Elucidation of Active Sites for Low-Temperature CO Oxidation over Ceria Supported Copper Catalysts that are 100% regenerable after SO2 poisoning.

Carlos  Garcia Vargas, Washington State University / EMSL-PNNL

Removing harmful CO from exhaust emissions is a critical objective in the automotive industry, particularly at temperatures below 150 ºC. We have recently used ​high temperature synthesis method (atom trapping) to produce PGM ​single atom catalysts that are thermally stable and active for CO oxidation at low temperatures. However, the automotive industry currently consumes nearly 50% of global PGM demand, which makes the development of non-PGM catalysts critical to ensuring the PGM supply chain.

In this work, we demonstrate how ​atom trapping can also be used to synthesize earth abundant, non-PGM Cu/CeO₂ catalyst, which shows outstanding CO oxidation activity and thermal durability under simulated exhaust conditions. With the use of CO probe reactions, spectroscopic observations, density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations, we have unambiguously elucidated the nature of the active site on Cu₁/CeO₂. We report how Cu₁ single atoms play a crucial role as active centers for the activation of CO while at the same time promoting the low temperature activation of lattice oxygen. Furthermore, we report that CO oxidation activity can be regenerated 100% after SO₂ poisoning, which makes this material a promising candidate for realistic aftertreatment applications.