JPS59199519A - Manufacture of halosilane by treating waste silicon- containing reaction block - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating residual silicon powder, and in particular to a method for producing halosilanes from residual silicon powder.

Current industrial methods for producing organohalosilanes are well known and described in US Pat. No. 2,380,995. This patent describes the direct reaction of silicon particles with an orc halide such as methyl chloride to produce organochlorosilanes. Copper particles are mixed with silicon particles, thereby forming reactive rings or reactive contact rings. When carried out industrially, this reaction is generally carried out in one of three types of equipment: a stirred reactor, such as that described in Sellers, U.S. Pat. No. 2,449,821; 2,389,931; or a rotary kiln.

Organotrichlorosilane and diorganodichlorosilane are the two basic products of the direct process reaction described above.

Dark compounds are utilized in the preparation of organopolysiloxane resins such as those described in US Pat. No. 2,2582'18 and US Pat. No. 2,258,222. Other products include organopolysiloxane fluids such as those described in US Pat. Nos. 2,469,888 and 2,469,890 as well as organopolysiloxane elastomers as described in US Pat. No. 2,448,756. Generally, it is preferable to produce dioxidoxychlorosilane from an industrial standpoint. Solellah is commonly utilized to make linear polysiloxane fluids and polymers used in the production of various room temperature curable silicone rubber compositions and thermoset rubber elastomers.

At some stage in making organochlorosilanes by direct methods, the reactive ring containing silicon particles or the reactive catalytic ring becomes less reactive and it is desirable to replace the reactive catalytic ring. For example, waste silicon particles or less reactive silicon particles are removed from the reaction vessel, new silicon particles are inserted therein, and the reaction is then restarted. When a reactive catalytic ring becomes less reactive or less reactive, and when it is replaced with a new batch of silicon, the less reactive or less reactive catalytic ring is generally replaced with the remaining silicon, the residual silicon. Also referred to as powder, residual silicon-containing contact mass or residual contact ring, these terms are used interchangeably herein.

The old solution to this problem was to discard the remaining contact annulus, however, there remains considerable reactive silicon in the remaining contact mass, and to avoid disposal problems and for economic reasons. Therefore, it is desirable to utilize at least some of the remaining silicon values in the remaining contact mass.

The weight ratio of organotrichlorosilane (known as T) to diorganodichlorosilane (known as D) can be maintained at a desired degree for an extended period of time, thereby producing diorganodichlorosilane. Much work has been done to identify ways to more completely utilize the residual silicon particles in the reactors used to carry out the direct synthesis of organochlorosilanes so as to yield maximum utilization of the silicon particles. Ta. In the production of organochlorosilanes by the direct method of Rochiyo, US Pat.
Preferably it does not exceed 35. However, in most industrial manufacturing operations, this ratio is found to be around 0.15 lehers when starting the reactor with new material, but to rise to levels of about 0.02 lehers or more after the reaction has progressed. has been done.

One breakthrough in this field is the U.S. patent ff13.
There is a method published by Dotson in issue 133109. Dotson describes that by passing the particles used from a fluidized bed reactor into an external fluidized energy mill, silicon particles can be utilized more completely and the amount of diorganodichlorosilane can be maximized. As an alternative to an external flow energy mill, Dotson also passes spent silicon particles recycled from the reactor through multiple tuning fork jets placed at the base of the reactor, causing the particles to collide with each other or It is also described that particles can be caused to collide with the walls of a particle, resulting in fragmentation of the particles.

By utilizing the dot run method, the ratio can be adjusted to the desired 0.
15 levels can be kept close and 0 for a long time.
It has been found that larger amounts of diorganodichlorosilane can be obtained from the same mackerel silicon particles by being able to maintain the level below 35. However, it has also been found that the Dotson process results in an underutilization of about 12-15% of the silicon that is trapped in the reactor and must be removed from the process as waste silicon.

It was generally believed that such silicon had been depleted or used up and therefore could no longer be utilized. It is desirable to utilize this waste silicon for economic reasons and to avoid the problems normally encountered in disposal. Further T
It would even be desirable to find a new process that could utilize substantially all of the silicon values in the remaining silicon-containing contact mass after the /D ratio has increased to undesirable levels.

US Pat. No. 4,281,149 s=: to Scheid describes a method for treating silicon particles in such silicon reactor systems, thereby improving the usefulness of silicon metal particles. The Shaed method describes a method for treating silicon particles having an average diameter size of less than 40μ,
Such particles can be ωf polished to remove the surface coating thereon, and the polished particles can be returned to the reactor for further use.

U.S. Pat. No. 4,307,242, which is incorporated herein by reference, describes another method for recovering and recycling silicon fines in an organochlorosilane reactor system. The method published by Sarr and Ritzer involves distinguishing the direct contact mass by particle size, thereby distinguishing between the most poisoned and relatively unpoisoned impure (waste) silicon particles. and recycling only such unpoisoned particles, thereby improving the availability of silicon. In this way, instead of discarding the gold nugget of waste silicon fines from the direct process, only a small portion of the waste silicon fines needed at a given time is discarded. No. 4,307,242 describes fine flow powder (
one or more mechanical cyclones to recover any residual contact mass or residual silicon). This fine effluent powder is generally waste reaction mass from reactors that produce orcattrichlorosilane and diorganodichlorosilane products. Crude T and D products are recovered from the top of the cyclone and these products may contain small amounts of very fine entrained particles therein. The remainder of the reaction mass is pneumatically treated in a mechanical cyclone and directed to a hopper for alternating arrangement. At the stage of negligence described by Sir and Ritzer, U.S. Pat.
It is desirable to obtain useful products from the relatively unpoisoned portion of the secondary cyclone fines obtained from the Mombetsu process of No. 3072.42. It is also desirable to obtain useful products from silicon and residual silicon-containing contact mass obtained from other sources.

One such useful product that can be obtained from various reactions with silicon is monohydric trichlorosilane (H81C
13) is trichlorosilane named here.

