CN1157259A - Trichlorosilane production process - Google Patents

Abstract

A method for producing trichlorosilane, comprising reacting silicon particles, tetrachlorosilane and hydrogen in a fluidized bed at 400-700° C. in the presence of an externally added catalyst containing copper silicide; and producing a catalyst containing copper and silicon method.

Description

The production method of trichlorosilane

The present invention relates to a process for the production of trichlorosilane by reaction between silicon particles, tetrachlorosilane and hydrogen. More specifically, it relates to a method for producing trichlorosilane which can stably carry out the above-mentioned reaction in a fluidized bed at an extremely high reaction rate.

Trichlorosilane (SiHCl ₃ ) is widely used as a raw material for producing high-purity silicon. That is, the following reaction can occur when trichlorosilane is reacted with hydrogen gas at a temperature of 1000° C. or higher, thereby separating silicon.

Generally, trichlorosilane can be produced by the reaction between silicon particles and hydrogen chloride. When tetrachlorosilane incidentally produced in the above silicon production method is separated from the reaction gas and converted into trichlorosilane used as a raw material, high-purity silicon can be favorably produced on an industrial scale.

A method for converting tetrachlorosilane into trichlorosilane industrially employs a reaction of hydrogenating tetrachlorosilane into trichlorosilane as represented by the following reaction formula.

The reaction is usually carried out on a fluidized bed formed in a fluidized bed reactor, the reaction temperature is 400-600° C., and the molar ratio of hydrogen to tetrachlorosilane is about 2-5.

However, the above reaction involves problems such as extremely low reaction speed and extremely low productivity. In order to solve these problems, it is necessary to adopt some means, such as increasing the size of the reactor.

On the other hand, it has been proposed that a catalyst containing copper or its compound be used to increase the reaction rate.

Japanese Laid-Open Patent Application No. 56-73617 discloses a method for producing trichlorosilane using copper powder as a catalyst. This publication states that it is possible to produce trichlorosilane from silicon and hydrogen chloride and convert tetrachlorosilane to into trichlorosilane method. It states that copper particles are used as catalysts in the above reactions.

Japanese Laid-Open Patent Application No. 60-36318 discloses a method for converting tetrachlorosilane into trichlorosilane by flowing hydrogen and tetrachlorosilane over silicon particles to interact with these silicon particles at 500-700° C. reaction. It states that cuprous chloride can be used as a catalyst in the above reaction.

Furthermore, Japanese Laid-Open Patent Application No. 63-100015 discloses a method for reacting tetrachlorosilane with hydrogen or hydrogen and hydrogen chloride in a flowing state at a temperature of 150° C. or higher. In the examples disclosed in this publication, the reaction was carried out in an autoclave at 260°C. It indicates a catalyst containing metallic copper, metallic halides (including iron halides) and bromides and iodides of iron, aluminum or vanadium as the catalyst used in the above reaction.

These known copper-based catalysts, ie catalysts containing metallic copper, copper chloride or the like, are particularly good catalysts when the reaction of silicon particles, hydrogen and tetrachlorosilane is carried out in a fixed bed. However, when the reaction is carried out in a fluidized bed at a temperature of 400°C or higher (which is the most commonly used in industry), if these catalyst materials are introduced directly or mixed with silicon particles into the fluidized bed during the reaction If the reaction is carried out in a non-bed reactor, the copper-based catalyst or silicon particles will agglomerate, thereby disrupting the flow state, resulting in hindering continuous stable operation or reducing the reaction rate.

The inventors of the present invention conducted continuous research to solve the above-mentioned problems and found that adding a copper-based catalyst as copper silicide to a reaction system prevents the agglomeration of the copper-based catalyst or silicon particles with high reliability.

They also found that catalyst systems consisting of the above copper silicide in combination with an iron component, or copper silicide, an iron component, and an aluminum component further improved the rate of the conversion to trichlorosilane .

It is therefore an object of the present invention to provide a process for the production of trichlorosilane by reacting silicon particles, tetrachlorosilane and hydrogen in a fluidized bed at high temperature, wherein a novel catalyst system containing copper silicide is used, Trichlorosilane can thus be produced more stably and at higher reaction rates than processes using known copper-based catalysts.

A second object of the present invention is to provide a method for the production of trichlorosilane which further improves the reaction rate of the conversion reaction into trichlorosilane by employing a novel catalyst system in which the above-mentioned silicification Copper is combined with an iron component, or with an iron component and an aluminum component.

The above and other objects and advantages of the present invention will become more apparent from the following description.

According to the present invention, the first object and advantage of the present invention can be obtained by a process comprising combining silicon particles, tetrachlorosilane and hydrogen in the presence of an additional catalyst containing copper silicide at 400 React at -700°C in a fluidized bed.

