JP2002029729A - Process for converting high-boiling residue into monosilane by direct method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a monosilane production process for converting a high- boiling residue derived from a reaction of hydrogen chloride with metalloid silicon, into monosilane by a method known as a direct method. SOLUTION: This process involves a conversion stage for bringing such a high-boiling residue into contact with gaseous hydrogen in the presence of an amount of an aluminum trichloride catalyst, effective in promoting conversion of the high-boiling residue into monosilane, wherein at least one portion of the required amount of the aluminum trichloride catalyst is produced in the above conversion stage using a direct method and an isolation stage of the converted monosilane, at the respective sites of these stages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing monosilane from high boiling residues obtained from the reaction of hydrogen chloride with silicon metalloid in a process known as the "direct process". The process of the present invention comprises contacting the high boiling residue with hydrogen gas in the presence of a catalytic amount of aluminum trichloride effective to promote the conversion of the high boiling residue to monosilane. At least a portion of the aluminum trichloride catalyst required for the process is generated in situ during the direct method and isolation of the high boiling residue.

[0002]

BACKGROUND OF THE INVENTION In the preparation of trichlorosilane in a direct process, a complex mixture is formed, which is typically distilled to separate the trichlorosilane from other components present in the mixture. After separation of trichlorosilane, 8
A high boiling residue remains above 0 ° C. and above the boiling point of trichlorosilane. The high-boiling residue consists of as little as 10% by weight of trichlorosilane in a recent commercial operation of the direct process. Therefore, it is desirable to convert high boiling residues to commercially valuable products in order to reduce by-product disposal and improve raw material utilization.

The "direct method" is described in the patent literature, for example, US Pat. Nos. 2,380,995 and 2,488,487.
No., etc. are well described. The high-boiling fraction remaining after monosilane overhead distillation is, for example, a complex compound consisting of silicon-containing high-boiling compounds with SiSi, SiOSi and SiCSi bonds in the molecule. The high boiling fraction also contains finely divided silicon and metals or their compounds. Typical high boiling residues obtained from direct distillation products are disclosed in US Pat. No. 2,598,435.
No. 2,681,355.

[0004] US Patent No. 2,606,811 teaches a hydrogenation method in which a compound containing a halogen and a Si-Si bond is heated to a temperature of at least 300 ° C in the presence of hydrogen. However, the synthesis product is a monosilane and there is no teaching of aluminum trichloride as a catalyst.

US Pat. No. 3,639,105 discloses hydrosilanes by contacting disilane and hydrogen gas under pressure and heating the mixture in the presence of a transition metal such as palladium on charcoal. Describes the method of manufacture. The disilane is part of the mixture from the direct method. A process for producing high yield hydrosilanes by reacting methylchloropolysilane with hydrogen gas at 25 ° C. to 350 ° C. under pressure in the presence of a copper catalyst is described in US Pat. No. 4,079,071. Have been. Neil (Ne
ale) states that the methylchloropolysilane can be one which is typically produced as a by-product of the direct process. Useful copper catalysts, copper metals, copper salts, and complexes of copper salts with organic ligands as described by Neil.

US Pat. No. 4,393,229 teaches a process for converting alkyl-rich disilanes to halogen-rich polysilanes in the residue resulting from the production of alkylhalosilanes. The method comprises treating an alkyl-rich disilane containing residue with an alkyl trihalosilane or silicon tetrahalide at elevated temperature in the presence of a catalyst and a catalytic amount of a hydrosilane accelerator. Aluminum trichloride is a useful catalyst when used with hydrosilane promoters in the process. Further, the resulting halogen-rich polysilane can be cleaved in a separate step to produce the monosilane.

US Pat. No. 5,175,329 describes a process for the preparation of organosilanes from high-boiling residues obtained from the direct process, which results in a net consumption of organotrichlorosilane. In that process, the high boiling residue is contacted with an organotrichlorosilane and hydrogen gas in the presence of both a hydrogenation catalyst and a redistribution catalyst.

