PdCu Alloy Catalyst for Inhibition-free, Low-temperature CO Oxidation

Abstract

Designing robust catalysts for low-temperature oxidation is pertinent to the development of advanced combustion engines to meet increasingly stringent emissions limitations. Oxidation of CO, hydrocarbon, and NO pollutants over platinum-group catalysts suffer from strong inhibition due to their competitive adsorption, while coinage metals are generally slow at activating O2. Through computational screening, we discovered a PdCu alloy catalyst that completely oxidizes CO below 150 °C without inhibition by NO, propylene or water. This is attributed primarily to geometric effects and the presence of CO bound to Pd sites within the Cu-rich surface of the PdCu alloy. We demonstrate that the novel PdCu catalyst can be used in tandem with a PtPd catalyst to achieve sequential, inhibition-free, complete oxidation of CO in a two-bed system, while also achieving 50 % NO conversion below 120 °C. Moreover, neither water nor propylene adversely affect the low temperature CO oxidation activity.