Oxidation of Diesel Particulates by Catalyzed Wall-Flow Monolith Filters

Regeneration characteristics of three catalyzed wall-flow monolith (WFH) diesel particulate filters (one commercial filter and two experimental filters designated GMR-Pt and GMR-Ag, respectively) were compared in dynamometer tests with a GM 4.3 L diesel engine, All three filters regenerated at temperatures below 540°C, the lowest exhaust temperature at which an uncatalyzed filter could be regenerated. Momentary throttling of the engine intake air increased both the rate and extent of the commercial trap regeneration, but had little affect on the experimental traps. The results of this study indicate that exhaust temperatures of 500°C or above are required for rapid regeneration of all three traps. Such temperatures are not readily attained with GM 4.3 L and 6.2 L vehicles. More active catalytic filters and additional modifications to the engine operation are required before catalyzed wall-flow monolith filters can be effectively employed on GM diesel engines.