Pd-based TWC catalyst for reduction of cold-start hydrocarbon emissions

摘要

Hydrocarbon(HC) adsorption behavior on Pd based catalyst was appeared during a cold-start period of actual driving cycle.XPS analysis suggested that the HC adsorption were occurred after Pd valence-state change from Pd oxide to Pd metal.Since Pd based catalyst showed relatively good light-off performance,the combination of HC adsorption and early light-off activity has led to an improvement of overall HC emission reduction.Use of zeolite combined with Pd based catalyst maximized HC adsorption between 20 to 40 seconds of the cold-start period at fresh,while these incremental effects contributed from zeolite were disappeared after 900 deg C aging.