ Cl ₂ SiH3Cl + SiHCl ₃ (3) 2SiH ₃ ClSiH4 + SiH ₂ Cl ₂ in total (4) 4SiHCl ₃ SiH4 ₃ +3SiCl _4There are various disproportionation catalysts at that time. Although some methods have been proposed, they have advantages and disadvantages. For example, the method using nitriles (USP2732282) requires a lower reaction temperature.
It is necessary to operate at a temperature of 150°C or higher, and the method using dimethylformamide or dimethylbutyramide (US Pat. No. 3,222,511) had drawbacks such as easy catalyst deterioration. In order to improve these drawbacks, for example, α-oxoamines, especially tetramethylurea,
Method using N-methylpyrrolidone etc. (USP4038371, USP4018871), tetramethylguanidine, 1,3 dimethylimidazolidinone, ε
A method using caprolactam, trimethylsilylimidazole, etc. (Japanese Unexamined Patent Publication No. 17918/1982), a method using higher tertiary amines (Japanese Patent Application No. 149996/1982)
) have been proposed. However, these catalysts either have a low disproportionation rate or react with chlorosilane to form a coagulable solid, so even if sufficient stirring is performed to disperse the catalyst, agglomeration occurs in various parts of the device, causing various operational problems. It had drawbacks such as causing [Problems to be Solved by the Invention] The present invention provides that, as a catalyst effective for disproportionation of chlorosilanes, a tertiary amine or a tertiary amine to which hydrogen chloride is added can improve the disproportionation rate of chlorosilanes. The company discovered that the catalyst can be used quickly, and even if it reacts with chlorosilane to form a solid substance, it becomes smooth and resistant to agglomeration, reducing equipment troubles. . Upon further investigation, the present inventor found that a nitrogen compound having an electron donating group exhibits a performance almost similar to that of a tertiary amine, and came to propose the present invention. [Means for Solving the Problems] That is, the first aspect of the present invention is a mixture of 98 to 20 mol% of a nitrogen compound having an electron-donating group other than a tertiary amine and 2 to 80 mol% of hydrogen chloride and/or The second invention is a disproportionation catalyst for chlorosilane, characterized in that it consists of a reactant, and the second invention is a catalyst for disproportionation of chlorosilane, which is characterized in that a raw material chlorosilane such as toluchlorosilane is supplied to a reaction column having a distillation function in which a disproportionation catalyst is present. However, in a method for obtaining a silane compound having more hydrogen atoms than the raw material chlorosilane from the upper part of the reaction tower, and extracting a mixed liquid of a silane compound having more chlorine atoms and a catalyst from the bottom of the reaction tower, the disproportionation catalyst is Nitrogen compounds with electron-donating groups excluding tertiary amines98-20
A mixture of mol% and hydrogen chloride 2 to 80 mol% and/or
Or, it is a continuous production method of a silane compound characterized by being a reactant. The present invention will be explained in more detail below.
Nitrogen compounds having an electron donating group other than tertiary amines (hereinafter simply referred to as nitrogen compounds having an electron donating group) include oxoamines, nitriles,
There are azo compounds, silazane compounds, nitro compounds, etc., but oxoamines are preferred, and among them, tetramethylurea, N-methylpyrrolidone, morpholine, ε-caprolactam, N-methylcaprolactam, sarcosine anhydride, bispentamethylene urea, 1,3 dimethylthiourea , 1,3 dimethylimidazolidinone are good, and tetramethylguanidine and trimethylsilylimidazole are also effective. These substances exhibit some degree of catalytic activity even when used alone, but when they coexist with hydrogen chloride, the rate of disproportionation increases, and even if solids are formed, they do not aggregate and are better dispersed by stirring. No more deposits in the system. The ratio of the nitrogen compound having an electron donating group and hydrogen chloride is 98 to 20 mol% for the former and 2 to 80 mol% for the latter, and the nitrogen compound having an electron donating group and hydrogen chloride are in the form of a mixture and/or a reactant. It can be either. If the proportion of hydrogen chloride is less than 2 mol%, the effect of improving the disproportionation reaction rate is small, and if it exceeds 80 mol%, most of it will exist in the chlorosilane as a catalyst solid, and the fluidity will decrease. becomes scarce. Preferred proportions are 95 to 70 mol% of the nitrogen compound having an electron donating group and 5 to 30 mol% of hydrogen chloride. When the catalyst of the present invention is used in combination with a tertiary amine represented by the general formula R ₃ N (where R is an alkyl group having 4 or more carbon atoms), the tertiary amine is easily soluble in chlorosilane. This is preferable because the fluidity of the entire reaction solution can be improved. The combined amount of the tertiary amine is 5 to 95 mol% relative to 95 to 5 mol% of the nitrogen compound having an electron donating group, preferably 50 to 95 mol% relative to 50 to 5 mol%.
It is. The tertiary amine may be mixed in advance with a nitrogen compound having an electron-donating group and then hydrogen chloride is added, or hydrogen chloride may be added to the nitrogen compound having an electron-donating group and then the tertiary amine is mixed with a nitrogen compound having an electron-donating group. grade amines may be mixed. Examples of the tertiary amine include tri-n-octylamine, tri-n-butylamine, tri-n-pentylamine, and methyldioctylamine, but tri-n-octylamine and tri-n-butylamine are most suitable in terms of availability and effectiveness. The second aspect of the present invention is to supply raw material chlorosilane to a reaction column having a distillation function in which a disproportionation catalyst is present,
A silane compound with more hydrogen atoms than the raw material chlorosilane is obtained from the upper part of the reaction tower, and a mixed solution consisting of a by-product silane compound with more chlorine atoms and a catalyst is extracted from the bottom of the reaction tower, and then the silane compound and the catalyst are extracted. A method for continuously producing silane compounds such as monosilane, monochlorosilane, dichlorosilane, etc., in which the catalyst is separated and the catalyst is circulated to a reaction column, in which the catalyst described in the first aspect of the present invention is used as a disproportionation catalyst. . This will be explained in more detail below. In the present invention, chlorosilane refers to SiHCl ₃ ,
