Abstract
White smoke emission is observed at tailpipe of diesel engine when unburned hydrocarbons (HCs) are stored on diesel oxidation catalyst (DOC) under low gas temperatures. In this research, it was investigated that effects of HCs adsorbed on alumina and zeolite coated on DOC for white smoke emission by change of zeolite content and specific surface area (SSA) of alumina. HCs poisoning on platinum group metal (PGM) may occur by rapid HCs desorption from zeolite and degrade the HCs oxidation performance of DOC, leading to white smoke emission. Therefore, adopting small SSA alumina to DOC can reduce the adsorbed HCs amount on alumina inhibiting HCs poisoning on PGM, thus improve HCs oxidation performance. This improvement achieved not only the reduction in white smoke emission but also the improvement of HCs and carbon monoxide clarification during New European Driving Cycle mode compared to conventional DOC specifications.
