JPS62143813A - Production of silicon tetrachloride - Google Patents

Abstract

PURPOSE:To simplify the structure of a reactor, facilitate the selection of a material and increase the conversion, by feeding excess Cl2 and H2 and utilizing heat of reaction forming HCl in bringing chlorine into contact with a mixture of an SiO2-containing material with carbon to produce SiCl4. CONSTITUTION:A mixture of an SiO2-containing material with carbon is fed from a storage tank 1 to a reactor 3 to form a raw material layer 9. H2 is fed from an H2 feeding pipe 5 and Cl2 is fed from a Cl2 feeding pipe 6 to ignite a burner 7. Reaction for forming HCl is initiated to introduce HCl and the residual Cl2 heated to a high temperature by this reaction into the lower part of the reactor 3 and the Cl2 is reacted with the mixture of the SiO2- containing material with carbon to form SiCl4. The reaction product gas is then cooled in a cooler 10 to separate the resultant liquefied SiCl4 in a separator 11. The residual gas is absorbed in water in an HCl absorption column 12. According to this method, the structure of the reactor 3 is simplified and the selection of the material and temperature control are facilitated. Since a high temperature of >=1,200 deg.C can be attained, the conversion can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing silicon tetrachloride, which is useful as a raw material for the synthesis of various organosilicon compounds, as well as for the synthesis of fine silica, high-purity synthetic quartz, silicon carbide, silicon nitride, etc. It is something.

Conventional technology As for the manufacturing method of silicon tetrachloride.

(1) Reaction between metallic silicon or silicon alloy and hydrogen chloride, (2) Reaction between silicon carbide>whale and chlorine.
The drawback is that the raw materials are expensive because it requires a huge amount of electricity to make.

Therefore, as a □ method using SiO2 directly as a raw material, (3)
A method for producing silicon tetrachloride by bringing chlorine into contact with a mixture of SiO2-containing substances such as silica stone and carbon, 5i02+2C+2CJ12→5iCus+2CO(D
has been proposed, but this method requires too much reaction with chlorine.
A good yield cannot be obtained unless the process is carried out at a high temperature of 1-1°C or higher,
The disadvantage is that it is not easy to heat the reactor.

Conventionally, reactors are heated by electric heating, but (V reactor inner surface needs to be made of a material that is corrosion resistant and has poor heat conduction, and the outer wall needs to be made of metal for strength.) In order to install the heater outside, a considerable amount of work is required, and in order to heat the reactor inside, the selection of the material for the heating element becomes a major problem.

Problems to be Solved by the Invention The present invention, in the third method described above, uses a heating means that does not rely on electric heating to improve the structure of the reactor by 1+'J.
It is an object of the present invention to provide a method for producing silicon tetrachloride which can be made into rlj- and which makes it easy to select the material.

Structure of the Invention Means for Solving the Problems The method for producing silicon tetrachloride according to the present invention comprises contacting a mixture of a SiO2-containing substance and carbon with chlorine to produce 4t1! In producing silicon oxide, excess chlorine and hydrogen are supplied to the reaction system to cause a hydrogen chloride production reaction, and the reaction system is maintained at a temperature of 1000° C. or higher using the heat generated at that time.

5i02-containing substances include silica stone, fly ash,
All raw materials normally used for the production of silicon tetrachloride, such as silica sol, can be used.

In addition, activated carbon, coke, Grapheye I, etc. can be used as iRJ<''.

Use on iR! □I: is 5i as seen in the above formula (1)
It is preferable that the molar ratio is 2 times j11 or more than 02.

The mixture of the SiO2-containing substance and carbon described in 1-1 may be a mixture of fine powders, but it is preferable to form the mixture into pellets.

The shape of the reactor is not particularly limited, and may be either a continuous type or a batch type as long as it has a reaction section for chlorine and hydrogen at the bottom of the reactor, but a continuous type is preferred.

Types include fixed bed type, moving bed type, fluidized bed type, etc.

A higher yield can be obtained by setting the reaction temperature to 1000°C or higher, preferably 1200°C or higher.

The reaction temperature can be easily controlled by changing the amount of excess chlorine and hydrogen added.

Out of the reactor [1 to 4 J! A mixture of silicon monide, hydrogen chloride, and CO is discharged, and the mixture is first cooled to liquefy and separate silicon tetrachloride, and then washed with water to recover hydrogen chloride as an aqueous hydrochloric acid solution.

To explain this process with reference to FIG. 1, the raw material (Si
A chlorine and hydrogen reaction section 4 is provided at the bottom of the reactor 3, which is provided with a storage tank 1 (mixed fine powder or pellets of 02-containing substance and carbon) and a raw material supply valve 2, and a hydrogen supply pipe 5.1 is provided here.
1! A raw material supply pipe 6 and an ignition burner 7 are provided. Symbol 8 is a discharge pipe for reaction residue.

By supplying the raw material from the storage 46i to the reactor 3 to form a material layer 9, supplying hydrogen from the hydrogen supply pipe 5 and chlorine from the chlorine supply pipe 6, and igniting it with the burner 7, a hydrogen chloride production reaction starts. occurs, and the hydrogen chloride and remaining salt heated by this reaction are also introduced into the lower part of reactor 3, where element 111 reacts with the mixture of 5i02-containing material and carbon to form silicon tetrachloride.

When the reaction product residue is cooled in the cooler 10, silicon tetrachloride is liquefied, so it is separated in the separator 11, and the remaining gas is sent to the HC absorption tower 12 and absorbed in water. Symbol 13 is a wooden supply pipe,
14 is a discharge pipe for the generated hydrochloric acid. Since gas containing CO is discharged from a part of the gas discharge pipe 15 of the HCI absorption tower, it can also be used as a chemical reactor 15 raw material or fuel.
Ir ability.

Byproduct J'1! The acid can be used for purposes such as pickling, or it can be electrolyzed to recover hydrogen and chlorine and recycled to the reaction system.

Ii! The degree of excess of the element is 1 ton of excess! Jll is the reaction heat required to maintain the temperature of the silicon tetrachloride production reaction section in the reactor 3 at 1000° C. or higher, and is determined by taking into account heat loss in the reactor. The hydrogen supply rate is set to 1, which corresponds to 11i of excess chlorine.
・Example 5 Silica stone with an i02 content of 90% or more was finely pulverized, and carbon black of twice the molar ratio was added thereto, and the mixture was molded into a 4 mm φ x 5 mm belen I.

11194 g of H2 and C2 were flowed each, and at the point 1 ν when the reactor temperature reached 1200°C, 300 g of raw material pellets per hour were supplied to the reactor by parts, and the blowing gas etc.
- was changed to 6.3 sentences per minute for C2 and 3.8 sentences per minute for H2, and about 30 g of reaction residue was extracted per hour from the bottom of the reactor.

The reaction continued as it was, but the temperature was well controlled.

Gas containing 5iCi4 continuously flowed out from the northern part of the reactor.

Effects of the invention (1) The structure of the reactor is simplified and the selection of materials becomes easier.

(2) Temperature control becomes easier.

(3) High temperatures of 1200° C. or higher can be achieved and the reaction rate can be increased.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the manufacturing process of silicon tetrachloride according to the present invention.

Claims (1)

[Claims] When producing silicon tetrachloride by bringing chlorine into contact with a mixture of a SiO_2-containing substance and carbon, excess chlorine and hydrogen are supplied to the reaction system to cause a hydrogen chloride production reaction, and the heat generated at that time causes the reaction to occur. A method for producing silicon tetrachloride, which comprises maintaining a system at 1000°C or higher.