Hollow MnOx-CeO2 mixed oxides as highly efficient catalysts in NO oxidation.

A series of hollow MnOx-CeO 2 mixed oxide catalysts were prepared by employing carbon as hard templates. The activity tests reveal that the catalytic performance of MnOx-CeO 2 (CS) samples are more active than that of MnOx-CeO 2 (AC) sample, indicating carbon sphere (CS) as a more effective carbon template. Among these samples, MnOx-CeO 2 (CS1) sample exhibits the best activity, for which a maximal NO conversion (∼82%) could be attained at 220 °C when GHSV = 120,000 h −1 . In addition, the NO conversion could be further improved with lower NO initial concentration or higher O 2 content. Under the simulated flue gas condition, the activity of MnOx-CeO 2 (CS1) sample is barely affected by the presence of CO 2 , but the influence of H 2 O and SO 2 couldn’t be neglected. The characterization result proves that the core-shell hollow structure has been successfully synthesized over MnOx-CeO 2 binary oxides. For the hollow MnOx-CeO 2 sample, the mesopore structures are formed and the MnOx oxides are highly dispersed on CeO 2 support. Among these samples, MnOx-CeO 2 (CS1) sample possesses the largest S BET and V total values. The result of H 2 -TPR and oxygen pulse measurement indicates that MnOx-CeO 2 (CS) samples, especially MnOx-CeO 2 (CS1) exhibits the best redox property. Moreover, more amount of high valence Mn as redox active sites and more oxygen vacancies exist in MnOx-CeO 2 (CS1) proved by XPS technique. Overall, these properties may contribute to the excellent activity. [ABSTRACT FROM AUTHOR]