Synthesis and Characterization of Mn–Ce–VOx/TiO2 Nanocomposite for SCR of NOx at Low Temperatures: Role of Mn, Ce and V Oxide

Abstract

Mn–Ce–VOx/TiO2 (MnCeVTi), Mn–CeOx/TiO2 (MnCeTi) and Mn–VOx/TiO2 (MnVTi) nanocomposites as SCR DeNOx catalysts were synthesized by a modified sol–gel method. All catalysts shows high NOx conversion of over 90% at low temperature between 125 and 200 °C with GHSV of 30,000 h−1. MnCeVTi catalyst demonstrates the highest NOx conversion and produces the least byproduct N2O at 110–310 °C. The co-presence of Ce, V and Mn inhibits the growth of rutile, decreases crystallinity of anatase TiO2 and manganese oxides, reduces grain size, increases BET specific surface area and pore volume. There are most chemisorbed oxygen, appropriate Mn3+/Mn4+ and the synergistic effect of Ce and V on MnCeVTi sample. The acid sites on MnCeVTi are most below 280 °C and in widest temperature range. Lewis acid sites play a leading role in SCR reaction on MnCeVTi catalyst. These helps to optimize the SCR catalytic performance of MnCeVTi, on which E-R and L–H mechanism may coexist in the reaction.