Nitrogen oxide storage material and exhaust gas purification method

Patent metadata

Field	Value
Publication number	US-11298674-B2
Application number	US-201916375369-A
Country	US
Kind code	B2
Filing date	Apr 4, 2019
Priority date	Apr 24, 2018
Publication date	Apr 12, 2022
Grant date	Apr 12, 2022

Abstract

An object of the present disclosure is to provide an NOx storage material having sufficient NOx storage capacity even in a low temperature region and a production method thereof.An NOx storage material including a composite oxide of silver and gallium. The composite oxide of silver and gallium is preferably a delafossite-type composite oxide. The composite oxide is produced by dissolving a silver salt and a gallium salt in a solvent and baking the solution, wherein the molar ratio of silver:gallium is preferably from 2:8 to 7:3.

First claim

What is claimed is:

1. An NOx storage material comprising a composite oxide of silver and gallium and an exhaust gas purification device having a catalyst metal downstream of said NOx storage material, wherein the concentration of the composite oxide is 1.7 mmol/g or more and the composite oxide is a delafossite-type composite oxide.

2. The NOx storage material and exhaust gas purification device according to claim 1 , wherein the composite oxide further contains aluminum.

3. A method for producing the NOx storage material according to claim 1 , comprising dissolving salts of metals constituting the composite oxide in a solvent, and baking the solution.

4. The method according to claim 3 , wherein the molar ratio of silver:gallium or silver:(gallium+aluminum) in the composite oxide is from 2:8 to 7:3.

5. An NOx storage device having the NOx storage material according to claim 1 .

6. An exhaust gas purification method comprising causing an exhaust gas discharged from an internal combustion engine to flow through the NOx storage device according to claim 5 and then flow through an exhaust gas purification device having a catalyst metal.

Assignees

• Toyota Motor Co Ltd

Inventors

• Nagata Naoto
• Shimoyama Daisuke

Classifications

• F01N3/0814

  combined with catalytic converters, e.g. NOx absorption/storage reduction catalysts · CPC title

• B01D53/9422 Primary

  for removing nitrogen oxides by NOx storage or reduction by cyclic switching between lean and rich exhaust gases (LNT, NSC, NSR) · CPC title

• F01N3/10

  by thermal or catalytic conversion of noxious components of exhaust · CPC title

• B01D2255/20738

  Iron · CPC title

• B01J20/28059

  being less than 100 m2/g · CPC title