Catalysts reforming methane gases into hydrogen and methods for synthesizing the same, and methods for reforming methane gases using said catalysts

Patent metadata

Field	Value
Publication number	US-9295975-B2
Application number	US-201113807178-A
Country	US
Kind code	B2
Filing date	Jun 24, 2011
Priority date	Jun 28, 2010
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A method for synthesizing a catalyst which reforms a methane gas into a hydrogen gas efficiently at a relatively low temperature comprising a palladium deposition step in which a manganese dioxide having a ramsdellite-type crystal structure is immersed in a palladium-containing aqueous solution to allow the palladium to be deposited on the surface of said manganese dioxide, and a heat treatment step in which said manganese dioxide having the palladium deposited thereon is heated under a reducing atmosphere to change said manganese dioxide to a manganese oxide Mn 3 O 4 having the palladium carried thereon.

First claim

The invention claimed is:

1. A method for synthesizing a methane gas reforming catalyst which is a method for synthesizing a catalyst which reforms a methane gas into a hydrogen gas comprising:
a palladium deposition step in which a manganese dioxide having a ramsdellite-type crystal structure is immersed in a palladium-containing aqueous solution to allow a metallic palladium having a particle size of 10 nm or less to be deposited on a surface of said manganese dioxide in the solution, and
a heat treatment step in which said manganese dioxide having the metallic palladium deposited thereon is heated under a gas mixture of methane gas and argon gas atmosphere to change said manganese dioxide to a manganese oxide Mn 3 O 4 having the metallic palladium carried thereon.

2. The method for synthesizing a methane gas reforming catalyst according to claim 1 wherein said heat treatment step involves heating said manganese dioxide having the metallic palladium deposited thereon under the gas mixture atmosphere at a temperature of 150° C. to 700° C.

3. The method for synthesizing a methane gas reforming catalyst according to claim 1 wherein said manganese dioxide having the ramsdellite-type crystal structure employed in said palladium deposition step is obtained by adding to an aqueous solution of a manganese compound comprising a divalent manganese ion, an alkali reagent to precipitate a manganese hydroxide, further adding an aqueous hydrogen peroxide to convert said manganese hydroxide to a manganese oxide, followed by recovering this manganese oxide which is then brought into contact with a dilute acid.

4. The method for synthesizing a methane gas reforming catalyst according to claim 2 wherein said manganese dioxide having the ramsdellite-type crystal structure employed in said palladium deposition step is obtained by adding to an aqueous solution of a manganese compound comprising a divalent manganese ion, an alkali reagent to precipitate a manganese hydroxide, further adding an aqueous hydrogen peroxide to convert said manganese hydroxide to a manganese oxide, followed by recovering this manganese oxide which is then brought into contact with a dilute acid.

Assignees

• Koyanaka Hideki
• Tsujimoto Masahiko
• Univ Kyoto

Inventors

• Koyanaka Hideki
• Tsujimoto Masahiko

Classifications

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J35/70

  characterised by their crystalline properties, e.g. semi-crystalline (catalysts comprising carbon B01J21/18; molecular sieves B01J29/00) · CPC title

• B01J35/393

  Metal or metal oxide crystallite size · CPC title

• C01B2203/1064

  Platinum group metal catalysts · CPC title