Revealing the unexpected promotion effect of EuO_x on Pt/CeO₂ catalysts for catalytic combustion of toluene

Pt/Eu₂O₃-CeO₂ materials with different Eu concentrations were prepared and applied to toluene destruction, and the remarkable promotion impact of EuO_x on Pt/CeO₂ can be observed. The characterization results reveal that the presence of EuO_x significantly enhances the redox property, lattice O concentration, and Ce³⁺ ratio of the Pt/CeO₂ material, which facilitates the dispersion and activity of Pt active sites and thus accelerates the decomposition process of toluene. Among all catalysts, a sample with an Eu content of 2.5 at.% (Pt/EC-2.5) possesses the best catalytic activity with 0.09 vol% of toluene completely destructed at 200 °C under a relatively high GHSV of 50000 h⁻¹. The possible reaction pathway and mechanism of toluene combustion over Pt/Eu₂O₃-CeO₂ samples are presented according to in-situ DRIFTS, which confirms that the toluene oxidation process obeys the Mars-van Krevelen mechanism with aldehydes and ketones as primary organic intermediates.