JPH0692249B2 - Treatment method for polychlorosilanes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention treats hydrogen and silicon chloride in the presence or absence of metallic silicon to treat polychlorosilanes produced as a by-product when the silicon chloride is reduced. Regarding the method.

Examples of the silicon chloride include trichlorosilane and silicon tetrachloride. Trichlorosilane is present in the state where silicon tetrachloride is reduced, and polycrystalline silicon is present in the state where trichlorosilane is reduced by the Siemens method. These are used as raw materials for manufacturing elements such as semiconductors and solar cells.

[Conventional technology]

The polychlorosilanes are represented by the following general formulas (1) (2) (3)
And a mixture of the compounds represented by (4).

SinCl ₂ n ₊₂ n ≧ 2 (1) SinHmCl ₂ n _{+ 2-} m n ≧ 2, m ≧ 1,2 n + 2-m ≧ 1 (2) SinCl ₂ n ₊₂ Ol n ≧ 2, n−1 ≧ 1 ( 3) SinHmCl ₂ n _{+ 2-} mOl n ≧ 2, m ≧ 1,2n + 2-m ≧ 1, n−1 ≧
1 (4) As described in JP-A-60-81010 and JP-A-58-217422, the polychlorosilanes are reacted with hydrogen and silicon tetrachloride in the presence or absence of metallic silicon to obtain trichlorosilane. It is a polychlorosilane that is a by-product when producing chlorosilane.

JP-A-60-81010 discloses a method for producing trichlorosilane by equilibrating hydrogen and silicon tetrachloride at high temperature and then quenching. JP 58-217422
The publication discloses a method for producing trichlorosilane by reacting hydrogen, metallic silicon and silicon tetrachloride at high temperature. The polychlorosilanes are in the form of brown liquids, sometimes viscous liquids. The polychlorosilane comes into contact with water or water in the air, and changes into a substance that ignites and explodes due to an off-white impact.

In the past, the polychlorosilane was neutralized by stirring it with an aqueous solution of sodium hydroxide, but the solid particles produced by the treatment reaction had an impact ignitability and the treatment had to be interrupted.

Japanese Unexamined Patent Publication (Kokai) No. 58-180494 proposes a method of treating a chlorosilane compound, which is a by-product during the production of trichlorosilane by the reaction of silicon metal and hydrogen chloride, with a concentrated aqueous hydrogen chloride solution or an aqueous calcium chloride solution.

However, in the prior art, when attempting to treat the polychlorosilanes, a safe treatment method has been demanded because ignition occurs during the treatment and solid particles generated by the treatment reaction cause impact.

[Problems to be Solved by the Invention]

The present invention solves the problems of ignition during the treatment of the polychlorosilane and ignition of solid particles generated by the treatment reaction.

[Means for Solving the Problems]

The present inventor has conducted extensive studies on a treatment method for the polychlorosilanes, and as a result, a hydroxide of an alkaline earth metal,
It was found that the alkaline earth metal oxide or ammonia can be safely used.

That is, in the present invention, hydrogen and silicon chloride are reacted in the presence or absence of metallic silicon, and when the silicon chloride is reduced, polychlorosilanes produced as a by-product are alkaline earth metal hydroxides,
A method for treating by-produced polychlorosilanes, which comprises treating with an oxide of an alkaline earth metal or ammonia.

As the alkaline earth metal hydroxide used in the present invention, calcium hydroxide and magnesium hydroxide are easily available, and as the alkaline earth metal oxide, calcium oxide and magnesium oxide are easily available. It is easier to operate the alkaline earth metal hydroxide or oxide prepared in advance as a saturated aqueous solution or slurry. The alkaline earth metal hydroxide or oxide used in the present invention is preferably in powder form for preparing a slurry.
Ammonia is easier to operate when used as an aqueous solution, and may be used as a saturated aqueous solution after diluting. The polychlorosilanes may be used as they are or may be diluted with silicon tetrachloride and treated. The treatment of the present invention does not require heating or cooling and is effectively carried out at a temperature of 0 to 50 ° C. It is possible to carry out at a temperature exceeding 50 ° C, but if it is carried out at a high temperature, ignitable solid particles are easily generated. The treatment is effectively performed by keeping the pH of the treatment liquid at 7.0 to 14.0. When the pH is less than 7.0, ignitable solid particles are easily generated. The device used for processing is not limited,
The stirring tank type is easy to operate. The treatment method may be a batch method or a continuous method.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples, but these are merely examples and the present invention is not limited thereto.

Example 1 A 500 ml round-bottom glass flask was charged with 280 g of a 15 wt% calcium hydroxide slurry, and the mixture was kept at 20 ° C. with stirring at 300 rpm. 265 mol / h of silicon tetrachloride, 530 of hydrogen
The by-product polychlorosilanes were obtained by distillation from the reaction solution obtained by supplying the reaction solution at a rate of mol / h to a graphite reactor kept at 1250 ° C. and then rapidly cooling it. 36.7 g of this by-product polychlorosilane was added dropwise over 30 minutes. Stirring was continued for another 30 minutes, but during this period, no ignition occurred in the flask. The pH of the liquid after the reaction was 7.9. Thereafter, solid particles generated by the reaction were separated by filtration, washed with water, and dried under a nitrogen atmosphere. A drop-type impact tester (manufactured by Kamijima Seisakusho Co., Ltd.) was used to measure the impact ignition properties of the dried solid particles. The amount of impact given is displayed as the product of the weight (kg weight) of the weight dropped and the height (m) of the weight dropped. As a result of the measurement, it weighs 1.0 kg.
It did not ignite even when given a shock of m.

