Method for producing highly pure platinum powder, as well as platinum powder that can be obtained according to said method, and use thereof
View Patent ↗A method for producing highly pure platinum on an industrial scale, as well as the use of said highly pure platinum. According to the method, a hexahalogenoplatinate is reduced to platinum in acidic conditions.
1. Method for producing highly pure platinum, comprising:
producing a mixture comprising a nitrogen-containing hexahalogenoplatinate and water having a pH value of 0 to 4;
heating the mixture to a temperature of 30° C. or higher;
carrying out a reduction of the mixture at a pH value during the reduction of 0 to 4 in order to precipitate platinum in the form of a platinum sponge.
2. Method according to claim 1 , further comprising:
producing the mixture comprising a nitrogen-containing hexahalogenoplatinate and water by a process comprising adjusting the pH of a precursor of said mixture to a pH value to 0 to 4;
heating the mixture to a temperature of 30° C. or higher;
adding a reduction agent to the mixture in order to precipitate platinum in the form of a platinum sponge.
3. Method according to claim 1 , wherein
the hexahalogenoplatinate has a solubility in water of 8 g/1,000 mL or less at 20° C.
4. Method according to claim 1 , wherein the hexahalogenoplatinate is a hexachloroplatinate.
5. Method according to claim 1 , wherein the nitrogen-containing hexahalogenoplatinate forms, in the presence of a reducing agent, platinum in the form of a platinum sponge and a heat-decomposable salt and/or water-soluble salt as side product.
6. Method according to claim 1 , wherein the hexahalogenoplatinate is ammonium hexachloroplatinate.
7. Method according to claim 1 , wherein the mixture is heated to 35 to 80° C., optionally while stirring it.
8. Method according to claim 1 , wherein the the temperature is kept below 80° C. while adding a reducing agent.
9. Method according to claim 1 , wherein the temperature of the resulting reaction mixture is adjusted to 85° C. or higher after adding a reducing agent.
10. Method according to claim 9 , wherein the temperature of the resulting reaction mixture is adjusted to be 90° C. or higher after adding the reducing agent, for 1 to 10 hours.
11. Method according to claim 1 , which further comprises adding a reducing agent, wherein the reducing agent comprises hydrazine, hydrazine-hydrate, hydrazine hydrohalogenide, ascorbic acid, formic acid, oxalic acid and/or hydroquinone or hydroquinone derivatives and mixtures of said reducing agents.
12. Method according to claim 11 , wherein the reducing agent is selected from hydrazine, hydrazine-hydrate, and hydroquinone.
13. Method according to claim 1 , wherein the nitrogen-containing hexahalogenoplatinate is produced by converting a solution of a dihydrogen hexahalogenoplatinate in acidic conditions into a nitrogen-containing hexahalogenoplatinate.
14. Method according to claim 1 , wherein the nitrogen-containing hexahalogenoplatinate is produced by converting a solution of a dihydrogen hexahalogenoplatinate in the presence of ammonium chloride into ammonium hexahalogenoplatinate.
15. Method according to claim 14 , wherein the dihydrogen hexahalogenoplatinate is a dihydrogen hexachloroplatinate that is converted into ammonium hexachloroplatinate in the presence of ammonium chloride, optionally with the ammonium hexachloroplatinate forming a precipitate.
16. Method according to claim 13 , wherein the solution of the dihydrogen hexahalogenoplatinate is produced by contacting a dissolved hexahalogenoplatinate to an acidic ion exchanger.
17. Method according to claim 16 , wherein the solution of the dihydrogen hexahalogenoplatinate is produced by contacting an alkali hexahalogenoplatinate or an ammonium hexahalogenoplatinate to an acidic ion exchanger.
18. Method according to claim 17 , wherein the solution of the dihydrogen hexahalogenoplatinate is produced by contacting a potassium hexahalogenoplatinate or an ammonium hexahalogenoplatinate to an acidic ion exchanger.
19. Method according to claim 1 , wherein the platinum sponge is separated, optionally washed, and heat treated at a temperature of 350° C. or higher.
20. Method according to claim 1 , comprising the steps:
(i) producing a solution comprising dihydrogen hexachloroplatinate through contacting a dissolved hexachloroplatinate to an acidic ion exchanger;
(ii) producing a nitrogen-containing hexachloroplatinate through converting the dihydrogen hexachloroplatinate solution in acidic conditions into a nitrogen-containing hexachloroplatinate;
(iii) producing a mixture comprising the nitrogen-containing hexachloroplatinate and water, adjusting the pH value of 0 to 4;
(iv) heating the mixture to a temperature of 30° C. or higher;
(v) adding a reducing agent and reducing the mixture at a pH value of 0to 4;
(vi) precipitating platinum in the form of a platinum sponge;
(vii) separating the platinum sponge, optionally washing the platinum sponge with hydrochloric acid and fully deionised water;
(viii) heat-treating the platinum sponge at a temperature above 350° C.
21. Method according to claim 1 , wherein partial steps or the entire method can be implemented in continuous manner.
22. Method according to claim 1 , which is feasible to produce 5 kg or more of highly pure platinum/24 hours with the method.
23. Method according to claim 20 , wherein the dihydrogen hexachloroplatinate is converted in the presence of ammonium chloride into ammonium hexachloroplatinate forming a precipitate of the nitrogen-containing hexachloroplatinate.