US2025313981A1PendingUtilityA1

Method of manufacturing a platinum complex for plating

57
Assignee: JOHNSON MATTHEY PLCPriority: Aug 4, 2022Filed: Jul 21, 2023Published: Oct 9, 2025
Est. expiryAug 4, 2042(~16 yrs left)· nominal 20-yr term from priority
Inventors:Alan BoardmanDavid Ian James KreigerNigel Anthony Powell
C25D 3/50
57
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Claims

Abstract

A method of manufacturing a plating solution comprising a platinum (II) complex, comprising the steps of: (i) preparing an acidic aqueous solution comprising a chloride-free platinum (IV) compound and a source of nitrous acid (HNO2) as a reducing agent; (ii) heating the solution from step (i) in order to promote the reduction of platinum (IV) to platinum (II) and decomposition of residual nitrous acid. Also described is a platinum plating solution produced by this process.

Claims

exact text as granted — not AI-modified
1 . A method of manufacturing a plating solution comprising a platinum (II) complex, comprising the steps of:
 (i) preparing an acidic aqueous solution comprising a chloride-free platinum (IV) compound and a source of nitrous acid (HNO 2 ) as a reducing agent;   (ii) heating the solution from step (i) in order to promote the reduction of platinum (IV) to platinum (II) and decomposition of residual nitrous acid.   
     
     
         2 . The method according to  claim 1 , wherein the source of nitrous acid in step (i) is a metal nitrite salt. 
     
     
         3 . The method according to  claim 2 , wherein the molar ratio of Pt(IV) nitrite at the beginning of step (i) is between 1:2 to 1:10. 
     
     
         4 . (canceled) 
     
     
         5 . The method according to m wherein the source of nitrous acid is selected from magnesium nitrite, calcium nitrite or strontium nitrite. 
     
     
         6 . The method according to  claim 1 , wherein the source of nitrous acid is a M x [Pt(NO 2 ) 4 ] salt, where x=2 when M has a charge of +1 and x=1 when M has a charge of +2. 
     
     
         7 . (canceled) 
     
     
         8 . The method according to  claim 1 , wherein the platinum (IV) compound is hexahydroxyplatinic (IV) acid (H 2 Pt(OH) 6 ) or a salt thereof. 
     
     
         9 . The method according to  claim 1 , wherein the pH of the solution in step (i) is <6. 
     
     
         10 . (canceled) 
     
     
         11 . The method according  claim 1 , wherein an acid is added in step (i). 
     
     
         12 - 15 . (canceled) 
     
     
         16 . The method according to  claim 1 , wherein the mixture from step (i) is heated to a temperature of at least 50° C. in step (ii). 
     
     
         17 . The method according to  claim 1 , comprising a subsequent step of using the product of step (ii) for plating. 
     
     
         18 . A method according to  claim 1 , wherein the source of nitrous acid is a metal nitrite and comprising a step (iii) of adding an acid or salt and precipitating the metal countercation of the source of nitrous acid as a salt. 
     
     
         19 . The method according to  claim 18 , wherein the acid is oxalic acid and a metal oxalate is precipitated. 
     
     
         20 . The method according to  claim 18 , wherein the source of nitrous acid is selected from magnesium nitrite, calcium nitrite or strontium nitrite, the acid is oxalic acid and magnesium oxalate, calcium oxalate or strontium oxalate is precipitated in step (iii). 
     
     
         21 . The method according to  claim 18 , wherein the acid is phosphoric acid and a metal phosphate is precipitated. 
     
     
         22 . The method according to  claim 18 , wherein the source of nitrous acid is selected from magnesium nitrite, calcium nitrite or strontium nitrite, the acid is phosphoric acid and magnesium phosphate, calcium phosphate or strontium phosphate is precipitated in step (iii). 
     
     
         23 . The method according to  claim 18 , wherein the acid is sulfuric acid and a metal sulfate is precipitated. 
     
     
         24 . The method according to  claim 18 , wherein the source of nitrous acid is selected from magnesium nitrite, calcium nitrite or strontium nitrite, the acid is sulfuric acid and magnesium sulfate, calcium sulfate or strontium sulfate is precipitated in step (iii). 
     
     
         25 . The method according to  claim 18 , wherein the source of nitrous acid is selected from calcium nitrite or strontium nitrite, the acid is sulfuric acid and calcium sulfate or strontium sulfate is precipitated in step (iii). 
     
     
         26 . The method according to  claim 18 , comprising a subsequent step of using the product of step (iii) for plating. 
     
     
         27 . A platinum plating solution produced by the process according to  claim 1 .

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