# US 8,465,701 B2 · Catalyst material for producing oxygen gas from water

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- Number: US 8,465,701 B2
- Document ID: US8465701B2
- Status: Granted
- Kind: B2
- Application number: 12/450,430
- Filed: 2008-03-25
- Published: 2010-08-05
- Granted: 2013-06-18
- Earliest claimed: 2007-03-27
- Assignees: Kyoto University
- Applicants: Hideki Koyanaka
- Inventors: Hideki Koyanaka
- Web page: https://patentgrep.com/patent/US8465701B2

## CPC

- B01J 35/613: {10-100 m2/g}
- B01J 23/34: Manganese
- B01J 35/45: Nanoparticles
- B01J 35/58: Fabrics or filaments
- B01J 35/615: {100-500 m2/g}
- B01J 35/633: {less than 0.5 ml/g}
- B01J 35/647: {2-50 nm}
- B01J 35/70: characterised by their crystalline properties, e.g. semi-crystalline (catalysts comprising carbon B01J21/18; molecular sieves B01J29/00)
- B01J 37/08: Heat treatment {(B01J37/0009, B01J37/0018 take precedence)}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- C01B 13/0207: {Water}
- C01G 45/024: Manganese dioxide
- H01M 4/8621: {containing only metallic or ceramic material, e.g. made by sintering or sputtering}
- H01M 4/9016: {Oxides, hydroxides or oxygenated metallic salts}
- H01M 4/92: Metals of platinum group (H01M4/94 {, H01M4/9058} take precedence)
- H01M 8/1016: characterised by the electrolyte material (H01M8/12 takes precedence)
- H01M 8/1246: the electrolyte consisting of oxides
- B01J 2235/00: Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties
- B01J 2235/15: X-ray diffraction
- B01J 2235/30: Scanning electron microscopy; Transmission electron microscopy
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01P 2004/02: obtained by optical microscopy
- C01P 2004/04: obtained by TEM, STEM, STM or AFM
- C01P 2004/10: extending in one dimension, e.g. needle-like
- C01P 2004/45: Aggregated particles or particles with an intergrown morphology
- C01P 2004/61: Micrometer sized, i.e. from 1-100 micrometer
- C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer
- C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer
- C01P 2006/12: Surface area
- C01P 2006/14: Pore volume
- C01P 2006/16: Pore diameter
- C01P 2006/17: Pore diameter distribution
- H01M 2300/0071: Oxides
- Y02E 60/50: Fuel cells
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01G: COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts or peroxyacids C01B15/00; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium, or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds containing nitrogen, other non-metals and metal C01B21/082}; metal amides C01B21/092; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanamide C01C3/16; thiocyanates C01C3/20)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Provided is a catalyst material comprising aggregates of nanoneedles of mainly R-type manganese dioxide and having a mesoporous structure. With this, water can be oxidatively decomposed under visible light at room temperature to produce oxygen gas, proton and electron. Also provided is a catalyst material comprising aggregates of nanoparticles of mainly hydrogenated manganese dioxide. With this, acetic acid or an inorganic substance can be synthesized from carbon dioxide gas.

## Claims

### Claim 1

A catalyst material for producing oxygen gas, proton and electron by oxidatively decomposing water, which comprises aggregates of nanoneedles of mainly R-type manganese dioxide and has a mesoporous structure.

### Claim 2 (depends on 1)

The catalyst material as claimed in claim 1, wherein the mesoporous structure has a mean pore diameter falling within a range of from 3 nm to 30 nm, a BET specific surface area of from 40 to 200 m2/g, and a total pore volume falling within a range of from 0.1 to 0.5 cm3/g.

### Claim 3 (depends on 1, 2)

The catalyst material as claimed in claim 1 or 2, wherein the manganese dioxide nanoneedles have a diameter falling within a range of from 1 nm to 50 nm and a length falling within a range of from 3 nm to 500 nm.

### Claim 4 (depends on 1, 2)

The catalyst material as claimed in claim 1 or 2, wherein the manganese dioxide aggregates have a diameter falling within a range of from 1 to 100 μm.

### Claim 5

A catalyst material for producing acetic acid or an organic substance from carbon dioxide gas, which comprises aggregates of nanoparticles of mainly hydrogenated manganese dioxide having an R-type crystal structure and an epsilon-type crystal structure.

### Claim 6 (depends on 5)

The catalyst material as claimed in claim 5, wherein the aggregates of nanoparticles of hydrogenated manganese dioxide are aggregates of nanoneedles of hydrogenated manganese dioxide and have a mesoporous structure.

### Claim 7 (depends on 6)

The catalyst material as claimed in claim 6, wherein the mesoporous structure has a mean pore diameter falling within a range of from 3 nm to 30 nm, a BET specific surface area of from 40 to 200 m2/g, and a total pore volume falling within a range of from 0.1 to 0.5 cm3/g.

### Claim 8 (depends on 6, 7)

The catalyst material as claimed in claim 6 or 7, wherein the hydrogenated manganese dioxide nanoneedles have a diameter falling within a range of from 1 nm to 50 nm and a length falling within a range of from 3 nm to 500 nm.

