Methods for synthesizing nanometer-sized manganese dioxides having ramsdellite-type crystal structures as well as methods for producing hydroxide ion-derived proton, electron and oxygen using manganese dioxides

Patent metadata

Field	Value
Publication number	US-9586836-B2
Application number	US-201113637499-A
Country	US
Kind code	B2
Filing date	Mar 25, 2011
Priority date	Mar 26, 2010
Publication date	Mar 7, 2017
Grant date	Mar 7, 2017

Abstract

By means of a series of wet multistage oxidation process comprising: Step 1 for adding an alkaline reagent to an aqueous solution of a manganese compound containing a divalent manganese thereby precipitating a manganese hydroxide; Step 2 for adding an aqueous hydrogen peroxide while keeping the temperature of the water of the aqueous solution comprising the manganese hydroxide at room temperature thereby converting into a manganese oxide; and also Step 3 for adding a dilute acid to the manganese oxide in a state where the water is coexisting, a nanometer-sized manganese dioxide having a ramsdellite-type crystal structure is obtained.

First claim

The invention claimed is:

1. A method for synthesizing a manganese dioxide comprising a series of wet multistage oxidation process comprising: Step 1 for adding an alkaline reagent to an aqueous solution of a manganese compound containing a divalent manganese thereby precipitating a manganese hydroxide; Step 2 for adding an aqueous hydrogen peroxide while keeping the temperature of the water of said aqueous solution at room temperature thereby converting said manganese hydroxide into a manganese oxide; and Step 3 for adding a dilute acid to said manganese oxide in a state where the water is coexisting thereby obtaining a nanometer-sized manganese dioxide having a ramsdellite-type crystal structure.

2. The method for synthesizing a manganese dioxide according to claim 1 wherein the compound containing the divalent manganese is a manganese chloride or a manganese sulfate.

3. A method for synthesizing a manganese dioxide comprising, after completing Step 3 of claim 1 , adding another aqueous solution of a manganese compound containing a divalent manganese to said nanometer-sized manganese dioxide and heating.

4. The method for synthesizing a manganese dioxide according to claim 3 wherein the another aqueous solution of a manganese compound containing a divalent manganese is acidic.

5. The method for synthesizing a manganese dioxide according to claim 3 wherein the compound containing the divalent manganese in the another aqueous solution is a manganese chloride or a manganese sulfate.

6. A method for producing a hydroxide ion-derived proton comprising the following steps:
(1) a step for adding an alkaline reagent to an aqueous solution of a manganese compound containing a divalent manganese thereby allowing a manganese hydroxide to be precipitated;
(2) a step for adding an aqueous hydrogen peroxide while keeping the temperature of the water of said aqueous solution at room temperature thereby converting said manganese hydroxide into a manganese oxide;
(3) a step for adding a dilute acid to said manganese oxide in a state where the water is coexisting thereby obtaining a nanometer-sized manganese dioxide having a ramsdellite-type crystal structure; and,
(4) a step for placing said manganese dioxide from step (3) in a water thereby producing a proton from a hydroxide ion contained in the water.

7. The method for producing a hydroxide ion-derived proton according to claim 6 wherein the pH of the water of step (4) is within the range of 4.5 to 10.

8. A method for charging a hydroxide ion-derived electron comprising the following steps:
(1) a step for adding an alkaline reagent to an aqueous solution of a manganese compound containing a divalent manganese thereby allowing a manganese hydroxide to be precipitated;
(2) a step for adding an aqueous hydrogen peroxide while keeping the temperature of the water of said aqueous solution at room temperature thereby converting said manganese hydroxide into a manganese oxide;
(3) a step for adding a dilute acid to said manganese oxide in a state where the water is coexisting thereby obtaining a nanometer-sized manganese dioxide having a ramsdellite-type crystal structure; and,
(4) a step for placing said manganese dioxide from step (3) in a water thereby allowing a hydroxide ion-derived electron contained in the water to be charged on a surface of said manganese dioxide.

9. The method for charging a hydroxide ion-derived electron according to claim 8 wherein the pH of the water of step (4) is within the range of 4.5 to 10.

10. A method for producing a hydroxide ion-derived oxygen comprising the following steps:
(1) a step for adding an alkaline reagent to an aqueous solution of a manganese compound containing a divalent manganese thereby allowing a manganese hydroxide to be precipitated;
(2) a step for adding an aqueous hydrogen peroxide while keeping the temperature of the water of said aqueous solution at room temperature thereby converting said manganese hydroxide into a manganese oxide;
(3) a step for adding a dilute acid to said manganese oxide in a state where the water is coexisting thereby obtaining a nanometer-sized manganese dioxide having a ramsdellite-type crystal structure; and,
(4) a step for placing said manganese dioxide from step (3) in a water thereby producing an oxygen gas from a hydroxide ion contained in the water.

11. The method for producing a hydroxide ion-derived oxygen according to claim 10 wherein the pH of the water of step (4) is within the range of 4.5 to 10.

12. A method for recovering a noble metal ion from a water comprising the following steps:
(1) a step for adding an alkaline reagent to an aqueous solution of a manganese compound containing a divalent manganese thereby allowing a manganese hydroxide to be precipitated;
(2) a step for adding an aqueous hydrogen peroxide while keeping the temperature of the water of said aqueous solution at room temperature thereby converting said manganese hydroxide into a manganese oxide;
(3) a step for adding a dilute acid to said manganese oxide in a state where the water is coexisting thereby obtaining a nanometer-sized manganese dioxide having a ramsdellite-type crystal structure; and,
(4) a step for adjusting the pH of an aqueous solution containing a noble metal, to which the manganese dioxide from step (3) is added, to pH 4.5 to 10, thereby allowing a noble metal ion in the aqueous solution to be deposited as a metal on a surface of said manganese dioxide.

13. A method for synthesizing a manganese dioxide comprising, after completing Step 3 of claim 2 , adding another aqueous solution of a manganese compound containing a divalent manganese to said nanometer-sized manganese dioxide and heating.

14. The method for synthesizing a manganese dioxide according to claim 13 wherein the another aqueous solution of a manganese compound containing a divalent manganese is acidic.

15. The method for synthesizing a manganese dioxide according to claim 13 wherein the compound containing the divalent manganese in the another aqueous solution is a manganese chloride or a manganese sulfate.

16. The method for synthesizing a manganese dioxide according to claim 4 wherein the compound containing the divalent manganese in the another aqueous solution is a manganese chloride or a manganese sulfate.

17. The method for synthesizing a manganese dioxide according to claim 14 wherein the compound containing the divalent manganese in the another aqueous solution is a manganese chloride or a manganese sulfate.

Assignees

• Koyanaka Hideki
• Tsujimoto Masahiko
• Univ Kyoto

Inventors

• Koyanaka Hideki
• Tsujimoto Masahiko

Classifications

• C01P2004/16

  Nanowires or nanorods, i.e. solid nanofibres with two nearly equal dimensions between 1-100 nanometer · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• C23C18/1637

  metallic substrate · CPC title

• C23C18/1635

  Composition of the substrate · CPC title

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title