Method for producing high-purity hydrogen gas and/or nanomagnetite

Patent metadata

Field	Value
Publication number	US-10899610-B2
Application number	US-201715490301-A
Country	US
Kind code	B2
Filing date	Apr 18, 2017
Priority date	Mar 29, 2013
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

The disclosure relates to a method for producing hydrogen gas and/or magnetite comprising the steps of reacting a wüstite-containing material, such as steel slags, with H 2 O at a temperature ranging from 150° C. to 500° C., cooling down the gaseous reaction product to separate hydrogen gas from water steam and collecting hydrogen gas, and recovering magnetite from the solid reaction product.

First claim

The invention claimed is:

1. A method for producing magnetite comprising the steps of:
(o′) combining a wüstite-containing material and a liquid aqueous solution of liquid water and one or more acids to form a reaction mixture, and then
(a′) exposing the reaction mixture to a reaction condition comprising:
a pH of the aqueous solution less than 7 when said aqueous solution is at 25° C. and 1 bar, and
a pressure defined to maintain the water in a partial liquid state at a temperature ranging from 100 to 500° C., and maintaining the reaction mixture under the reaction condition for a reaction period of sufficient duration to obtain a solid product comprising magnetite, and then

(b′) recovering the magnetite in the form of particles comprising three populations of size: from 10 to 20 nm, from 100 to 200 nm, and from 1 to 200 μm, wherein more than 25% by weight of the particles have a nanometric size.

2. The method according to claim 1 , wherein the temperature during step (a′) is from 150° C. to 500° C.

3. The method according to claim 2 , wherein the temperature during step (a′) is from 150° C. to 350° C.

4. The method according to claim 1 , wherein the pressure during step (a′) is from 5 to 700 bar.

5. The method according to claim 1 , wherein the pH of the aqueous solution is from 2 to 5.

6. The method according to claim 5 , wherein the pH of the aqueous solution is from 2.5 to 3.

7. The method according to claim 1 , wherein the aqueous solution comprises an organic acid comprising a group capable of complexing iron ions.

8. The method according to claim 1 , wherein the wüstite-containing material is steel slag.

9. The method according to claim 8 , wherein the steel slag used in step (a′) is decalcified steel slag.

10. The method according to claim 8 , wherein steel slags is selected from basic oxygen furnace steel slag and electric arc furnace steel slag.

11. The method according to claim 1 , wherein the step (b′) of recovering magnetite comprises magnetic separation.

12. The method according to claim 1 , wherein the magnetite particles recovered at step (b′) comprise nanometric sized particles and micrometric sized particles and wherein the method comprises, after step (b′), a step (c′) of separating the nanometric sized particles from the magnetite particles obtained at the end of step (b′).

13. The method according to claim 1 , wherein the wüstite-containing material is wüstite.

14. The method according to claim 1 , wherein the aqueous solution further includes carboxylic acid, wherein the carboxylic acid maintains the pH of the aqueous solution at less than 7.

15. A method for producing hydrogen gas comprising the steps of:
(o′) combining c steel slags including wüstite-containing material and a liquid aqueous solution of liquid water and one or more acids to form a reaction mixture, and then
(a) exposing the reaction mixture to a reaction condition comprising:
a pH of the aqueous solution less than 7 when said aqueous solution is at 25° C. and at 1 bar, and
a pressure defined to maintain the water in a partial liquid state at a temperature ranging from 150° C. to 500° C., and maintaining the reaction mixture under the reaction condition for a reaction period of sufficient duration to generate hydrogen gas;

(b) cooling down the reaction product of step (a) to separate the hydrogen gas from water steam; and
(c) collecting the hydrogen gas, wherein the hydrogen purity is higher than 99.9 molar % and a production rate is up to about 30 NL of hydrogen per kg of steel slags.

16. The method according to claim 15 , wherein step (a) is carried out without adding a catalyst.

17. The method according to claim 15 , wherein, prior to step (a), said steel slags are carbonated.

18. The method according to claim 15 wherein the hydrogen purity is higher than 99.995 molar %.

19. A method for producing hydrogen gas and magnetite comprising the steps of:
(o′) combining steel slags including wüstite-containing material and a liquid aqueous solution of liquid water and one or more acids to form a reaction mixture, and then
(a) exposing the reaction mixture to a reaction condition comprising:
a pH of the aqueous solution less than 7 when said aqueous solution is at 25° C. and at 1 bar, and
a pressure defined to maintain the water in a partial liquid state at a temperature ranging from 150° C. to 500° C. and
maintaining the reaction mixture under the reaction condition for a reaction period of sufficient duration without adding a catalyst to obtain reaction products:

in the form of a gaseous phase comprising a hydrogen gas, and
in the form of a solid product comprising magnetite;
(b) cooling down the reaction product in the form of a gaseous phase of step (a) to separate the hydrogen gas from water steam; and
(c) collecting the hydrogen gas, wherein the hydrogen gas purity is higher than 99.9 molar % and a production rate is up to about 30 NL of hydrogen per kg of steel slags;
(b′) recovering the magnetite from the solid product comprising magnetite obtained at the end of step (a) in the form of particles comprising three populations of size: from 10 to 20 nm, from 100 to 200 nm, and from 1 to 200 μm.

20. The method according to claim 19 , wherein more than 25% by weight of the magnetite particles have a nanometric size.

Assignees

• Centre Nat Rech Scient
• Univ Aix Marseille

Inventors

• Brunet Fabrice
• Malvoisin Benjamin
• Vidal Olivier
• Goffe Bruno
• Crouzet Camille

Classifications

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title