Example 2 Under the same conditions as in Example 1, 220 g of 15 wt% magnesium hydroxide slurry was used instead of 280 g of 15 wt% calcium hydroxide slurry. There was no ignition in the flask during stirring. The pH after the reaction was 7.6. It did not ignite even when given an impact of 1.0 kg weight / m with an impact tester.

Example 3 Under the same conditions as in Example 1, the same procedure was performed using 212 g of 15 wt% calcium oxide slurry instead of 280 g of 15 wt% calcium hydroxide slurry. There was no ignition in the flask during stirring. The pH after the reaction was 11.9. It did not ignite even when given an impact of 1.0 kg weight / m with an impact tester.

Example 4 Under the same conditions as in Example 1, 280 g of the 15 wt% calcium hydroxide slurry was replaced with 152 g of the 15 wt% magnesium oxide slurry, and the same procedure was carried out. There was no ignition in the flask during stirring. The pH after the reaction was 9.1. It did not ignite even when given an impact of 1.0 kg weight / m with an impact tester.

Example 5 A 500 ml glass round bottom flask was charged with 15 wt% calcium hydroxide slurry at a rate of 9.3 g / min and the same polychlorosilanes used in the treatment of Example 1 at a rate of 1.2 g / min. Each was dripped and supplied with stirring at 300 rpm. Thirty minutes after the start of dropping, the slurry-like reaction liquid was extracted at a rate of 10.5 g / min and continuously treated. The treatment was continuously carried out for 3 hours, but there was no ignition in the flask. The solid particles generated by the reaction were separated by filtration, washed with water, dried under a nitrogen atmosphere, and measured by an impact tester. 1.0 kg weight
It did not ignite even when given a shock of m.

Example 6 To a 1000 ml glass round bottom flask, 25 wt% aqueous ammonia solution was added dropwise at a rate of 2.4 g / min, and the same polychlorosilanes used in the treatment in Example 1 were added dropwise at a rate of 1.2 g / min. Then, it was fed at 300 rpm with stirring. Start dripping 3
After 0 minutes, the slurry-like reaction liquid was extracted at a rate of 3.6 g / min and continuously treated, but no ignition occurred in the flask. The solid particles generated by the reaction were separated by filtration, washed with water, dried under a nitrogen atmosphere, and measured by an impact tester. 1.0 kg
It did not ignite even when given a heavy m impact.

Example 7 A 500 ml round-bottom glass flask was charged with 280 g of a 15 wt% calcium hydroxide slurry, and the mixture was kept at 20 ° C. with stirring at 300 rpm. A silicon tetrachloride: hydrogen molar ratio of 3: 2 was supplied to a metallic silicon fluidized bed reactor (inside diameter 10 cm) kept at 450 ° C., and the reaction liquid obtained was distilled as a by-product to produce polychlorosilane. I got a kind. 36.7 g of these polychlorosilanes were added dropwise over 30 minutes. Stirring was continued for another 30 minutes, but during this period, no ignition occurred in the flask. After that, the solid particles generated by the reaction are separated by filtration, washed with water, dried under a nitrogen atmosphere, and then measured by an impact tester to find that the weight is 1.0 kg / m.
It did not ignite even when given a shock.

Comparative Example 1 Under the same conditions as in Example 1, the same procedure as in Example 1 was repeated except that 151 g of a 15 wt% sodium hydroxide aqueous solution was used instead of the 15 wt% calcium hydroxide slurry. Ignition occurred in the flask during stirring. The solid particles produced in the reaction are separated by filtration,
After washing with water, it was dried in a nitrogen atmosphere, and the impact ignitability of the solid particles was measured.

Comparative Example 2 Under the same conditions as in Example 1, the same procedure was carried out by using 59 g of 35 wt% hydrogen chloride aqueous solution instead of 15 wt% calcium hydroxide slurry water. Ignition occurred in the flask during stirring. Solid particles generated in the reaction are separated by filtration, washed with water,
When the solid particles were dried under a nitrogen atmosphere and the impact ignitability of the solid particles was measured, it was ignited at 0.04 kg weight · m.

Comparative Example 3 Under the same conditions as in Example 1, a 15 wt% calcium hydroxide slurry was used instead of the 15 wt% calcium hydroxide slurry.
It carried out similarly using 6g. There was no ignition in the flask during stirring. The solid particles produced in the reaction are separated by filtration,
It was dried in a nitrogen atmosphere without washing with water, and the impact ignitability was measured to find that it did not ignite at 1.0 kgf / m.

However, the solid particles produced by the reaction were separated by filtration, washed with water, dried under a nitrogen atmosphere, and the impact ignitability of the solid particles was measured.

Comparative Example 4 Under the same conditions as in Example 1, 280 g of the 15 wt% calcium hydroxide slurry was replaced with 100 g of the 15 wt% calcium hydroxide slurry aqueous solution, and the same procedure was performed. There was no ignition in the flask during stirring. The pH after the reaction was 1.1. After washing with water, it was dried in a nitrogen atmosphere, and the impact ignitability of the solid particles was measured. As a result, it was ignited with an impact tester at an impact of 0.03 kg weight · m.

〔The invention's effect〕

The present invention can safely treat the polychlorosilanes as described above.

Claims (1)

[Claims] 1. A polychlorosilane produced as a by-product during the reaction of hydrogen with silicon chloride in the presence or absence of metallic silicon to reduce the silicon chloride is a hydroxide of an alkaline earth metal or an alkaline earth metal. A method for treating by-produced polychlorosilanes, which comprises treating with an oxide of the above or ammonia.