Method for producing silicon metal and porous carbon

Patent metadata

Field	Value
Publication number	US-9862612-B2
Application number	US-201314408006-A
Country	US
Kind code	B2
Filing date	May 22, 2013
Priority date	Jun 20, 2012
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

The method for producing silicon metal and porous carbon from rice hulls is provided. The method comprises a first step S 1 of producing a rice hull charcoal M 2 containing SiO 2 and C by heat treatment of rice hulls M 1 ; a second step S 4 of exposing the rice hull charcoal M 4 to at least any one of heated first inert gas G 2 or reducing gas to produce SiC; a third step S 5 of exposing SiC to a heating atmosphere containing Cl 2 gas to produce SiCl 4 and porous carbon P 1 ; a fourth step S 7 of reacting SiCl 4 and Zn to produce silicon metal P 2 and ZnCl 2 ; and a fifth step S 9 of electrolyzing ZnCl 2 to produce Zn and Cl 2 gas. The Cl 2 gas in the fifth step S 9 is used in the third step S 5 , and Zn in the fifth step S 9 is used in the fourth step S 7.

First claim

What is claimed is:

1. A method for producing silicon metal and porous carbon comprising:
a first step of producing a rice hull charcoal containing silicon oxide and carbon by heat treatment of rice hulls;
a second step of exposing the rice hull charcoal to at least any one of heated first inert gas or reducing gas to produce silicon carbide;
a third step of exposing the silicon carbide to a heating atmosphere containing chlorine gas to produce silicon chloride and porous carbon;
a fourth step of reacting the silicon chloride and zinc metal to produce silicon metal and zinc chloride; and
a fifth step of electrolyzing the zinc chloride to produce zinc metal and chlorine gas;
wherein the chlorine gas in the fifth step is used in the third step, and the zinc metal in the fifth step is used in the fourth step,
wherein the fourth step comprises:
a step of heating the silicon chloride to a temperature of 600° C. or higher and 1100° C. or lower to generate gas of the silicon chloride;
a step of reacting the gas of silicon chloride with vapor of the zinc metal to produce the silicon metal and the zinc chloride; and
a step of cooling the zinc chloride to liquefy the zinc chloride.

2. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the first step, a number of moles of carbon is triple or more a number of moles of SiO 2 in the composition of the rice hull charcoal produced.

3. The method for producing silicon metal and porous carbon according to claim 1 , wherein the rice hull charcoal is treated with an acid solution prior to the second step.

4. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the second step, the first inert gas contains at least one of Ar and He, and the rice hull charcoal produced in the first step is heated to a temperature of 1200° C. or higher and 2000° C. or lower.

5. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the second step, the reducing gas contains one of H 2 and CO, and the rice hull charcoal produced in the first step is heated to a temperature of 1200° C. or higher and 2000° C. or lower.

6. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the second step, the silicon carbide is produced under a pressure of less than 1 atm.

7. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the third step, the atmosphere containing chlorine gas is heated to a temperature of 1000° C. or higher and 1600° C. or lower.

8. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the third step, the gas of silicon chloride is discharged from the heating atmosphere to separate the silicon chloride from the porous carbon.

9. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the fourth step, gas of the zinc chloride is discharged from the atmosphere containing the gas of silicon chloride and vapor of the zinc metal to separate the zinc chloride from the silicon metal.

10. The method for producing silicon metal and porous carbon according to claim 1 ,
wherein, in the third step, the heating atmosphere contains a mixed gas of the chlorine gas and a second inert gas or chlorine gas.

Assignees

• Sumitomo Electric Industries

Inventors

• Ishikawa Shinji
• Adachi Toru
• Yamashita Taiichiro

Classifications

• C01B33/033 Primary

  by reduction of silicon halides or halosilanes with a metal or a metallic alloy as the only reducing agents · CPC title

• C01B32/05

  Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30 · CPC title

• C01B32/00

  Carbon; Compounds thereof (C01B21/00, C01B23/00 take precedence; percarbonates C01B15/10; carbon black C09C1/48) · CPC title

• C01B33/021

  Preparation (chemical coating from the vapour phase C23C16/00) · CPC title