A Bifunctional Pt/CeO2-Cu1/CeO2 Catalyst System for Isooctane Oxidation under Fully Simulated Engine-Exhaust Condition: Eliminating the Inhibition by CO

Pt-based catalysts, because of their outstanding activity for hydrocarbon oxidation, are widely used in the engine-exhaust aftertreatment system to remove hydrocarbon emissions. However, the CO and NOx present in real engine exhausts compete with hydrocarbons for active Pt sites, and thus inhibit hydrocarbon oxidation. In this work, we evaluated the inhibition effects of CO and NO on isooctane oxidation over a Pt/CeO2 catalyst under the simulated condition of the US DRIVE test protocol (S-GDI, stoichiometric gasoline direct injection). We also leveraged a low-cost single-atom Cu-1/CeO2 catalyst, which is highly active for low-temperature CO oxidation, to eliminate the inhibition effect of CO. Specifically, by physically mixing Cu-1/CeO2 and Pt/CeO2, all the CO is completely converted below 200 degrees C under simulated exhaust condition, which helps lower the isooctane oxidation temperature. However, the unconverted NO still strongly suppresses HC oxidation. Possible strategies to address the NO inhibitor were proposed.