KR20010065810A - A process for preparing alkylhalosilane - Google Patents

Abstract

PURPOSE: Provided is the method of preparing alkylhalosilane in high yield and with low content of by-products to make it industrially useful. CONSTITUTION: The preparation process includes feeding alkyl halide gas and inert gas or their mixture at 5-12cm/sec speed to silicone metal powder in the fluidized bed reactor and activating for 0.1-7 hours at 320-400°C under 0-5 atm. with mainly copper catalyst and zinc, Sb, phosphorous and cesium as additional catalysts; lowering the temperature to 240-320°C at 0-8 atm. and feeding alkyl halide gas at 7-12cm/sec into the above fluidized bed reactor and obtaining the product. The copper catalyst is composed of element copper, its halides or its oxides. 1-10 weight part of the active ingredient is used against the 100 weight part of silicone metal. For other catalysts used are 0.0l-3.0 wt. part of zinc, 0.001-0.1 wt. part of Sb, 0.01-0.5 wt. part of phosphorous and 0.05-2.0 wt. part of cesium against 100 wt. part of silicone metal. When the mixed gas of alkyl halide and inert gas is used, no less that 50% of alkyl halide gas is included.

Description

A process for preparing alkylhalosilane

The present invention relates to a method for preparing alkyl halosilane, and more particularly, to an inert gas or an alkyl halide gas in a metal silicon powder in a catalyst system composed of a copper catalyst and a cocatalyst of zinc, tin, phosphorus and cesium as an activating gas. After activating the catalyst by inflow and fluidization, the alkyl halide gas is introduced into the reactive gas to react to improve the yield of the alkyl halosilane, as well as to minimize the amount of by-products, and to provide excellent fluidization, reactivity and durability. It relates to a process for preparing alkyl halosilanes which is very useful.

The preparation method according to the present invention is referred to as Direct Synthesis or Rochow Synthesis. In this method, an alkyl halide and a metal silicon powder are reacted in the presence of a copper catalyst to represent an alkyl halide represented by the following Chemical Formula 1. Rosilane is obtained (US Pat. No. 2,380,995).

(R) _n Si (X) _4-n

In Formula 1, R is an alkyl group having ₁ to ₄ carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, a butyl group; X is a halogen atom, specifically, a chloro atom, a bromo atom, a fluoro atom; n is 0 or an integer of 1 to 4;

Among the alkyl halosilane compounds obtained by the above-described direct synthesis method, dialkyldihalosilane is a main compound widely applied industrially as a basic raw material for making silicone oil, silicone polymer, silicone rubber and the like. As described above, dialkyldihalosilane has the highest economic value among the alkylhalosilane compounds. Thus, in the synthesis method of alkylhalosilane, the ratio of trialkylhalosilane (T) / dialkyldihalosilane (D) is used. And a method for increasing the yield of dialkyldihalosilane by lowering the production amount of high fertilizers and increasing the reactivity and persistence.

Regarding the method for synthesizing alkylhalosilanes for the efficient production of dialkyldihalosilanes, some techniques using copper catalysts composed of copper or copper halides and other promoters are known. As an example, methods for the formation of contact mixtures used to prepare alkylhalosilanes are known [Organohalosilanes precursors to silicones ", RJH Voorhoeve, pp 160-161, Elsevier Publishing Company, New York, 1967, in reactors. After adding the contact mixture, the inert gas is introduced below the minimum fluidization rate, and the temperature is gradually raised to 350 ° C. at 5 ° C. per minute and maintained for 2 to 3 hours to activate the contact mixture. Agglomeration of copper has the disadvantage of poor fluidization, reactivity and persistence, and very high T / D ratio.

