Cerium-modified manganese octahedral molecular sieves as catalysts for selective catalytic reduction

Patent metadata

Field	Value
Publication number	US-2016346770-A1
Application number	US-201415031041-A
Country	US
Kind code	A1
Filing date	Mar 14, 2014
Priority date	Mar 14, 2013
Publication date	Dec 1, 2016
Grant date	—

Abstract

Catalysts and articles useful for selective catalytic reduction (SCR) are disclosed. The catalyst comprises a cerium oxide and an octahedral molecular sieve (OMS) comprising manganese oxide. The catalysts, which comprise 0.1 to 50 wt. % of cerium, can be made by doping, ion-exchange, deposition, or other techniques. Also disclosed is an SCR process in which a gaseous mixture comprising nitrogen oxides is selectively reduced in the presence of a reductant and the cerium-modified OMS catalyst. The cerium-modified manganese oxide OMS catalysts offer unexpected advantages for selective catalytic reduction, especially NH 3 -SCR, including improved thermal stability and improved activity for NOx conversion, especially at relatively low temperatures (100° C. to 250° C.).

First claim

We claim:

1 . A catalyst useful for selective catalytic reduction, comprising:
(a) an octahedral molecular sieve (OMS) comprising manganese oxide; and (b) a cerium oxide; wherein the catalyst comprises from 0.1 to 50 wt. % of cerium.

2 . The catalyst of claim 1 made by adding a cerium compound during synthesis of the OMS.

3 . The catalyst of claim 1 made by contacting the OMS with an aqueous solution of a cerium compound and drying the resulting ion-exchanged material.

4 . The catalyst of claim 1 made by depositing a cerium compound on the OMS from a solution, dispersion, or suspension, and concentrating the resulting mixture.

5 . The catalyst of claim 4 made by incipient wetness.

6 . The catalyst of claim 1 calcined at a temperature within the range of 300° C. to 650° C. following its preparation.

7 . The catalyst of claim 1 wherein the octahedral molecular sieve is OMS-2.

8 . The catalyst of claim 1 wherein the cerium oxide is selected from the group consisting of cerium(III) oxide, cerium(IV) oxide, and mixtures thereof.

9 . The catalyst of claim 1 comprising from 5 to 15 wt. % cerium.

10 . The catalyst of claim 1 wherein the OMS is formed in the presence of cerium dioxide.

11 . A process which comprises selectively reducing a gaseous mixture comprising nitrogen oxides in the presence of a reductant and the catalyst of claim 1 .

12 . The process of claim 11 wherein the reductant is selected from the group consisting of ammonia and C 1 -C 8 hydrocarbons.

13 . The process of claim 11 wherein the reductant is ammonia.

14 . The process of claim 11 wherein the catalyst is a cerium-doped OMS-2.

15 . The process of claim 11 wherein the catalyst is a cerium oxide on OMS-2.

16 . The process of claim 11 wherein the catalyst is cerium-exchanged OMS-2.

17 . The process of claim 11 wherein % conversion of nitrogen oxides at temperatures within the range of 100° C. to 200° C. improves compared with that of a similar process in which a cerium-free OMS catalyst is used.

18 . The process of claim 11 wherein the catalyst demonstrates improved thermal stability compared with that of a cerium-free OMS catalyst.

19 . An article for treating a gas containing nitrogen oxides, comprising a substrate and, deposited on the substrate, a catalyst of claim 1 .

Assignees

• Johnson Matthey Plc

Inventors

• Kilmartin John
• Fisher Janet Mary
• Collier Jillian Elaine
• Thompsett David
• Rajaram Raj Rao

Classifications

• B01D53/8628

  Processes characterised by a specific catalyst · CPC title

• B01J37/033 Primary

  Using Hydrolysis · CPC title

• B01D2251/2062

  Ammonia · CPC title

• B01J37/03

  Precipitation; Co-precipitation · CPC title

• B01J37/0215

  Coating · CPC title