Soot combustion activity of NOx-sorbing Cs–MnOx–CeO2 catalysts

Activities of Cs-loaded MnOx–CeO2 for combustion of model diesel soot (carbon black) and sorptive NO uptake have been studied. MnOx–CeO2 is a pseudo-solid solution having redox properties favorable for soot oxidation. The addition of Cs not only lowered the temperature of soot ignition (Ti), but also increased oxidative NOx adsorption to form nitrate on the surface. Soot ignition over Cs–MnOx–CeO2 was further promoted in a stream of NO/O2, presumably because nitrate on the surface plays a role of an oxidizing agent. Soot ignition started just before sharp desorption of NOx, suggesting that adsorbed nitrate species would directly interact with soot.