Regarding the process for preparing alkyl halosilanes, US Pat. No. 5,783,721 discloses a technique for limiting fluidization conditions in the process for preparing alkyl halosilanes; U.S. Patent 5,117,030 discloses the use of zinc or zinc halides, tin or tin halides, cesium or cesium chlorides; U. S. Patent No. 5,654, 460 discloses the use of aluminum, aluminum alloys or aluminum halides; US Patent No. 4,602101 discloses a technique using phosphorus or phosphorus alloy; U.S. Patent 4,656,301 discloses a technique using antimony or an antimony alloy.

Thus, the present invention has been made to solve the problem of the increase in the T / D ratio and the fluidization, reactivity and persistence in the conventional method of producing an alkyl halosilane as described above. As a result, prior to carrying out the reaction of the metal silicon powder and the alkyl halide, the catalyst system composed of a copper catalyst and a cocatalyst of zinc, tin, phosphorus and cesium is pretreated with an activating gas under an appropriate temperature condition above the reaction temperature. The present invention has been completed by carrying out the reaction with halides.

Accordingly, an object of the present invention is to provide an industrially advantageous method for producing alkyl halosilanes, which has excellent fluidization, reactivity and durability, and has a high yield of dialkyldihalosilane (D).

The present invention is a method for producing an alkyl halosilane by reacting a metal silicon powder and an alkyl halide,

Inert gas, alkyl halide or mixtures thereof in the metal silicon powder in a fluidized bed reactor under a catalyst system composed of 320 to 400 ° C. temperature, 0 to 5 atm pressure and a copper catalyst and a promoter of zinc, tin, phosphorus and cesium Activating gas consisting of 5 to 12 cm / sec at a fluidization rate to activate for 0.1 to 7 hours; Preparation of the alkyl halosilane consisting of a step of introducing an alkyl halide into the fluidized bed reactor at a 7 to 15 cm / sec fluidization rate under a 240 to 320 ℃ temperature and 0 to 8 atm pressure conditions to produce an alkyl halosilane The method is characterized by that.

Referring to the present invention in more detail as follows.

The metal silicon powder used in the present invention has a purity of at least 97% or more and preferably 98% or more. Impurities contained in the metal silicon powder are important factors that greatly affect the reactivity, selectivity, and T / D ratio during the synthesis of alkyl halosilanes. Commonly contained impurities include aluminum, calcium, iron, titanium, and the like. The particle diameter of the high-purity metallic silicon powder as described above is preferably 10 to 300 µm, preferably 10 to 250 µm. If the particle size of the metal silicon powder is too small, it is difficult to maintain uniform fluidization conditions due to the cohesion between the particles and coagulation between the particles, but in view of reactivity, the use of metal silicon powder with a small particle size is preferred. . The reason is that the small particle size of the silicon powder with the large surface area improves the heat transfer between the particles during the reaction and ultimately the reactivity. Therefore, the use of metal silicon powder having an excessively small particle size is not preferable because the reactivity is excellent but causes partial overheating to increase the T / D ratio.

The present invention is characterized by using a catalyst system composed of a copper catalyst and a cocatalyst containing a specific metal, and various elements constituting the catalyst system of the present invention may be included in a metal or metal ion form. Therefore, the amount of use of various elements constituting the catalyst system defined below is based on the amount of active elements.

Copper used as a catalyst can be used in various kinds. For example, they are microcopper powder, flaky copper, a copper oxide, a copper halide. Such a copper catalyst is used in an amount of 1 to 10 parts by weight, preferably 2 to 8 parts by weight, based on 100 parts by weight of the metal silicon powder.

Cocatalysts include zinc, tin, phosphorus and cesium. Zinc is used for zinc element, zinc halide (eg zinc chloride), zinc alloy, zinc oxide and the like, 0.01 to 3.0 parts by weight based on 100 parts by weight of the metal silicon powder. Tin is used for tin element, tin halide (tin chloride), tin alloy, tin oxide and the like, and 0.001 to 0.1 parts by weight based on 100 parts by weight of the metal silicon powder. Phosphorus element, phosphorus alloy etc. are used, 0.01-0.5 weight part based on 100 weight part of metal silicon powders. As the cesium, cesium metal, cesium halide (eg cesium chloride), and the like are used, and 0.05 to 2.0 parts by weight based on 100 parts by weight of the metal silicon powder is used.