Research on the effect of HCI during methylchlorosilane synthesis
It is reported on page 138 of Voorhave's Orkach-halosilane, Precursor to Silicones, published by Elspear in 1967. 6:1~1:6
Reactions carried out using metallic grade silicon in the presence of copper catalysts at various molar ratios of methyl chloride to hydrogen chloride in the range of However, all these reactions are 300
℃, and there are no reports of temperature selection effects due to Voorhave.

In U.S. Patent No. 24884E37, Barry et al.
It has been found that the yield of "more valuable monoalkyl silicon halides" is increased by the simultaneous introduction of hydrogen halides, such as HCI, with alkyl halides when contacted with silicon or with alloys or mixtures of silicon and metals at elevated temperatures.

Although Barry et al. reported a temperature range of 200-550°C, they found that mixtures of hydrogen chloride and raw methyl chloride produced increased yields of monomethyl silicon chloride, and any temperature selection There are no reports of effectiveness or improved yields of monohydrogen trihalosilanes.

U.S. Patent for a method for treating waste metal reaction mass from the direct production of organohalosilanes! No. 2,803,521, Nirache et al. describe the best known and widely used reaction of methyl chloride and silicon at 200-500° C., usually in the presence of copper or copper chloride, and often with H, C1 as additional reactants. An industrial application of the direct method has been reported. According to Nirache et al.
This reaction is performed using various methylchlorosilanes such as CH3S.
iCla, (CHs)2 S iC12, (CH3)
3S iC1, and CH3H81C1. However, Nirache et al. treat the waste (residual) silicon-containing reaction mass by dispersing the reaction mass in water or dilute hydrochloric acid and contacting the dispersion with a chlorine source at temperatures between 20 and 100°C. The silicon particles settle and separate from the supernatant, and the metal salts in the supernatant are precipitated, collected, and reused as new catalyst. Nirache et al. do not teach the production of monohydrogen trichlorosilane from waste metal reaction mass, nor do they report temperature selection effects.

Among the well-known uses of trichlorosilane is the λ-hydrosilylation of trichlorosilane (monohydrogen trichlorosilane) to make organofunctional silanes, and the UK Patent Application G published March 5, 1980 by Unirna et al.
There are uses for trichlorosilane as a raw material in the production of ultrapure silicon, such as discussed in No. B2028289. Recent developments in the semiconductor industry include electronic equipment,
There is an increasing demand for low-cost ultra-pure silicon for photovoltaic cells, solar cells, etc.

Unirna et al. further show that trichlorosilane and silicon tetrachloride are made by the reaction of silicon and hydrogen chloride. Furthermore, in U.S. Patent No. 2,380,995, Rochiyo is C
ompt, rend, Volume 122, Page 531 (189
reported the reaction between silicon and hydrogen chloride as described by Kom in 1996), in which 300-44
A mixture of about 80% trichlorosilane and 20% silicon tetrachloride is obtained by passing hydrogen chloride through a silicon-filled iron tube heated to 0°C.

It is therefore desirable to provide an alternative source for trichlorosilane, to provide an economical method of making trichlorosilane, and to provide a synthesis for making trichlorosilane that improves the yield of trichlorosilane. It is rare. It would also be desirable to provide an improved method for controlling residual silicon-containing contact mass obtained from the production of organohalosilanes by direct process reactions.

Therefore, the main object of the present invention is to provide a method for utilizing the residual silicon obtained from the production of organochlorosilanes.

Another object of the invention is to provide an improved process for obtaining trichlorosilane from silicon.

Another object of the present invention is to provide a method for producing trichlorosilane from the remaining contact rings.

Yet another object of the present invention is to provide a method for improving the amount of heptad-monohydrogen trihalosilanes (trihalosilanes) obtained from the reaction of alkyl halides with silicon in a direct metal catalytic process.

Another object of the present invention is to provide a process for improving the yield of monohydrogen trichlorosilane (trichlorosilane) obtained from residual silicon-containing catalytic mass obtained from the production of organochlorosilane by metal catalytic direct reaction. It is in.

Other objects and advantages of the invention will become apparent from the detailed description below.

According to the present invention, monohydrogen trihalosilanes are produced from residual silicon obtained from the production of organohalosilanes by a direct metal catalytic process, in which the residual silicon is simultaneously contacted with gaseous hydrogen halides and gaseous alkyl halides. heating the remaining silicon-contacted mass to a temperature below that at which substantial alkylation of the remaining silicon-contacted mass occurs, thereby causing the residual silicon to react at said temperature; It consists of producing a reaction product containing a monohydrogen trihalosilane. According to the present invention, there are strict restrictions on the selection of the temperature at which the remaining silicon contact mass is heated, which prevents or retards the alkylation of the remaining silicon contact mass and promotes the hydrohalogenation of the remaining silicon contact mass. Must be temperature. Generally, the temperature at which hydrohalogenation of silicon in the residual silicon contact mass occurs is from about 200 DEG C. to about 350 DEG C. Temperature selectivity can alternatively be expressed as the temperature below which substantial alkylation of the remaining silicon contact mass occurs.

According to at least some of the objects of the present invention, there is also provided a method for improving the amount of monohydrogen trihalosilanes obtained from the reaction of gamma alkyl halides with silicon in a direct metal catalytic process, which is simultaneously contacted with a gaseous alkyl halide and a gaseous hydrogen halide to form a silicon-contacted mass, preventing or retarding alkylation of the silicon-contacted mass and causing hydrohalogenation of the silicon-contacted mass. about 200 to about 350
°C and heating the silicon-contacted mass at the selected temperature, thus reacting the silicon with the gaseous alkyl halide and the gaseous hydrogen halide at the selected temperature to improve the monohydrogen trihalosilane. It consists of producing a certain yield.

