JP2000297092A - Production of organohalosilane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily, surely and selectively use active metal silicon particles in the Rochow reaction and produce the subject compound by reacting the specific metal silicon particles with an oreganohalide in the presence of a copper catalyst. SOLUTION: (A) Metal silicon particles having <=0.3 wt.%, preferably <=0.25 wt.%, more preferably <=0.2 wt.% amount of surface oxygen which is a difference of oxygen concentrations obtained by respectively analyzing the oxygen in metals of the metal silicon particles and small lumps of a metal silicon raw material for obtaining the metal silicon particles by pulverization and preferably having <=0.01 g.oxygen/m2.Si surface area and 10 μm to 10 mm average particle diameter are reacted with (B) an organohalide in the presence of (C) a copper catalyst to produce the objective compound. The Rockow reaction is a reaction for reacting an alkyl halide such as methyl chloride or an aryl halide such as a chlorinated benzene with the metal silicon in the presence of the copper catalyst and a promoter and affording an organochlorosilane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Roch (Roch)
ow) A method for producing an organohalosilane by a reaction.

[0002]

2. Description of the Related Art The synthesis of organohalosilanes such as methylchlorosilane is industrially carried out by using a copper catalyst comprising an organic halide such as an alkyl halide or a phenyl halide and metal silicon particles. The reaction is carried out at 250 to 500 ° C. by a so-called Rochow reaction in which a reaction is directly carried out in the presence of a mixed catalyst to which an appropriate promoter has been added. In this reaction, the selectivity of dimethyldichlorosilane, which is the most demanded in the synthesis of methylchlorosilane, should be increased, and in the synthesis of phenylsilane, a composition that meets the demands of diphenyldichlorosilane and phenyltrichlorosilane, which are in high demand, can be obtained. Meanwhile, keeping the reaction speed high is the key technology.

Further, this reaction requires a long time for activation until the reaction reaches a steady state, while the steady state is relatively short, and the activity of the diorganodichlorosilane is reduced by the reduction of the contact activity with time. The yield decreases, for example, in the synthesis of methylsilane, high fractions such as disilane and methyltrichlorosilane due to side reactions increase, and it is necessary to replace the contact body in the reactor. Is also a big problem. Since the Rochow reaction is mainly performed in a fluidized bed or a stirred fluidized bed, various proposals have been made regarding the particle size of metal silicon particles suitable for forming a fluidized bed.

In this reaction, the cost of metal silicon in the raw material cost is high, so that the reaction rate of metal silicon is increased, and at the same time, various types of by-products are usually generated in addition to the main component diorganodichlorosilane. As a by-product, it is important to control the production ratio of this by-product under reaction conditions that are in line with the supply and demand balance of organochlorosilane. This reaction is usually carried out industrially using a reactor such as a fluidized bed, a vibrating fluidized bed, or a stirred fluidized bed in a manner in which a contact body is added to the reaction system. This mechanism is not always clear because it is a very complex gas-solid heterogeneous reaction that occurs at the surface and that the catalyst system is also a solid. And the properties of the metal silicon particles to be used (production area,
It is empirically known that the performance of this reaction is greatly affected by factors such as the manufacturer, the production equipment, and the crushing method) .Several proposals have been submitted, but there is no established theory. In the case of metallic silicon, it is in a state in which a test is performed in advance to determine whether or not this use is possible. As described above, since the metal silicon factors affecting the reaction have not been clarified, this point has been very actively discussed recently in the metal silicon society (for example, Si
silicone forthe Chemical Ind
industry IV: Geiranger, Norwa
y, June 3-5, 1998).

