Abstract
Three-way catalysts (TWC) coated within gasoline particulate filter (GPF) walls (TWC/GPF) were tested in a gasoline direct injection (GDI) engine to investigate the impact of engine oil-derived chemicals on TWC performance and possible deactivation factors. Catalyst performance of the lab-aged TWC/GPFs was retarded with ash loading, especially NOx conversions under 300 °C. Characterization results from the lab-aging condition show that while the disruption of oxygen storage capacity (OSC) materials was found to be minor or negligible, Pd particle growth and weakened Pd–OSC interaction were observed. In comparison, the field-aged TWC/GPF showed more apparent degradation of TWC components due to engine-oil-derived chemicals; the formation of CePO4 and Ce2(SO4)4 results in decreasing OSC that lowers oxygen release capability, in addition to more noticeable Pd particle growth and weakened Pd–OSC interaction. Different from the lab-aged TWC/GPF, the degree of deactivation in the field-aged TWC/GPF appeared to increase along the direction of the flow path in the order of outlet > mid > inlet, proposing that engine-oil-derived chemicals accelerated TWC deactivation when combined with increased exhaust temperatures.
