JP2906919B2 - Method for producing trialkoxysilane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently producing a trialkoxysilane useful as a raw material for a silane coupling material or the like.

[0002]

2. Description of the Related Art Alkoxysilanes are useful as various silane coupling agents and as raw materials for insulating thin films. In particular, trialkoxysilanes have SiH bonds in their molecules.
Moreover, since it is chemically more stable than monoalkoxysilane and dialkoxysilane, its demand is high, and an inexpensive and efficient production method is required.

Hitherto, as a method for producing trialkoxysilane, a method using chlorosilanes and lower alkyl alcohol as raw materials is known. However, chlorosilanes are expensive and, in addition to the intended alkoxysilane, hydrochloric acid is used. Are by-produced, so that there are disadvantages such as difficulty in purifying the product and corrosion of the reactor.

On the other hand, a method called a direct method of reacting metal silicon with an alkyl alcohol is known, and this method is performed in a gas phase or a liquid phase in the presence of, for example, a copper catalyst. This reaction can be said to be an industrially and economically advantageous method because the target trialkoxylan can be produced in a one-step reaction, but it has a serious problem that the silicon conversion is low, and a large amount of unreacted metallic silicon is produced. Since it is discharged as industrial waste, there are environmental problems.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have found that the conversion rate of metal silicon is high, the amount of unreacted metal silicon is reduced, and the emission of industrial waste is suppressed. ,
As a result of intensive studies on a method for producing trialkoxylan which is also environmentally improved, the present invention has been completed.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a process for producing trialkoxysilane by reacting silicon metal with an alkyl alcohol having 1 to 4 carbon atoms in the presence of a catalyst. This is a method for producing trialkoxysilane , wherein the reaction is performed in a liquid phase using 0.37% by weight of metallic silicon.

[0007] The metal silicon used as one of the raw materials in the method of the present invention has an aluminum content of 0.30-0.
37% by weight, more preferably 0.31 to 0.36% by weight, particularly preferably 0.32 to 0.35% by weight of metallic silicon. If the aluminum content is less than 0.30% by weight or exceeds 0.37% by weight, the conversion of metallic silicon may decrease. Note that aluminum may exist in various forms such as metallic aluminum, an aluminum compound, or an aluminum alloy in metallic silicon, but the aluminum content in the present invention is a value calculated as an aluminum atom.

The method for producing metal silicon having a controlled aluminum content in the metal silicon used in the present invention is, for example, ferrosilicon, particularly preferably ferrosilicon having a silicon content of 92% by weight, A method of reacting a hydrochloric acid solution is preferred.

The other impurities in the metallic silicon are not particularly limited, and metallic silicon having a purity of 80% by weight or more is preferable, and the types and amounts of the other impurities are not particularly limited. , For example, Fe, C
a and the like may be contained as impurities by up to 1% by weight, respectively.

The shape of the metallic silicon is preferably granular, and the particle size is not particularly limited.
The following is preferable, and the average particle diameter is more preferably 25 to 500.
μm, particularly preferably an average particle size of 50 to 300 μm.

The lower alkyl alcohol having 1 to 4 carbon atoms, which is another raw material, may be linear or branched, and specifically, methanol, ethanol,
n-propanol, iso-propanol, n-butanol
And sec-butanol, iso-butanol and tert-butanol. Methanol and ethanol are preferred, and among them, ethanol is particularly preferred.

The lower alkyl alcohol has a purity of 95% by weight.
More preferably, the content of water is reduced to 2000 ppm or less, more preferably 500 ppm or less by treatment with a dehydrating agent.

The supply rate of the lower alkyl alcohol to the reaction system is preferably from 10 to 1,000 mmol / hr, more preferably from 50 to 500 mmol / hr, per mole of silicon metal. 1,00
If the amount exceeds 0 mmol / hr, the amount of unreacted lower alkyl alcohol increases, which further leads to a decrease in the conversion rate of metal silicon, which is not economical.

The lower alkyl alcohol may be supplied alone or may be supplied after diluting with a diluent gas. The diluent gas is not particularly limited as long as it does not react with the raw material or trialkoxysilane. For example, nitrogen,
Examples include argon and hydrogen.

As the catalyst in the present invention, any of commonly used catalysts such as a copper catalyst, a zinc catalyst and a nickel catalyst can be used, and there is no particular limitation, but a copper catalyst is particularly preferred. Specific examples include copper salts such as cuprous chloride, cupric chloride, copper bromide, copper iodide, copper fluoride, copper carbonate, copper sulfate, copper acetate, copper oxalate, copper thiocyanate, and the like. Examples thereof include copper-containing inorganic compounds such as cuprous copper, cupric hydroxide, copper cyanide, copper sulfide, and copper oxide; organic copper compounds such as methyl copper and ethyl copper; and metallic copper.