The second object and advantage of the present invention can be obtained by using a catalyst comprising a combination of copper silicide and an iron component, or a combination of copper silicide and an iron component and an aluminum component .

Fig. 1 is a sectional view of a fluidized bed reactor used in the process of the present invention.

In the present invention, the source of tetrachlorosilane as a raw material is not particularly limited, but it is industrially preferable to use tetrachlorosilane incidentally produced by a deposition reaction of high-purity silicon because the material is inexpensive. In the deposition reaction of high-purity silicon, this by-produced tetrachlorosilane is obtained in a state that it contains unreacted trichlorosilane, hydrogen chloride and the like. In the present invention, tetrachlorosilane may be used when it is or is substantially pure tetrachlorosilane from which the other components have been separated. However, it is preferred to use substantially pure tetrachlorosilane because it increases the conversion of the reaction.

In the present invention, the silicon particles are not particularly limited, but metallurgical grade silicon particles having a silicon content of 75% by weight or higher, preferably 95% or higher, are preferably used. Preferably, the silicon particles have a larger surface area to increase the reaction speed on the surface of the silicon particles in the reaction system.

The reaction of the present invention is usually carried out using a fluidized bed reactor as described hereinafter. In this case, the silicon particles preferably have an average particle diameter of 100-300 microns in order to obtain a good flow state.

In the present invention, hydrogen is not particularly limited, and they may be a kind of hydrogen produced by a known method, or incidentally produced by other production methods or similar methods, and are not limited to its source.

In the present invention, as a method of reacting silicon particles with a mixed gas of tetrachlorosilane and hydrogen, it is possible to use them in a fluidized bed at a temperature of 400-700° C., preferably at 450 The method of reacting with each other at a temperature of -600°C. The reaction is usually carried out in a fluidized bed system, and silicon particles, tetrachlorosilane and hydrogen can be supplied continuously or intermittently. Preferably, silicon particles are intermittently supplied according to their consumption, while tetrachlorosilane and hydrogen are continuously supplied.

Figure 1 is a cross-sectional view of a typical fluidized bed system reactor useful in practicing the process of the present invention.

Reactor 1 comprises superelevation (freeboard) part 2 and fluidized bed part 3, and it is equipped with delivery gas introduction pipe 5, the gas disperser 4 that links to each other with the end of pipe 5 at the bottom of fluidized bed part and in fluidized bed part. The upper end of the bed part is open to the particle delivery pipe 6. The particle discharge pipe 8 is opened toward the middle portion of the fluidized bed portion 3 at its beginning and its other end is connected to a reaction gas discharge pipe 10 through a fine particle collecting cyclone 7 . In this way, the gas containing particles (formed in the fluidized bed portion) of the fluidized bed 11 is separated into fine particles in the fine particle collecting cyclone 7 , and then the gas is discharged from the reaction gas discharge pipe 10 . Be equipped with a kind of silk flow valve 9 at the beginning of particle discharge pipe 8.

In the above reactor, silicon particles are fed through the particle delivery pipe 6 . In this case the catalyst, which will be described in detail hereinafter, can be simultaneously fed through the particle delivery pipe 6 . Simultaneously, tetrachlorosilane and hydrogen may be fed through the gas disperser 4 from the transfer gas introduction pipe 5 , thereby forming the fluidized bed 11 .

Tetrachlorosilane and hydrogen diluted with an inert gas that does not participate in the reaction, such as nitrogen or argon, may be fed.

In the above reactor, the silicon particles can be introduced into the fine particle collecting cyclone from the particle discharge pipe 8 together with the exhaust gas and discharged from the reaction gas discharge pipe 10 as a gas substantially free of particles.

In the present invention, the amounts of tetrachlorosilane and hydrogen to be fed can be appropriately determined within a range ensuring a flow velocity at which a fluidized bed can be formed. For the ratio of tetrachlorosilane to hydrogen, 1 to 5 moles of hydrogen are usually supplied to 1 mole of tetrachlorosilane. However, since the total amount of trichlorosilane produced is the product of the degree of conversion of the conversion reaction into trichlorosilane and the flow rate of tetrachlorosilane fed to the reactor, it is preferred that 1 mole of tetrachlorosilane be supplied to Into 1-3 moles of hydrogen.

In the present invention, it is important to carry out the reaction of the above-mentioned silicon particles, tetrachlorosilane, and hydrogen as raw materials in the presence of a catalyst containing copper silicide.

By supplying the copper component as copper silicide into the reaction system for the catalyst, the agglomeration of the copper component or the silicon particles can be effectively prevented, and the reaction can be stably performed without lowering or changing the formation of the particles. The reaction rate in a fluidized bed. Clogging of the reactor, in particular of the particle outlet, by agglomerated particles can advantageously be prevented.