By supplying gaseous hydrogen chloride and gaseous methyl chloride to the residual silicon contact mass, the alkylation reaction between silicon and methyl chloride is suppressed when the reaction is carried out at the selected low temperature. This was proved by the method of the present invention. Although there is a slight disadvantage in the silicon utilization by using the process of the present invention compared to the silicon utilization of the reaction between gaseous hydrogen chloride and metallic quality silicon in the absence of methyl chloride, The process of the present invention remains desirable where a source of methyl chloride is readily available. However, it has been demonstrated that silicon utilization is increased in the process of the present invention over the actual silicon utilization when methyl chloride is used in the absence of hydrogen chloride. It has been found that not only monohydrogen trichlorosilane but also silicon tetrachloride can be produced along with various methyltrichlorosilanes. However, by selecting a reduced operating temperature, suppression of the formation of methylchlorosilane by suppression of alkylation is achieved, while promoting the hydrochlorination reaction to form monohydrogentrichlorosilane.

The present invention involves reacting silicon, particularly residual silicon obtained from the production of organohalosilanes by a direct metal contact method, with gaseous alkyl halides in the presence of gaseous hydrogen halide to produce monohydrogentrihalosilane (HSxXs).
(X is halogen). Conventional reactions have been substantial alkylation reactions of residual silicon resulting in the production of alkyl silicon halides with only small amounts of hydrohalogenation. In accordance with at least some objects of the present invention, by controlling the temperature, i.e., by conducting the reaction at a lower selected temperature, the yield of monohydrogen trihalosilanes is substantially improved; In this case, the product is primarily monohydrogen trihalosilane. In order to achieve improved yields of monohydrogentrihalonranes, there are strict regulations on temperature selection, such that the silicon or residual silicon-contacting mass is heated at a temperature below the temperature at which substantial alkylation of the silicon or residual silicon-contacting mass occurs. Heat at low temperature.

The primary alkyl halide silicon product resulting from silicon alkylation is Barry et al., US Pat. No. 2,488,487.
and U.S. Pat. No. 2,803,521 to Nirache et al. The results of alkylation and hydrohalogenation by contacting metallic quality silicon with methyl chloride and hydrogen chloride in various ratios at constant temperature are also shown in the above-mentioned paper by Woerheve. The examples and explanations of Barry et al. show that without temperature selection, alkylation of silicon is the predominant reaction when methyl chloride and hydrogen chloride are brought into contact with silicon in the presence of a metal catalyst at elevated temperatures. be able to. Nirache et al. 20 in the presence of hydrogen chloride and copper as added reaction components
Various methylchlorosilanes obtained from the reaction of methyl chloride and silicon at temperatures between 0 and 500°C are described. According to the process of the present invention, the alkylation reaction is inhibited, prevented or delayed, while the hydrogenhalogenation reaction is accelerated by careful selection and control of the reaction temperature.Wurheve describes this phenomenon in 300' He showed that this could also be achieved by changing the molar ratio of methyl chloride to hydrogen chloride while maintaining a constant temperature at C. For example, by increasing the amount of hydrogen chloride, Wuhrhave showed that although the amount of various methylchlorosilanes decreased, , showed that the amount of trichlorosilane in the product increased.

Using methyl chloride as the gaseous alkyl halide,
When hydrogen chloride is used as gaseous hydrogen halide,
and when the reaction is carried out by a direct method using a suitable catalyst such as copper, the product is generally silicon tetrachloride (5iC1
4) , monohydrogen trichlorosilane (otherwise referred to herein as trichlorosilane) (HSiCl3)
, methylhydrogendichlorosilane (CHs HS x
C12), methyltrichlorosilane (CH3SiC1
3), dimethyldichlorosilane ((CH3)2SiC1
□), trimethylchlorosilane ((CH3)3SyuC1
) and generally hexachlorodisilane (C13S 1-
SICI3) and the remainder consisting of several components including various siloxanes. The remainder is generally referred to as the high-boiling fraction, containing components with boiling points above 70°C. As mentioned above, according to the method of the present invention, gaseous no.
In preferred embodiments where the alkyl oxygenide is methyl chloride and the gaseous hydrogen halide is hydrogen chloride, the desired product is monohydrogentrichlorosilane.

In a preferred embodiment of the process of the invention, the silicon is a residual silicon-containing contact mass obtained from the direct synthesis or production of organochlorosilanes using a metal catalyst during the reaction, for example. In the method of the present invention, the residual silicon is a waste contact mass from a direct method using a metal catalyst and thus contains a metal catalyst, or the metal catalyst is a metal catalyst present in the silicon contact mass. Metal catalyst may be added to the silicon contact mass when this is not possible or when it is desired to make up for insufficient metal catalyst in the remaining contact mass. Generally, according to the invention, the residual silicon-containing contact mass may contain other auxiliaries and additives added during the direct process reaction, or additives and auxiliaries that do not interfere with the process of the invention. It may be added to accelerate the hydrohalogenation reaction or for other suitable purposes.