Of the above, cuprous chloride is more preferred, and particularly cuprous chloride produced by a wet method (hereinafter, referred to as wet method cuprous chloride) is preferred.

The wet cuprous chloride is cuprous chloride produced by crystallizing cuprous chloride in a solvent, separating and drying the cuprous chloride. Specifically, for example, a copper piece is added to an aqueous cupric chloride solution and crystallized as cuprous chloride, which is separated and then produced by drying, or copper sulfate, hydrochloric acid, copper and The cuprous chloride produced by the dissolution reaction using sodium chloride is crystallized and separated,
What was manufactured by drying is mentioned. This wet cuprous chloride is clearly distinguished from cuprous chloride produced by a dry method, that is, cuprous chloride produced using metallic copper and chlorine gas as raw materials.

The purity of the catalyst is preferably at least 90% by weight.
If it is less than 90% by weight, the conversion of metal silicon may be reduced.

The particle size of the catalyst is preferably less than 40 μm, more preferably less than 2 μm. If it is more than 40 μm, the reaction rate may be reduced, which may lead to a reduction in the conversion of metallic silicon.

The particle size of the catalyst can be freely adjusted depending on the production conditions. However, if it is too fine, the efficiency of the crystallization and drying steps in the production process is poor, and the surface of the particles is deactivated by heat, moisture and the like. As a particularly preferable method, the particle size of the wet-process cuprous chloride is set to 20 μm.
m, and then pulverizing to a particle size of less than 2 μm by a ball mill or the like. The pulverization is preferably performed in air with low moisture, more preferably in nitrogen.

In general, the catalyst is supplied to the reaction system separately from the metal silicon. However, the catalyst may be mixed with the metal silicon in advance or supplied with the metal silicon. May be.

The catalyst is preferably activated together with metallic silicon and supplied to the reaction system. The activation method is 100
The heat treatment is preferably performed at a temperature in the range of from 0C to 600C, particularly preferably from 130C to 230C. If the temperature is lower than 100 ° C., it takes time to activate the catalyst, which is not efficient. If the temperature is higher than 600 ° C., the catalytic action may be deactivated. Activation is also
It may be carried out before adding to the solvent, or in the solvent while usually blowing an inert gas.

The amount of the catalyst used is preferably 0.5 to 50 parts by weight, more preferably 5 to 30 parts by weight, based on 100 parts by weight of metallic silicon. If the amount is less than 0.5 part by weight or more than 50 parts by weight, the conversion of silicon may be reduced.

In the present invention, in order to further improve the silicon conversion, it is preferable that aluminum and / or an aluminum compound (hereinafter, simply referred to as aluminums) is present in the reaction system. In addition, the aluminums here are distinguished from aluminum in metallic silicon.

Examples of the aluminum include aluminum metal, aluminum metal such as aluminum alloy with Si, Mg, and Ca; aluminum halide such as aluminum chloride, aluminum bromide, aluminum fluoride, and aluminum iodide; aluminum carbonate; and aluminum sulfate. And aluminum-containing inorganic compounds such as aluminum hydroxide, aluminum sulfide and the like, and aluminum-containing organic compounds such as aluminum acetate, aluminum oxalate and trialkoxyaluminum. Particularly, aluminum metal such as metal aluminum and aluminum alloy Is preferred. The aluminums may be used alone or in combination of two or more.

The amount of aluminum is preferably 0.01 to 10 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of metallic silicon. If the amount is less than 0.01 part by weight or exceeds 10 parts by weight, the silicon conversion rate may decrease.

In the case of an aluminum alloy, the content of aluminum is preferably 50% by weight or more, more preferably 85% by weight or more.

The aluminums may be supplied to the reaction system alone, or may be supplied as a mixture with metallic silicon or a catalyst.

The reaction of the present invention is performed in a liquid phase . Hereinafter, the present invention will be described specifically.

The shape of the reactor does not matter as long as the metallic silicon can be kept in a good dispersion state. An outer jacket for cooling or heating may be provided outside the reactor, and fins inside the reactor to improve heat transfer,
What provided a coil etc. may be used. Usually, the reactor is a pipe for supplying a silicon raw material and an alcohol, which are reaction raw materials, a discharge pipe for a reaction liquid containing a generated trialkoxysilane as a main component and containing other by-product silicon compounds and unreacted alcohol, and a reaction pipe. It has an outlet for later residue. In addition, as a material of the reactor, a quartz tube, a glass tube, a metal tube, or the like can be used, and there is no particular limitation.