Although copper silicide may exist in the reaction system independently of the silicon particles, it is preferably present on the surface of the silicon particles in view of reactivity and easy handling.

In this case, "the surface of the silicon particle" represents the range which can be measured by the EDS (energy dispersive spectrometer) of a scanning electron microscope. Since the signal from the EDS indicates the ratio of the components present on the surface of the particle, the composition on the surface of the particle can be known by analyzing the signal from the EDS. Furthermore, after setting the acceleration transformer of the electron microscope to 20KV and the surface of the particles could be seen, the magnification was set to 1000 times. Thereafter, the X-ray intensity of the EDS in a 10-micrometer square in the field of view was measured, thereby obtaining the composition ratio of the components on the surface from the intensity ratio.

As copper silicide present on the surface of silicon particles, suitable are particles having an alloy composition containing 85% by weight or less of copper. If the concentration of copper on the surface exceeds 85% molar, the particles will agglomerate as the temperature rises. This is because the upper limit of the stable alloy composition ratio of copper and silicon is Cu ₅ Si, that is, the concentration of copper is 83.3 mol%. Under conditions where particle agglomeration is likely to occur, for example, when small particles having an average particle diameter of 100 microns or less are used as a catalyst, the alloy composition ratio of copper to silicon is preferably Cu ₄ Si, that is, copper The concentration is 80% molar or less. Under conditions where agglomeration is more likely to occur, the alloy composition ratio of copper to silicon is preferably Cu ₃ Si, that is, the concentration of copper is 75 mol% or less. Although in actual conditions, the concentration of copper is sometimes above 85%, the essence of the present invention is to prevent copper containing an unstable silicide of excess copper and metallic copper that is easily agglomerated with other particles from being exposed to the surface of the particles superior.

Even when there is a small region with the above-mentioned high concentration of copper, if the region with the high concentration of copper occupies 10% or less of the total surface area of the particles, it will not cause problems similar to the deterioration of the flow state. question. Accordingly, the silicon particles with copper silicide used in the present invention are preferably an alloy of copper and silicon having a copper content of 85 mole percent or less present on 90% or more of the surface area of the silicon particles.

It is considered important that copper silicide must exist near the surface of the particles participating in the reaction. According to the method provided by the present invention for producing silicon particles having copper silicide on the surface, at least 80% of the copper silicide can be present at a depth of up to 10 micrometers (calculated from the surface), so that the amount of copper used can be reduced, while remaining catalytic. The amount of copper silicide present at a depth of up to 10 microns (calculated from the surface) was determined by the method described below.

A few grams of silicon particles with adjusted particle size are immersed for 5-30 seconds in about 100 ml of a mixture solution containing 70% concentration of nitric acid and 50% concentration of hydrofluoric acid in a mixing ratio of 10 to 1 while stirring , and then introduce the solution into a large volume of water to quench the reaction. After separation of the particles by filtration and rapid drying, the weight of the particles was determined. How many silicon particles are dissolved in the solution can be known from the reduction in weight, and these conditions are repeated one or more times to dissolve the particles until a portion with an average depth (calculated from the surface) of 10 microns or less is removed. Below 10 microns is known from the difference between the amount of copper contained in the whole particle before dissolving the surface and the copper content in the whole particle dissolved and removed by the above method to a depth of 10 microns (calculated from the surface) The copper content in the portion of the depth (calculated from the surface). The copper content in the whole particle can be measured by ICP (Induced Coupled Plasma) spectrometry by completely dissolving the particle in a mixed aqueous solution of nitric acid and hydrofluoric acid.

In the present invention, the amount of the catalyst (in terms of copper atoms) is preferably 0.1 to 30 parts by weight based on 100 parts by weight of silicon present in the reaction system of the trichlorosilane production reaction. In order to improve the degree of conversion and stabilize the flow state, it is more preferable to use 0.2-20 parts by weight of the catalyst.

In this case, since silicon components are also contained in silicon particles having copper silicide, silicon particles can also be considered as silicon present in the reaction system.

Therefore, even if a catalyst having a copper content of 0.1 to 30 parts by weight is prepared in which only silicon particles having copper silicide exist in the reaction system, the reaction can be satisfactorily performed.

Since the copper contained in the added copper silicide reacts with silicon in the reaction system and is continuously converted into copper silicide and remains in the reaction system, once it is added to the reaction system, it is sufficient to compensate Reduction of the amount of copper silicide caused by particle removal to control the iron component (described later) or reduction of the amount of copper silicide pulverized and diffused outside the reaction system, and newly added copper silicide is hardly necessary.

The method for producing the silicon particles advantageously used in the present invention having copper silicide at least on the surface is not particularly limited, for example, the silicon particles can be produced by the following method.

