Effects of exposed crystal facet on SO 2 resistance of α-Fe 2 O 3 for selective catalytic reduction of NO x with NH 3

In this study, the effects of crystal facet on the NH 3 -SCR activity and SO 2 resistance of α -Fe 2 O 3 catalysts were investigated. Compared with Fe 2 O 3 (Slice) with (110) and (104) exposed and Fe 2 O 3 (Rod) with (110) and (012) exposed, Fe 2 O 3 (Cube) with only (012) facet exposed showed the worst fresh catalytic activity and SO 2 resistance. The results of H 2 -TPR, XPS, and in situ DRIFTS indicated that the lowest redox capacity resulted in the nonexistence of NO x activation on the surface of fresh Fe 2 O 3 (Cube). NH 3 -SCR on Fe 2 O 3 (Cube) could only be completed through the reaction between NO x and pre-adsorbed NH 3 species. For Fe 2 O 3 (Slice), most Fe 3+ was maintained, and the highest acid amount after SO 2 treatment was helpful for its outstanding SO 2 resistance. Considering the sequence of catalytic performance, designing α-Fe 2 O 3 catalyst with (104) not (012) crystal facet exposed was helpful for improving the SO 2 resistance of Fe 2 O 3 catalysts. Graphical Abstract