Effect of Sulfates on the Reaction Pathway Over CeO2‐Based Catalyst for NH3‐SCR

ABSTRACT CeO 2 ‐H 2 SO 4 (C‐S), CeO 2 ‐TiO 2 (C‐T), and CeO 2 ‐TiO 2 ‐H 2 SO 3 (C‐T‐S) were used for the selective catalytic reduction of NO with NH 3 (NH 3 ‐SCR). Nearly 100% NO x conversion of C‐T‐S was achieved at 250°C–450°C. When the concentration of Ce 2 (SO 4 ) 3 was excessively high, it causes tightly binding with Ce 3+ ions in CeO 2 , prevents some Ce 3+ ions from effectively participating in redox reactions, and results in the inferior SCR activity. Consequently, C‐T‐S possessed the superior catalytic performance due to the optimal content of sulfates. Furthermore, the presence of NO 2 facilitated the rapid SCR reaction on C‐T‐S, thereby further enhancing the catalytic activity. Additionally, the formation of Ce 2 (SO 4 ) 3 on C‐T‐S could increase the number of acid sites, particularly Brönsted acid sites, resulting in the improvement of SCR performance. C‐S, C‐T, and C‐T‐S mainly followed the Langmuir–Hinshelwood (L–H).