In an atmosphere of a non-oxidizing gas, silicon particles having an average particle diameter of 50 μm to 2 mm and cuprous chloride particles and/or cupric chloride particles having an average particle diameter of 1 mm or less are heated at a temperature of at least 250° C. Lower the heat.

In the above method, the silicon particles used as a raw material are not particularly limited if they are metallurgical grade silicon having a silicon content of 75% or more. It can contain impurities such as iron and aluminum. Examples of silicon particles include No. 1 silicon and No. 2 silicon described by JIS-G2312 and No. 1 iron silicon and No. 2 iron silicon described by JIS-G2302. Preferably, raw material silicon particles obtained by mechanically grinding the metallurgical-grade silicon or using chemical treatment methods, such as acid grinding to control its particle diameter and particle size distribution, can be used, so that the reaction product can be used as Catalyst for fluidized bed reaction to produce trichlorosilane. Generally speaking, when there are two kinds of particles with different average particle sizes in the fluidized bed, if their true densities are almost the same and their particle diameter ratio is 5-6 times, the state of homogeneous mixture will disappear, and there will be Particles with larger particle diameters will gather in the lower part of the fluidized bed, and this state is called "stratified state".

As mentioned above, since the average particle diameter of the silicon particles used as the raw material for the fluidized bed reaction, that is, the average particle diameter of the silicon particles in the reactor, is 100-300 microns, the silicon particles of the added additive preferably have an average particle diameter of 20 microns or more but 2 mm or less so that they mix uniformly without stratification in the fluidized bed. Copper silicide particles with small particle diameters are characterized by easy formation of agglomerates. If the particles have a particle diameter of 20 µm or less, when the catalyst is added during the reaction, a problem is easily caused due to agglomeration immediately after the addition. For the above reasons, the average particle diameter should be between 30 microns and 2 mm, preferably between 50 microns and 1.5 mm, more preferably between 100 microns and 1.5 mm.

Preferably, the copper chloride used is not coarse particles with an average particle diameter of 1 mm or more. The reason is that since the average particle diameter of metallurgical grade silicon as the catalyst material is 30 microns-2 mm, if the average particle diameter of copper chloride exceeds 1 mm, it will be covered on the copper chloride due to the reduction of copper chloride. Copper silicides containing excess copper elements are formed on metallurgical grade silicon particles. Since this copper silicide is extremely viscous, it can easily cause further agglomeration between particles when it is used as a catalyst. This is going to be the cause of some trouble.

The average particle diameter of copper chloride refers to the diameter of a single copper chloride particle rather than the particle agglomeration, because the individual particles are not separated during the process of forming copper silicide and can be properly separated and used normally by stirring the particle agglomeration . As copper chloride, copper (I) chloride or copper (II) chloride can be used, and its purity is not particularly limited.

In this reaction, metallurgical-grade silicon particles and copper chloride are first uniformly mixed with each other, and the resulting mixture is kept at a temperature of 250°C or higher in an atmosphere of a non-oxidizing gas to form copper silicide, said Non-oxidizing gases, such as nitrogen, hydrogen, argon or mixtures thereof, do not produce unwanted oxides or chlorides. Although there is no problem when the mixture is in a static state, more uniform silicon particles can be obtained by stirring with a fluidized bed or a rotating drum. When the temperature of the mixture product is raised, copper silicide is formed on the surface of the silicon particles, while hydrogen chloride and an acidic component such as tetrachlorosilane or trichlorosilane are produced. The time required for heating varies to some extent with the heating state or kind of ambient gas, but the completion of the copper silicide formation process can be estimated from the disappearance of acidic components in the circulating ambient gas.

In the above reaction, the ratio of silicon particles to copper chloride particles is determined according to the addition range of copper silicide.

Therefore, silicon particles having copper silicide at least on the surface can be produced by the above method.

In the present invention, copper silicide has a catalytic effect even if it is used alone. However, studies conducted by the inventors have shown that catalytic activity can be remarkably improved by the presence of an iron component or an iron component and an aluminum component in addition to copper silicide in the reaction system.

In the present invention, the components of iron and aluminum as a catalyst can be added to the reaction system in any manner, and iron and aluminum are not particularly limited as long as they can be added in solid form, such as metal or metal silicide thereof. Can.

The amount of the catalyst consisting of iron or iron and aluminum is not particularly limited. However, if it is too small, the reaction rate cannot be improved, but if it is too large, the microparticles that are reacting substances themselves will be covered with nonreactive substances.

Therefore, for the amount of the catalyst composed of iron or iron and aluminum, the content of iron should be 0.3-40% by weight, preferably 0.5-30% by weight (based on the silicon present in the reaction system), while the content of aluminum should be 0.3-40% by weight. The content should be 0.1-3% by weight, preferably 0.2-2% by weight, more preferably 0.2-2% by weight.