Refers to one or more selected from SiH ₂ Cl ₂ and SiH ₃ Cl. The amount of catalyst relative to the raw material chlorosilane is 2 to 50 mol%, preferably 5 to 40 mol%. If the amount of catalyst exceeds 50 mol%, the fluidity of the entire reaction solution will be impaired. Moreover, if it is less than 2 mol %, the effect of increasing the disproportionation rate is small. The reaction column used in the present invention is in the form of a distillation column, such as a plate column partitioned with sieve trays or bubble cap trays, or a packed column filled with a packing such as a Raschig ring or a Pall ring. Any structure may be used as long as the reaction column has a distillation function, but since the disproportionation reaction of the silane compound according to the present invention is a liquid phase reaction, a reaction column with a large liquid hold-up is desirable. The temperature inside the reaction tower is not constant, but a temperature distribution occurs. In other words, in the reaction column, separation by distillation occurs simultaneously with the reaction, so the temperature at the top of the column is low and the temperature at the bottom is high.
It is carried out in the range of °C. At temperatures below 10°C, the reaction rate is low and the disproportionation reaction does not substantially proceed;
If the temperature exceeds 200°C, thermal decomposition of the catalyst tends to occur, which is not preferable. In addition, since the reaction takes place in a boiling state, the gauge pressure must be set between 0 and 20 to maintain the reaction temperature above.
It is around Kg/cm. The raw material chlorosilane supplied to the reaction tower undergoes reaction and separation as described above, and due to the difference in boiling point, monosilane,
The concentration distribution occurs in the order of monochlorosilane, dichlorosilane, trichlorosilane, and silicon tetrachloride. Next, referring to the drawings, the drawings are explanatory diagrams of an apparatus used in an embodiment of the present invention. Raw material chlorosilane such as trichlorosilane is supplied to the upper middle section of the reaction tower 1 through the raw material supply conduit 4 . Reaction column 1 is a stainless steel distillation column with a column diameter of 93 mm, a height of 2000 mm, and 18 plates, each tray having a pore size of 1.5 mm.
This is a sieve tray with 37 holes. A stainless steel condenser 3 is installed at the top of the reaction tower 1.
The jacket can be cooled by passing methanol dry ice through it. Furthermore, a reboiler 2 containing a built-in heater with a maximum output of 1KW is provided at the bottom of the reaction tower 1. In the reaction column 1, the asymmetric reaction and separation by distillation occur simultaneously, and the gas rich in low-boiling components produced by the disproportionation reaction moves upward, is cooled in the condenser 3, condenses the accompanying high-boiling components, and then becomes a liquid. It is condensed in a stainless steel condenser 6 cooled with nitrogen, and collected as a liquid in a collecting storage tank 7. On the other hand, high-boiling components such as trichlorosilane and silicon tetrachloride generated in the disproportionation reaction migrate to the bottom of the column.
Together with the catalyst, it is extracted from the boiler 2 into the evaporation tank 9 while its liquid level is adjusted. The evaporation tank 9 is a stainless steel container with an internal volume of 3 and equipped with a stirrer, and is equipped with a jacket. The evaporation tank is heated by circulating heated heat transfer oil. This evaporation tank 9 is operated at a temperature higher than the boiling point of silicon tetrachloride produced in the disproportionation reaction and lower than the catalyst, and trichlorosilane and silicon tetrachloride extracted from the reboiler 2 are evaporated and cooled with methanol dry ice. It is collected in a condenser 11 and collected in a storage tank 12. The catalyst remaining in the evaporation tank 9 is extracted by a pump 10 and circulated to the top of the reaction tower 1 again. In this case, when the hydrogen chloride concentration in the catalyst has not reached a predetermined value, hydrogen chloride is supplied from the supply pipe 13. [Example] A more specific explanation will be given below with reference to Examples and Comparative Examples. Example 1 Using 1 mole of trichlorosilane (SiHCl ₃ ) in a SUS304 autoclave (equipped with jacket and stirrer) with an internal capacity of 500 c.c., the reaction temperature, type of catalyst, amount of hydrogen chloride added, and amount of catalyst added were adjusted. The disproportionation reaction was carried out in a closed state as shown in Table 1, and the amount of chlorosilane in the gas phase was determined over time by gas chromatography. In addition, in the gas phase
The change in the amount of SiHCl ₃ corresponds to the conversion rate, and Table 1 shows the time required for the SiHCl ₃ concentration to reach a constant value and the SiHCl ₃ concentration at that time. 1st
The table shows that the shorter the time, the faster the conversion rate (disproportionation rate), and the lower the SiHCl ₃ concentration value, the better the conversion rate. Table 1 also shows the equilibrium SiHCl ₃ concentration determined by calculation for reference. Hydrogen chloride was added by pressurizing and sealing a gas amount corresponding to a predetermined amount into an autoclave. Example 2 In Example 1, the raw material SiHCl ₃ was changed to SiH ₂ Cl ₂ and a disproportionation reaction was carried out under the conditions shown in Table 2. The SiH ₄ concentration in the gas phase was determined by gas chromatography and the concentration became constant. The time and the concentration at that time are the second
Shown in the table. For reference, the equilibrium SiH ₄ gas phase concentration determined by calculation is shown in Table 2. Example 3 An experiment was carried out in the same manner as in Example 1 except that a mixture of a tertiary amine and a nitrogen compound having an electron donating group to which hydrogen chloride was added was used as a catalyst. The results are shown in Table 3. Example 4 In Example 3, when the raw material was changed to dichlorosilane, values almost equivalent to those shown in Example 2 were obtained. Comparative Example 1 In the same manner as shown in Example 1, an experiment was conducted with no addition of HCl and with too much HCl. The results are shown in Table 1. Comparative Example 2 In the same manner as shown in Example 2, an experiment was conducted in which HCl was not added and in which a large amount of HCl was added. Comparative Example 3 An experiment similar to Example 3 was conducted using a mixture of tri-n-octylamine and tetramethylurea or tetramethylguanidine (without adding HCl) as a catalyst. The results are shown in Table 3.

