Promotion Effect of Fe Species on SO<sub>2</sub> Resistance of Cu-SSZ-13 Catalysts for NO<i><sub>x</sub></i> Reduction by NH<sub>3</sub>
Lijuan Xie, Chang Liu, Yun Deng, Fudong Liu, Wenquan Ruan
Abstract
In this study, homogeneous precipitation and self-assembly methods were used for the preparation of two kinds of Fe-containing Cu-SSZ-13 catalysts (CuFe-SSZ-13HDP and Cu-SSZ-13@FexOy), respectively. Both of them maintained a NOx conversion of ∼46% at 225 °C after poisoning with 100 ppm SO2 at 400 000 h–1. Fe species promoted the SO2 resistance of Cu-SSZ-13 significantly. The structure–activity relationship and reaction mechanism were explored to explain the promotion effect in detail. For CuFe-SSZ-13HDP, some active Fe species were maintained during SO2 poisoning, which increased the reactivity between NH3-adsorbed species and NOx in the presence of SO2. The characteristic contributed to its better SO2 tolerance. For Cu-SSZ-13@FexOy, Fe species protected some Cu species from forming CuSO4 and decreased the amount of ammonium sulfate on the catalyst surface due to their special distribution. Better NOx activation after SO2 poisoning was the most important reason for its better SO2 tolerance.