Method of selective extraction of platinoids, from a support containing same, with an extraction medium consisting of a supercritical fluid and an organic ligand

Patent metadata

Field	Value
Publication number	US-10494695-B2
Application number	US-201515506267-A
Country	US
Kind code	B2
Filing date	Sep 2, 2015
Priority date	Sep 3, 2014
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

The present invention relates to a method of selective extraction of a platinoid, from a ceramic support containing a metal, comprising the following successive steps: a) the support is brought into contact, with an extraction medium consisting of a pressurized dense fluid containing an organic ligand that is selective for the metal and that is capable of forming a complex with the metal in the 0 state; whereby a ceramic support depleted in the metal, or even free of the metal, and, a medium consisting of the fluid containing the complex of the organic ligand with the metal in the 0 state are obtained; b) the fluid is brought back to atmospheric pressure and to ambient temperature, whereby the complex separates from the fluid; c) the ceramic support depleted in the metal, or even free of the metal, and the complex, are recovered.

First claim

The invention claimed is:

1. A method of selective extraction of a metal of the family of platinoids, from a ceramic support containing said metal, comprising the following successive steps:
a) said ceramic support containing said metal is brought into contact, in an extraction chamber, with an extraction medium consisting of a pressurized dense fluid and of an organic ligand that is selective for the metal and that is capable of forming a complex with said metal in the 0 state; whereby the complex with said metal in the 0 state is formed, and a ceramic support depleted in said metal, or, optionally, free of said metal, and a medium consisting of the pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state are obtained;
b) said pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state is brought back to atmospheric pressure and to ambient temperature, whereby the complex of the organic ligand with the metal in the 0 state separates from the fluid;
c) the ceramic support depleted in said metal, or, optionally free of said metal, and the complex of the organic ligand with the metal in the 0 state, are recovered,
wherein the pressurized dense fluid is at a pressure of 50 to 700 bars, and at a temperature from 15° C. to 200° C., and
wherein the organic ligand that is selective for the metal is selected from thiols of formula RSH, in which R represents a linear or branched alkyl group of 1 to 20 C.

2. A method according to claim 1 , wherein the metal of the family of platinoids is selected from the group consisting of platinum, palladium, rhodium, ruthenium, gold, silver, and alloys and mixtures thereof.

3. A method according to claim 1 , wherein the metal is in the form of nanoparticles dispersed on at least one external surface of the ceramic support and the metal is extracted in the form of nanoparticles of the metal in the (0) metal state.

4. A method according to claim 1 , wherein the fluid is selected from the group consisting of carbon dioxide; helium; xenon; nitrogen; nitrous oxide; sulphur hexafluoride; gaseous alkanes of 1 to 5 carbon atoms; gaseous fluorinated hydrocarbons; gaseous chlorinated and/or fluorinated hydrocarbons; ammonia; and mixtures thereof.

5. A method according to claim 1 , wherein the pressurized dense fluid is in the liquid state, dense gas state, or in the supercritical state.

6. A method according to claim 1 , wherein the organic ligand that is selective for the metal represents from 1 to 20% by weight of the extraction medium.

7. A method according to claim 1 , wherein, simultaneously to being brought into contact, the support and/or the extraction medium are subjected to a mechanical action.

8. A method according to claim 7 , wherein the mechanical action is selected from the group consisting of one or more among an agitation, a turbulence, a shear, an electromechanical action and an ultrasonic action.

9. A method according to claim 1 , which further comprises, at the end of step c), a step d) during which the metal is recovered from the complex.

10. A method according to claim 9 , wherein the metal is recovered from the complex by thermal treatment of the complex.

11. A method according to claim 1 , which is carried out in static mode, and which further comprises, prior to step a), a step a1):
a1) the ceramic support containing the metal, and the organic ligand that is selective for the metal and that is capable of forming a complex with said metal in the 0 state are placed in the extraction chamber, then the fluid is introduced into the extraction chamber, and a temperature and a pressure are established in the extraction chamber such that the fluid is dense and pressurized;

and wherein, during step b), the pressure in the extraction chamber is brought back to atmospheric pressure, the temperature is brought back to ambient temperature, the fluid is evacuated from the extraction chamber in the form of a stream of gas, the complex is carried away with the stream of gas, and optionally the complex is recovered in a separator placed at the outlet of the extraction chamber.

12. A method according to claim 11 , wherein during step a) the ceramic support containing the metal is brought into contact with the extraction medium for a duration of 1 to 24 hours.

13. A method according to claim 11 , wherein the proportion by weight of the ceramic support containing the metal compared to the volume of selective organic ligand is 0.01 g/mL to 0.5 g/mL.

14. A method according to claim 11 , wherein during step a1) the ceramic support containing said metal and the selective organic ligand are placed in the extraction chamber in such a way that the ceramic support containing the metal and the selective organic ligand are in direct contact.

15. A method according to claim 11 , wherein during step a1) the ceramic support containing said metal and the selective organic ligand are placed in the chamber in such a way that the ceramic support containing the metal and the selective organic ligand are not in direct contact.

16. A method according to claim 1 , which is carried out in dynamic mode, and which further comprises, prior to step a), steps a1), a2), and a3):
a1) the selective organic ligand is placed in a solubilization chamber in fluidic communication with the extraction chamber, and the ceramic support containing the metal is placed in the extraction chamber; then
a2) a stream of pressurized dense fluid is sent continuously into the solubilization chamber, whereby is obtained the extraction medium consisting of the pressurized dense fluid and of the selective organic ligand;
a3) a stream of the extraction medium is sent continuously into the extraction chamber;

and wherein, at the end of step a), a stream of the pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state is drawn off from the extraction chamber and sent into a reservoir in which steps b) then c) are carried out.

17. A method according to claim 16 , wherein, during step b), the pressure in the reservoir is brought back to atmospheric pressure, the temperature is brought back to ambient temperature and the fluid is evacuated from the reservoir in the form of a gas whereas the complex of the organic ligand with the metal in the 0 state remains in the reservoir.

18. A method according to claim 1 , wherein R represents a linear or branched alkyl group of 1 to 12 C.

Assignees

• Commissariat Energie Atomique

Inventors

• Goettmann Frédéric
• Hertz Audrey
• Mongin Sandrine

Classifications

• C22B7/009

  General processes for recovering metals or metallic compounds from spent catalysts (for recovering specific metals C22B11/00 - C22B61/00) · CPC title

• C22B11/048 Primary

  from spent catalysts · CPC title

• B22F2009/001

  from scrap particles · CPC title

• B01D11/0292

  Treatment of the solvent · CPC title

• B01D11/0203

  with a supercritical fluid · CPC title