Influence of composite after-treatment catalyst on particle-bound polycyclic aromatic hydrocarbons–vapor-phase emitted from modern advanced GDI engines

With mutagenic and cacogenic potential polycyclic aromatic hydrocarbons (PAHs) generated from engine source which have contributed to a substantial share of air toxic, so in order to characterize and eliminate the PAHs emissions of commercial engine fuelled, an experimental study has been carried out on a V6 gasoline engine working in spark-ignition (SI) and homogeneous charge compression ignition (HCCI) equipped with smart three-way catalyst converter (TWC). The particle phase and gas phase of PAH_S in engine exhaust, downstream and upstream the catalyst were collected by stainless-steel cartridges containing XAD-2 resin to capture PAHs species. The vapour phase and particulate bound PAHs compounds observed with two and three rings to exist almost entirely in the gas phase, on the other hands, five or more fused rings are predominantly adsorbed on soot particles, the intermediate – 4 ring PAH_S exist in the two PAH_S phases, naphthalene is the most abundant polycyclic aromatic hydrocarbon that was detected in the exhaust vapour-phase on both engine modes. The prototype catalytic converter eliminates most of the polycyclic aromatic hydrocarbons species in both PAH_S phases, particle phase and gas phase, except for NAP species. A prototype catalyst showed higher efficient conversion on PAH_S particulate-bound phase than vapor phase for both engine modes. However, when hydrogen was added upstream of the catalyst, the catalyst conversion efficiency in reducing naphthalene was increased by approximately 20%.