Method for preparing trichlorosilane and dichlorosilane by hydrogenating silicon tetrachloride through microwave plasma

Abstract

The invention provides a method for preparing trichlorosilane and dichlorosilane by hydrogenating silicon tetrachloride through microwave plasma, which aims to solve the problems of high energy consumption, low single-pass conversion rate and high equipment investment in the catalytic hydrogenation of the silicon tetrachloride by a Siemens method and problems of high energy consumption and material consumption and difficult industrialization in hydrogenating the silicon tetrachloride by a conventional thermal plasma method and a radio-frequency induction plasma method in the conventional polysilicon industry. The method comprises the following steps: forming a stable cold plasma through arced hydrogen, argon or a mixture of the two under excitation of microwaves; forming a plasma jet flowby a plasma torch under the condition of the flow of the arced gas; and ejecting feed gas into a specific area of the plasma jet flow to form an active particle consumption zone in which the silicon tetrachloride is hydrogenated into trichlorosilane. The single-pass conversion rate of the silicon tetrachloride of the method reaches about 60 percent; and the method has the advantages of simple subsequent treatment of a product, low requirement on equipment and operation control, and easy realization of industrialization.

Description

technical field [0001] The invention relates to a method for producing trichlorosilane, in particular to a method for producing trichlorosilane and dichlorosilane by using microwave plasma hydrogenation technology. Background technique [0002] In the current industrial production of polysilicon at home and abroad, most production plants adopt the Siemens method, using trichlorosilane chemical vapor deposition of polysilicon. Trichlorosilane is produced by catalytic reaction of hydrogen chloride and metallurgical silicon under the conditions of 300°C and 0.45MPa, and silicon tetrachloride is the main by-product of the reaction. Among the synthetic products, trichlorosilane accounts for about 80%, and silicon tetrachloride accounts for about 20%. The synthesis gas is separated by cold distillation, silicon tetrachloride is separated as a by-product, and the purified trichlorosilane enters the next step of polysilicon vapor deposition reaction. [0003] The gas-phase deposit...

AI Technical Summary

Problems solved by technology

[0007] 1. A lot of impurities are introduced in the reaction, which brings difficulties to the subsequent purification;

[0008] 2. The one-time conversion rate of the reaction is low, the product needs to be separated and purified many times, and the energy consumption is high;

[0009] 3 The reaction is high temperature and high pressure, high equipment requirements and high operating costs

Therefore these two kinds of plasma methods are bound to consume a large amount of energy and raw materials, and the economic benefits are poor.

[0015] 2 The electric fields used to excite plasma by these two methods are non-enclosed electric fields. Industrial production must use high-power plasma generators. High-power non-enclosed electric fields bring great challenges to security measures and safe production. It is difficult to achieve industrialization

[0016] 3 The uniformity of the electric field used to stimulate the discharge generated by these two methods is poor, the plasma ionization degree is low, and there are few active particles for the reaction, resulting in a low conversion rate of silicon tetrachloride

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