One-pot synthesis of Cr alpha Mn beta CeTiOx mixed oxides as NH3-SCR catalysts with enhanced low-temperature catalytic activity and sulfur resistance

A series of Cr alpha Mn beta CeTiOx catalysts were prepared using one-pot precipitation method and evaluated for the selective catalytic reduction (SCR) of NO with ammonia. Among the catalysts prepared, the Cr0.006Mn0.05CeTiOx catalyst exhibited the highest low-temperature activity and widest activity window ( > 90% NO conversion at 160-425 degrees C) as well as outstanding sulfur resistance. The catalysts were characterized using XRD, NH3/NO/SO2 + O-2-TPD, XPS, in situ DRIFT, and so on. The amorphous Cr0.006Mn0.05CeTiOx catalyst had a larger specific surface area, high ammonia adsorption and strong acidity, resulting in an improved catalytic activity. A high ratio of surface adsorption oxygen and Ce3+ promoted the formation of NO2, a key intermediate gas in the fast SCR reaction. Furthermore, in situ DRIFT showed that the SCR reaction followed the Eley Rideal and Langmuir Hinshelwood mechanisms. Moreover, the synergetic effect of Cr and Mn inhibited the accumulation of hydrogen sulfate or sulfate considerably. (C) 2022 Elsevier Ltd. All rights reserved.