In the present invention, the ratio of each copper, iron and aluminum in the reaction system can be known by maintaining a material balance in the reaction system and each component can be adjusted according to the above ratio to make it fall within the above within range.

In order to carry out a more uniform reaction, it is more preferable to add iron and aluminum as the above-mentioned catalysts while existing on the surface or inside of silicon particles (as a raw material), even when they are added in the form of metal or metal silicide to the reaction system.

Therefore, as at least a part of copper, iron and aluminum, silicon particles containing a large amount of these metal components, or silicon particles having these metal components or the above-mentioned metal silicide bonded to the surface are preferably advantageously used.

As silicon particles containing a large amount of at least one of copper, iron and aluminum, silicon particles containing impurities such as iron or aluminum can be used. Examples of silicon particles containing impurities such as iron or aluminum include No. 1 silicon and No. 2 silicon described by JIS-G2312 and No. 1 iron-silicon and No. 2 iron-silicon described by JIS-G2302. Copper silicide silicon particles are given as the raw material.

In addition to the above feeding method, copper, iron and aluminum as catalysts may be fed into the reaction system as a compound or mixture containing copper and iron or a compound or mixture containing copper, iron and aluminum.

Although the added iron component remains in the reaction system like the copper component, when it is supplied as an impurity of silicon particles, the concentration of iron gradually increases with the consumption of silicon particles in the reaction system.

When the concentration of iron becomes particularly high, for example, the proportion of iron exceeds the upper limit of the above range of 40% by weight (based on silicon in the reaction system), the degree of conversion will decrease due to the above reasons. Therefore, it is necessary to remove the iron component from the reaction system or newly add silicon particles after a lapse of the reaction time to control the iron concentration within the above-mentioned range. The method used to remove the iron component is not particularly limited, and smaller particles can be removed from the system by using a cyclone to circulate the particles and periodically changing the classification efficiency of the cyclone. Since a large amount of iron silicide is contained in the smaller particles in this case, the iron component can be removed with higher selectivity.

In addition, the aluminum component is converted into aluminum chloride by its reaction with tetrachlorosilane in the reaction system, which is different from copper and iron. Aluminum chloride is a gas at 400°C or higher, so it can be removed from the system. In order to keep aluminum as a catalyst always present in the reaction system, it is preferable to control the concentration of aluminum within the above-mentioned range by including it in silicon particles instead of adding it in powder form.

According to the present invention, clogging of the feed line and deterioration of the flow state due to agglomeration caused when copper powder or copper chloride is added as a catalyst do not occur at all. In other words, trichlorosilane can be continuously and stably produced for a long period of time at a high degree of conversion while maintaining the same flow state as when charged with general metallurgical-grade silicon particles.

The reaction of silicon particles, tetrachlorosilane and hydrogen can be carried out in the presence of a catalyst containing an iron component or an iron component and an aluminum component in addition to copper silicide, so that the reaction speed can be increased and the reaction time can be shortened. Therefore, the size of the reactor can be reduced by the process of the invention using this catalyst.

The following examples and comparative examples serve to further describe the present invention. However, it should be understood that the present invention is not limited to these Examples.

In the following Examples and Comparative Examples, the average particle diameter, degree of conversion and reaction speed are data obtained as described below. (average particle diameter)

The predetermined particles are classified with a classifying sieve. The sieves were cumulatively added from the sieve with the smallest particle diameter, and when the cumulatively added value reached 50% by weight, the value was taken as the average particle diameter. (degree of conversion)

Utilize gas chromatography to measure the gas concentration before and after adding the raw materials into the reactor, when the molar number of the tetrachlorosilane fed into the reaction system is set as 100%, the tetrachlorosilane converted into trichloro The percentage of silane is obtained from the following equation. Degree of conversion (%)=[moles of tetrachlorosilane converted into trichlorosilane]/[moles of tetrachlorosilane fed]×100 (reaction speed)

The degree of conversion according to the above is obtained from the following equation.

R＝1/tIn(c ₀ /c ₀ -c) where

R: Response speed;

t: reaction time or average contact time between the silicon particles and the gas in the case of a reaction with a fluid gas;

c ₀ : the equilibrium conversion rate at the reaction temperature (24% when the reaction is carried out at 500° C. and 0.7 MPaG); and

c: Degree of conversion (%) at reaction time t. (composition of silicon particles used)

Silicon particles of two different compositions as shown in A and B in Table 1 below were used.

