SCR catalysts having improved low temperature performance, and methods of making and using the same

Patent metadata

Field	Value
Publication number	US-10272419-B2
Application number	US-201514633777-A
Country	US
Kind code	B2
Filing date	Feb 27, 2015
Priority date	Feb 28, 2014
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

SCR-active molecular-sieve based catalysts with improved low-temperature performance are made by heating a molecular-sieve in a non-oxidizing atmosphere with steam (hydrothermal treatment), or in a reducing atmosphere without steam (thermal treatment), at a temperature in the range of 600-900° C. for a time period from 5 minutes to two hours. The resulting SCR-active iron-containing molecular sieves exhibit a selective catalytic reduction of nitrogen oxides with NH3 or urea at 250° C. that is at least 50% greater than if the iron-containing molecular-sieve were calcined at 500° C. for two hours without performing the hydrothermal or thermal treatment.

First claim

What is claimed is:

1. A method of making an SCR-active molecular sieve-based catalyst, the method comprising performing a hydrothermal treatment on an iron-containing molecular sieve in a non-oxidizing atmosphere at a temperature in the range of 600-900° C. for a time period from 5 minutes to two hours, where the molecular sieve is a zeolite having an AEI, AFX, CHA, FER, or SFW framework.

2. The method according to claim 1 , wherein the hydrothermal treatment is performed at a temperature in the range of 650-850° C. for a time period from 15 minutes to two hours.

3. The method according to claim 1 , wherein the zeolite is FER and the hydrothermal treatment is performed at a temperature in the range of about 700 to about 900° C. for a time period from 5 minutes to two hours.

4. The method according to claim 1 , wherein the non-oxidizing atmosphere comprises nitrogen.

5. The method according to claim 1 , wherein the non-oxidizing atmosphere is a reducing atmosphere.

6. The method according to claim 5 , wherein the reducing atmosphere comprises hydrogen gas.

7. The method according to claim 1 , wherein the iron-containing molecular sieve subjected to the hydrothermal treatment is in powder form.

8. The method according to claim 1 , wherein the iron-containing molecular sieve subjected to the hydrothermal treatment is in the form of an extruded unsupported catalyst or a coating on a support body.

9. The method according to claim 1 , wherein the iron-containing molecular sieve is prepared by contacting a molecular sieve with an iron salt.

10. A method of making an SCR-active molecular sieve catalyst, comprising performing a hydrothermal treatment on an iron-containing molecular sieve at a temperature in the range of 600-900° C. for a time period from 5 minutes to two hours, then introducing oxygen into the atmosphere during at least a portion of the time when the iron-containing molecular sieve cools from the hydrothermal or thermal treatment temperature to ambient temperature, where the molecular sieve is a zeolite having an AEI, AFX, CHA, FER, or SFW framework.

11. The method according to claim 10 , wherein the hydrothermal treatment is performed using a means providing mixing, temperature and atmospheric control.

12. The method according to claim 10 , wherein the hydrothermal treatment is performed in an inclined rotary calcination oven in which the iron-containing molecular sieve in powder form is exposed to a countercurrent flow of gas constituting a non-oxidizing or reducing atmosphere.

13. A method of making an SCR-active molecular sieve catalyst, comprising performing a hydrothermal on an iron-containing molecular sieve in a non-oxidizing atmosphere at a temperature in the range of 600-900° C. for a time period from 5 minutes to two hours, then introducing oxygen into the non-oxidizing atmosphere during at least a portion of the time when the iron-containing molecular sieve cools from the hydrothermal treatment temperature to ambient temperature, where the molecular sieve is a zeolite having an AEI, AFX, CHA, FER, or SFW framework.

Assignees

• Johnson Matthey Plc

Inventors

• Chandler Guy Richard
• Collier Jillian Elaine
• Green Alexander Nicholas Michael
• Duran-Martin Desiree
• Phillips Paul Richard
• Rajaram Raj Rao
• Reid Stuart David

Classifications

• B01J37/10 Primary

  in the presence of water, e.g. steam · CPC title

• B01J29/763

  CHA-type, e.g. Chabazite, LZ-218 · CPC title

• B01J29/072 Primary

  Iron group metals or copper · CPC title

• B01J29/68

  Iron group metals or copper · CPC title

• B01J29/46 Primary

  Iron group metals or copper · CPC title