Catalyst for direct NOx decomposition and a method of forming and using the catalyst

Patent metadata

Field	Value
Publication number	US-9868111-B2
Application number	US-201615055555-A
Country	US
Kind code	B2
Filing date	Feb 27, 2016
Priority date	Feb 27, 2016
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A process of forming a direct NOx catalyst includes the steps of providing a palladium salt, providing a silicon oxide support material, mixing the palladium salt and silicon oxide support material in an aqueous solution, evaporating the aqueous solution forming a solid, calcining the solid, and then exposing the calcined solid to a pretreatment gas at a specified temperature to form a desired direct NOx catalyst. When the process includes exposing the calcined solid to helium gas at a temperature of from 650 to 1000° C. the catalyst may include a mixture of palladium and palladium oxide having a particle size of from 5 to 150 nm where the palladium particles are discrete particles without sintering and the mixture may include 41% by weight palladium oxide and 51% by weight palladium metal.

First claim

What is claimed is:

1. A process of forming a direct NOx catalyst comprising the steps of:
providing a palladium salt;
providing a silicon oxide support material;
mixing the palladium salt and silicon oxide support material in an aqueous solution;
evaporating the aqueous solution forming a solid;
calcining the solid;
treating the calcined solid to helium gas at a temperature of from 650-1000° C. forming the direct NOx catalyst.

2. The process of claim 1 wherein the palladium salt is selected from the group consisting of: nitrates, chlorides and acetates.

3. The process of claim 1 wherein the step of calcining includes exposing the solid to a temperature of from 450° C. to 650° C. for a time period of from 3 to 10 hours.

4. The process of claim 1 wherein the formed direct NOx catalyst includes a mixture of palladium and palladium oxide having a particle size of from 5-150 nm wherein the palladium particles are discrete particles without sintering.

5. The process of claim 1 wherein the formed direct NOx catalyst includes 41% by weight palladium oxide and 51% by weight palladium metal.

6. The process of claim 1 wherein the formed direct NOx catalyst has a NOx conversion of from 20 to 40% at a temperature of from 300 to 500° C.

7. The process of claim 1 wherein the formed direct NOx catalyst has a NOx conversion of from 0 to 25% at a temperature of from 650 to 800° C.

8. A process of forming a direct NOx catalyst comprising the steps of:
providing a palladium salt;
providing a silicon oxide support material;
mixing the palladium salt and silicon oxide support material in an aqueous solution;
evaporating the aqueous solution forming a solid;
calcining the solid;
treating the calcined solid to hydrogen gas at a temperature of from 300-1000° C. forming the direct NOx catalyst.

9. The process of claim 8 wherein the palladium salt is selected from the group consisting of: nitrates, chlorides and acetates.

10. The process of claim 8 wherein the step of calcining includes exposing the solid to a temperature of from 450° C. to 650° C. for a time period of from 3 to 10 hours.

11. The process of claim 8 wherein the formed direct NOx catalyst includes palladium particles having a particle size of from 50-2000 nm.

12. The process of claim 8 wherein the formed direct NOx catalyst has a NOx conversion of from 10 to 50% at a temperature of from 300 to 800° C.

13. A process of forming a direct NOx catalyst comprising the steps of:
providing a palladium salt;
providing a silicon oxide support material;
mixing the palladium salt and silicon oxide support material in an aqueous solution;
evaporating the aqueous solution forming a solid;
calcining the solid;
treating the calcined solid to oxygen gas at a temperature of from 50-650° C. forming the direct NOx catalyst.

14. The process of claim 13 wherein the palladium salt is selected from the group consisting of: nitrates, chlorides and acetates.

15. The process of claim 13 wherein the step of calcining includes exposing the solid to a temperature of from 450° C. to 650° C. for a time period of from 3 to 10 hours.

Assignees

• Toyota Eng & Mfg North America

Inventors

• Gunugunuri Krishna Reddy
• Peck Torin C
• Ling Chen
• Jia Hongfei

Classifications

• B01J35/45

  Nanoparticles · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J37/035

  Precipitation on carriers · CPC title