What is important is the reaction activity of the metal silicon particles as a reactant. This has also been studied from various angles, and various proposals have been made (for example, characteristics of the metal silicon itself). Has been made. More specifically, it is already known that aluminum present as an impurity in metallic silicon is effective as a co-catalyst for the Rochow reaction. To be there, H. M.
Rong et al. Suggested that only the active aluminum among the impurities present in the metallic silicon was needed, and suggested a method of measuring it and recommended its use (Procee).
eding Silicon for the Che
medical Industry, p. 69 (199
8)). Japanese Patent Application Laid-Open No. 6-234776 discloses a method for quantifying a dispersion state of an intermetallic compound as an impurity in metal silicon and a selection criterion for controlling reactivity. The lump is cut, the surface is mirror-finished, the form is observed microscopically with a microscope, the structure factor is quantified as a QF value, and the most reactive is to use metal silicon having a value of 18 to 60. It is highly desirable and preferred. Furthermore, there has been proposed a method of adding copper to molten metal silicon and evaluating it based on the form of the used touch body (US Pat. No. 5,281,739).

However, as a result of the present inventors performing these additional tests, it was found that none of them could be distinguished by these methods, but rather that they were all effective only in special limited systems. It could not be adopted as an effective method.

In general, the surface of metal silicon is oxidized and is covered with stable silicon oxide, so that the internal oxidation does not proceed beyond a certain thickness, and the metal silicon is made stable. However, silicon itself has a very high oxidizing property, and there is no metallic silicon having no oxide film in air, as is known from silicon for semiconductors. It has been known that the surface of the metal silicon particles for the Rochow reaction has an oxide film to some extent, which affects the Rochow reaction. Regarding the reactivity and selectivity of an oxide film of metal silicon in a methylsilane reaction, G.S. J. Hutch
ing's report (Silicon for the C)
chemical Industry, Geirenge
r, Norway, p. 85-98 (1992)); Laroze's report (Silicon fort)
he Chemical Industry II, L
eon, Norway, p. 121-127 (199
4)), which describes the effect on the reactivity and selectivity of the oxide film. However, these measurements are performed on metal silicon particles by local analysis of the oxide film by XPS. L. Falconer et al. (J. Cata.
l. vol. 159, p. 31-41 (1996))
Discusses the oxide film, crystal orientation and reactivity using a silicon wafer, but does not apply to the actual surface of the metal silicon particles for the Rochow reaction. It did not specify metal silicon particles.

As described above, the conventionally proposed method is as follows.
It is not necessarily general for industrial use, and when the Rochow reaction is actually performed on metal silicon particles determined by these criteria under conditions where the other factors are completely the same, the results of the reaction vary. It was big. As described above, the conventionally proposed property specification of metal silicon particles can be applied in a special reaction system,
Active metal silicon particles that can be industrially practically used and methods for evaluating the same have been continuously demanded.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for producing an organohalosilane in which active metal silicon particles can be easily and reliably selected and used in such a Rochow reaction. Aim.

[0010]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object, and as a result, measured the activity of metal silicon particles used in the Rochow reaction as the amount of surface oxygen. The thickness of the oxygen film formed on the surface of the metal silicon to be formed is largely related to the thickness of the oxygen film. In this case, as a method of measuring the amount of surface oxygen, metal silicon particles and pulverization to obtain the metal silicon particles are used. A small mass of the metallic silicon raw material to be measured is separately measured by an oxygen in metal analysis method (inert gas melting furnace oxygen fractionation method), and a measurement method in which the difference is determined as the surface oxygen content is effective. If metal silicon particles having a surface oxygen content of 0.3% by weight or less are selected and used, an organic halide and metal silicon powder are required to directly act to synthesize the corresponding organohalosilane. Metal silicon particles having a high activity can be reliably selected, and the reaction activation time until a steady state, which is referred to as a bite of the reaction of the touch body which was a bottleneck in the reaction, is reduced, and furthermore, the steady state is achieved. Therefore, even if the reaction rate is increased, the selectivity can be improved, and as a result, the effective utilization rate of silicon can be increased. Although the method was separately used and industrially used after evaluating its reaction activity, it has been found that such a bypass process problem can be solved.

Accordingly, the present invention provides a method for producing a fine powder having an average particle diameter of 10 μm or less.
In a method of producing organohalosilane by reacting 10 mm of metal silicon particles with an organohalide in the presence of a copper catalyst, the metal silicon particles are used as the metal silicon particles and a metal for pulverizing the metal silicon particles to obtain the metal silicon particles. An organohalosilane characterized by selectively using metal silicon particles having a surface oxygen content of 0.3% by weight or less, which is a difference in oxygen concentration obtained by analyzing a small lump of a silicon raw material in oxygen in a metal. And a method for producing the same. In this case, it is possible to select and use a metal silicon particle having a surface area of 0.01 g · oxygen / m ² · Si or less.

