Fuel-borne catalyst scheme avoids NO2 emission problem of precious-metal catalyts for DPF regeneration

Diesel Fuel News, June 23, 2003

Associated Octel reported in a paper (SAE 2 003-01-1883) here that an iron-based fuel-borne catalyst (FBC) not only aids regeneration of a DPF in light- and heavy-duty vehicles, but also avoids lung-irritating [NO.sub.2] slip that can be found with some precious-metal catalyzed DPF systems. This FBC/DPF scheme also seems to work better than conventional DPFs for engines with relatively "cold" duty cycles, the investigators found.

In light-duty tests, "only a brief excursion above a gas temperature of 400[degrees]C was necessary to initiate a regeneration which was then self-sustaining" despite subsequent lower temperature operation, Octel research Paul Richards reported here. The DPF not only slashed PM mass emissions but also PM number emissions by at least two orders of magnitude. The FBC/DPF combo also not only avoided an increase of [NO.sub.2] but also [N.sub.2]O emissions, he said.