Cracking process for byproduct chlorosilane high-boiling residue in polycrystalline silicon production

Abstract

The invention provides a cracking process for a byproduct chlorosilane high-boiling residue in polycrystalline silicon production. The cracking process comprises the following steps: filtering the byproduct chlorosilane high-boiling residue in polycrystalline silicon production to remove amorphous silicon in the byproduct chlorosilane high-boiling residue so as to obtain a purified high-boiling residue; and cracking hydrogen chloride and the purified high-boiling residue by using a catalyst to obtain a cracking product system, wherein the catalyst comprises macroporous resin and organic amineloaded on the macroporous resin, and the organic amine is selected from and any one or more of tri-n-butylamine, tri-n-octylamine, N,N-dimethylaniline, dioctadecyl secondary amine and perfluorotriethylamine. A framework of macroporous resin serving as a carrier in the catalyst is high in compatibility with the chlorosilane high-boiling residue, more reaction interfaces are provided, and organic amine loaded on the framework is enriched in micropores, so that the reaction of the inner surface and the outer surface of the resin is more thorough, the conversion rate can be increased, and the pyrolysis temperature can be reduced. The catalyst can be recycled. Before entering macroporous resin, amorphous silicon in the polysilicon production byproduct is removed through filtration, and resin pores are prevented from being blocked.

Description

technical field [0001] The invention relates to the technical field of polysilicon production, in particular to a cracking process for polysilicon production by-product chlorosilane high boilers. Background technique [0002] In the process of producing polysilicon by the improved Siemens method, SiHCl 3 and H 2 The gas enters the reduction furnace in a certain proportion, and the temperature of the silicon core carrier in the furnace reaches above 1050°C, and the SiHCl 3 and H 2 The mixed gas of SiHCl undergoes a reduction reaction on the surface of the carrier 3 +H 2 =Si+3HCl and thermal decomposition reaction 4SiHCl 3 =Si+3SiCl 4 +2H2, the generated silicon is deposited on the surface of the silicon core to form polycrystalline silicon rods. During the reduction process, in addition to silicon, SiCl 4 、SiH 2 Cl 2 、H 2 In addition to the formation of HCl, etc., there is also Si 2 Cl 6 、Si 2 HCl 5 、Si 2 h 2 Cl 4 , Cl 6 OSi 2 and Si 3 Cl 8 A series of b...

AI Technical Summary

Problems solved by technology

[0005] The main purpose of the present invention is to provide a cracking process of polysilicon production by-product chlorosilane high boilers to solve the problem of high cost of chlorosilane high boiler cracking catalysts in the prior art

Images