According to the present invention, a long period of time has conventionally been required in the organochlorosilane synthesis reaction (so-called Rochow reaction) of an alkyl halide such as methyl chloride or an aryl halide such as benzene chloride with a metal catalyst in the presence of a copper catalyst and a cocatalyst. The reduction of the activation time (induction period) to the required steady state and the reaction rate and selectivity of silane formation are important issues, and a method for solving this problem is to improve the catalyst composition and to further reduce the metal silicon particles themselves. Although an improvement was necessary, the present invention optimizes the metal silicon particles by elucidating the mechanism of the silane reaction, thereby solving these problems of the Rochow reaction, and making a particularly desirable diorganodihalo. It is possible to increase the selectivity of silane, and it is possible to achieve an improvement in the reaction result. In addition, it is possible to omit a precedent reaction test having a large variation, and it is possible to quantitatively manage the Rochow reaction.

Hereinafter, the present invention will be described in more detail.
In the present invention, an organohalide (organic halide) such as an alkyl halide or an aryl halide is allowed to act on metal silicon particles in the presence of a copper catalyst to obtain a compound represented by the general formula (1): R _m H _n SiX _4-mn (1) (Wherein, R represents an alkyl group having 1 to 4 carbon atoms or an aryl group such as a phenyl group, X represents a halogen atom such as chlorine or bromine, m represents 1, 2 or 3, and n represents 0, 1). Or 2, but m + n is an integer of 4 or less.) This is related to metal silicon particles which are a reactant used in a so-called Rochow reaction for synthesizing an organohalosilane represented by the following formula: Time required for activation until the reaction reaches a steady state reaction, that is, shortening the induction period,
The present invention relates to selection of active metal silicon particles capable of maintaining high activity in a steady state, a method for evaluating the activity thereof, and use of the particles in a Rochow reaction.

More specifically, metallic silicon is produced by reducing silica together with a carbonaceous material in a high-temperature arc furnace at a temperature of 2500 ° C. or more, and requires a large amount of electric energy and is a material that is inevitably expensive. It is. Therefore, the cost of organohalosilanes, which are precursors of silicone resins made from this material, is dependent on the conversion rate of this expensive metallic silicon to silane (this reaction produces various by-product silanes by side reactions). Therefore, it depends greatly on the production rate (ie, selectivity) of the effective silane in view of the demand balance, and furthermore, the magnitude of the reaction rate which is regarded as important as an industrial process. Therefore, from such a viewpoint, the silicone maker collectively refers to the selectivity and the reaction rate of the product as the reactivity, and demands metal silicon that can exhibit high reactivity with its own manufacturing apparatus. On the other hand, metal silicon manufacturers also use the Rochow reaction and metallic silicon for producing trichlorosilane, which is a semiconductor material similar to the Rochow reaction, because more than half of the total metal silicon consumption is used in these industries. In addition, we actually simulated the reaction and conducted research on the creation of metallic silicon with high reactivity and good selectivity. From the viewpoint of the metallic silicon manufacturer, various amounts of impurities, impurity forms, manufacturing methods, cooling methods, etc. The fact is that we are conducting improvement research from an angle. The results of this research on metallic silicon for chemicals are based on the “Silico International Conference on Metallic Silicon, which is held regularly in Norway once every two years.
n for Chemical Industry ”, and information is exchanged.
The chow reaction itself has not been clearly elucidated, and metal silicon has been evaluated by various companies at present.

