Active oxygen-assisted NO-NO2 recycling and decomposition of surface oxygenated species on diesel soot with Pt/Ce0.6Zr0.4O2 catalyst

A Pt/Ce0.6Zr0.4O2 catalyst was synthesized by impregnating a Ce0.6Zr0.4O2 support with Pt(NO3)2 solution. This material exhibits higher catalytic activity than Pt/Al2O3 for soot oxidation under loose contact conditions in both NO + O2 and O2 atmospheres. The results show that the pronounced activity of this catalyst is attributed to a synergistic effect arising from the combination of Pt and Ce0.6Zr0.4O2 solid solution, leading to a remarkable increase in the availability of active oxygen at temperatures as low as 450 °C. The NONO2 recycling efficiency is improved over Pt/Ce0.6Zr0.4O2 catalyst, enhancing the ability of the NO2-soot reaction to generate surface oxygenated complexes (SOCs) on the soot. More importantly, the catalytic oxidation of these SOCs can be accelerated with the participation of active oxygen from the CeO2-ZrO2 solid solution. As a result, during soot oxidation under NO + O2, the light-off temperature of the Pt/Ce0.6Zr0.4O2 catalyst is lowered by 34 °C than that of Pt/Al2O3 catalyst.

Graphical AbstractThe synergistic effect between Pt and CeZr increases the availability of active oxygen which in turn accelerates NO ↔ NO2 recycling and the oxidation of SOCs, resulting in enhanced catalytic activity during soot oxidation.Figure optionsDownload as PowerPoint slide