Table 1 Fe Al Cu Cr Ni mn (weight%) A 0.12 0.51 <0.01 0.44 <0.01 0.02 B 0.09 0.05 <0.01 0.01 <0.01 0.01 Ti Ca C P B As (weight%) (PPM) A 0.01 0.03 0.02 20 20 <10 B <0.01 0.01 0.01 <10 <10 <10 Embodiment 1 (adopt copper silicide alone)

5 kg of silicon particles with an average particle diameter of 150 μm and a composition as shown in Table 1 A (98% purity) were mixed with 2 kg of monovalent copper (I), and the copper passed through a pore diameter of 2 mm. sieve, and the resulting mixture was kept at 300° C. for 12 hours while gently blowing a mixture gas consisting of nitrogen and hydrogen in a fluidized bed to conduct a reaction in a mixing ratio of 1:1. After cooling, the reaction product was taken out and weighed, and its weight was 6.2 kg. Part of the reaction product was dissolved in a mixed aqueous solution of nitric acid and hydrofluoric acid, and the copper content in the reaction product was determined by ICP (Induced Coupled Plasma) spectrometry. The copper content was found to be about 20% by weight. The X-ray intensities at four different random points (points A, B, C and D) were measured by EDS, the results shown in Table 2 were obtained.

Table 2 Si Cu Fe Al Intensity ratio (point A) 0.90 0.09 0.01 0.00 Intensity ratio (point B) 0.78 0.20 0.02 0.00 Intensity ratio (point C) 0.45 0.45 0.07 0.03 Intensity ratio (point D) 0.14 0.81 0.03 0.02

Magnification: 1000×, measurement area: 10 ^-14 mm ² .

The intensity ratio is the ratio of the intensity of each atom to the sum of the total intensities of the above four atoms (as 1).

Thereafter, 35 kg of silicon particles with an average particle diameter of 150 micrometers and a composition as shown in A in Table 1 (purity 98%) were charged into the fluidized bed reactor shown in Figure 1, and by using a mixed gas A fluidized bed was formed, the mixed gas was composed of hydrogen and tetrachlorosilane (2.5:1 molar ratio), the flow rate was 100 Nm ³ /hour, the temperature was 500° C., and the pressure was 0.7 MPaG.

A reactor as shown in Fig. 1 having the following features was used. h1 (height from the top of the dispersion plate to the bottom of the fluidized bed part): 650mmh2 (height of the slope part): 150mmh3 (height of the super high part): 1100mmh4 (height of the cyclone): 380mmh5 (the upper part of the cyclone Height): 150mmh6 (the height of the particle discharge pipe): 1000mmd1 (the inner diameter of the fluidized bed part): 298mmd2 (the inner diameter of the super high part): 478mmd3 (the inner diameter of the upper part of the cyclone): 115mmd4 (the inner diameter of the particle discharge pipe): 30mm

The degree of conversion gradually increases with time from the beginning of the reaction, but then becomes constant. The degree of conversion at this time is shown in Table 3.

After the degree of conversion remains unchanged, 6 kg of silicon particles containing copper silicide prepared by the above method are continuously added to supplement the reduction in the number of silicon particles caused by the fluidization of the reaction, thereby maintaining the height of the fluidized bed to a certain degree . The proportion of copper atoms based on silicon atoms was 6% by weight. The degree of conversion rises rapidly immediately upon introduction of small amounts of catalyst.

The degree of conversion at the completion of the 6 kg catalyst addition is shown in Table 3. During the introduction of the catalyst, clogging of the feed line did not occur at all, and no change in the fluidized state was observed.

Even after 6 kg of silicon particles containing copper silicide as a catalyst were completely introduced, the reaction was continued for 60 days while continuously feeding silicon particles not containing copper silicide, thereby maintaining the height of the fluidized bed to some extent. The degree of conversion after 60 days is shown in Table 3.

table 3 Determination time of degree of conversion The degree of conversion of tetrachlorosilane (%) After initiating the reaction with metallurgical-grade silicon particles alone 9.0 After the degree of conversion has stabilized 13.1 After adding 6 kg of silicon particles containing copper silicide 20.0 After adding 6 kg of catalyst for 60 days 19.8

As shown in Table 3, even in the long-term reaction, a decrease in the degree of conversion was rarely seen, and a decrease in the fluidized state was not seen during the reaction. In addition, after the reaction was forced to stop, the reactor was opened after cooling, and the inside of the fluidized bed reactor and silicon particles taken out were observed. In either case no bulky product or the like was seen.

One hour after the addition of the above copper silicide, the reaction rate was found to be 0.39 sec ^-1 . Example 2

Prepare silicon particles with different copper silicide contents as shown in Table 4 by changing the conditions for preparing copper silicide in Example 1, and add them to the reactor to ensure the presence of the silicon particles in the fluidized bed as shown in Table 4. The indicated copper content was used to react.

In the above reaction, the degree of conversion and the reaction rate of tetrachlorosilane obtained in the same manner as in Example 1 are also shown in Table 4.