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〔Effect of the invention〕

According to the present invention, the following effects are achieved. (1) Compared to conventional catalysts, conversion rates close to equilibrium conversion rates can be obtained at low temperatures below 150°C. (2) The time required to reach the equilibrium conversion rate is short and the disproportionation rate increases, so the equipment can be made smaller. (3) Since the catalyst does not solidify, long-term continuous operation is possible.

[Brief explanation of drawings]

The drawing is an explanatory diagram of an apparatus used in an example of the present invention. DESCRIPTION OF SYMBOLS 1... Reaction tower, 2... Reboiler, 3... Condenser, 4... Raw material supply conduit, 5... Control valve, 6...
Condenser, 7... Collection storage tank, 8... Needle valve, 9... Evaporation tank, 10... Pump, 11... Condenser, 12... Storage tank, 13... Hydrogen chloride supply pipe.

Claims (1)

[Scope of Claims] 1. A chlorosilane comprising a mixture and/or reactant of 98 to 20 mol% of a nitrogen compound having an electron-donating group other than a tertiary amine and 2 to 80 mol% of hydrogen chloride. Disproportionation catalyst. 2 Raw material chlorosilane such as trichlorosilane,
A silane compound containing more hydrogen atoms than the raw material chlorosilane is obtained from the top of the reaction column, while a silane compound containing many chlorine atoms and a silane compound containing many chlorine atoms are obtained from the bottom of the reaction column. In the method of extracting a mixture of catalysts, the disproportionation catalyst comprises 98 to 20 mol% of a nitrogen compound having an electron-donating group excluding tertiary amines and 2 to 80 mol% of hydrogen chloride.
A continuous method for producing a silane compound, characterized in that it is a mixture and/or reactant with mol%.