Catalyst construction for treating lean burn engine exhaust

摘要

An exhaust purification device for a fossil fuelled engine, comprising a series of alternately blocked laminar flow channels (42) defining inlet sections, cross-flow sections, and exit sections. The flow channels have porous (foraminous) walls (45) and a predetermined hydraulic diameter. The device also has a plurality of NOx reacting pellets (55) packing at least certain of the inlet sections of the channels (42); the pellets have a diameter generally approaching the hydraulic diameter and are comprised of at least dolomitic carbonate. The device has a three-way catalyst (i.e., selected Pd, Pt or Rh) coating (56) at least on the walls (45) of the outlet sections.