The Rochow reaction is a gas-solid heterogeneous reaction between metallic silicon which is a solid at a high temperature and organohalide which is a gas at a high temperature via a catalyst, and its reactivity is a property of metallic silicon as a crystal. Therefore, the method of quantifying the dispersion state of the intermetallic compound, which is an impurity in metallic silicon, which is proposed in Japanese Patent Application Laid-Open No. 6-234776, and the selection criteria for controlling the reactivity are proposed. Makes sense at first glance and is helpful. In this method, the metal silicon block is cut, the surface is mirror-finished,
The surface is microscopically observed with a microscope for a metallurgical morphology, the structure factor is quantified as a QF value, and the use of metallic silicon having a value of 18 to 60 is most highly reactive and preferable. And

However, for ordinary industrial metal silicon,
As a result of analyzing the size of crystallites by the present inventors, it has been found that crystallites of industrial grade metallic silicon are on the order of mm because silicon has high crystallinity. On the other hand, the metal silicon particles actually used for the reaction are at most about 100 μm, which indicates that the metal silicon particles used for the Rochow reaction have several crystallites or less. That is, from these, it was found that the form of the intermetallic compound as an impurity in the metal silicon observed by microscopy does not necessarily represent the crystallinity of the metal silicon which affects the reactivity.

Further, since crystal defects are present in this zone portion, the portion containing the impurities selectively comes out to the surface by pulverization of the metal silicon. M. R
ong et al., Proceeding Silicon f
or the Chemical Industry,
p. 69 (1998) suggests that the aluminum present on the surface of metal silicon particles is active, based on the measurement method (measured by the extraction amount with an aqueous hydrochloric acid solution). Good. However, this part selectively appears on the surface by grinding,
The extraction amount is proportional to the abundance of aluminum, and the extraction rate is almost constant. M. Rong et al. Cannot be applied to the reaction.

As described above, the Rochow reaction is a gas-solid heterogeneous reaction between organohalide which is a gas at a high temperature and metal silicon particles which are a solid at a high temperature. La
roze's report (Silicon for the C)
chemical Industry II, Leon,
Norway, p. 121-127 (1994)). L. Falconer et al. (J. Catal.
vol. 159, p. 31-41 (1996)), it is sufficiently expected that the reactivity greatly depends on the crystal orientation of the metal silicon particles and the surface state of the oxide film and the like. However, J. L. Falcone
A detailed examination of the report by R. et al., in fact, only describes the selectivity and selectivity of metal silicon oxide film in the methylsilane reaction using silicon for semiconductors, and it is impossible to apply it to actual industrial metal silicon particles. There is. In addition, G.
Laroze's report does not clarify the specific measurement method.

Since silicon has high reactivity in air, an oxide film is formed on the surface of metal silicon by contact with air. Generally, the grinding, transport, storage, etc. of the metal silicon lump are performed in an inert gas or an atmosphere with a low oxygen concentration in order to avoid the risk of dust explosion during the grinding, but it is not necessary to completely remove the oxygen. The fact is that an oxide film always exists on the surface. It is also empirically known that the reactivity differs depending on the storage conditions.

On the other hand, in the production process of silicon metal for industrial use,
In order to reduce impurities such as aluminum and calcium, after tapping into a tap container called a ladle, oxygen or air is blown from below in a molten state to remove these impurities as oxides. Although silicon is also slightly oxidized, in this case, the generated silicon monoxide has a high vapor pressure, and as described above, silicon has high crystallinity, so that silicon oxide (silicon monoxide, silicon dioxide)
Is eliminated as slag with the crystal growth by cooling, so that there is almost no oxygen in the metallic silicon.

Therefore, the present inventors have found that most of the oxygen measured by the oxygen analysis method in an inert gas melting furnace for metallic silicon particles is oxygen present on the surface thereof (Table 1). Of course, small particles of slag may be contained inside depending on the manufacturing method, so that confirmation is necessary for analysis.

As a result of the above examinations, the surface oxygen of the metal silicon particles was determined to be higher in the inert gas melting furnace for each of the metal silicon particles and the small lumps (the small lumps of the metal silicon raw material crushed to obtain the particles). Oxygen analyzer (generally referred to as an oxygen analyzer in metal, for example, E
MGA-650), and the difference is defined as the surface oxygen content. Further, they have found that it is effective to calculate the amount of oxygen per unit area by dividing this value by the surface area of the metal silicon particles.