### Claim 9 (depends on 6, 7)

The catalyst material as claimed in claim 6 or 7, wherein the aggregates of hydrogenated manganese dioxide nanoneedles have a diameter falling within a range of from 1 to 100 μm.

### Claim 10

A method for producing a catalyst material for producing oxygen gas, proton and electron by oxidatively decomposing water, which comprises burning a divalent manganese compound, followed by acid-treating and thereafter drying the compound,
wherein the divalent manganese compound is manganese carbonate.

### Claim 11 (depends on 10)

The method for producing a catalyst material as claimed in claim 10, wherein the compound is, after dried, further washed with water or with hot water.

### Claim 12

A method for producing a catalyst material for producing acetic acid or an organic substance from carbon dioxide gas, which comprises burning a divalent manganese compound, and then acid-treating the compound,
wherein the divalent manganese compound is manganese carbonate.

### Claim 13 (depends on 12)

The method for producing a catalyst material as claimed in claim 12, wherein the divalent manganese compound is, after burned and acid-treated, further washed with water.

### Claim 14 (depends on 12)

The method for producing a catalyst material as claimed in claim 12, wherein the divalent manganese compound is, after burned and acid-treated, further dried and the acid-treated.

### Claim 15 (depends on 14)

The method for producing a catalyst material as claimed in claim 14, wherein the compound is, after dried and before acid-treated, washed with water or with hot water.

### Claim 16 (depends on 1, 2)

A method for producing oxygen gas from water by using a catalyst material of claim 1 or 2, wherein the catalyst material is contacted with an aqueous acid solution under visible light to produce oxygen gas.

### Claim 17 (depends on 5, 6, 7)

A method for synthesizing acetic acid or an organic substance by decomposing carbon dioxide gas by the use of a catalyst material of any of claims 5 to 7, wherein carbon dioxide gas is contacted with the catalyst material in the presence of an aqueous acid solution.

### Claim 18 (depends on 1, 2)

A method for generating electric energy by using a catalyst material of claim 1 or 2, wherein the catalyst material is contacted with an aqueous acid solution under visible light.

### Claim 19 (depends on 1, 2)

A hydrogen gas sensor comprising a catalyst material of claim 1 or 2, a pair of electrodes connected to each other via the catalyst material, and a voltage detecting unit for detecting the potential difference between the electrodes, wherein hydrogen gas introduced to the side of one electrode connected with the electrode material is contacted with the electrode in the presence of water, the hydrogen ion thus generated dissolves in water to be an aqueous acid solution, the acid solution is contacted with the catalyst and decomposed to generate electric energy, and the resulting potential difference between the electrodes is detected with the voltage detecting unit to thereby detect the hydrogen gas.

### Claim 20

A method for synthesizing acetic acid, comprising the steps of:
Burning a manganese carbonate and acid-treating it with an acid-treating liquid to obtain carbon dioxide gas and a paste of aggregates of nanoparticles of mainly hydrogenated manganese dioxide having an R-type crystal structure and an epsilon-type crystal structure, and
contacting the paste of aggregates of nanoparticles with the carbon dioxide gas to obtain acetic acid.

### Claim 21

A method for synthesizing a saccharide, comprising the steps of:
burning a manganese carbonate and acid-treating it with an acid-treating liquid to obtain a paste of aggregates of nanoparticles of mainly hydrogenated manganese dioxide having an R-type crystal structure and an epsilon-type crystal structure, and
drying the paste of aggregates of nanoparticles in air, wherein a liquid containing saccharide is bled out from the paste of aggregates of nanoparticles.

### Claim 22

A method for recycling an acid-treatment liquid (waste liquid), which comprises burning a divalent manganese compound, followed by acid-treating the compound to obtain the acid-treatment liquid, adding an oxidizing agent and an alkali compound to the acid-treatment liquid to thereby precipitate manganese oxide, then acid-treating, and drying the manganese oxide precipitate to obtain R-type manganese dioxide.

### Claim 23 (depends on 22)

The method for recycling an acid-treatment liquid according to claim 22, wherein the divalent manganese compound is manganese carbonate.

### Claim 24

A method for recycling an acid-treatment liquid (waste liquid), which comprises burning a divalent manganese compound, followed by acid-treating the compound to obtain the acid-treatment liquid, and adding potassium permanganate to the acid-treatment liquid to obtain manganese dioxide.

### Claim 25 (depends on 24)

The method for recycling an acid-treatment liquid according to claim 24, wherein the divalent manganese compound is manganese carbonate.

### Claim 26

A method for recycling an acid-treatment liquid (waste liquid), which comprises burning a divalent manganese compound, followed by acid-treating the compound to obtain the acid-treatment liquid, and adding an alkali metal or alkaline earth metal carbonate to the acid-treatment liquid to obtain manganese carbonate.

### Claim 27 (depends on 26)

The method for recycling an acid-treatment liquid according to claim 26, wherein the divalent manganese compound is manganese carbonate.