Hydrogenation process for silicon tetrachloride and process for preparing high-purity silicon from trichlorosilane

Abstract

The invention provides a hydrogenation process for silicon tetrachloride and a process for preparing high-purity silicon from trichlorosilane. The process for preparing high-purity silicon from trichlorosilane comprises the following steps: (1) introducing trichlorosilane gas and hydrogen into a micro-channel mixing and heating device for heating and mixing so as to obtain a heated gas mixture; (2) conveying the heated gas mixture into a micro-channel reactor, heating the gas mixture and carrying out a reaction in the presence of a catalyst so as to obtain a reacted mixture; and (3) cooling the reacted mixture and carrying out solid-gas separation so as to obtain high-purity silicon and a cooled gas mixture, and separating and recycling each component in the cooled gas mixture. The invention also discloses a hydrogenation process for silicon tetrachloride. Compared with the prior art, the hydrogenation process for silicon tetrachloride and the process for preparing high-purity silicon from trichlorosilane in the invention have the beneficial effects that the conversion rates of silicon tetrachloride and trichlorosilane can reach 50% or above; and through combination of the processes with micro-chemical technology, the conversion rates are increased, security of the production processes is improved, and energy consumption is reduced.

Description

technical field [0001] The invention specifically relates to a process for hydrogenating silicon tetrachloride and a process for preparing high-purity silicon from trichlorosilane. Background technique [0002] With the rapid development of the photovoltaic industry, polysilicon, the raw material for solar cells, is seriously in short supply, which has greatly stimulated the development of my country's polysilicon industry. Domestic polysilicon manufacturers continue to increase and their scale continues to expand. At present, most of the domestic polysilicon manufacturers adopt the Siemens improved method to produce polysilicon, but the production of one ton of polysilicon will produce 12-16 tons of by-product silicon tetrachloride. Silicon tetrachloride is a colorless, transparent and poisonous liquid with difficult It has a suffocating odor and easily reacts with water to form silicon dioxide and hydrogen chloride. A 5,000t / a polysilicon plant will produce 60,000-80,000 ...

AI Technical Summary

Problems solved by technology

At present, most of the domestic polysilicon manufacturers adopt the Siemens improved method to produce polysilicon, but the production of one ton of polysilicon will produce 12-16 tons of by-product silicon tetrachloride. Silicon tetrachloride is a colorless, transparent and poisonous liquid with difficult Suffocating odor, easily reacts with water to form silicon dioxide and hydrogen chloride

A 5,000t / a polysilicon plant needs to produce 60,000-80,000 tons of silicon tetrachloride. If so much silicon tetrachloride is not effectively utilized, it will not only increase production costs, affect corporate efficiency, and even pollute the environment. It is even more detrimental to the clean development of the entire polysilicon industry

However, both the hot hydrogenation method and the cold hydrogenation method have certain problems. The hot hydrogenation method has high reaction temperature, complicated process flow, difficult device operation, low conversion rate and high energy consumption; while the cold hydrogenation technology of some manufacturers Relying on the introduction of foreign methods, lack of independent research and development capabilities, poor ability to deal with silicon tetrachloride, and many operational problems

[0007] The reaction principle of polysilicon made from trichlorosilane is: SiHCl 3 +H 2 =Si+3HCl; its process is very similar to the thermal hydrogenation process of silicon tetrachloride, but there are still big differences in the reaction conditions, equipment and other aspects, as far as the thermal hydrogenation process is concerned

[0011] Similarly, the process of preparing polysilicon by hydrogen reduction has disadvantages such as low conversion rate and high energy consumption.

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