JPS63210011A - Production of silane - Google Patents

Abstract

PURPOSE:To obtain silane stably in high yield and with high controllability of reaction, by carrying out disproportionation reaction of a specified trialkoxy silane in gaseous phase using an oxide of a metal of the group IV of the periodic table as catalyst. CONSTITUTION:Aimed silane is obtd. by carrying out a disproportional reaction of alkoxysilane (e.g. trimethoxysilane) expressed by the formula (wherein R<1>, R<2>, R<3> are 1-3C alkyl) in gaseous phase at 100-500 deg.C using an oxide of a metal of the group IV of the periodic table as catalyst. Specific examples for the oxide of the metal of the group IV of the periodic table are pref. TiO2, Co3O4, MnO2, etc. By this constitution, the control of the disproportionation reaction of trialkoxysilane is facilitated. Particularly, the reaction can be stopped immediately at emergency by interrupting the feed of trialkoxysilane to a reaction tube.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for producing silane, and more particularly, it relates to a method for producing silane without disproportionation of trialkoxysilane!
This article relates to an improved method for making one.

(Prior Art) Silane is a substance useful as a raw material for 1-bit single film growth of amorphous silicon for photosensitive drums and electronic copying machines, polycrystalline silicon for semiconductors, and epitaxial silicon.

Conventional industrial methods for producing silane include: (1) a method of avoiding the reaction of magnesium silicide and ammonium chloride in liquid ammonia (for example, Japanese Patent Publication No. 38-19951), (2)
A method of reducing chlorosilane with a metal hydride such as lithium hydride (for example, Japanese Patent Publication No. 39-3660,
(Special Publication No. 59-1211),
A method of disproportionation in the presence of a catalyst such as a compound containing an oxoamine group (for example, JP-A-59-54617),
or (2) a method of disproportionating trialkoxysilane in a liquid phase in the presence of a catalyst such as sodium ethoxide, magnesium acetylacetonate, lithium chloride, or hexamethylphosphoric triamide (for example, Japanese Patent Publication No. 51-20440,
Japanese Patent Publication No. 60-4195) and the like are known.

[Problem that the invention seeks to solve]

Among these conventional manufacturing methods, the first method requires the use of special compounds such as magnesium silicide, and requires equipment to maintain high pressure and low humidity because it uses liquid ammonia. The disadvantage is that line investment requires a large amount of money.

There is also the problem of disposing of the muddy residue of magnesium salt containing ammonia.

The second method requires the use of dangerous compounds that must be handled carefully, such as aqueous metal compounds, and also generates numerous byproducts such as chlorine and lithium chloride, which can be disposed of as waste. In order to prevent it from going outside, it is necessary to develop a complicated recycling system for collection and reuse.Also, a common problem with the third method is that measures must be taken to prevent FA from eating the equipment since chlorosilane is used as the starting BIFI. There is a drawback that it requires

The fourth method is based on the fact that trialkoxysilanes are more easily disproportioned than trichlorosilanes, and that the reaction proceeds even at room temperature in the presence of an appropriate catalyst, yielding disproportionated products such as silanes. This is a method in which disproportionation is carried out under mild heating conditions through a liquid phase reaction. However, although this method appears to be an ideal manufacturing method, it is actually not. This is because there are problems in terms of ease of reaction control, which is essential when producing dangerous compounds such as silane on an industrial scale. In other words, in the method of disproportionating trialfukidisilane by liquid phase reaction, if you want to stop the reaction quickly midway through, even if you stop heating the reactor and cool it to room temperature, the reaction liquid system Since the catalyst is always in contact with the catalyst as a dissolved, suspended or solid state, the reaction does not come to a complete stop quickly and has a serious drawback in that it cannot be stopped in an emergency manner.

It is an object of the present invention to solve these problems, to facilitate the control of the disproportionation reaction of trialkoxysilane, and to provide a method for selectively producing silane with good yield.

[Means for solving problems]

As a result of detailed research on the disproportionation reaction of alkoxysilanes, the present invention is based on the results of detailed research on the disproportionation reaction of alkoxysilanes.
The present invention was completed by discovering that oxides of metals belonging to the fourth period of the periodic table are suitable for use as fixed catalysts and have a high catalytic effect.

The present invention provides a trialkoxysilane represented by the general formula [AJOR2[AI: This method of producing silane is characterized by carrying out a disproportionation reaction in a gas phase system using an oxide of a metal belonging to the fourth period of the JjJ table of elements as a catalyst.

The trialkoxysilane as a raw material used in the present invention has the general formula [AI], even if it has the same alkoxy group, it is a mixed l-realkoxysilane having two kinds of varnished earth alkoxy groups. Examples include trimethoxysilane, triethoxysilane, tripropoxysilane, [-liisoproboxysilane, ethoxydimethoxysilane, jetoxymethoxysilane, dimethoxysilane, jetoxyisopropoxysilane, etc. .

