Abstract
NOx and NO2 emission characteristics of heavy duty diesel vehicles that have aftertreatment devices for emission reduction such as Diesel Particulate Filter (DPF) or urea SCR to meet the Japanese '05 emission regulation are investigated. Most of urea SCR vehicles increased NOx by increase of total driving distance, due to HC poisoning of the SCR catalyst and deterioration of NO2 formation for pre-DOC, though both NOx and NO2 emission of DPF vehicles little changed. NO2 emission in urea SCR vehicles decrease in most cases by catalyst deteriorations, but NO2 increased in some cases if only SCR catalyst is poisoned.
