Influence of nonmetallic elements doping on the NH3-SCR activity and properties of Ce20W10Ti100Oz catalyst via melamine modification

Abstract

In this study, the melamine (Mel) modification method was adopted to optimize the NH3-SCR activity of Ce20W10Ti100Oz doped with C or/and N elements. It was found that with the improved doping of C or/and N into the lattice of anatase TiO2 of Ce20W10Ti100Oz, the dispersion of tungsten/cerium species and the conversion of partial Ce4+ to Ce3+ on its surface were significantly enhanced, resulting in a large improvement of its surface chemical adsorbed oxygen(Oα) concentration. Interestingly, the enhancement of Mel/Ti(SO4)2 mass ratio slightly decreases the surface N/Oα concentrations, but further improves the surface Ti concentration and Ce3+/(Ce3++Ce4+) molar ratio. Furthermore, Mel modification increases the surface/sub-surface oxygen relative concentrations of Ce20W10Ti100Oz, although decreases its low-temperature reducibility and acidity. Due to the larger N doped amount, Ce20W10Ti100Oz-Melt:Ti ​= ​1:2 shows higher surface acidity and Oα/(Oα+Oβ) molar ratio than Ce20W10Ti100Oz-Melt:Ti ​= ​4:2, which might be responsible for its improved catalytic performance due to the melamine (Mel) modification.