Unraveling SO2-tolerant mechanism over Fe2(SO4)3/TiO2 catalysts for NO . reduction

Developing low-temperature SO 2 -tolerant catalysts for the selective catalytic reduction of NO x is still a challenging task. The sulfation of active metal oxides and deposition of ammonium bisulfate deactivate catalysts, due to the difficult decomposition of the as-formed sulfate species at low temperatures ( < 300 degrees C). In recent years, metal sulfate catalysts have attracted increasing attention owing to their good catalytic activity and strong SO 2 tolerance at higher temperatures ( > 300 degrees C); however, the SO 2 -tolerant mechanism of metal sulfate catalysts is still ambiguous. In this study, Fe 2 (SO 4 ) 3 /TiO 2 and Ce 2 (SO 4 ) 3 /TiO 2 catalysts were prepared using the corresponding metal sulfate salt as the precursor. These catalysts were tested for their low-temperature activity and SO 2 tolerance activity. Compared to Ce 2 (SO 4 ) 3 /TiO 2 , Fe 2 (SO 4 ) 3 /TiO 2 showed significantly better low-temperature activity and SO 2 tolerance. It was demonstrated that less surface sulfate species formed on Fe 2 (SO 4 ) 3 /TiO 2 and Ce 2 (SO 4 ) 3 /TiO 2 . However, the presence of NO and O 2 could assist the decomposition of NH 4 HSO 4 over Fe 2 (SO 4 ) 3 /TiO 2 at a lower temperature, endowing Fe 2 (SO 4 ) 3 /TiO 2 with better low-temperature SO 2 tolerance than Ce 2 (SO 4 ) 3 /TiO 2 . This study unraveled the SO 2 -tolerant mechanism of Fe 2 (SO 4 ) 3 /TiO 2 at lower temperatures ( < 300 degrees C), and a potential strategy is proposed for improving the low-temperature SO 2 -tolerance of catalysts with Fe 2 (SO 4 ) 3 as the main active component or functional promoter. (c) 2021 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

Developing low-temperature SO2-tolerant catalysts for the selective catalytic reduction of NOx remains a challenging task. Metal sulfate catalysts have attracted attention due to their good catalytic activity and high-temperature SO2 tolerance, but the mechanism of SO2 tolerance in metal sulfate catalysts is still unclear.