US Pat. No. 5,430,168 teaches the preparation of monosilane from high boiling residues obtained from the direct reaction of methyl chloride with silicon metalloid.
The method comprises the step of producing a mixture of an organotrihalosilane and a high boiling residue in the presence of hydrogen gas and a catalytic amount of aluminum trichloride. The process results in the consumption of organotrihalosilanes and the conversion of high boiling residues to useful monosilanes.

[0009]

SUMMARY OF THE INVENTION The present invention provides a process for converting high boiling residues of disilane from the production of trichlorosilane to commercially useful monosilane. The method comprises contacting a non-methyl containing high boiling residue obtained from the reaction of hydrogen chloride with silicon metalloid with hydrogen gas in the presence of a catalytic amount of aluminum trichloride. Further, at least a portion of the catalyst in the present process can be generated in situ during the performance of the direct process and isolation of the high boiling residue.

[0010]

SUMMARY OF THE INVENTION The present invention is a method for producing monosilane from a high boiling residue obtained from the reaction of hydrogen chloride with silicon metalloid. The method is based on the formula H _b
The high-boiling residue consisting of disilane represented by Si ₂ Cl _6-b (where b = 0 to 4) and hydrogen gas are mixed at a temperature of 150 ° C. to 500 ° C. with high-boiling residue monosilane 345 kPa to 68,900 kP in the presence of a catalytic amount of aluminum trichloride effective to promote conversion to
a) making contact under the pressure of a.

The process is carried out in a standard pressurizable reactor suitable for contacting with chlorosilane. The method can be performed as a batch method or a continuous method. The method can be performed, for example, in a continuous stirred-tank reactor, a bubble column reactor, a trickle bed reactor, or a plug flow reactor.

[0012] The high boiling point residue used in the present method is 80 ° C or lower.
Having the above boiling point, hydrogen chloride and silicon meta
Of trichlorosilane obtained from the reaction product with Lloyd
Obtained from distillation. The high-boiling residues useful in the present process are of the formula H
_bSi₂Cl_6-b(Where b = 0-4)
Consisting of disilane. The preferred disilane is Cl₆S
i₂And HCl₅Si₂It is. Of such high boiling residues
A typical composition is Cl ₆Si₂, HCl₅Si₂, H₂
Cl₄Si₂, H₃Cl₃Si₂, And H₄Cl₂Si
₂68% by weight of disilane such as HCl₅Si₂O, C
l₆Si₂O, H₂Cl₄Si₂O, H₃Cl₃Si₂
O and H₄Cl₂Si₂31% by weight disilium like O
Xane; 0.5% by weight of other high boiling silicon-containing compound;
And silicon and aluminum, calcium, iron and them
Solid particles containing low levels of metals such as
Consists of 0.5% by weight.

[0013] The high boiling residue is 345 kPa to 6
It is brought into contact with hydrogen gas under a pressure of 8,900 kPa. The pressure of hydrogen gas is 2,000 kPa to 10,000 kP
a is desirable, but 4,000 kPa to 7,500 kPa
Is more desirable. The weight ratio of high-boiling residue to hydrogen gas is in the range of 0.1: 1 to 100: 1. The weight ratio of the high-boiling residue to hydrogen gas is preferably 0.1: 1 to 500: 1, and most preferably 20: 1 to 200: 1.

In another embodiment of the present invention, the compound of formula H _b S
The disilane represented by i ₂ Cl _6-b (where b = 0-4) is recovered from the high boiling residue and from 150 ° C. to 5 ° C.
At a temperature of 00 ° C. and in the presence of a catalytic amount of aluminum trichloride,
It is brought into contact with hydrogen gas under a pressure of 345 kPa to 68,900 kPa.

The high-boiling residue comprises a catalytic amount of
Contacted with hydrogen gas in the presence of minium. The term `` catalyst
The amount is the conversion of disilane to monosilane in the high-boiling residue.
Sufficient aluminum trichloride to promote the conversion of
It is understood to mean. More specifically, a catalytic amount of trisalt
Aluminum chloride is converted to Cl in the high boiling residue.₆Si ₂
And HCl₅Si₂Disilanes such as silicon tetrachloride and
And sufficient to promote conversion to trichlorosilane.
means. The concentration of aluminum trichloride is aluminum trichloride
0.1, based on the total weight of the sodium and high boiling residues.
01 to 15% by weight is desirable, and 0.01 to 2% by weight is the most preferable.
Suitable.