The reaction system may be either a batch system in which the total amount of the metal silicon and the catalyst is initially charged or a continuous system in which the metal silicon and the catalyst are continuously supplied during the reaction.

In carrying out the production method of the present invention , a solvent is used. The solvent is not particularly limited as long as it is an inert solvent which does not react with the metal silicon, the catalyst and the trialkoxysilane, but a solvent having a high boiling point and being stable is preferable. For example, paraffinic hydrocarbons such as octane, decane, dodecane, tetradecane, hexadecane, octadecane, eicosane, etc .; And diphenyl hydrocarbons such as diphenyl, diphenyl ether, monoethyldiphenyl, diethyldiphenyl and triethyldiphenyl or hydrides thereof, alkylnaphthalene hydrocarbons or hydrides thereof, and triphenyl hydrocarbons or hydrides thereof. Of these, alkylbenzene hydrocarbons are preferred, and dodecylbenzene is particularly preferred. These solvents may be used alone or in combination of two or more.

The preferable ratio of the metal silicon to the solvent is preferably from 0.1 kg to 1 kg, more preferably from 0.3 kg to 0.7 kg, per liter of the solvent.

[0034] The reaction temperature of the present invention is preferably from 100 ° C to 300 ° C, particularly preferably from 150 ° C to 230 ° C.
If the temperature is lower than 100 ° C., the conversion rate of metal silicon is reduced. If the temperature is higher than 300 ° C., the lower alkyl alcohol may be decomposed by contact with the metal silicon or the catalyst to deactivate the catalyst due to water generated.

The reaction of the present invention may be carried out at normal pressure, increased pressure or reduced pressure, but is preferably at normal pressure because the apparatus is simple, economical and advantageous.

The trialkoxysilane obtained in the present invention has an alkoxy group corresponding to the lower alkyl alcohol used as a raw material, and specifically includes trimethoxysilane, triethoxysilane, tri-n-propoxysilane, Triisopropoxy silane, tri-n-butoxy silane, tri-sec-butoxy silane, triisobutoxy silane, tri-tert-butoxy silane, and the like, and more preferred as the trialkoxy silane produced in the present invention. Are trimethoxysilane and triethoxysilane, and triethoxysilane is most suitable.

The reaction product obtained by the reaction system of the present invention contains a high concentration of trialkoxysilane, and contains tetraalkoxysilane and other by-products and unreacted alcohol. The alkoxysilane can be easily separated and obtained from this reaction product by distillation or other conventional methods.

The reaction solvent after the separation of trialkoxysilane and the like is in a reddish brown slurry state by the copper powder generated during the reaction and the unreacted metal silicon. Since almost no residue is left, the reaction residue is in a small amount and can be easily separated by filtration, centrifugation or the like. Most of the separated solid content reaction residue is copper powder, and the amount of unreacted metallic silicon is very small. The solvent recovered by filtration can be reused.

[0039]

Next, the present invention will be described with reference to examples and comparative examples. In this specification, the selectivity of trialkoxysilane and the conversion of metal silicon are values calculated by the following equations. Trialalkoxysilane selectivity (mol%) = [(mol number of trialkoxysilane) / (mol number of trialkoxysilane + mol number of tetraalkoxysilane)] × 100 Metallic silicon conversion (wt%) = 100 -[(Weight of metallic silicon in reaction residue) / (weight of charged metallic silicon)] × 1
00

Example 1 A 500 ml glass reactor equipped with a raw material blowing pipe, a thermometer, a stirrer, a cooler and a cooling liquid outlet was charged with 300 ml of dodecylbenzene as a solvent, and metal silicon (ferromagnetic material having a silicon content of 92% by weight) was charged. A reaction product of silicon and a hydrochloric acid solution of iron chloride; silicon content: 99.0% by weight; aluminum content: 0.32% by weight; iron content: 0.37% by weight; 15 g of cuprous (95% purity) was charged. Then, at 200 ° C. while stirring and mixing while supplying nitrogen (30 ml / min).
For 10 hours to activate the catalyst. In addition,
As the above wet method cuprous chloride, copper sulfate, hydrochloric acid, copper and salt are dissolved and reacted to crystallize cuprous chloride,
This is separated and dried to obtain solid cuprous chloride, which is then subjected to ball milling to obtain a particle size of 0.06-1.
Those having a size of 48 μm were used.

