Deep filtration and catalytic oxidation: an effective way for soot removal

Catalytic and uncatalytic axial flow ceramic foam traps for soot removal were prepared and tested at the exhaust of a gas oil burner. Soot filtration efficiencies of uncatalytic and catalytic traps were comparable and depended on the burner operating conditions. A threshold temperature of the catalyst of about 330 degreesC was determined. Above such a temperature while the pressure drop through the uncatalytic trap increases continuously because of soot load, that through the catalytic trap reaches a steady-state value where the soot amounts captured and burned on the trap were equivalent. Also radial flow ceramic foam traps were prepared and tested at the exhaust of a common rail diesel engine. Their behaviours reflected those of the corresponding axial flow traps. A model descriptive of the relevant phenomena (filtration, combustion and pressure drop time evolution) occurring all over the traps was formulated. It is able to yield the overall trap performances although further improvements are needed in the catalytic case. (C) 2002 Elsevier Science B.V. All rights reserved.