Process for operating a fluidized bed reactor

Patent metadata

Field	Value
Publication number	US-2016145109-A1
Application number	US-201414899143-A
Country	US
Kind code	A1
Filing date	Jun 17, 2014
Priority date	Jun 27, 2013
Publication date	May 26, 2016
Grant date	—

Abstract

Yield of products of increased purity from a fluidized bed reactor where silicon is produced or consumed is enhanced by purging with inert gas, purging with hydrogen gas, and purging with a chlorosilane-containing gas. The purging with hydrogen is conducted at an elevated temperature.

First claim

1 - 8 . (canceled)

9 . A process for operating a fluidized bed reactor in an operation for preparing trichlorosilane from silicon and HCl or from silicon and H 2 /tetrachlorosilane or in an operation for preparing silicon from trichlorosilane, comprising purging the reactor and the input gas lines at room temperature with an inert gas at a gas rate of 10 to 500 m 3 (STP)/h for 0.5 to 10 hours in a purge (a); then purging the reactor and input gas lines with H 2 in a purge (b), wherein the purging with H 2 is concurrent with heating to a temperature of 100-1000° C., and the purging is conducted for 2 to 100 hours with a gas flow rate of 200 to 1000 m 3 (STP)/h; and purging the reactor and the input gas lines with trichlorosilane or with a mixture comprising trichlorosilane in a purge (c) for 2 to 50 hours with an amount of purge gas such that a concentration of a trichlorosilane or trichlorosilane mixture based on a total gas rate conveyed through a fluidized bed is 10 mol % to 50 mol % and a concentration of the trichlorosilane or trichlorosilane mixture based on a total gas rate conveyed through a reaction gas nozzle is 20 mol % to 50 mol %.

10 . The process of claim 9 , wherein purge operations in the sequence (a)-(b)-(c) are followed by deposition of polycrystalline silicon on seed particles from a reaction gas comprising trichlorosilane.

11 . The process of claim 10 , wherein the reaction gas comprises hydrogen and trichlorosilane.

12 . The process of claim 9 , comprising a deposition of polycrystalline silicon on seed particles in which a reaction gas comprises trichlorosilane, followed by termination of a supply of reaction gas comprising trichlorosilane, purging the reactor and the input gas lines with H 2 in a purge (b), wherein the purging with H 2 is concurrent with heating to a temperature of 100-1000° C., wherein the purging is conducted for 1 to 20 hours with a gas rate of 50 to 800 m 3 (STP)/h; and then purging the reactor and the input gas lines at room temperature with an inert gas at a gas rate of 10 to 500 m 3 (STP)/h for 1 to 20 hours, and then opening and disassembling the reactor.

13 . The process of claim 12 , wherein the reactor is subsequently reassembled and seed particles are added.

14 . The process of claim 13 , comprising effecting a further purge of the reactor and the input gas lines with an inert gas between disassembly and reassembly of the reactor.

15 . The process of claim 9 , wherein one or more of the purges (a),(b) and (c) is/are enhanced by pressure swing purging.

16 . The process of claim 9 , wherein the inert gas is nitrogen or a noble gas or mixture thereof.

Assignees

• Wacker Chemie Ag

Inventors

• Weckesser Dirk

Classifications

• C01B33/10763 Primary

  from silicon · CPC title

• C01B33/1071

  Tetrachloride, trichlorosilane or silicochloroform, dichlorosilane, monochlorosilane or mixtures thereof · CPC title

• C01B33/027

  by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material · CPC title

• C01B33/03

  by decomposition of silicon halides or halosilanes or reduction thereof with hydrogen as the only reducing agent · CPC title

• C01B33/10757

  with the preferential formation of trichlorosilane · CPC title