The catalyst used in the present invention is an oxide of a metal belonging to period 4 of the periodic table of elements. Examples of the metal oxides include titanium oxides, vanadium oxides, chromium oxides,
Examples include manganese oxides, iron oxides, cobalt oxides, nickel oxides, copper oxides, zinc oxide, etc.
Among these, titanium dioxide, tricobalt tetroxide, and manganese oxide are preferred as 14. In addition, these catalysts may be used not only alone, but also in combination of two or more,
It may be used in the form of an inorganic compound such as alumina or silica, or a natural inorganic substance such as diatomaceous earth, or a glass or porcelain Raschig ring, or in a mixed form.

The reaction of the present invention is carried out in a gas phase system, in which a reaction tube filled with a catalyst is heated and trialkoxysilane vapor is introduced into the reaction tube to carry out the disproportionation reaction.

Trialconi-1 disilane is vaporized and diluted with a gas such as helium, argon, nitrogen, hydrogen, etc., or fed directly into the reaction tube without dilution, but the reaction temperature can be kept constant by heating it in advance with a preheater. Easy to keep.

The reaction temperature is preferably 100-500℃, 150-350℃
The range is more preferable. If the temperature is lower than 100℃, the conversion rate of trialkoxysilane will be too low, and if the temperature is lower than 500℃, the conversion rate of trialkoxysilane will be too low.
If the amount exceeds 100%, the generated silane will be easily decomposed.

The reaction formula is R20R2 R3oR3 (wherein R is an alkyl Lt having 1 to 3 carbon atoms, which is R, R2, or R3).

[For production]

In the present invention, since an oxide of a metal belonging to the fourth period of the periodic table is selected as a catalyst, it is possible to carry out a disproportionation reaction in which trialkoxysilane is passed through the fixed catalyst layer as a gas, thereby making it possible to carry out the disproportionation reaction of trialkoxysilane as a gas. By controlling the amount of feed, the reaction can be easily controlled. That is, in extreme cases, it has become possible to emergency stop the reaction by stopping the supply. Combined with the high effectiveness of the catalyst, there is good selectivity in that no dialkoxysilane or monoalkoxysilane is produced, which facilitates the purification of the product.

〔Example〕

The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 0.5 g of tricobalt tetroxide was filled into a glass reaction tube,
It was heated to 250°C in an electric furnace. A mixture of vaporized trimethoxysilane (flow rate ff 12.4 d/gin) and helium (flow rate ff 12.4 d/gin) and helium (flow ff 20 + li!/l lin) was heated in a preheater for 2
After heating to 50° C., the mixture was supplied to a reaction tube to carry out a disproportionation reaction, and the gaseous reaction mixture coming out of the reaction tube was analyzed by gas chromatography every 30 minutes. The composition ratio of unreacted trimethoxysilane, silane, and tetramethoxysilane remained almost constant during the reaction. Dimethoxysilane and monomethoxysilane could not be detected during the reaction.

The analysis results 3 hours after starting the reaction showed that the conversion rate of trimethoxysilane = 58%, the yield of silane with respect to the supplied trimethoxysilane: 58% (the yield of silane with respect to the converted trimethoxysilane: 100%) ), yield of tetramethoxysilane based on supplied trimethoxysilane:
58% (yield of tetramethoxysilane relative to converted trimethoxysilane: 100%) and no Afll organisms could be detected.

Examples 2 to 9 Silane was produced by carrying out a disproportionation reaction using the same gas phase reactor as in Example 1 under substantially the same reaction conditions, but with different types of catalysts. The results are shown in Table 1.

In this case as well, even when the conversion rate of trialkoxysilane was low, no formation of dialkoxysilane or monoalkoxysilane was observed.

〔Effect of the invention〕

According to the present invention, the disproportionation reaction of trialkoxysilane can be easily controlled, and in particular, in an emergency, the reaction can be stopped immediately by stopping the supply of trialkoxysilane to the reaction tube. In addition, the selectivity of the catalyst is good,
Since silane and atraalcohol silane can be selectively separated and dialkoxysilane and monoalkoxysilane, which are intermediate products of the disproportionation reaction, are not produced, single lll lt purification of the product is easy. Therefore, the yield is good.

This invention has great practical effects because the reaction of silane, which is a dangerous compound, can be carried out under safe control without producing any by-products other than tetraalkoxysilane.

Claims (1)

[Claims] 1. General formula [A] [A]: ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (However, R^1, R^2 and R^3 are alkyl groups having 1 to 3 carbon atoms. A method for producing silane, which comprises subjecting a trialkoxysilane represented by 2. The method for producing silane according to claim 1, wherein the oxide of a metal belonging to the fourth period of the periodic table is titanium dioxide, tricobalt tetroxide, or manganese oxide. 3. The method for producing silane according to claim 1 or 2, wherein the gas phase disproportionation reaction is carried out at a temperature of 100 to 500°C. 4. The method for producing silane according to claim 1 or 2, wherein the gas phase disproportionation reaction is carried out at a temperature of 150 to 350°C. 5. The method for producing silane according to any one of claims 1 to 4, wherein the trialkoxysilane is trimethoxysilane.