Direct synthesis or production of organosilanes is described above and also in US Pat. No. 238.0995. The present invention can be carried out without further treatment of the residual silicon-containing contact mass left after the direct synthesis of, for example, US Pat. No. 2,380,995. However, in a preferred embodiment, the residual silicon-containing contact mass is, for example, milled, separated,
It is further processed to remove portions of the remaining contact mass that would poison and otherwise interfere with the hydrohalogenation reaction by treatment with agents to dissolve or extract non-reactive substances and the like. In one preferred embodiment, the residual silicon-containing contact mass obtained from the direct synthesis may be treated as described in Sur and Ritzer, US Pat. No. 4,307,242. According to this method (this U.S. patent is incorporated herein by reference), a silicon-containing contact mass, referred to as a "flow contact arm powder" or "silicon fine powder", is subjected to an aerodynamic centrifugal separation machine. send. This sorting machine is a device that can separate cyclone fine powder into different fractions depending on particle size. Most commonly, the coarser fines are recycled to the organochlorosilane reactor and the finest fraction is discarded. However, according to US Pat. No. 4,307,242, the so-called finest fraction primarily contains the highest percentage of non-silicon impurities, and a decision must be made as to whether to discard or recycle the size fraction. In a method for purifying silicon metal contact mass from a direct organohalosilane reactor system according to U.S. Pat. No. 4,307,242, a portion of the reactor contact arm is analyzed for particle size distribution and the analyzed contact rings are It is divided into relatively pure 1st ryobun and relatively impure 2nd ryobun, and the 1st and 2nd ryobun are separated. The fine silicon powder or effluent contact arm powder is collected in a secondary cyclone, passed through a receiver popper and then through a transfer hopper, and then the fine silicon powder is separated by a mechanical, preferably aerodynamic or centrifugal separator. Pass it through the Monbetsu machine. These fine powders are defined herein as silicon fine powders collected from secondary cyclones used to separate waste silicon fine powders obtained from direct process production of organochlorosilanes. In a preferred embodiment of the invention, a relatively pure separated secondary cyclone fine powder is contacted simultaneously with a gaseous hydrogen halide, such as hydrogen chloride, and a gaseous alkyl halide, such as methyl chloride, at a temperature that is equal to or less than the residual silicon-containing contact temperature. selecting a temperature from about 200 to about 350° C. that prevents or retards alkylation of the mass and promotes hydrohalogenation of the remaining silicon-containing contact mass, and heating the remaining silicon-containing contact mass at the selected temperature; death,
This allows silicon to react with the casseous alkyl halide and gaseous hydrogen halide at selected temperatures to produce improved yields of monohydrogen trihalosilanes.

In another embodiment, the residual silicon source is Cain's finely ground particles taken from the method and apparatus described in Dotson, U.S. Pat. No. 31,331'09, which patent is incorporated herein by reference. . In this patent, silicon-containing particles from a fluidized bed reactor are passed through an external fluid energy mill, or they are passed through a number of superneck jets placed at the bottom of the reactor, and the particles collide with each other or the reactor The silicon particles are shattered as a result of the collision. Any residual silicon-containing contact mass that has been pulverized by crushing individual particles of the silicon-containing mixture, eg, from compaction, impact, abrasion, grinding, etc., can be used in the process of the invention.

In some cases, new silicon powder, which has never been used in the method described above, can be used as the silicon source. For example, finely divided silicon, which preferably does not contain contaminants that could cause contamination of the final product, can be used in the process of the invention in combination with a suitable catalyst, such as those well known to those skilled in the art.

There are no strict restrictions on the size of the silicon or residual silicon particles that may be used in the process of the invention; the silicon or residual silicon may be in any finely divided form, and for best results it is generally The silicon has an average particle diameter ranging from about 20μ to about 200μ. Preferably, at least 25% by weight of the silicon particles have an actual diameter in the range of about 20 microns to about 200 microns. As previously mentioned, various types of silicon alloys, residual silicon alloys, or corresponding mixtures of silicon or residual silicon and metals may be used in the process of the present invention.

Examples of silicon alloys or mixtures that can be used include calcium-silicon alloys, calcium-manganese-silicon alloys,
Includes manganese-zirconium-silicon alloy, iron-silicon alloy, titanium-silicon alloy, zirconium-silicon alloy, copper-silicon alloy, homogeneous mixture of silicon and copper, nickel, tin, or silver, etc.

There are no limitations as to the equipment that may carry out the process of the invention, but the equipment can suitably contact silicon or residual silicon with alkyl halides and hydrogen halides;
The equipment must be able to maintain and control the selected temperature for the hydrohalogenation reaction. The reactor or reaction chamber may be of any suitable size or shape and is preferably constructed from materials that do not interfere with or corrode the reaction components and products and/or by-products. The apparatus must be capable of heating the silicon or silicon-containing contact arm to the critical temperature or temperature range described above. The process according to the invention can be carried out continuously, intermittently or batchwise. Any suitable prior art is available to implement this method.

One method for carrying out the process of the present invention is a fixed bed of residual silicon kept at a selected temperature that retards or prevents alkylation and promotes hydrohalogenation, or mixed with hydrogen halide therein. The process consists of conducting the alkyl halide. In another experiment, while keeping the tumbler heated at a selected temperature, the tumbler containing residual silicon is rotated,
This can be carried out by simultaneously passing alkyl halide and hydrogen halide vapors through an externally heated tumbler. Yet another method of carrying out the process of the invention consists in preheating the vapor mixture, prior to contact with the residual silicon, to a selected temperature that promotes hydrohalogenation and inhibits alkylation.

There are no strict restrictions on the introduction of gases and/or vapors into the reaction chamber; the hydrogen halide gas and the alkyl halide gas or vapor may be mixed before being introduced into the reaction chamber or vessel, or they may be separated. may be introduced into the reaction chamber or container at any time. Conventional metering and/or metering equipment may be used to provide suitable ratios of gases in the reaction chamber or vessel. It is also within the scope of this invention to feed multiple streams of waste into the reactor.