In addition, specific examples of the alkyl halide used in the present invention include methyl chloride, ethyl chloride, methyl bromide, ethyl bromide and the like. When the alkyl halide is introduced into the reactor to be heated to 50 to 350 ° C., the reason is that if the temperature of the alkyl halide is less than 50 ° C., the temperature of the reactor may be lowered to maintain an appropriate temperature for the reaction. This is because the reactivity decreases, and if the temperature exceeds 320 ° C., it is difficult to control the heat of reaction generated during the reaction, thereby greatly increasing the amount of by-products.

On the other hand, the production method of the alkyl halosilane according to the present invention is by a direct synthesis process, the method of activating the contact mixture consisting largely of the metal silicon powder and catalyst system, and the activated contact mixture with the alkyl halide Reaction is divided into steps to produce alkyl halosilane.

As a first step, the step of activating the contact mixture is a solid-gas reaction, in which the contact mixture is activated prior to carrying out the present reaction of the metal silicon powder and the alkyl halide.

According to the experimental results of the present inventors, the type of activating gas used in the activation step of the contact mixture is somewhat different depending on the type of copper used as a catalyst.

That is, when a copper catalyst is used as a copper halide, an inert gas, an alkyl halide gas, or a mixed gas thereof can be used as the activation gas, and particularly preferably an inert gas is used.

On the other hand, when the copper catalyst used is a copper element or a copper oxide, an alkyl halide gas is essentially used as an activating gas, and a mixed gas with an inert gas is used as necessary. In this case, when using a mixed gas as the activating gas, the alkyl halide gas is preferably contained at least 50% by volume in the total mixed gas. The reason is that the halogen atom is necessary for the activation of the contact mixture, and if the copper halide is used as the copper catalyst, it can be activated even without introducing an alkyl halide, but in the case of the copper element or the copper oxide, the minimum amount required for activation is required. This is because the above alkyl halide should be introduced. As the activation condition of the contact mixture, the temperature is 320 to 400 ° C., the pressure is 0 to 8 atm, preferably 0 to 5 atm, and the fluidization rate is 1 to 15 cm / sec, preferably 5 to 12 cm / sec. . In particular, the activation temperature is very important to maintain the alkyl halosilane production temperature (240 ~ 320 ° C) or more, if the activation temperature is maintained below 320 ° C by-products are excessively generated is undesirable.

In addition, in the preparation method according to the present invention, the activation reaction is very important. If the alkylhalosilane production process is performed without the step of activating the contact mixture or the uniformly not sufficiently activated catalyst, Copper elements, copper oxides or copper chlorides used as precipitates with copper, agglomeration occurs. As a result, inactivated and agglomerated copper is not fluidized and sinks to the bottom of the reactor, which inhibits fluidization of the entire reactor, resulting in partial overheating. This is generated to surround the surface of the metal silicon powder to reduce the reaction area, eventually increasing the ratio of T / D, decreases the reactivity and the persistence of the reaction is also significantly reduced. On the basis of the above reasons, the activation step of the contact mixture in the present invention is very important.

If the above activation process proceeds sufficiently, the reaction of the activated contact mixture and alkyl halide performed next is good even if the synthesis conditions are poor, such as the ratio of T / D, reactivity, and high fertilizer. However, if the contact mixture is not properly activated, the reaction results such as the ratio of T / D, reactivity, and high fertilization are low even though the conditions for reacting the contact mixture with the alkyl halide remain optimal.