The sample will be described in more detail. Since metal silicon particles have a high oxidizing property, the sample is collected in an inert gas stream, and the handling during measurement, such as sample weighing, is performed in a glove box filled with an inert gas. Do with. When mounting the sample on the device, perform the process immediately and avoid contact with air as much as possible. As the metal silicon small lump, a small lump of 20 to 100 mg is collected from the crushed metal silicon lump, and the small lump is measured as it is. By calculating this difference, it is actually Roc
The amount of oxygen on the surface of the metal silicon particles subjected to the how reaction is measured.

The feature of the present invention is the selection of metallic silicon by measuring the amount of oxide film on the surface of metallic silicon particles. As a result of comparison of various metallic silicon, the average particle diameter is 10 μm.
It is a metal silicon particle of 10 to 10 mm, and the amount of oxygen present on the surface by the above measurement is 0.3% by weight or less, preferably 0.01 g · oxygen / m ² · Si surface area or less. there were. That is, in this evaluation, the amount of oxygen present on the surface of the metal silicon particles was measured separately for the metal silicon particles and the small lumps thereof by an oxygen-in-metal analysis method (inert gas melting furnace oxygen analysis method). A method for measuring the amount of oxygen is appropriate, which eliminates the need for a separate reaction in advance for testing and enables quantitative management.

As described above, the present invention is based on the above evaluation method.
0.3% by weight or less, preferably 0.25% by weight
Wt% or less, more preferably 0.2 wt% or less
Elementary particles are selected. In this case, the surface oxygen content
The lower limit is not particularly limited. Furthermore, the above gold
The criteria for selection of the silicon metal particles are 0.01 g · oxygen / m ^Two
-Si surface area or less, especially 0.005 g-oxygen / m^Two・ S
i surface area or less, especially 0.003 g · oxygen / m^Two・ S
It may be less than the i-surface area.

The organohalosilane of the present invention can be produced by using known methods and conditions except that the above-mentioned metal silicon particles are used. For example, as the copper catalyst and co-catalyst, known ones can be used, and as the organic halide, methyl chloride, ethyl chloride, phenyl chloride and the like,
Alkyl halides and aryl halides having an alkyl group and an aryl group according to the organohalosilane to be produced can be used. In the present invention, for example, the above formula (1)
Can be produced at a high yield, especially a diorganodihalosilane of m = 2 and n = 0.

The amount of the copper catalyst to be added is as follows.
The amount can be 0.1 to 10 parts by weight based on 00 parts by weight. Further, various known cocatalysts can be added to the copper catalyst.

FIG. 1 shows an example of an apparatus for producing an organohalosilane. Reference numeral 1 denotes a fluidized-bed reactor, and a raw material supply tank 3 is connected to a lower part thereof through a raw material supply pipe 2. Metallic silicon and the above-mentioned copper catalyst or a mixed catalyst of a copper catalyst and a co-catalyst are introduced into the lower part of 1. Reference numeral 4 denotes a raw material organic halide tube through which a heater 5 is interposed.
And a gas or vapor of an organic halide is introduced from the bottom of the reactor 1 to form a fluidized bed 1 a of the metal silicon and the catalyst in the reactor 1. In the figure, reference numeral 6 denotes a cooler.

The organic halide gas or vapor is preferably introduced at a linear velocity of 2 to 10 cm / sec in a steady state. The reaction is usually 250 to 350
C. can be performed.

The organohalosilane obtained by the reaction is introduced into the first cyclone 8 through a discharge pipe 7 connected to the top of the reactor 1, and the associated solid particles are separated (the solid particles are returned to the first cyclone 8). The fluid particles are returned to the fluidized bed 1a through a pipe 9), and the solid particles still entrained in the second cyclone 10 are separated (the solid particles are stored in the separated granular material storage layer 11), and then the first silane condenser 12, Further, the organohalosilane is condensed in the second silane condenser 13 and stored in the silane storage layer 14. The exhaust gas after the solid particles are separated and the organohalosilane is condensed and separated is partly or entirely part of the circulating gas compressor 15.
Is returned to the reactor 1 again through the organic halide return pipe 16 in which is interposed. The return pipe 16 is connected to the raw organic halide pipe 4.