- In a preferred embodiment, this method 41 is carried out by forming a fluidized bed of residual silicon or silicon, contacting them with a suitable gas or steam while keeping the residual silicon or silicon in the form of a fluidized bed. Various embodiments for maintaining a fluidized bed of residual silicon can be used, including the use of gas or vapor velocities sufficient to maintain the residual silicon in a fluidized state within the reactor. This can be accomplished by injecting the alkyl halide and/or hydrogen halide into the particulate residual silicon at a rate suitable to fluidize the particulate material. The optimum rate of gas and/or steam can be determined by one skilled in the art and will depend on various operating conditions. When using a stirred reactor or when using a rotary kiln, the gas velocity or flow rate can be less than or equal to the minimum velocity required to fluidize the silicon in the reactor and reduce the oxidation required for reaction with the silicon. The theoretical amounts of hydrogen and alkyl 10genide can be more accurately reflected. Other conventional fluidization means may be used to maintain the bed of residual silicon in a fluidized state while in contact with the alkyl halide and the hydrogen halide, and to maintain the bed of residual silicon in a fluidized state. It is also within the scope of the invention to utilize a combination of the following measures. Inert gases such as nitrogen may be used to fluidize the remaining silicon-containing contact arms or to supplement other means of fluidization, although this is generally undesirable due to the need for strong venting means. A conventional fluidized bed reactor is described in Reed et al. US Pat. No. 2,389,931. Other means for contacting the residual silicon with the scrap material
- includes means by a stirred prototype reactor or conventional rotary kiln as described in Seller US Pat. No. 2,449,821. The means for heating the residual silicon bed in the reactor and maintaining the residual silicon bed at a selected temperature that promotes the hydrohalogenation reaction and inhibits the gamma alkylation reaction may be any conventional means. , gas and/or
Both internal and external sources of cooling and/or heating, including or steam heating, can be used in the method of the invention. The aforementioned documents provide examples of conventional means for heating beds contained therein.

In a preferred embodiment of the invention the alkyl halide is methyl chloride (CH3C1). In general, the alkyl halides that can be used in the process of the invention include the general formula %, where X is a halogen and n is an integer from 1 to 4.
Including those with. Alkyl groups having 1 to 4 carbon atoms can be straight-chain or branched. Halogen can be chlorine, bromine, iodine or fluorine. In the process of the invention, alkyl halides (or mixtures of alkyl halides) may be used during the reaction.

The preferred hydrogen halide used in the process of the invention is hydrogen chloride. However, in various embodiments, hydrogen bromide, hydrogen iodide or hydrogen fluoride can be used as the hydrogen halide. It is also possible to use mixtures of hydrogen halides in the process of the invention.

There are no strict restrictions on the amounts or proportions of hydrogen halides and alkyl halides used in the process of the invention. Usually from 05 to 20 parts by volume of hydrogen halide are used for 1 part by volume of vaporized alkyl halide, but if desired hydrogen halide can be used in larger or smaller proportions. In certain embodiments, the molar ratio of alkyl halide to hydrogen halide is about 6=
It is in the range of 1 to about 0.

However, in certain preferred embodiments, the molar ratio of alkyl halide to hydrogen halide ranges from about 321 to about 1=3. In one preferred embodiment of the invention, when the alkyl halide is methyl chloride and the hydrogen halide is hydrogen chloride, the molar ratio of methyl chloride to hydrogen chloride is about 3:1. As mentioned above, it has been reported by Woerheve that as the amount of hydrogen chloride increases, the amount of trichlorosilane increases in the reaction of silicon with methyl chloride and hydrogen chloride at a temperature of 300° C. in the presence of a copper catalyst.

There are no strict limitations on the rate of gas or vapor flow in the process of the present invention, but in a preferred embodiment, about 0.05% of the alkyl halide in one pass through the bed of residual silicon.
Control to increase consumption of 5 or more. - Since it is sometimes difficult to achieve high conversion rates in multiple passes, a significant proportion of the vapor flowing out of the bed, e.g.
Approximately 0.08 can be recycled into the bed to effect further consumption of alkyl halide. Such vapor recirculation has the additional advantage of making the temperature throughout the reaction zone more uniform, and tends to cause reactions not locally in the bed, but throughout large portions of the residual silicon-containing bed. During operation in this manner, effluent from the residual silicon bed,
That is, a portion of the vapor exiting the reactor may be removed from the reaction system and cooled to condense the products therein. The operation may be continued until the silicon in the remaining silicon is consumed to a desired point. As previously mentioned, a batch process is also possible; in some cases the reactor can be initially charged with the alkyl halide and hydrogen halide and maintained at the desired selected temperature until the reaction is complete.

Completion or substantial completion of the reaction can be readily determined by product analysis as detailed below.

As mentioned above, the reaction temperature of the residual silicon with the alkyl halide and hydrogen halide is subject to strict regulations and must be selective in order to achieve the desired hydrohalogenation of the silicon. The residual silicon contact arm, i.e., the residual silicon in the presence of hydrogen halides and alkyl halides, is about 200 ml, depending on process variables.
Selectively heated at a temperature in the range of ~350<0>C. Therefore, in order to achieve improved yields of monohydrogen trihalosilanes by the process of the invention, the remaining silicon contact arms are treated with gaseous hydrogen halide at a temperature below that at which substantial alkylation of the silicon occurs or is promoted. and heating in the presence of a gaseous alkyl chloride. Generally, in the production of monohydrogen trichlorosilane, residual silicon is used at a temperature lower than the temperature at which substantial alkyl formation of the residual silicon occurs, and at a temperature at which substantial hydrogenation of the silicon occurs, which is about 20°C.
Heat in the presence of methyl chloride and hydrogen chloride at a temperature of 0 to about 350°C. Generally, substantial hydrogenation is considered to be reached when about 15% by weight of the product is monohydrogen trihalosilane as determined by gas chromatography. Generally, the distribution of organohalosilanes in the product is about 70% when measured by gas chromatography.
Alkylation is considered to have substantially occurred when the total amount is greater than or equal to % by weight. For example, in order to improve the amount of monohydrogen trihalosilane in the reaction product between silicon and alkyl halogenide and hydrogen halide in the residual silicon contact mass, the temperature is about 200 to about 350°C. 1 m of the silicon contact arm, at a temperature between this temperature, the alkylation of the silicon contact arm is stopped, and the silicon contact arm is hydrogenated by hydrogenation, and the silicon contact arm is heated at a selected temperature to convert the silicon into a gas. The reaction with alkyl decagenide and hydrogen decagenide results in an improved yield of monohydrogen trino\rosilane.

