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.

Site requirements for inhibition-free CO oxidation over silica-supported bimetallic PdCu alloys

“…These are indicators that there is diversity in the types of Pd atoms available for binding under these conditions between the four materials, such as different faceted bridge sites. 18 Fig. 5 shows the evolution of the spectra for the TPD experiments on all materials.…”

“…In our recent work, 17,18 we demonstrated experimentally that PdCu catalysts outperform their monometallic Pd counterparts, in terms of both CO oxidation activity and NO inhibition. We attributed these effects to the electronic exchange of Cu and Pd, as well as the mobility of Cu from the bulk to the surface upon light-off, which offers a binding site for O 2 to adsorb and react.…”