NOx adsorber formulations getting better but still a long way to go

Diesel Fuel News, March 17, 2003

U.S. EPA's tests of NOx adsorbers on a medium-heavy-duty diesel engine (see SAE 2003-010042) show that more recent technology is better than older technology on durability. EPA's tests in Ann Arbor, Mich., on "zero-sulfur" fuel (<0.7 ppm sulfur) over 100 to 250 hours at high-temp AVL mode 8 show that thermal stability is improving.

Future tests will use 15-ppm ULSD fuel and high-temperature desulfurization excursions (600-700[degrees]C) to evaluate NOx trap durability and resistance to sintering. "Development is moving at a rapid pace, so we're optimistic," EPA's Charles Schenk said. "Adsorber suppliers are learning how to stabilize [catalyst] washcoats" for heavy-duty application. The researchers hope to put a combined PM/NOx trap (four-channel system) on a Freightliner L-60 truck (with the 5.9 liter engine) this summer and take emissions measurements with a portable emissions recording device.