AMMONIA SLIP CATALYST DESIGNED TO BE FIRST IN AN SCR SYSTEM

摘要

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.

主权项

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.