Synthesis of Mn/Cu co-doping mesoporous carbon by template method for gas phase mercury removal

Abstract

Mn/Cu co-doping mesoporous carbon sorbent (MnCux-C) was synthesized via using hard template method. Thymol blue (C27H30O5S) was used as carbon source and MCM-41 was applied as template agent. Copper nitrate trihydrate (Cu(NO3)2·3H2O) and manganese acetate tetrahydrate (MnC4H6O4·4H2O) was in-situ co-doped with carbon source as Cu/Mn metals precursor. Mercury removal on the MnCux-C sorbent was investigated on a fixed bed experimental apparatus. The physical and chemical characteristics of the MnCux-C sorbent were investigated by using BET, SEM, FTIR, XRD and XPS, respectively. Combing with mercury programmed temperature desorption (Hg-TPD) and density functional theory (DFT), the mechanism of mercury adsorption on the MnCux-C sorbent was revealed. The results showed that the synthesized MnCu0.1-C sorbent displayed high mercury removal performance at 150℃, which was considered to be a potential sorbent for mercury removal from industrial flue gas. Mn doping on the mesoporous carbon greatly improved the mercury removal ability of sorbent with mercury capture rate increasing from 6 % to 89 %. Doping of Cu can effectively improve the SO2 tolerance of the MnCu0.1-C sorbent for mercury removal. With different concentration of SO2 existing in flue gas, the MnCu0.1-C sorbent still kept high mercury removal ability. O2 in flue gas promoted mercury removal on the MnCu0.1-C sorbent with main product of HgO. In the presence of SO2, a small amount of HgSO4 formed on the MnCu0.1-C sorbent. The DFT analysis further displayed that Hg0 was mainly chemisorbed on the surface of MnCu0.1-C sorbent with formation of HgO.