Temperature selectivity can be readily determined by product analysis by monitoring the product stream, gas recycle flow, gas in the reaction chamber, etc. by gas chromatography or similar means for determining the composition of the gas. This specific flow or chamber monitoring may be intermittent or continuous and can be carried out using conventional equipment and methods well known to those skilled in the art. amount, i.e., when it appears in a substantial amount in the stream or room being monitored;
Suppressing the alkylation of silicon in the residual silicon mass, No.1
The temperature is lowered to promote hydrogenation. Furthermore, in some cases it may be necessary to suppress the temperature within a range that suppresses alkylation and promotes chlorohydrogenation. For example, when the reaction becomes exothermic after its initiation, it is desirable to control the temperature within a range that inhibits silicon alkylation and promotes silicon hydrohalogenation. This can also be determined by monitoring the flow and/or gas in the room as described above, and taking appropriate action to provide normal cooling and/or to stop heating to maintain the selected temperature. I can do it. In view of the foregoing, the selected temperature may also include a temperature range within which the alkylation reaction is suppressed and the hydrohalogenation reaction is promoted.

Certain variables that effect the reaction between silicon and alkyl halides and hydrogen halides in the residual silicon contact mass include the particular alkyl and hydrogen halides used as starting materials and the conditions under which the reactions are conducted. Examples include contact time of reaction components, amount of silicon, particle size, etc. Historically, the rate constant is different for each reaction and under changing conditions, and this has an effect on temperature selection; however, as a practical matter, temperature selection can be determined at any given time by monitoring the product gases as described above. Most easily determined for reaction conditions, reaction components, and reactor equipment.

The reaction is usually carried out at atmospheric pressure, but at lower or very high pressures, e.g. 20001 bs/in.
．． Optionally, diluents such as carbon dioxide, carbon oxide, silicon tetrachloride, nitrogen, and various other inert gases may be added.

The products formed by the process of the invention can be collected and separated using conventional equipment and methods. For example, the products from the reactions of the present invention can be suitably collected and the monohydric trichlorosilane separated therefrom by any suitable method.

One method of collection is condensation in a conventional condenser cooled to about -20°C with a suitable coolant, such as a methanol-based coolant. This condenses monohydrogen trichlorosilane, silicon tetrahalides, organohalosilanes and other by-products and residues. They can be suitably collected and then separated by any suitable separation method, including fractional distillation.

It is desirable to carry out the process under anhydrous conditions to prevent the formation of hydrolysis by-products and other undesirable by-products that reduce the yield of general dimonohydrogen trihalosilanes. Therefore, in preferred embodiments, steps may be taken to exclude moisture from the apparatus and reaction components.

The following examples are illustrative of the invention and are not intended to limit the scope of the invention.

As a reactor, a motor-driven discontinuous chain A for bed stirring
i Length 4 with agitator and special flange end plug
5.7cm (18in, ), diameter 2.54ct
2.54 crn (1 m
) An electrically heated and stirred reactor was used. The tube section was divided into an upper reaction zone and a lower reaction zone, and each reaction zone was equipped with an independent heater to maintain the desired temperature set. The reactor shell or shell was well insulated to prevent heat loss and fluctuations. Inlets were provided at the bottom of the tube for supplying gas and/or vapor sources, ie alkyl halides and/'% hydrogen halide. 1 was provided with an outlet at the top and equipped with a suitable condenser for the discharge of liquid trichlorosilane product and by-products and gases. Appropriate glass and plastic fittings and tubing were used to minimize the corrosive effects of the reactant gases.

For these examples the reactions were carried out batchwise.

The residual silicon-containing contact arms used in the following examples were comprised of secondary cyclone fine powder previously described in the manner described in U.S. Pat. No. 4,307,242. The residual silicon secondary cyclone fine powder was analyzed and found to contain about 2.1% by weight of carbon,
3.8% by weight copper, 27% by weight iron, 1.7% by weight aluminum, ■. It contained 0% by weight zinc, 69.0% by weight silicon, and residual chlorine hydrogen and traces of other elements. The indicated amount of secondary cyclone powder was placed in the stirred bed reactor described above. The reaction zone temperature was maintained at the selected temperature throughout the experiment. Methyl chloride and/or anhydrous hydrogen chloride were metered into the reaction zone by a linear mass flow meter at the rates indicated in each example. The reaction was carried out at three temperatures: 300°C, 1250°C and 200°C. For reaction studies, a thermocouple probe was used to establish the reactor internal temperature profile with nitrogen flow. Temperature control settings were measured in this manner. The reaction conditioner continuously monitored the reactor external temperature (both reaction and upper zone).

The methyl chloride reaction component flow was standardized using a series hollow meter linear mass flow meter. Hydrogen chloride co-priming was achieved using a linear mass flowmeter with appropriate correction factors.

The reaction rate was determined by the recovery of crude product per unit time. The methylchlorosilane crude (crude fraction) was corrected or normalized for unreacted methyl chloride based on gas chromatography analysis. The degree of utilization of dispensing elements is
Calculated by subtracting the silicon consumed to form the product from the initial silicon a degree as determined by the alkaline fusion method of contact ring samples. For this reason, it is advisable to use appropriate silicon analysis.

Crude product distribution was determined by gas chromatography. The residue or high boiling content was also determined by gas chromatography. Methyl chloride, hydrogen chloride or mixed methyl chloride/
For comparative total material yields at various temperatures using hydrogen chloride, the contact ring was reacted until consumed, ie, no additional crude product was formed.

Example 1 A sample of 502 of the above secondary cyclone fine powders was placed in the reactor and anhydrous hydrogen chloride was fed into the reactor at 11008 CC. The reactor was maintained at normal pressure and heated at 300°C. The product was analyzed as described above and approximately 76% of the silicon in the secondary cyclone powder was converted to product, 94-4% of which consisted of trichlorosilane and silicon tetrachloride. Approximately 46% by weight of the effluent was considered i% Nb point residue, ie, it had a boiling point above 70°C, and about half of it was hexachlorodisilane. The results are shown in Tables 1 and 2 below for comparison.