Aluminum trichloride is converted to a process as a compound. Or, produced in situ by the conversion of a material that produces aluminum trichloride. All or part of the catalytic amount of aluminum trichloride is produced in situ during the direct process and during the distillation to produce high boiling residues. The aluminum and chlorine raw materials required for the production of aluminum trichloride can be the raw materials used in the direct process, in particular silicon metalloid and hydrogen chloride feed. The catalytic amount of aluminum trichloride is
It can be the sum of the in situ formed aluminum trichloride remaining in the mixture isolated from the direct process.

The process is carried out at a temperature of from 150 ° C. to 500 ° C., preferably in the range of from 250 ° C. to 425 ° C., most preferably from 225 ° C. to 350 ° C.

The monosilanes prepared by this method are described by the formula H _y SiCl _{4-y where} y = 0-4. Preferred monosilanes are silicon tetrachloride and trichlorosilane. Monosilane is recovered by standard methods for separating liquid mixtures, for example, distillation.

The following example is provided to illustrate the invention.

EXAMPLE 1 The ability to convert high boiling residues with in situ produced aluminum trichloride as a catalyst was evaluated in a stirred-tank batch reactor. The reactor was a 450 ml air stirred Parr Bomb reactor.
To the reactor was added a 100 g sample of the high boiling residue from the reaction of hydrogen chloride with silicon metalloid. Aluminum trichloride present was generated in situ during the preparation and isolation of the high boiling residue. 828 hydrogen into the reactor
The reactor was added with stirring at a pressure of 0 kPa, and the reactor was cooled to 3 kPa.
Heated to 00 ° C. for 2 hours. Samples from the reactor were analyzed by gas chromatography (GC) using a thermal conductivity detector (TCD). Table 1 shows the initial composition weight% and the final composition weight% of the high boiling point residue.

The high-boiling residue composition first composition final composition by weight% by _{weight% HSiCl 3 - 8.7 SiCl 4 77.4} 75.2 Cl 3 SiSiCl 3 14.9 9.4 undetermined 7.7 6.7

 ──────────────────────────────────────────────────の Continued on front page (72) Inventor Bruce Roberts Clam 47250 Madison Sunrise Drive, Indiana, USA 240 (72) Inventor Robert Frank Jarvis, Jr. 48842, Michigan, USA Midland Wild Pin Court 4519 F-term (reference) 4G069 AA02 AA08 BB08A BB08B BC16A BC16B CB81 DA05 FA01 4G072 AA11 AA12 AA14 GG02 GG03 HH07 KK09 MM01 RR01

Claims (6)

[Claims] 1. The reaction of hydrogen chloride with silicon metalloid
From the formula H_bSi ₂Cl_6-b(Where b = 0 to
High-boiling residue consisting of disilane represented by 4)
And hydrogen gas at 345 kPa to 68,900 kPa
At a temperature of 150 ° C. to 500 ° C. under a pressure of
Effective amount of catalyst to promote conversion of distillate to monosilane
Contacting in the presence of aluminum trichloride
Hydrogen chloride and silicon metalloy
Of the high-boiling residue obtained from the reaction with
Conversion method. 2. The monosilane of the formula H _y SiCl
The method of claim 1, wherein the method is represented by _4-y , wherein y is 0-4. 3. The method according to claim 1, wherein the high-boiling residue is a distillation fraction obtained from distillation of a reaction product of hydrogen chloride and silicon metalloid. 4. The method of claim 1, wherein the weight ratio of said high-boiling residue to hydrogen gas is in the range of 0.01: 1 to 1000: 1. 5. The method according to claim 1, wherein the concentration of the aluminum trichloride is 0.01 to 15% by weight based on the total weight of the aluminum trichloride and the high-boiling residue. Method. 6. The method of claim 1, wherein at least a portion of the aluminum trichloride is formed in situ during the formation of the high boiling residue.