Table 4 Copper atom content (%) conversion degree (%) and reaction speed* (second ^-1 ) in copper silicide in fluidized bed After the degree of transformation has stabilized after 60 days 1 5 0.3 16.0(0.24) 14.0(0.19) 2 2 0.5 17.5(0.29) 15.5(0.23) 3 10 0.5 17.5(0.29) 15.5(0.23) *The value is indicated in parentheses.

As shown in Table 4, even in the long-term reaction, the decrease in the degree of conversion was rarely seen and the decrease in the fluidized state was not seen during the reaction. In addition, after the reaction was forced to stop, the reactor was opened after cooling, and the inside of the fluidized bed reactor and silicon particles taken out were observed. In either case no bulky product or the like was seen. Comparative Example 1

6 kg of silicon particles with an average particle diameter of 150 microns and a composition as shown in Table 1 (98% purity) were uniformly mixed with 470 grams of cuprous chloride with an average particle diameter of 50 microns. Using the same fluidized bed reactor as in Example 1, the reaction was started with silicon particles alone under the same conditions as in Example 1. After the degree of conversion stabilized, 6 kg of the above-mentioned mixture of cuprous chloride and silicon particles was introduced into the reactor in the same manner as in Example 1. It can be seen that the pressure drop of the fluidized bed gradually exhibits abnormal fluctuations and the fluidized state becomes extremely poor. A large amount of flowing particles was discharged from the reaction gas discharge pipe 10 located above the fine particle collecting cyclone 7 and the degree of conversion was lower than that before the catalyst was added. The change in the degree of conversion of this Comparative Example 1 is shown in Table 5.

table 5 Determination time of degree of conversion The degree of conversion of tetrachlorosilane (%) After adding metallurgical-grade silicon particles to stabilize the degree of conversion 13.3 After adding 6 kg of catalyst 9.0

When the reactor was opened to observe the particles after cooling, agglomeration of copper powder and agglomeration of metallurgical-grade silicon particles and copper powder could be seen in the taken out particles. Furthermore, when observing the inside of the reactor, it can be seen that the inside of the particle discharge pipe 8 connected below the fine particle collection cyclone 7 is partly clogged with coarse products. Comparative Example 2

6 kg of silicon particles with an average particle diameter of 150 microns and a composition as shown in Table 1 (98% purity) were uniformly mixed with 300 grams of electrolytic copper powder with an average particle diameter of 5 microns. Using the same fluidized bed reactor as in Example 1, the reaction was started with silicon particles alone under the same conditions as in Example 1. After the degree of conversion was stabilized, 6 kg of the above mixture of electrolytic copper powder and silicon particles was introduced into the reactor in the same manner as in Example 1. It can be seen that the pressure drop of the fluidized bed gradually exhibits abnormal fluctuations and the fluidized state becomes extremely poor. A large amount of flowing particles was discharged from the reaction gas discharge pipe 10 located above the fine particle collecting cyclone 7 and the degree of conversion was lower than that before the catalyst was added. The change in the degree of conversion of this Comparative Example 1 is shown in Table 6.

Table 6 Determination time of degree of conversion The degree of conversion of tetrachlorosilane (%) After adding metallurgical-grade silicon particles to stabilize the degree of conversion 13.3 After adding 6 kg of catalyst 9.0

When the reactor was opened to observe the particles after cooling, agglomeration of copper powder and agglomeration of metallurgical-grade silicon particles and copper powder could be seen in the taken out particles. Furthermore, when observing the inside of the reactor, it can be seen that the inside of the particle discharge pipe 8 connected below the fine particle collection cyclone 7 is partly clogged with coarse products. Embodiment 3 (adding iron and aluminum)

35 kg of silicon particles containing iron and aluminum shown in A in Table 1, with a purity of 98%, and an average particle size of 150 microns were added to the reactor in the fluidized bed as shown in Figure 1, by using a The mixture gas was blown, and the reaction was carried out at a temperature of 500°C and a pressure of 0.7 MPaG in the presence of a catalyst prepared by adding copper and iron to achieve the composition shown in Table 7, the mixed gas consisting of hydrogen and tetrachlorosilane, the molar ratio is 2.5:1, and the flow rate is 100Nm ³ /hour.

The above-mentioned copper was provided by allowing copper silicide to exist on the surface of the silicon particles in the same manner as in Example 1.

