JPH0688774B2 - Disproportionation method for halogenated silanes - Google Patents

Description

TECHNICAL FIELD The present invention relates to a disproportionation method of halogenated silanes. More specifically, it relates to a disproportionation method of halogenated silanes using a specific catalyst.

2. Description of the Related Art Silanes such as monosilane and dichlorosilane are used in applications such as semiconductors, solar cells, and photoconductor drums, and the demand for them has increased significantly in recent years. Examples of methods for producing these monosilanes, dichlorosilanes and the like include a method of reducing a tetrahalogenated silane, a method of reacting an alloy of silicon with hydrochloric acid, or a method of disproportionating a trihalogenated silane. Are known.

Problems to be Solved by the Invention However, the method of disproportionating a trihalogenated silane into a monosilane, a monohalogenated silane, a dihalogenated silane, etc. is industrially the cheapest in the monosilane, monohalogenated silane, dihalogenated silane, etc. (Hereinafter, simply referred to as silanes) is expected to be a method of using nitriles such as adiponitrile (US Patent No.
2732282), a method using an aliphatic cyanamide (US Pat. No. 273228), and many other methods using a homogeneous catalyst are known, but a large amount of energy is required for separating the catalyst from the reaction product and / or the raw material. However, there is a problem that it takes time. On the other hand, methods using a solid catalyst such as a method using an anion exchange resin (Japanese Patent Publication No. 52-18678) and a method using a reaction product of amino alcohol and silica (Japanese Patent Laid-Open No. 156907) are known. However, in the former case, the catalyst is expensive and there is a problem in heat resistance, and in the latter case, there is a problem that the catalyst activity is low and it is not practical.

DISCLOSURE OF THE INVENTION The present inventors have completed the present invention by solving the above problems and earnestly investigating a disproportionation method of halogenated silanes using a highly active solid catalyst.

That is, the present invention is a disproportionation method for halogenated silanes, which comprises bringing the halogenated silanes into contact with a polymer of pyrroles.

Examples of the halogenated silanes in the present invention include chlorosilanes such as monochlorosilane, dichlorosilane and trichlorosilane; and fluorinated silanes such as monofluorosilane, difluorosilane and trifluorosilane as typical compounds. In the present invention, disproportionation is defined as a reaction that produces silanes with fewer halogen atoms than the starting halogenated silanes. For example, trichlorosilane is disproportionated to form a mixture of monosilane, monochlorosilane, dichlorosilane, trichlorosilane and tetrachlorosilane, which is a reaction. Industrially, it is useful to produce the above-mentioned silanes using trichlorosilane and / or trifluorosilane as a starting material.

Polymers of pyrroles used as catalysts in the present invention include pyrrole, N-alkylpyrrole, N-arylpyrrole, 3-alkylpyrrole, 3-arylpyrrole, 3,4-dialkylpyrrole, 3,4-diarylpyrrole and the like. These pyrrole polymers are used as a method of obtaining these polymers (Advances in Hete
Ro-cyclic chemistry, Vol. 15, p. 67 (1973), Electropolymerization method (Journal of chemical Society chemica)
l.communication (1979) page 635) is known.

When a polymer of pyrroles is used as a catalyst for the disproportionation reaction, the one obtained by the above method can be used as it is, but it can also be used by supporting it on a suitable carrier.

As a method for obtaining a polymer of pyrroles supported on such a carrier, a method of co-grinding a polymer of pyrroles and a carrier or an electrolytic polymerization method as disclosed in JP-A-59-168010 or Is a polymer of pyrrole supported on a carrier by impregnating heat-resistant resin particles or particles of an inorganic compound such as silica, alumina, talc, diatomaceous earth with an oxidizing agent, and then contacting them with pyrrole or a derivative thereof. And can be used for the disproportionation reaction of halogenated silanes. Polymers of these pyrroles may be activated by heat treatment at a temperature of 30 ° C. or higher, and may be heat treated at 30 ° C. to 500 ° C. prior to use.

As the contacting method in the present invention, a method of dispersing the above-mentioned polymer of pyrroles in a halogenated silane in a liquid phase, or preferably a fluidized bed filled with a polymer of pyrroles supported on a carrier or Can be employed in which a halogenated silane is brought into contact with the gas phase or liquid phase in a fixed bed reactor. The temperature of the disproportionation reaction may be room temperature to 300 ° C, preferably 20 to 200 ° C.

The reaction time is not particularly limited, and an appropriate reaction time may be set so as to obtain a desired composition, and it is usually several seconds to several hours.

Effects By carrying out the method of the present invention, it becomes possible to disproportionate halogenated silanes extremely efficiently to produce desired silanes, which is of great industrial value.

Examples The present invention will be further described below with reference to Examples.

