US2012199787A1PendingUtilityA1

Aqueous solution of chromium salt and method for producing same

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Assignee: KOTAKI HIDEKIPriority: Dec 10, 2003Filed: Dec 27, 2011Published: Aug 9, 2012
Est. expiryDec 10, 2023(expired)· nominal 20-yr term from priority
Inventors:Hideki KotakiTomohiro BandaTakashi HaraNobuo Takagi
C01G 37/04C23C 22/46C23C 2222/10C01B 25/37C01G 37/14C23C 22/47C01G 37/00
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Claims

Abstract

Disclosed is an aqueous solution of a chromium salt, in which the oxalic acid content is 8% by weight or less relative to chromium. In the aqueous solution of the chromium salt, the total organic carbon content is 4% by weight or less relative to chromium. The chromium salt is preferably a chromium chloride, a chromium phosphate, or a chromium nitrate. The chromium chloride preferably contains a basic chromium chloride represented by the composition formula Cr(OH) x Cl y (wherein 0<x≦2, 1≦y<3, and x+y=3). The chromium phosphate is preferably one represented by the composition formula Cr(H 3-3/n PO 4 ) n (wherein n is a number satisfying 2≦n≦3). The chromium nitrate is preferably a basic chromium nitrate represented by the composition formula Cr(OH) x (NO 3 ) y (wherein 0<x≦2, 1≦y<3, and x+y=3).

Claims

exact text as granted — not AI-modified
1 - 23 . (canceled) 
     
     
         24 . An aqueous solution of a chromium phosphate, wherein the chromium phosphate is represented by the composition formula Cr(H 3-3/n PO 4 ) n  (wherein n is a number satisfying 2≦n≦3) and substantially no hexavalent chromium is present in the aqueous solution, and wherein an oxalic acid content is 8% by weight or less relative to chromium, and a total organic carbon content is 4% by weight or less relative to chromium. 
     
     
         25 . The aqueous solution of the chromium phosphate according to  claim 24 , wherein concentrations of impurity metal ions in the aqueous solution satisfy Na≦30 ppm and Fe≦20 ppm. 
     
     
         26 . The aqueous solution of the chromium phosphate according to  claim 24 , wherein concentrations of impurity anions in the aqueous solution satisfy Cl≦10 ppm and SO 4 ≦100 ppm. 
     
     
         27 . The aqueous solution of the chromium phosphate according to  claim 24 , wherein the aqueous solution is obtained by a method comprising the step of mixing phosphoric acid with an aqueous solution of chromic acid in advance to increase an acidity in a reaction system, and then adding an organic reducing agent. 
     
     
         28 . The aqueous solution of the chromium phosphate according to  claim 27 , wherein the organic reducing agent is methanol or ethylene glycol. 
     
     
         29 . The aqueous solution of the chromium phosphate according to  claim 28 , wherein the organic reducing agent is methanol. 
     
     
         30 . A method for producing an aqueous solution of a chromium phosphate, wherein the chromium phosphate is represented by the composition formula Cr(H 3-3/n PO 4 ) n  (wherein n is a number satisfying 2≦n≦3) and substantially no hexavalent chromium is present in the aqueous solution,
 the method comprising the step of adding phosphoric acid and at least one organic reducing agent selected from monohydric alcohols and dihydric alcohols to an aqueous solution of chromic acid. 
 
     
     
         31 . The method according to  claim 30 , wherein phosphoric acid is mixed with the aqueous solution of chromic acid in advance to increase an acidity in a reaction system, and then the organic reducing agent is added. 
     
     
         32 . The method according to  claim 30 , wherein the organic reducing agent is methanol or ethylene glycol. 
     
     
         33 . The method according to  claim 32 , wherein the organic reducing agent is methanol.

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