Method for producing redox-active Ti(IV) coordination compounds

• US 9,409,842 B1
• Filed: 04/13/2015
• Issued: 08/09/2016
• Est. Priority Date: 04/13/2015
• Status: Active Grant

• Current Assignee: Tronox LLC (Tronox Holdings Plc)
• Original Assignee: Cristal Inorganic Chemicals Switzerland Ltd.
• Inventors: Goodman, Malcolm G., Fu, Guoyi
• Primary Examiner(s): Gonzalez, Porfirio Nazario
• Application Number:
  US14/685,291
• Time in Patent Office: 484 Days
• Field of Search: 556/54, 556/55, 556/56
• US Class Current: 1/1
• CPC Class Codes: C07C 37/66 by conversion of hydroxy groups to O-metal groups
• CPC Class Codes: C07C 51/418 Preparation of metal complexes containing carboxylic acid moieties
• CPC Class Codes: C07F 7/003 without C-Metal linkages
• CPC Class Codes: H01M 2300/0002 Aqueous electrolytes
• CPC Class Codes: H01M 8/188 by recharging of redox couples containing fluids; Redox flow type batteries
• CPC Class Codes: H01M 8/20 Indirect fuel cells, e.g. fuel cells with redox couple being irreversible H01M8/18 takes precedence
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A method for producing an aqueous solution of a redox-active coordination compound of a transition metal which can be used directly as an electrolyte in a flow battery wherein the method comprises reacting a freshly precipitated hydrous transition metal oxide with a chelating agent and a base in an aqueous reaction medium to produce a solution of the corresponding redox-active transition metal coordination compound.

Claims

1. A method for producing a redox-active coordination compound of a transition metal selected from the group consisting essentially of titanium, aluminum, chromium, iron, vanadium, manganese, cerium, and uranium which comprises:

(a) precipitating a soluble salt of the transition metal with a base in an aqueous reaction medium to form freshly precipitated hydrous transition metal oxide;

(b) separating the freshly precipitated hydrous transition metal oxide from the aqueous reaction medium; and

(c) reacting the freshly precipitated hydrous transition metal oxide with a chelating agent and a base in a second aqueous reaction medium to produce a solution of the corresponding redox-active transition metal coordination compound.

2. The method of claim 1 wherein the redox-active coordination compound is Ti(IV) and the method comprises:

(a) precipitating a soluble titanium salt with a base in an aqueous reaction medium to form freshly precipitated hydrous titanium oxide;

(b) separating the freshly precipitated hydrous titanium oxide from the aqueous reaction medium; and

(c) reacting the freshly precipitated hydrous titanium oxide with a chelating agent and a base in a second aqueous reaction medium to produce a solution of the corresponding redox-active Ti(IV) coordination compound.

3. The method of claim 2 wherein the freshly precipitated hydrous titanium oxide in step (b) is separated by filtration and washing with water.

4. The method of claim 2 which includes the additional steps of:

(d) crystallizing the corresponding Ti(IV) coordination compound to form a crystalline solid; and

(e) separating the crystalline solid from the aqueous solution.

5. The method of claim 2 wherein the soluble titanium salt in step (a) is selected from TiOCl₂ and TiOSO₄, and the base in step (a) is selected from NaOH, KOH, and NH₄OH.

6. A method for producing a Ti(IV) redox-active coordination compound which comprises:

(a) precipitating a metalloorganic compound of titanium with water to form freshly precipitated hydrous titanium oxide;

(b) separating the freshly precipitated hydrous titanium oxide from the aqueous reaction medium; and

(c) reacting the freshly precipitated hydrous titanium oxide with a chelating agent and a base in a second aqueous reaction medium to produce a solution of the corresponding redox-active Ti(IV) coordination compound.

7. The method of claim 6 wherein the metalloorganic compound of titanium is selected from the group consisting essentially of titanium tetraisopropoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetraethoxide, and titanium tetramethoxide.