The speed 1 hour after the start of the reaction is shown in Table 7, the degree of conversion that became stable after the start of the reaction and the conversion after the reaction was continued for 60 days while continuously feeding silicon particles to maintain the height of the fluidized bed to a certain degree The extent is shown in Table 8. Comparative Example 3

The same reaction test as in Example 1 was carried out, but no catalyst was added to the reaction system and only silicon shown in B in Table 1 was used. The reaction rate 1 hour after the start of the reaction is shown in Table 7, the degree of conversion that became stable after the start of the reaction and the degree of conversion after the reaction was continued for 60 days while continuously feeding silicon particles to maintain the height of the fluidized bed to a certain extent are shown in Table 8. Comparative Examples 4-6 and Examples 4 and 5

The same reaction test as in Example 1 was carried out, but as shown in Table 7, only 1 or 2 different catalysts were added to the reaction system. The reaction rate 1 hour after the start of the reaction is shown in Table 7, the degree of conversion that became stable after the start of the reaction and the degree of conversion after the reaction was continued for 60 days while continuously feeding silicon particles to maintain the height of the fluidized bed to a certain extent are shown in Table 8. The above-mentioned copper was provided by allowing copper silicide to exist on the surface of the silicon particles in the same manner as in Example 1.

Table 7 catalyst The ratio of the system to the system (silicon atomic weight%) Response speed (second ^-1 ) Cu Fe Al Example 3 Add Cu, Fe and Al 1.0 2.0 0.51 0.97 Comparative Example 3 No catalyst components added 0 0.09 0.05 0.07 Comparative Example 4 Fe only 0 1.6 0.05 0.19 Comparative Example 5 Join Al only 0 0.09 0.51 0.16 Comparative Example 6 Add Fe and Al 0 2.0 0.51 0.25 Example 4 Add Cu and Al 1.0 0.09 0.51 0.42 Example 5 Add Cu and Al 1.0 2.0 0.05 0.59

Table 8 Conversion degree (%) After the degree of transformation has stabilized 60 days later Example 3 22.7 21.0 Comparative Example 3 6.6 13.1 Comparative Example 4 13.9 14.5 Comparative Example 5 12.4 12.0 Comparative Example 6 16.3 15.0 Example 4 20.5 20.2 Example 5 22.4 21.0 Example 6-9

The same reaction test as in Example 5 was performed by changing the concentration of the catalyst in the reaction system as shown in Table 9. The reaction rate 1 hour after the start of the reaction is shown in Table 9, the degree of conversion that became stable after the start of the reaction and the degree of conversion after the reaction was continued for 60 days while continuously feeding silicon particles to maintain the height of the fluidized bed to a certain extent are shown in Table 10.

Table 9 The proportion of silicon atoms in the system (weight%) Response speed (second ^-1 ) Cu Fe al catalyst Example 6 1.0 0.4 0.51 1.9 0.59 Example 7 1.0 twenty three 0.51 24.5 0.87 Example 8 1.0 13 0.51 14.5 1.12 Example 9 1.0 2.0 2.8 5.8 1.72

Table 10 Conversion degree (%) After the degree of transformation has stabilized 60 days later Example 6 22.4 20.5 Example 7 23.5 21.5 Example 8 24.0 22.5 Example 9 24.0 22.5

Claims (10)

CLAIMS 1. A process for the production of trichlorosilane comprising reacting silicon particles, tetrachlorosilane and hydrogen in a fluidized bed at 400-700° C. in the presence of an additional catalyst containing copper silicide. 2. The method of claim 1, wherein the catalyst comprises copper silicide in combination with an iron component, or copper silicide in combination with an iron component and an aluminum component. 3. The method of claim 2, wherein the combination of copper silicide and iron component or the combination of copper silicide, iron component and aluminum component in the reaction system is adjusted to ensure that the ratio of copper atoms is 0.1-25 % by weight, the proportion of iron atoms is 0.3-40% by weight, and the proportion of aluminum atoms is 0.1-3% by weight (based on silicon atoms). 4. The method of claim 2, wherein metallurgical grade silicon particles containing 0.3% by weight or more of iron atoms (based on silicon atoms) are added at the beginning of the reaction. 5. The method of claim 2, wherein aluminum is added to the reaction system as aluminum-containing silicon particles. 6. The method of claim 2, wherein iron is added to the reaction system as iron-containing silicon particles. 7. The method of claim 1, wherein copper silicide is added to the reaction system as copper-containing silicon particles having copper silicide present at least on the surface of the particles. 8. The method for preparing the copper-containing silicon particles as claimed in claim 7, comprising the silicon particles with an average particle diameter of 50 microns-2 mm and cuprous chloride with an average particle diameter of 1 mm or less The particles and/or copper chloride particles are heated at a temperature of at least 250° C. in an atmosphere of a non-oxidizing gas that does not generate oxides or chlorides. 9. The method of claim 8, wherein the cuprous chloride and/or cupric chloride are used in an amount of 30 parts by weight (based on 100 parts by weight of silicon particles) based on copper atoms. 10. The method of claim 8, wherein silicon particles are produced having 80% copper silicides present in portions (calculated from the surface) at a depth of less than 10 micrometers.