Zoned catalytic filters for treatment of exhaust gas

摘要

Provided is an SCRF article having different SCR catalysts compositions disposed on a wall-flow filter substrate in zones that are arranged in series with respect to the inlet and outlet faces of the substrate. Also provided is method of reducing backpressure and ammonia slip that involves the use of such SCRF articles.

主权项

1. A catalyst article comprising:
a. a wall flow monolith having an inlet face end and an outlet face and an axis of gas flow from said inlet face to said outlet face; b. a first SCR catalyst composition comprising a molecular sieve framework at a first sieve concentration and an exchanged metal at a first metal concentration, wherein said first SCR catalyst is disposed in a first zone; and c. a second SCR catalyst composition comprising said molecular sieve framework and said exchanged metal, wherein the molecular sieve framework is at a second sieve concentration that is below said first sieve concentration, and/or the exchanged metal is at a second metal concentration that is below said first metal concentration, wherein said second SCR catalyst is disposed in a second zone; wherein said first zone and second zone are disposed within a portion of said wall flow monolith and in series along said axis, and wherein said first zone is disposed proximal to said inlet face, and said second zone is disposed proximal to said outlet face.