Ammonia slip catalyst designed to be first in an scr system

Patent metadata

Field	Value
Publication number	US-2016367973-A1
Application number	US-201615184055-A
Country	US
Kind code	A1
Filing date	Jun 16, 2016
Priority date	Jun 18, 2015
Publication date	Dec 22, 2016
Grant date	—

Abstract

Catalyst articles having an ammonia slip catalyst (ASC) comprising a blend of platinum on a support with low ammonia storage and a first SCR catalyst, and a second catalyst, such as a diesel oxidation catalyst, a diesel exotherm catalyst (DEC), a NOx absorber, a selective catalytic reduction/passive NOx adsorber (SCR/PNA), a cold-start catalyst (CSC) or a three-way catalyst (TWC) are disclosed. The catalyst articles can also contain one or two additional SCR catalysts. The catalysts can be present in one of various configurations. The catalytic articles are useful for selective catalytic reduction (SCR) of NOx in exhaust gases and in reducing the amount of ammonia slip. Methods of using the catalytic articles in an SCR process, where the amount of ammonia slip is reduced, are also described.

First claim

We claim:

1 . A catalyst article comprising a substrate comprising an inlet end and an outlet end, a first zone and a second zone, where the first zone comprises an ammonia slip catalyst (ASC) comprising a platinum group metal and a first SCR catalyst comprising a metal exchange molecular sieve, vanadium or a base metal, and the second zone comprises a second catalyst selected from the group consisting of a diesel oxidation catalyst (DOC), a diesel exotherm catalyst (DEC), a catalyzed soot filter (CSF), a NOx absorber, a selective catalytic reduction/passive NOx adsorber (SCR/PNA), a cold-start catalyst (CSC) or a three-way catalyst (TWC), where the first zone is located upstream of the gas flow relative to the second zone.

2 . The catalyst article of claim 1 , where the first zone and the second zone are located on the same substrate and the first zone is located on the inlet side of the substrate and the second zone is located on the outlet side of the substrate.

3 . The catalyst article of claim 1 , further comprising a second substrate, where the first zone is located on a first substrate and the second zone is located on the second substrate and the first substrate is located upstream of the second substrate.

4 . The catalytic article of claim 1 , where the ammonia slip catalyst comprises a bottom layer comprising a platinum group metal and a top layer comprising the first SCR catalyst located over the bottom layer.

5 . The catalytic article of claim 1 , where the ammonia slip catalyst comprises a blend of a platinum group metal on a support with low ammonia storage and a first SCR catalyst.

6 . The catalyst article of claim 1 , where the second zone comprises a blend of an oxidation catalyst and a second SCR catalyst.

7 . The catalytic article of claim 1 , further comprising a second SCR catalyst, where the second SCR catalyst is located between the ammonia oxidation catalyst and the second catalyst.

8 . The catalytic article of claim 1 , where the platinum group metal comprises platinum, palladium or a combination of platinum and palladium.

9 . The catalyst article of claim 1 , where the platinum group metal is on a support with low ammonia storage.

10 . The catalyst article of claim 1 , where platinum is present from at least one of: (a) 0.01-0.3 wt. %, (b) 0.03-0.2 wt. %, (c) 0.05-0.17 wt. %, and (d) 0.07-0.15 wt. %, inclusive, relative to the weight of the support of platinum+the weight of platinum+the weight of the first SCR catalyst in the blend.

11 . The catalyst article of claim 7 , where the second SCR catalyst is a base metal, an oxide of a base metal, a molecular sieve, a metal exchanged molecular sieve or a mixture thereof.

12 . The catalyst article of claim 11 , where the molecular sieve or the metal exchanged molecular sieve is small pore, medium pore, large pore or a mixture thereof.

13 . The catalyst article of claim 1 , where the article comprises only one ammonia slip catalyst (ASC) and either (a) the second zone does not comprise a diesel oxidation catalyst (DOC) or (b) the DOC is not located adjacent to, and downstream of, the ammonia slip catalyst.

14 . The catalyst article of claim 1 , further comprising a third zone comprising an ASC catalyst, where the third zone is located between the first zone and the second zone.

15 . The catalyst article of claim 14 , where the PGM in the first zone comprises palladium in an amount sufficient to generate an exotherm.

Assignees

• Johnson Matthey Plc

Inventors

• Larsson Mikael
• Micallef David

Classifications

• B01D53/9418 Primary

  for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas · CPC title

• B01D2255/50

  Zeolites · CPC title

• Y02C20/10

  of nitrous oxide (N2O) · CPC title

• B01D53/9436

  Ammonia · CPC title

• B01J21/04

  Alumina · CPC title