As a second step, the activated contact mixture is reacted with an alkyl halide. If this process is not uniformly fluidized, the catalyst particles may be agglomerated and partially overheated as in the above activation process. These factors reduce the activity of the catalysts and decompose alkyl halides and alkyl halosilanes to increase the production of impurity carbon, and when carbon accumulates in the reactor, the selectivity decreases significantly, which lowers the yield of alkyl halosilanes. As well as functioning, it acts as a major factor to reduce the persistence. The size and particle distribution of the contact mixture particles are decisive factors in order to create uniform fluidization conditions. Contact mixtures with a small average particle diameter tend to have poor fluidization because small particles tend to clump and cause channeling.

At this time, the alkyl halide as the reactive gas may be introduced alone, or may be introduced as a mixed gas with an inert gas. In the present invention, helium, argon, nitrogen may be used as the inert gas, and considering the economic aspect, it is most advantageous to use nitrogen. The inflow of alkyl halides is to be charged at or above the theoretical amount to produce alkyl halosilanes, the inflow rate is maintained at or equal to or higher than the rate at which the contact mixture is fluidized, preferably 7-15 cm / is sec.

As the reaction conditions of the activated contact mixture and the alkyl halide, the temperature is 240 to 320 ° C., the pressure is 0 to 8 atm, and the fluidization rate is maintained to be 7 to 15 cm / sec.

On the other hand, a reactor suitable for carrying out the above alkylhalosilane preparation reaction is most suitable to use a fluidized bed reactor in view of high yield, selectivity, efficient use of energy, and the like. The fluidized bed reactor has a length / width (L / D) ratio of very important in order to provide good fluidization of the contact mixture and to prevent the fine silicon powder from flowing out of the reactor.

The present invention as described above will be described in more detail based on the following embodiments, but the present invention is not limited thereto.

Example 1 and Comparative Examples 1-1, 1-2

A glass filter and a glass condenser were installed in a glass fluidized bed reactor having a length L of 25.4 cm and a width D of 2.54 cm, and then heated at 200 ° C. for 2 hours while supplying nitrogen to remove moisture in the reactor. After 2 hours, the temperature was lowered to room temperature, and then the ethylene glycol was fed to the condenser to lower the temperature to -25 ° C. In order to prepare the contact mixture, 100 g of a metallic silicon powder (average particle diameter: 170 µm, manufactured by ELEKEM), 3.5 g of copper chloride, 0.004 g of tin, 0.1 g of zinc, and 0.1 g of cesium chloride were evenly mixed.

After the reactor internal temperature was raised to 340 ° C., the contact mixture was introduced into the reactor and nitrogen was supplied at a rate shown in Table 1 to activate the contact mixture. The pressure at this time was atmospheric pressure. The contact mixture was sufficiently activated by maintaining for 1 hour from when the temperature of the reactor was stabilized at 340 ° C. The contact mixture was sufficiently activated for 1 hour, and then the temperature was lowered to 280 ° C. and changed into methyl chloride instead of nitrogen to flow at a fluidization rate of 8 cm / sec to proceed sufficiently.

The following Table 1 is a case in which the reaction is performed using the same raw materials and methods as above, except that the activation conditions of the contact mixture are changed.

Example 2 and Comparative Examples 2-1, 2-2

The raw materials, the experimental apparatus, and the experimental method were the same as those used in Example 1 above. In order to prepare the contact mixture, 100 g of metal silicon powder (average particle size: 170 µm, manufactured by ELEKEM Co., Ltd.), 3.5 g of copper chloride, 1.0 g of zinc alloy, 1.0 g of tin alloy, and 0.4 g of phosphorus alloy were evenly mixed.

After the reactor internal temperature was raised to 340 ° C., the contact mixture was introduced into the reactor, and nitrogen was supplied at a rate shown in Table 2 to activate the contact mixture. The pressure at this time was atmospheric pressure. The contact mixture was sufficiently activated by maintaining for 1 hour from when the temperature of the reactor was stabilized at 340 ° C. The contact mixture was sufficiently activated for 1 hour, and then the temperature was lowered to 280 ° C. and changed into methyl chloride instead of nitrogen to flow at a fluidization rate of 8 cm / sec to proceed sufficiently.