[0031]

According to the present invention, it is possible to provide active metal silicon particles in the Rochow reaction, which leads to a reduction in the reaction rate, particularly the reaction rate in the activation period and the activation period itself. You can improve your own performance. In addition, by doing this, the activity itself of the metal silicon particles can be quantitatively predicted in advance without performing a preliminary test reaction with large variations.
The most suitable metal silicon particles for the Rochow reaction can be selected, and are industrially important and truly revolutionary.

[0032]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, parts are parts by weight.

[Experimental Examples] Various metallic silicon particles shown in Table 1 were analyzed and evaluated for reactivity. The results are also shown in Table 1.

[0034]

[Table 1]

[Examples and Comparative Examples] In a steel reactor having a spiral stirrer as shown in FIG. 1 and having a diameter of about 8 μm and having a mean particle size of about 50 μm as shown in Table 2, it was stored in air. Various kinds of metallic silicon powder (different production areas) 10
0 parts, nitrogen gas was introduced into the reactor at a linear velocity of 2 cm / sec, and the mixture was fluidized while stirring with a spiral stirrer.
The temperature was raised to 80 ° C. Thereafter, it is a flaky copper foil powder produced by stamping, and has an air-permeability specific surface area: 0.1.
80 m ² / g, average particle size: 47 μm, bulk specific gravity: 1.9
g / cm ³ of a flaky copper catalyst and 3 parts of a mixed catalyst obtained by mixing antimony, brass, and a co-catalyst mainly containing bronze were added,
Methyl chloride was gradually added while controlling the reaction temperature at 280 to 300 ° C. to cause a reaction.
The reaction was continued at m / sec. When the reaction was continued for 6 hours, the reaction was terminated. Table 3 shows the average silane production rate, the metal silicon consumption rate, and the composition of the produced silane during this period.

For comparison, Table 3 also shows the results of reacting metal silicon particles having a large amount of surface oxygen by increasing the contact with air during pulverization under the same conditions as in the examples.

[0037]

[Table 2]

[0038]

[Table 3]

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an apparatus for producing an organohalosilane.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fluidized bed reactor 1a fluidized bed 2 raw material supply pipe 3 raw material supply tank 4 raw material organic halide pipe 5 heater 6 cooler 7 discharge pipe 8 first cyclone 9 solid particle return pipe 10 second cyclone 11 separated granular material storage Layer 12 First silane condenser 13 Second silane condenser 14 Silane storage layer 15 Circulating gas compressor 16 Organic halide return pipe

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsuaki Furuya 2-31-1 Isobe, Annaka-shi, Gunma Shin-Etsu Kagaku Kogyo Co., Ltd. Gunma Office (72) Inventor Susumu Ueno 2-chome, Isobe, Annaka-shi, Gunma 13-1 Shin-Etsu Kagaku Kogyo Co., Ltd., Gunma Plant (72) Inventor Norio Shinohara 2-13-1, Isobe, Annaka-shi, Gunma Prefecture Shin-Etsu Kagaku Kogyo Co., Ltd. Gunma Plant (72) Inventor Tetsuya Inukai Gunma Prefecture 2-13-1, Isobe, Annaka-shi Shin-Etsu Kagaku Kogyo Co., Ltd. Gunma Office F-term (reference) 4H039 CA50 CF90 CL00 4H049 VN01 VP01 VQ02 VQ09 VR11 VR21 VR22 VR32 VS99 VT04 VT42 VT43 VW11

Claims (2)

[Claims] 1. A method for producing an organohalosilane by reacting metal silicon particles having an average particle size of 10 μm to 10 mm with an organohalide in the presence of a copper catalyst, wherein said metal silicon particles are used as said metal silicon particles and pulverized. Then, the metal silicon particles having a surface oxygen amount of 0.3% by weight or less, which is the difference in oxygen concentration obtained by subjecting the small pieces of the metal silicon raw material for obtaining the metal silicon particles to oxygen analysis in metal, are obtained. A method for producing an organohalosilane, which is selectively used. 2. The metal silicon particles have a content of 0.01 g · oxygen / m ^2.
2. The method according to claim 1, which has a Si surface area or less.