JPH0628734B2 - Method for producing halogenated silane disproportionation catalyst - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a catalyst used for producing chlorosilane, monosilane or fluorinated silane.

[Background technology]

Demand for monosilane and halogenated silanes has been increasing in recent years for semiconductors and solar cells. For example,
Monosilane is used for epitaxial semiconductors, oxide films, solar cells, and photoconductor drums, dichlorosilane is used for semiconductor epitaxial films, and fluorinated silane is used for solar cells.

Known methods for producing these monosilanes and halogenated silanes include a method of reacting magnesium silicide with hydrochloric acid and a method of reducing silicon tetrachloride with lithium aluminum hydride. However, monosilanes and halogenated silanes are produced. As a method, a method by disproportionation of halogenated silanes is considered to be a method for producing the cheapest monosilane and halogenated silanes.

This halogenated silane disproportionation method is, for example, 2HSiC ₃ H ₂ SiC ₂ + SiC ₄ 2H ₂ SiC ₂ H ₃ SiC + HSiC ₃ 2H ₃ SiCSiH ₄ + H ₂ SiC ₂ Although it is a manufacturing method, trichlorosilane, which is a raw material, is industrially mass-produced, so inexpensive monosilane and dichlorosilane can be manufactured.

The disproportionation reaction of chlorosilanes has been well known so far, and many patents have been filed for the catalyst.

U.S. Pat.No. 2732282, a method using nitriles such as adiponitrile, U.S. Pat.No. 2732280, a method using an aliphatic cyanamide, U.S. Pat.
There are patents for N-substituted pyrrolidone and Japanese Patent Publication No. 55-14046 for a method using tetraalkylurea. In all of these, the catalyst is dissolved in a solvent and reacted with the raw material or reacted with the raw material in a homogeneous phase. Such a method is adopted, and it takes time and cost to separate the catalyst and the reaction product, which is not practical.

Further, Japanese Patent Publication No. 52-18678 discloses anion exchange resins, and
-156907 discloses a patent using a reaction product of amino alcohol and silica as a catalyst. However, when these solid catalysts are used, there is an advantage that the catalyst and the reaction product can be easily separated, but the anion exchange resin has problems such as low heat resistant temperature and high cost. There is a problem that the reaction product of silica has low catalytic activity and is not practical.

[Disclosure of Invention]

The present inventors have earnestly studied the improvement of the drawbacks of conventionally known catalysts for disproportionation of halogenated silanes, and as a result, after silica gel was added and mixed in a mixed solution of amines and alcohols, solid- By separating the liquid and heating the residual solid in an inert gas atmosphere, the heat-resistant temperature is high,
A highly active solid catalyst was prepared, and it was found that monosilane, dichlorosilane, monofluorosilane, etc. can be easily obtained in a heterogeneous system by using this catalyst for the disproportionation reaction of halogenated silanes. Arrived

The aminos referred to in the present invention may be any of primary, secondary and tertiary amines. Further, a monoamine or a polyamine may be used, but a polyamine of a diamine or more is particularly preferable. Amino groups attached to or in the aliphatic chain (eg, decylamine, butanediamine, dibutylamine, tributylamine, diphenylethylenediamine, diethylenetriamine), or those attached directly to the ring nucleus (eg, phenylenediamine) , Diphenylamine, triphenylamine, N-ethyldiphenylamine, 4-aminodiphenylamine), or those in which an amino group is directly attached to a nitrogen-containing heterocyclic nucleus (for example, pyridinediamine). When these are used, they are used individually or as a mixture of two or more kinds.

The alcohol means an aliphatic alcohol such as methanol, ethanol, isopropanol, n-propanol and butanol, and in this case also, it is used alone or as a mixture of two or more kinds.

Silica gel refers to an amorphous silicic acid polymer, and any type can be used as long as it is derived from an aqueous solution of water glass-acid system.
The l type is preferred. The size of silica gel is not particularly limited, and any size may be used depending on the form of the reactor for disproportionation.

Inert gas is nitrogen, helium, neon, argon,
A gas that does not react with amines such as krypton or xenon, alcohols, or silica gel.

In preparing the catalyst, first, silica gel is added and mixed in a solution in which amines and alcohols are mixed at a weight ratio of 1: 100 to 100: 1. At this time, the silica gel is added in any amount as long as the silica gel is immersed in the solution. Further, when the mixed solution of the amines and alcohols and silica gel are mixed, heating can be carried out if necessary. The temperature for heating is not particularly limited, but from the viewpoint of workability, it is preferably the boiling point or lower of the solution under atmospheric pressure. Also, there is no particular limitation on the mixing time, but it is practically several minutes or more 100
It is preferably less than or equal to time.

The silica gel mixed in the solution is then removed by a mechanical solid-liquid separation method such as filtration, centrifugation, or stationary separation to remove the liquid phase components other than those adsorbed on the surface of the silica gel and those reacted on the surface. (However, it does not matter even if some liquid phase remains between the silica gel particles due to capillary action, etc.).

