Method for producing trichlorosilane by using silicon tetrachloride

Abstract

The invention provides a method for producing trichlorosilane by using silicon tetrachloride, which comprises the following steps of: a) refining the silicon tetrachloride; b) purifying hydrogen; c) mixing the silicon tetrachloride and the hydrogen; d) preheating the mixed gas of the silicon tetrachloride and the hydrogen by using one or two of steam and the tail gas of hydrogenation; e) hydrogenating the preheated mixed gas of the silicon tetrachloride and the hydrogen; and f) recovering the tail gas of the hydrogenation, and fractionating to obtain the trichlorosilane. In the method, before the silicon tetrachloride and the hydrogen are subjected to hydrogenation, the mixed gas of the silicon tetrachloride and the hydrogen is preheated by the steam and the tail gas of the hydrogenation, so that a needed temperature can be reached by consuming a little electricity during the hydrogenation, the energy source is saved, the hydrogenation has high speed and yield, and the reaction time is short. Therefore, the method is suitable for large-scale polycrystalline silicon production.

Description

technical field [0001] The invention relates to the field of polysilicon production, in particular to a method for producing trichlorosilane by hydrogenation of silicon tetrachloride. Background technique [0002] A large amount of by-product silicon tetrachloride will be produced in the process of producing polysilicon by the improved Siemens method. Silicon tetrachloride can easily react with water to form silicon dioxide and hydrogen chloride. Direct discharge will seriously affect the ecological environment. Silicon tetrachloride needs to be treated. Handle it properly. Silicon tetrachloride can be used to prepare white carbon black and organic silicon, but the market capacity of these products is small, and it is impossible to digest a large amount of silicon tetrachloride. With the continuous expansion of domestic polysilicon production capacity, recycling is a better way to solve the problem of a large amount of silicon tetrachloride produced in polysilicon productio...

AI Technical Summary

Problems solved by technology

[0003] The production of trichlorosilane can use the hydrochlorination method to pass silicon tetrachloride, hydrogen, hydrogen chloride, and silicon powder into the trichlorosilane synthesis furnace to produce trichlorosilane, but the process is long, the equipment is complicated, and the material requirements are harsh. The operating pressure is high, the conditions are difficult to control, it is difficult to achieve continuous and stable operation, and the safety is poor, so it cannot be widely used

[0004] The invention patent application with the publication number CN101445245 discloses another method for producing trichlorosilane with silicon tetrachloride, which is to feed silicon tetrachloride and hydrogen into a high-temperature hydrogenation device at a certain ratio, and generate trichlorosilane after the hydrogenation reaction occurs. Hydrogen chlorosilane, but because of the high temperature required for the reaction, the method consumes more energy

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