Removal of elemental mercury from flue gas by recyclable CuCl2 modified magnetospheres catalyst from fly ash. Part 1. Catalyst characterization and performance evaluation

• Different copper coordinations are existed in the catalyst with different Cu loading.
• At low Cu loading, isolated Cu2+ ions existed in a chlorine-free coordination.
• At high Cu loading, associated Cu2+ ions existed in a chlorine-enriched coordination.
• The chlorine-enriched coordination acted as the active adsorption sites for Hg0.
• The chlorine-free coordination is inactive for Hg0 removal.

To remove Hg0 from coal combustion flue gas and eliminate secondary pollution of spent sorbent, a novel magnetic catalyst based on CuCl2 modified magnetospheres from fly ash (CuCl2-MF) was developed. The solubility tests, electron paramagnetic resonance (EPR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and physical property measurement system with vibrating sample magnetometer (PPMS-VSM) were employed to characterize the catalyst. The effects of CuCl2 loading value and reaction temperature on Hg0 removal performance were studied using a laboratory-scale fixed-bed reactor. The results suggested that the CuCl2 loaded on the support is present mostly in an amorphous phase. Different copper coordinations are existed in the catalyst with different Cu loading: at low Cu loading, isolated Cu2+ ions existed in a chlorine-free coordination; at high Cu loading, associated Cu2+ ions existed in a chlorine-enriched coordination. The catalyst with optimal loading 6% CuCl2 attained the highest Hg0 removal efficiency (90.6%) at 150 °C. The chlorine-enriched coordination acted as the active adsorption sites for Hg0, while the chlorine-free coordination is inactive for Hg0 removal. The CuCl2-MF catalyst showed good resistance to SO2 for Hg0 removal in the presence of HCl. Further, the management method for spent catalyst containing mercury was proposed, and the economic analysis of the technology was also conducted.