High-boiling product cracking technology in polycrystalline silicon production

Abstract

The invention discloses a high-boiling product cracking technology in polycrystalline silicon production. The technology comprises the steps as follows: pretreatment: solid impurities and metal halides in a high-boiling product are removed and a first mixture is obtained; primary separation: the first mixture is separated at 50-150 DEG C and silicon tetrachloride and chlorosilane oligomer are obtained; cracking: the chlorosilane oligomer is cracked under the action of a catalyst and a chlorosilane mixture is obtained; secondary separation: the chlorosilane mixture is sent to a high-boiling product removal tower, the uncracked chlorosilane oligomer is removed, and single-silicon chlorosilane and noncondensable gas are obtained. According to the technology, the metal chlorides are removed, and the condition that the catalyst is deactivated due to the fact that the metal chlorides and the catalyst form complexes can be effectively prevented. The lower end of a settling tank is communicated with a socket pipe, and the socket pipe is used for leading out an oligomer mixture located on the upper layer after settlement, so that the catalytic cracking reaction of the oligomer mixture can be conducted more efficiently.

Description

technical field [0001] The invention relates to the field of polysilicon preparation, in particular to a process for cracking high boilers in polysilicon production. Background technique [0002] The current mainstream polysilicon production process in the world is the improved Siemens method. The process is to use H2 to reduce and precipitate SiHCl3 on a U-shaped silicon core rod in a high-temperature environment to prepare polysilicon. The whole process tends to be a closed loop, basically achieving clean and efficient polysilicon production. [0003] However, in the production process of chlorosilane and polysilicon, including cold hydrogenation, hydrochlorination and reduction processes, a small amount of high boiling substances are also produced. Among the high boiling substances, in addition to metal chlorides and solid particles, there are also chlorosilane oligomerization These chlorosilane oligomers are usually of the general formula Si n Cl 2n+2-m h m (n≥2, m≤2...

AI Technical Summary

Problems solved by technology

The method is to add high boilers and organic amine compound catalysts into the cracking reaction tower, and heat up to crack the high boilers. In this process, the solid particles in the chlorosilane high boilers cannot be effectively removed, so a large amount of catalysts are required. Increase production cost; in addition, a large amount of unreacted substances are obtained after one-time cracking in the cracking tower, and the unreacted substances cannot be effectively recycled, resulting in low efficiency, large amount of unreacted waste, and low recovery efficiency

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