Consolidation of DOC and DPF functions into a single component 2019-01-0583
Diesel Particulate Filters (DPFs) are in common use in many applications for particulate matter (PM) control. Most examples of DPF usage are preceded by a Diesel Oxidation Catalyst (DOC) providing NO2 for passive soot oxidation and fuel burning for active soot regeneration. The DPF is often catalyzed, (CDPF) to enhance passive regeneration by NO2, and to assist active regeneration by burning CO resulting from soot oxidation and any hydrocarbons passing through the DOC.
Some applications with favorable NOx to PM ratios can operate without active regeneration, including applications with only CDPF for cost and packaging space savings. However, eliminating the DOC for applications that require both types of regeneration is difficult, as active regeneration must be accomplished by burning fuel within CDPF, while adequately burning soot near the front. To meet this challenge, an effort was undertaken to optimize a CDPF catalytic coating architecture to consolidate the DOC and DPF functions into a single “DDPF”.
A matrix of DDPF samples defined by PGM amount and location was prepared to investigate the tradeoffs between active and passive regeneration characteristics. Passive regeneration was evaluated by pre-loading soot, then moving to favorable passive soot oxidation conditions and observing the rate of soot mass decline. Active regeneration performance was determined under steady state conditions during HC injection, and by using a “quench” test protocol where the inlet temperature is lowered during regeneration.