The remaining solid component mainly composed of silica gel (residual solid substance) becomes a catalyst by being heated in an inert gas atmosphere thereafter. The heat treatment temperature in this inert gas is 5
The temperature can be arbitrarily selected in the range of 0 ° C to 500 ° C, but usually 100 ° C or higher is preferred, and the optimum temperature at which the activity is highest can be selected depending on the amines, alcohols and silica gel used. The heating time is also not particularly limited, but in practice it is preferably several minutes or more and 100 hours or less.

In order to disproportionate the halogenated silanes, the starting halogenated silanes are contacted with the catalyst prepared by the above method at a reaction temperature of 0 to 300 ° C, preferably 20 to 200 ° C. In contacting the catalyst with the raw material, the raw material may be supplied in a gas phase or a liquid phase state to a flow type or batch type reactor. Trichlorosilane, dichlorosilane, monochlorosilane, difluorosilane, trifluorosilane, monofluorosilane and the like are used as the raw material halogenated silanes for the disproportionation reaction.

The present invention will be described below with reference to examples.

Example 1 (Preparation of catalyst) Diethylenetriamine was used as an amine, ethyl alcohol was used as an alcohol, and commercially available silica gel having a particle size of 35 to 48 mesh was predried at 120 ° C.

In the preparation, first, diethylenetriamine and ethanol were mixed in a weight ratio of 1:20. Particle size adjusted and pre-dried silica gel 1 in 30 m of this mixed solution
0 g was added and mixed and heated at 50 to 60 ° C. for 2 hours. Thereafter, the solution containing silica gel was filtered, and the filter residue was further washed with ethanol. The filter residue, which was washed with ethanol and consisted mainly of silica gel, was dried and then heat-treated at 180 ° C. for 2 hours in a nitrogen atmosphere to obtain a catalyst.

(Disproportionation reaction) 10 g of the catalyst prepared by the above method was used, and the inner diameter was 8 mm and the length was 40 cm.
It was filled in a U-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 100 ° C. in an oil bath. After the reactor reached 100 ° C., the supply of helium was stopped and trichlorosilane having a purity of 99.9% was added at 20 cc / min. Supplied by. The product was collected by a collector cooled with methanol-dry ice, and the composition of the product was analyzed by gas chromatography.

As a result, trichlorosilane was 85 mole%, dichlorosilane was 6.9 mole%, and silicon tetrachloride was 8.1 mole%, showing sufficiently high activity and selectivity.

Examples 2 to 4 Preparation of a catalyst and disproportionation of trichlorosilane were carried out in the same manner as in Example 1 except that amines and alcohols were changed.

The composition of the products after the disproportionation reaction with the amines and alcohols used is shown in the table below.

Example 5 Raw material for disproportionation reaction The disproportionation reaction was carried out under the same conditions and using the same catalyst as in Example 1 except that the halogenated silane was changed from trichlorosilane to dichlorosilane. The product was sampled in gaseous form and analyzed by gas chromatography. The analysis result of the product is monosilane 6.2mole%, monochlorosilane 23.3mole%, dichlorosilane 34.7mole%,
It was 35.8 mole% of trichlorosilane.

Example 6 Raw material for disproportionation reaction A disproportionation reaction was carried out under the same conditions as in Example 1, except that the halogenated silane was changed from trichlorosilane to difluorosilane. The product was sampled in gaseous form and analyzed by gas chromatography. The analysis result of the product is monosilane 3.2mole%, monofluorosilane 15.3mole%, difluorosilane 54.8mole%,
It was 26.7 mole% of trifluorosilane.

Comparative Example 1 (Preparation of catalyst) Ethanolamine was used as the amine, and commercially available silica gel having a particle size of 35 to 48 mesh was used as it was. 10 g of the above silica gel was put in 100 m of ethanolamine, mixed and heated at 120 ° C. for 2 hours, filtered and dried to obtain a solid product mainly composed of silica gel. This solid was heated at 180 ° C. for 2 hours to obtain a catalyst.

(Disproportionation reaction) 10 g of the catalyst prepared by the above method was used, and the inner diameter was 8 mm and the length was 40 cm.
It was filled in a U-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 100 ° C. in an oil bath. After the reactor reached 100 ° C., the supply of helium was stopped and trichlorosilane having a purity of 99.9% was added at 20 cc / min. Supplied by. 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 a very low activity of 98.7 mole%, dichlorosilane of 0.5 mole% and silicon tetrachloride of 0.8 mole%.

Claims (1)

[Claims] 1. A halogenated silane characterized in that silica gel is put into a mixed solution of amines and alcohols, mixed, and then solid-liquid separated, and the residual solid matter is heat-treated in an inert gas atmosphere. For producing a catalyst for disproportionation of a class of compounds.