Example 2 A stirred bed reactor was maintained at 250° C. at atmospheric pressure.
All reaction conditions and quantities were the same in this example as in Example 1. The analytical data of this example are shown in Tables 1 and 2.

Example 3 A stirred bed reactor was maintained at 200° C. at atmospheric pressure.
The reaction conditions and amounts were the same in this example as in Example 1. Data for this example are shown in Tables 1 and 2.

EXAMPLE 4 Residual silicon secondary cyclone powder taken from the same batch as each of the above Examples was prepared as described in Examples 1-3 above using a methyl chloride gas feed at normal pressure and 300° C. as in Example 1 above. The reaction was carried out in the same stirred bed reactor.

Anhydrous hydrogen chloride was not used in this example. Approximately 36%
A silicon utilization rate of 1.5% was achieved, with approximately 92% of the effluent consisting of methyltrichlorosilane and dimethyldichlorosilane, 2.6 Wft% of the product still boiling, and approximately 85% of the product remaining at the boiling point of 1.1°2. -trichlorotrimethyldisilane and 1°1',2,2-tetrachlorodimethyldisilane. Data for this example are shown in Tables 1 and 2.

Example 5 Another identical sample of secondary cyclone powder was treated by the method of Example 4, except that the reaction was carried out at normal pressure of 250°C. Data from this example is shown in Tables 1 and 2.

Example 6 50.02% of residual silicon secondary cyclone fine powder taken from the same batch as each of the above examples was chlorinated with a total molar throughput of gas per unit time being the same as that of each of the above examples. The reaction was carried out using both methyl gas and anhydrous hydrogen chloride gas at normal pressure and 300° C. in the same reaction vessel. The residue was weighed to achieve a 3:1 molar ratio of methyl chloride to hydrogen chloride distribution. A total silicon utilization of approximately 64% was achieved. About 59% by weight of the effluent was about 22% by weight of the effluent or the sum of silicon tetrachloride and trichlorosilane.
or methyl l-IJ fucuronrane and dimethyldichlorosilane, the balance was primarily about 12% by weight methylmonohydrogendichlorosilane, about 25% by weight trimethylchlorosilane and about 3.1% by weight balance/11t and dimethylmonohydrogen. It consisted of hydrogen chlorosilane. Data for this example are shown in Tables 1 and 2.

Example 7 The reaction conditions and amounts were the same as in Example 6 above, except that the reaction temperature was 250°C at normal pressure. Overall silicon utilization was 50%.

The data for this example are shown in Tables 1 and 2, which show that silicon utilization to the desired products trichlorosilane and silicon tetrachloride was approximately doubled by lowering the reaction temperature, i.e., 132 % was 25.5% at 250'C.

Example 8 In this example, the reaction conditions and temperature were the same as in Examples 6 and 7, except that a reaction temperature of 200° C. was used. Overall silicon utilization was 31%. Data for this example are shown in Tables 1 and 2.

From the above data, it can be seen that the residual silicon secondary cyclone fine powder and hydrogen chloride react easily at 300'C, 250C and 200'C to mainly generate trichlorosilane and silicon tetrachloride. At comparable temperatures, the reaction with hydrogen chloride (even at 200'C) yields significantly higher silicon utilization as opposed to the reaction with methyl chloride. Decreasing the temperature from 300'C to 250'C either had no effect on the overall silicon utilization by reactions using exclusively methyl chloride or hydrogen chloride, or there was a significant selectivity difference in the low-temperature methyl chloride reaction, i.e. a sharply reduced overall silicon utilization. There was a typical hatch E/F, decreased methylmonohydrogendichlorosilane formation and increased residue formation.The reactant components fed together, as represented by a 3:1 molar ratio of methyl chloride to hydrogen chloride, were: It changed the result.

(At 81,250°C, the overall silicon utilization rate is 100%.
It was lower than the hydrogen chloride method, but greater than the 100% methyl chloride method.

(bl At 300℃, the overall silicon utilization rate is 100%.
It was comparable to the hydrogen chloride supply reaction.

(At C1300'C, mixed feed methyl chloride to hydrogen chloride resulted in even more silicon utilization to form monotylchlorosilane than a 100% methyl chloride reaction at the same temperature.

(d) The reaction at 1200°C sharply inhibited the alkylation reaction, i.e. the reaction of methyl chloride with silicon, but resulted in a reduction in overall silicon utilization.

(e) The inclusion of hydrogen chloride causes a significant increase in the E/F of the methylchlorosilane product.

+f+Residue formation increases as reaction temperature decreases.

From the above data it is clear that at the selected low 1, hydrogen chloride and methyl chloride react with the silicon-copper mixture to form trichlorosilane and silicon tetrachloride.

In accordance with at least some objects of the present invention, the method provides trichlorosilane in substantial amounts by a hydrochlorination reaction conducted under selected warm conditions to suppress the alkylation reaction between methyl chloride and silicon. Proved that it can be manufactured.

By varying the reaction temperature and careful control of temperature, increased yields of trichlorosilane and silicon tetrachloride were achieved. Furthermore, the reaction in which the raw materials are fed together, i.e., in the presence of silicon at a low temperature in the range of about 200 to about 300°C, is a reaction in which both hydrogen chloride and methyl chloride are fed. The ability to selectively inhibit the methylchlorosilane reaction, that is, the alkylation reaction, was clearly demonstrated.

Although this method was not carried out using fresh silicon, the method of the present invention is applicable to such applications, and is capable of converting fresh silicon into a material that suppresses alkylation of silicon and causes hydrohalogenation of silicon. The reaction with the gaseous alkyl halide and gaseous hydrogen halide can be carried out at selected temperatures between 200 and about 350 DEG C., resulting in improved yields of monohydrogen trihalosilanes.

Although this invention has been described in particular detail with respect to certain preferred embodiments, it will be appreciated that modifications may be made within the scope of the invention.

