Method for producing conductive mayenite compound powder

Patent metadata

Field	Value
Publication number	US-9573822-B2
Application number	US-201314423303-A
Country	US
Kind code	B2
Filing date	Aug 20, 2013
Priority date	Aug 30, 2012
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

If a conductive mayenite compound having a large specific surface area is obtained, the usefulness thereof in respective applications is remarkably increased. A conductive mayenite compound powder having a conduction electron density of 10 15 cm −3 or more and a specific surface area of 5 m 2 g −1 or more is produced by: (1) a step for forming a precursor powder by subjecting a mixture of a starting material powder and water to a hydrothermal treatment; (2) a step for forming a mayenite compound powder by heating and dehydrating the precursor powder; (3) a step for forming an activated mayenite compound powder by heating the compound powder in an inert gas atmosphere or in a vacuum; and (4) a step for injecting electrons into the mayenite compound through a reduction treatment by mixing the activated mayenite compound powder with a reducing agent.

First claim

The invention claimed is:

1. A method for producing a mayenite compound, the method comprising:
(1) a step of forming a precursor powder of a mayenite compound by subjecting a mixture of a raw material powder of the mayenite compound and water to a hydrothermal treatment;
(2) a step of forming a mayenite compound powder by dehydrating the precursor powder by heating;
(3) a step of forming an activated mayenite compound powder by heating the mayenite compound powder in an inert gas atmosphere or in a vacuum in a temperature range of 400° C. to 1,000° C. for three hours or more; and
(4) a step of injecting electrons into the mayenite compound by mixing the activated mayenite compound powder with a reducing agent and heating the resulting mixture in a temperature range of 400° C. to 1,100° C. to conduct a reduction treatment,
wherein a conductive mayenite compound powder having a conduction electron concentration of 10 15 cm −3 or more and a specific surface area of 5 m 2 g −1 or more is obtained.

2. The method for producing a mayenite compound according to claim 1 , further comprising, after the step (4), (5) a step of repeating a rapid thermal annealing process including increasing a temperature at a rate of 30 to 60° C. min −1 and holding under heating in a range of 900° C. to 1,100° C.

3. The method for producing a mayenite compound according to claim 1 , wherein the mayenite compound is 12CaO.7Al 2 O 3 .

4. The method for producing a mayenite compound according to claim 1 , wherein the reducing agent is Ca or CaH 2 .

Assignees

• Tokyo Inst Tech
• Japan Science & Tech Agency

Inventors

• Hosono Hideo
• Hara Michikazu
• Inoue Yasunori
• Kitano Masaaki
• Hayashi Fumitaka
• Yokoyama Toshiharu
• Matsuishi Satoru
• Toda Yoshitake

Classifications

• C01B33/26

  Aluminium-containing silicates {, i.e. silico-aluminates} · CPC title

• B01J37/347

  Ionic or cathodic spraying; Electric discharge · CPC title

• B01J37/16

  Reducing · CPC title

• B01J21/16 Primary

  Clays or other mineral silicates · CPC title

• Y10T428/2982

  Particulate matter [e.g., sphere, flake, etc.] · CPC title