Combined promoting effects of platinum and MnOx–CeO2 supported on alumina on NOx-assisted soot oxidation: Thermal stability and sulfur resistance

MnOx–CeO2 mixed oxides were introduced into Pt/Al2O3 catalyst to reduce the amount of platinum and improve the catalytic activity for soot oxidation in presence of NOx. The catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), CO chemisorption, thermogravimetric (TG) analysis, Fourier transform infrared spectroscopy (FTIR), H2 temperature-programmed reduction (H2-TPR), NO temperature-programmed oxidation (NO-TPO) and soot temperature-programmed oxidation (soot-TPO). Due to the superior redox property, the introduction of MnOx–CeO2 mixed oxides effectively enhanced the catalytic activities of Pt/Al2O3 catalyst for NO oxidation and hereby for soot oxidation in NO + O2. The Pt/MnOx–CeO2/Al2O3 catalyst also exhibited high activities after the thermal ageing and sulfur poisoning, which are related to the intrinsic characteristics of MnOx–CeO2/Al2O3 and Pt as well as their synergistic effects. The deactivation mechanisms of different catalysts (Pt/Al2O3, MnOx–CeO2/Al2O3 and Pt/MnOx–CeO2/Al2O3) were discussed.

Light-off temperatures of different catalysts during the soot-TPO in NO + O2..Figure optionsDownload as PowerPoint slideHighlights
► Modification of MnOx–CeO2 enhances the soot oxidation activity of Pt/Al2O3 in NO + O2.
► The loading amount of Pt on Pt/Al2O3 catalyst can be halved by addition of MnOx–CeO2.
► The modified catalyst shows high activity after calcination at 800 °C for 100 h.
► It also exhibits superior sulfur resistance after treating in SO2 at 350 °C for 50 h.
► The activity of the sulfated catalyst is facilitated by the Pt-sulfates interaction.