Catalytic Light-off Performance of Thermal-aged Pd Three-way Catalyst and Surface Characterization of Pd Particles by FT-IR Spectroscopy

Abstract

Improvement of the activity of three-way catalysts (TWC) is extremely important to meet future emission regulations. In this study, the detailed catalytic behavior of Pd particles on ceria/zirconia was investigated by FT-IR. After severe engine bench aging at 1000°C, Pd particles were greater than 20nm and significant decrease of reaction rate constant for both CO oxidation and NO reduction were observed. Characterization results provided a causal relationship between deterioration of NO reduction and the disappearance of active linear-CO on the Pd surface. In addition, a CO oxidation reaction mechanism on the Pd surface is proposed. This work highlights how FT-IR can be used to understand Pd surface chemistry on the support materials.