Promotional effect and mechanism of Ce-modified VO-WO/TiO catalyst in low-temperature NH-SCR.

The enhancement effect of Ce modification on VO-WO/TiO catalysts at low temperatures was investigated for the selective catalytic reduction (SCR) of NO with NH (NH-SCR). By adding 9% CeO to 0.5%VO-3%WO/TiO catalyst, the low-temperature denitrification performance of CeVWTi catalyst after Ce modification was significantly improved, achieving a NO conversion above 90% within a broad temperature range of 200-350℃, with catalytic activity comparable to that of 3% VO-3% WO/TiO. The catalysts were characterized by XPS, H-TPR, NH, and NO-TPD. The results indicated that the Ce additive could enhance the adsorption of NO on CeVWTi catalyst due to the synergetic interaction among the Ce and V, W species. The interaction between V and Ce also promoted the formation of V and Ce on the surface of the catalyst, which was conducive to enhancing the adsorption and oxidation capacity of the catalyst for NO. Additionally, the introduction of Ce led to a substantial deposition of nitrate species on the surface of the catalyst, especially the increase of nitrite species, which was beneficial to the NH-SCR reaction process, resulting in a significant enhancement of the catalyst's low-temperature catalytic activity.