Improvement in the resistance to KCl and PbCl2 synergistic poisoning of the commercial SCR catalyst by Ce(SO4)2 modification: A combined experimental and spin-polarized DFT study

Abstract

The commercial selective catalytic reduction (SCR) catalysts are vulnerable to the synergistic poisoning of K and Pb species in flue gas, two common and typical components that can trigger severe damage on the physical and chemical properties of the catalysts. In this study, a Ce(SO4)2-V2O5-MoO3/TiO2 catalyst with 15 wt% Ce(SO4)2 loading was developed which maintained high activity under the synergistic poisoning of 2 wt% KCl and PbCl2. The resistance mechanisms were explored by a series of characterization techniques and density functional theory (DFT) calculations. The results indicated that the enhancement on the resistance to the synergistic poisoning of K and Pb species by the introduction of Ce(SO4)2 could be elucidated in three aspects. Firstly, the interactions between Ce(SO4)2 and K/Pb species protected the V and Mo species from the synergistic poisoning. Secondly, the Ce4+/Ce3+ redox couples and large amounts of chemisorbed oxygen improved the redox ability of the catalyst. Finally, the Ce(SO4)2 modified catalyst maintained a high surface acidity despite the synergistic poisoning of K and Pb species, which was beneficial for the adsorption of NH3 species and the following SCR process.