Ce-modified Rh overlayer for a three-way catalytic converter with oxygen storage/release capability

Abstract

A nanometric Rh overlayer exhibits excellent three-way catalytic activity under stoichiometric conditions. However, dynamic changes in the air-to-fuel (A/F) ratio under experimental conditions deteriorates the catalytic activity caused by the lack of oxygen storage/release capability of Rh. In this study, we first report that the surface modification of the Rh overlayer by a small amount of Ce using a sequential metal deposition technique based on the pulsed arc-plasma method enhances its three-way catalytic activity under A/F perturbation conditions. X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements revealed that the redox behavior of the surface Ce contributed to an oxygen storage/release and buffered the A/F change. The Ce-modified Rh overlayer with a metal honeycomb structure exhibited high activity for the three-way catalytic reaction even under A/F perturbation conditions at high space velocity. This novel catalytic converter is expected to be significantly process and energy saving compared to the conventional catalytic converter. Thus, the oxygen storage/release performance, heat resistance, and low-temperature activity can be improved by controlling the surface composition.