Example 1 (Production of Polymer) Dry silica gel (particle size: 10 to 40 mesh) was used as a carrier, and ferric chloride was used as a polymerization catalyst. All reactions were performed under a nitrogen stream. The silica gel was impregnated with ferric chloride prepared by mixing 10 g of the above silica gel and 0.3 g of ferric chloride in 20 ml of methanol, and then the methanol was evaporated. The silica gel treated in this way was packed in a glass tube,
Pyrrole was allowed to react by flowing with nitrogen gas at 0.1 ml / hr for 20 hours. After the reaction, the mixture was refluxed with methanol using a Soxhlet extractor for 2 hours to remove iron chloride and unreacted monomers. The yield was 10.9g.

(Disproportionation reaction) 10 g. Of the polymer prepared by the above method was filled in a U-shaped SUS tube flow type reactor having an inner diameter of 8 mm and a length of 40 cm. Thereafter, while flowing helium to sufficiently replace the inside of the reactor with helium, the reactor was heated to 140 ° C. in an oil bath. After the reactor reached 140 ° C., the supply of helium was stopped and trichlorosilane having a purity of 99.9% was supplied at 16 cc / min. The product was collected by a collector cooled with methanol-dry ice, and the composition of the product was analyzed by gas chromatography.

The results showed that trichlorosilane was 95.8 mole%, dichlorosilane was 1.5 mole%, and silicon tetrachloride was 2.1 mole%, showing that the pyrrole polymers used in the present invention have sufficient disproportionation activity.

Example 2 (Production of Polymer) 50 ml of a 5% ferric chloride aqueous solution and 50 ml of a 10% toluene solution of pyrrole were placed in an Erlenmeyer flask and stirred for 10 hours, and then polymerized granular polypyrrole was taken. After drying this granular polypyrrole, iron chloride was removed using a Soxhlet extractor in the same manner as in Example 1. The granular polypyrrole obtained is 2.
It was 1g. The same operation was repeated to obtain about 6 g of granular polypyrrole.

(Disproportionation reaction) 3 g of the polymer prepared by the above method was added to U having an inner diameter of 8 mm and a length of 40 cm.
It was filled in a letter-shaped SUS tube flow type reactor. Thereafter, while flowing helium to sufficiently replace the inside of the reactor with helium, the reactor was heated to 140 ° C. in an oil bath. After the temperature of the reactor reached 140 ° C, the supply of helium was stopped and trichlorosilane with a purity of 99.9% was added.
Supplied at 16 cc / min. The product was collected by a collector cooled with methanol-dry ice, and the composition of the product was analyzed by gas chromatography.

The results showed that 94.0 mole% of trichlorosilane, 2.4 mole% of dichlorosilane and 2.9 mole% of silicon tetrachloride showed sufficient disproportionation activity.

Example 3 (Production of polymer) N-methylpyrrole was blown in at a rate of 0.2 ml / min instead of 1.0 g of ferric chloride and pyrrole, and the same operation as in Example 1 was performed to remove iron chloride. The weight of the subsequent poly-N-methylpyrrole coated silica gel is 1
It was 1.1 g.

(Disproportionation reaction) 10 g of the polymer prepared by the above method was used for U having an inner diameter of 8 mm and a length of 40 cm.
It was filled in a letter-shaped SUS tube flow type reactor. After that, while flowing helium to sufficiently replace the inside of the reactor with helium, the reactor was heated to 120 ° C. in an oil bath. After the reactor reached 120 ° C, the helium supply was stopped and trichlorosilane with a purity of 99.9% was added.
Supplied at 16 cc / min. The product was collected by a collector cooled with methanol-dry ice, and the composition of the product was analyzed by gas chromatography.

The results showed that trichlorosilane had 82.3 mole%, dichlorosilane had 8.8 mole%, and silicon tetrachloride had 8.9 mole%, showing sufficiently high activity and selectivity.

Example 4 (Production of polymer) Activated alumina (KHD-46 manufactured by Sumitomo Aluminum Smelting Co., Ltd.)
After stirring 15 g and 1.5 g of ferric chloride in 30 ml of methanol, methanol was evaporated to prepare a ferric chloride-impregnated carrier. The activated alumina particles were packed in a glass tube, and 0.25 ml / min of N-metal pyrrole was passed along with nitrogen gas for 20 hours. The activated alumina containing poly-N-metalpyrrole was refluxed with methanol for 4 hours using a Soxhlet extractor to remove iron chloride. The yield after drying was 17.7 g.

(Disproportionation reaction) 10 g. Of the polymer prepared by the above method was filled in a U-shaped SUS tube flow type reactor having an inner diameter of 8 mm and a length of 40 cm. After that, while flowing helium to sufficiently replace the inside of the reactor with helium, the reactor was heated to 120 ° C. in an oil bath. After the reactor reached 120 ° C., the supply of helium was stopped and trichlorosilane having a purity of 99.9% was supplied at 16 cc / min. The product was collected by a collector cooled with methanol-dry ice, and the composition of the product was analyzed by gas chromatography.

The results showed that trichlorosilane had 84.6 mole%, dichlorosilane had 7.3 mole%, and silicon tetrachloride had 7.8 mole%, showing sufficiently high activity and selectivity.

Claims (1)

[Claims] 1. A method of disproportionating halogenated silanes, which comprises contacting the halogenated silanes with a polymer of pyrroles.