Process for producing chlorosilanes using a catalyst selected from the group of Co, Mo, W

Patent metadata

Field	Value
Publication number	US-11198613-B2
Application number	US-201716753935-A
Country	US
Kind code	B2
Filing date	Oct 5, 2017
Priority date	Oct 5, 2017
Publication date	Dec 14, 2021
Grant date	Dec 14, 2021

Abstract

Generally unusable or difficultly useable dusts of ultrahigh purity silicon can be used to produce chlorosilanes under reasonable reaction conditions by employing a catalyst containing one or more of Co, Mo, W. The process may be incorporated into an integral plant for the production of polycrystalline silicon.

First claim

The invention claimed is:

1. A process for producing chlorosilanes in a fluidized bed reactor comprising: reacting a hydrogen chloride-containing reaction gas with a particulate contact mass containing silicon and a catalyst, wherein the silicon consists of ultrahigh purity silicon having a purity>99.9%, wherein the catalyst comprises at least one element selected from the group consisting of Co, Mo and W, wherein the chlorosilanes have the general formula H n SiCl 4-n and/or H m CL 6-m Si 2 where n=1-3 and m=0-4, and wherein the catalyst is present in the contact mass in a total amount of 100 to 400 ppmw, based on the weight of the contact mass, the catalyst content in ppmw calculated as the element.

2. The process of claim 1 , wherein the catalyst further comprises at least one element selected from the group consisting of Zn, Cr and Ni.

3. The process of claim 1 , wherein the catalyst is present in the contact mass in metallic, oxidic, carbidic, alloyed and/or salt form.

4. The process of claim 1 , wherein the contact mass is a byproduct in the deposition of ultrahigh purity polycrystalline silicon and/or in the mechanical processing of ultrahigh purity polycrystalline/multicrystalline or single-crystal silicon.

5. The process of claim 4 , wherein the catalyst is constituent of an abraded material from comminution equipment, plant parts and/or pipelines associated with the deposition or the mechanical processing of the ultrahigh purity silicon.

6. The process of claim 1 , wherein the ultrahigh purity silicon has a Sauter mean diameter d 32 of 0.5 to 150 μm.

7. The process of claim 1 , wherein the ultrahigh purity silicon has a Sauter mean diameter d 32 of 1 to 100 μm.

8. The process of claim 1 , wherein the ultrahigh purity silicon has a Sauter mean diameter d 32 of 5 to 80 μm.

9. The process of claim 1 , wherein the process is performed at a temperature of 280° C. to 400° C.

10. The process of claim 1 , wherein the process is performed at an absolute pressure in the fluidized bed reactor of 0 to 0.5 MPa.

11. The process of claim 1 , wherein the hydrogen chloride and the ultrahigh purity silicon are present in a molar ratio of 10:1 to 3:1.

12. The process of claim 1 , wherein the hydrogen chloride and the ultrahigh purity silicon are present in a molar ratio of 7:1 to 3:1.

13. The process of claim 1 , wherein the reaction gas contains at least 50% by volume of hydrogen chloride.

14. The process of claim 1 , wherein the reaction gas contains at least 70% by volume of hydrogen chloride.

15. The process of claim 1 , wherein the ratio of fill height to reactor diameter is 10:1 to 1:1.

16. The process of claim 1 , wherein at least one the chlorosilane is selected from the group consisting of monochlorosilane, dichlorosilane, trichlorosilane, Si 2 C 6 , and HSi 2 Cl 5 .

17. The process of claim 1 , which is incorporated into an integrated system for producing polycrystalline silicon.

18. The process of claim 1 , wherein one or more of Co, Mo, and W is/are present in the form of a carbide or chloride.

19. The process of claim 1 , wherein the catalyst contains Mo and/or W.

Assignees

• Wacker Chemie Ag

Inventors

• Rimboeck Karl-Heinz
• Paetzold Uwe
• Sobota Marek

Classifications

• B01J23/8885

  containing also molybdenum · CPC title

• B01J23/24

  Chromium, molybdenum or tungsten · CPC title

• B01J23/888

  Tungsten · CPC title

• C01B33/10742 Primary

  prepared by hydrochlorination of silicon or of a silicon-containing material · CPC title