The following Table 2 is the case of performing the reaction with the same raw materials and methods as above, except that the activation conditions of the contact mixture are different.

Example 3-1, 3-2 and Comparative Example 3

The raw materials, the experimental apparatus, and the experimental method were the same as those used in Example 1 above. In order to prepare the contact mixture, 100 g of a metallic silicon powder (average particle diameter: 170 µm, manufactured by ELEKEM Co., Ltd.), 3.5 g of copper oxide, 1.0 g of zinc alloy, 1.0 g of tin alloy, and 0.4 g of phosphorus alloy were evenly mixed.

After the reactor internal temperature was raised to 340 ° C., the contact mixture was introduced into the reactor, and the nitrogen and methyl chloride mixtures were supplied at a linear speed of 8 cm / sec at a weight ratio shown in Table 3 to activate the contact mixture. The pressure at this time was atmospheric pressure. The contact mixture was sufficiently activated by maintaining for 1 hour from when the temperature of the reactor was stabilized at 340 ° C. The contact mixture was sufficiently activated for 1 hour, and then the temperature was lowered to 280 ° C. and changed to methyl chloride instead of the nitrogen and methyl chloride mixture to flow at a fluidization rate of 8 cm / sec to proceed sufficiently.

In Comparative Example 3, only the mixing ratio of Examples 3-1 and 3-2 and nitrogen and methyl chloride was different, and the composition of the contact mixture, the inflow rate of the activating gas, the temperature, the pressure, and the like were tested under the same conditions.

As described above, the production method according to the present invention specifically selects a new catalyst system and specifically configures a pre-reaction activation process for a contact mixture composed of such a catalyst system and a metal silicon powder, thereby providing an alkylhalosilane, in particular, a dialkyldihalo. It is very useful for the industrial production of dialkyldihalosilanes (D) because it greatly improves the yield for silanes and is excellent in fluidization, reactivity and persistence.

Claims (5)

In the method for producing an alkyl halosilane by reacting a metal silicon powder and an alkyl halide, Inert gas, alkyl halide gas or mixtures thereof in a fluidized bed reactor under a catalyst system consisting of a temperature of 320 to 400 ° C., a pressure of 0 to 5 atm and a catalyst of a copper catalyst and zinc, tin, phosphorus and cesium A process of activating the gas composed of gas at a flow rate of 5 to 12 cm / sec and activating for 0.1 to 7 hours, Alkyl halide, characterized in that the alkyl halide silane is introduced into the fluidized bed reactor at a temperature of 240 ~ 320 ℃ and 0 ~ 8 atm pressure at 7 to 12 cm / sec fluidization rate to prepare an alkyl halosilane Method for producing rosilane. The method of claim 1, wherein the copper constituting the catalyst is introduced in the form of a copper element, a copper halide or a copper oxide, characterized in that contained 1 to 10 parts by weight (based on the active element) with respect to 100 parts by weight of metal silicon. Method for preparing alkyl halosilanes. The method according to claim 1, wherein the cocatalyst is 0.01 to 3.0 parts by weight of zinc, 0.001 to 0.1 parts by weight of tin, 0.01 to 0.5 parts by weight of phosphorus and 0.05 to 2.0 parts by weight of cesium based on 100 parts by weight of the metallic silicon based on the active element. A method for producing an alkyl halosilane, which contains addition. The alkyl halosilane according to claim 1 or 2, wherein when the copper catalyst is a copper element or a copper oxide, an activating gas is an alkyl halide gas alone or a mixed gas of an alkyl halide gas and an inert gas. Manufacturing method. The method according to claim 4, wherein when the mixed gas of the alkyl halide gas and the inert gas is used as the activating gas, 50% by volume or more of the alkyl halide gas is included in the total mixed gas.