Next, the temperature of the reactor was maintained at 180 ° C.
Under stirring and mixing, while supplying nitrogen (30 ml / mi
n), 50 g / hr of vaporized ethanol from the blowing tube
Was supplied into a solvent to cause a reaction.

Five minutes after the start of the reaction, the product liquid began to distill from the cooler. The composition of the distilling product liquid was analyzed by gas chromatography, and the change over time in the composition was observed. The reaction was terminated when the ethanol composition reached 100%.

[0043]

According to the present invention, when producing a trialkoxysilane by reacting metal silicon with an alcohol having 1 to 4 carbon atoms in the presence of a catalyst, the aluminum content is 0.30 to 0.30.
By performing the reaction in the liquid phase using metallic silicon which is 0.37% by weight, the conversion of metallic silicon is high, and therefore,
This is a method for producing trialkoxylan which reduces the amount of unreacted metallic silicon, suppresses the discharge of industrial waste, and is also environmentally improved.

[0044]

[Table 1]

The content of the reactor after separation and acquisition of triethoxysilane was a reddish brown slurry, the solid content reaction residue obtained by filtration was mostly copper powder, and the amount of unreacted silicon was very small. . The solvent recovered by filtration was colorless and transparent and could be reused.

Example 2 As metallic silicon, metallic silicon (silicon content: 99.0% by weight, aluminum content: 0.31% by weight, iron content: 0.1% by weight)
The reaction was carried out in the same manner as in Example 1 except that 30% by weight and an average particle size of 100 μm were used. The reaction was completed in 30 hours.

Table 1 shows the results of analysis of the composition of all the obtained product solutions, and the selectivity of triethoxysilane and the silicon conversion based on the results.

Example 3 As metallic silicon, metallic silicon (silicon content 99.0% by weight, aluminum content 0.36% by weight, iron content 0.
The reaction was carried out in the same manner as in Example 1 except that 39% by weight and an average particle size of 100 μm) were used. The reaction was completed in 27 hours.

Table 1 shows the analysis results of the composition of all the obtained product liquids, and the selectivity of triethoxysilane and the silicon conversion rate based on the analysis results.

Example 4 A reaction was carried out in the same manner as in Example 2 except that 1 g of aluminum silicon (silicon content: 10 wt%) was further charged into the reactor. The reaction was completed in 30 hours.

Table 1 shows the analysis results of the composition of all the obtained product liquids, and the selectivity of triethoxysilane and the silicon conversion based on the results.

Comparative Example 1 As metallic silicon, metallic silicon (silicon content 99.3% by weight, aluminum content 0.25% by weight, iron content 0.
The reaction was carried out in the same manner as in Example 1 except that 22% by weight and an average particle size of 100 μm were used. The reaction was completed in 25 hours.

Table 1 shows the analysis results of the composition of all the obtained product liquids, and the selectivity of triethoxysilane and the silicon conversion rate based on the analysis results.

Comparative Example 2 As metallic silicon, metallic silicon (silicon content 98.9% by weight, aluminum content 0.38% by weight, iron content 0.
The reaction was carried out in the same manner as in Example 1 except that 43% by weight and an average particle size of 100 μm were used. The reaction was completed in 18 hours.

Table 1 shows the analysis results of the composition of all the obtained product liquids, and the selectivity of triethoxysilane and the silicon conversion based on the results.

Comparative Example 3 As metallic silicon, metallic silicon (silicon content: 98.9% by weight, aluminum content: 0.41% by weight, iron content: 0.1%)
The reaction was carried out in the same manner as in Example 1 except that 50% by weight and an average particle size of 100 μm were used. The reaction was completed in 16 hours.

Table 1 shows the analysis results of the composition of all the obtained product liquids, and the selectivity of triethoxysilane and the silicon conversion rate based on the results.

[0058]

According to the present invention, when producing a trialkoxysilane by reacting metal silicon with an alcohol having 1 to 4 carbon atoms in the presence of a catalyst, the aluminum content is 0.30 to 0.30.
By using metal silicon which is 0.37% by weight, the conversion rate of metal silicon is high, and therefore, the amount of unreacted metal silicon is reduced, the discharge of industrial waste is suppressed, and the environment is also improved. This is a method for producing trialkoxylan.

Claims (1)

(57) [Claims] 1. A method for producing trialkoxysilane by reacting metallic silicon with an alkyl alcohol having 1 to 4 carbon atoms in the presence of a catalyst, wherein the aluminum content is 0.30 to 0.1.
A method for producing a trialkoxysilane , wherein the reaction is performed in a liquid phase using metallic silicon of 37% by weight.