Claims (1)

[Claims] 1. In a method for producing monohydrogentrihalosilane from residual silicon obtained from the production of organohalosilane by a direct metal contact method, residual silicon is simultaneously contacted with gaseous hydrogen halide and gaseous alkyl halide. at least forming a residual silicon-contacted mass, heating the residual silicon-contacted mass at a temperature below that at which substantial alkylation of the residual silicon-contacted mass occurs, and thus reacting the residual silicon at said temperature to form a monomer. A method characterized in that a reaction product containing a hydrogen trihalosilane is produced. 2. The method of claim 1, wherein gaseous hydrogen halide and gaseous alkyl halide are contacted with a fluidized bed of residual silicon. 3. The method according to claim 1, wherein the gaseous alkyl halide is selected from the group consisting of chlorides, bromides, iodides, or fluorides of alkyl groups having 1 to 4 carbon atoms. 4. The method according to claim 1, wherein the gaseous hydrogen halide is selected from the group consisting of hydrogen chloride, hydrogen bromide, hydrogen iodide and hydrogen fluoride. 5 The gaseous hydrogen halide is hydrogen chloride, the gaseous alkyl halide is methyl chloride, and monohydrogen) IJ
3. The method according to claim 1 or 2, wherein the halosilane is monohydrogen trichlorosilane. 6. The method of claim 1, wherein the molar ratio of alkyl halide to hydrogen halide ranges from about 6:1 to about 1-0. 7. Selective heating of the residual silicon contact mass at a temperature of about 00°C to about 350°C.
The method described in section. 8. The method of claim 1 comprising collecting the reaction product and separating the monohydrogen trihalosilane therefrom. 9, about 6; feeding gaseous methyl chloride and gaseous hydrogen chloride to the fluidized bed of residual silicon at a molar ratio of methyl chloride to hydrogen chloride ranging from 1 to about 0;
Heating at a temperature of 0 to 300°C, but below the temperature at which substantial alkylation of the residual silicon occurs, to produce a product containing a substantial amount of monohydrogen trihalosilane and silicon tetrachloride. A method for producing monohydrogentrichlorosilane from residual silicon obtained from the production of organochlorosilane by a direct method, characterized by: 10. The method of claim 9, wherein the molar ratio of methyl chloride to hydrogen chloride is from about 3:1 to about 1:3. 11. The method of claim 9, wherein the residual silicon comprises silicon fines collected from a secondary cyclone used to separate waste silicon fines obtained from the direct production of organochlorosilanes. 12. The method of claim 9, comprising collecting the product and separating the monohydrogen trihalosilane therefrom. 13. Claim 9, wherein the molar ratio of methyl chloride to hydrogen chloride is about 3:1, the temperature is from about 200 to about 250'C, and the major product is monohydrogen trichlorosilane.
The method described in section. 14 Contacting silicon simultaneously with a gaseous alkyl halide and a gaseous hydrogen halide to form a silicon-contacted mass, reducing the temperature to prevent alkylation of the silicon-contacted mass, and halogenating the silicon-contacted mass. Selecting a temperature between about 200 and about 350° C. to effect hydrogenation, heating the silicon contact mass at the selected humidity and thus reacting the silicon with the gaseous alkyl halide and the gaseous hydrogen halide at the selected temperature. A method for improving the amount of monohydrogen trihalosilanes obtained from the reaction of silicon with an alkyl halide by a direct metal catalytic method, characterized in that the amount of monohydrogen trihalosilanes obtained is improved by a direct metal catalytic method. 15. Simultaneously contacting the remaining silicon with gaseous alkyl halide and hydrogen halide to form a residual silicon contact mass, controlling the temperature to prevent alkylation of the remaining silicon contact mass, and reducing the temperature to prevent alkylation of the remaining silicon contact mass. The remaining silicon-contacted mass is heated at a selected temperature between about 200 and about 350°C to cause hydrohalogenation, and the silicon in the remaining silicon-contacted mass is removed from the gas at the selected temperature. from the reaction of residual silicon obtained from the production of organohalosilanes by a direct metal catalytic process, characterized in that they are reacted with alkyl halides and gaseous hydrogen halides to produce improved yields of monohydrogen trihalosilanes. A method for improving the amount of monohydrogen trihalosilane obtained. 16. The method according to claim 14 or 15, wherein the gaseous alkyl halide and the gaseous hydrogen halide are brought into contact with a fluidized bed of silicon or residual silicon. Method. 17. Gaseous alkyl halide having 1 to 4 carbon atoms
16. The method according to claim 14 or 15, wherein the alkyl group is selected from the group consisting of chloride, bromide, iodide or fluoride of an alkyl group having the following. 18 Gaseous hydrogen halide, hydrogen chloride, hydrogen bromide,
The method according to claim 14 or 15, wherein the hydrogen iodide and hydrogen fluoride are selected from the group consisting of hydrogen iodide and hydrogen fluoride. 19. The method according to claim 14 or 15, wherein the gaseous hydrogen halide is hydrogen chloride, the gaseous alkyl halide is methyl chloride, and the monohydrogen trihalosilane is monohydrogen trichlorosilane. 20. Claim 14, wherein the molar ratio of alkyl halide to hydrogen halide ranges from about 6:1 to about 1:6.
or the method described in paragraph 15. 21. The method of claim 14 or claim 15, wherein the molar ratio of alkyl halide to hydrogen halide ranges from about 3:1 to about 1:3. 22 the gaseous hydrogen halide is hydrogen chloride, the gaseous alkyl halide is methyl chloride, the molar ratio of alkyl halide to hydrogen halide is in the range of about 3:1, and the selected temperature is in the range of about 200 to It is about 250'c,
16. A process according to claim 14 or claim 15, wherein silicon is thus reacted with methyl chloride and hydrogen chloride to produce a product comprising substantially monohydrogen trichlorosilane. 23. The method of claim 14 or 15, wherein the reaction product is collected and the monohydrogen trihalosilane is separated therefrom.