Halogen (Cl, Br, I) regulation Cu-BTC for NH3-SCR: NO and Hg0 removal and mechanism analysis

Abstract

Emissions of NOx and Hg0 in the atmosphere are primarily derived from coal-fired power plant flue gases. The control of these pollutants has emerged as a focal point of research in recent years. In this study, we synthesized a novel halogen-modified Cu-BTC catalyst designed for the synergistic removal of NO and Hg0. The results showed that: Cu-BTC catalyst maintained its original physicochemical properties even after being modified with different halogens (Cl, Br, I), and C-X (Cl, Br, I) bonds indicated the successful incorporation of halogens into the Cu-BTC. Furthermore, the catalytic performance was investigated through NH3-SCR method. Research indicated that halogens amplified the catalytic reduction of NO and the catalytic oxidation ability of Hg⁰. Furthermore, the effect of post-modification proved to be superior to pre-modification, following the order of Cl＞Br＞I. Under the conditions of 200 °C and 30000 h−1, the Cu-BTC-Cl catalyst exhibited the highest removal efficiency for both NO and Hg⁰, reaching 84.895 % and 76.841 %. While NO had a minor impact, NH₃ enhanced the removal of NO but inhibited the removal of Hg⁰. O2 significantly promoted pollutants removal, and the catalyst also showed strong resistance to both sulfur and water. The modified catalyst exhibited covalent C–Cl species, which effectively captured Hg0. Cu2+ participated in the removal of NO and Hg0, with partial transformation into Cu+.