| abstract |
An emission control system for internal combustion engines which emit carbonaceous soot particles, comprises a first catalyst effective to oxidise NO to NO 2 and a second catalyst effective at least to oxidise hydrocarbons, carbon monoxide and volatile organic fractions, each catalyst being supported on a honeycomb flow-through monolith comprising a plurality of cells, each defined by a cell wall, whereby soot particles trapped on or within said second catalyst monolith are combusted in the NO 2 -containing gas from said first catalyst, and wherein the first catalyst is supported on a flexible metal monolith whereby flexing and/or vibration of the honeycomb cell walls serves to minimise the collection of soot particles thereon. |