Novel sorbents of non-metal-doped spinel Co3O4 for the removal of gas-phase elemental mercury.
N-doping technology is introduced to improve Co3O4's Hg0 removal ability and anion activation ability for the first time. The adsorption tests show that N-doped Co3O4 has a higher S(BET) and greater Hg0 removal ability. The reaction mechanism has been carefully studied using a number of different analyses methods such as X-ray diffraction, Brunauer-Emmett-Teller, and X-ray photoelectron spectroscopy. The analysis results illustrate that N atoms have been doped into a Co3O4 matrix as anions and are thoughtto substitute for O atoms. Anions, such as Cl- and Br-, can be activated by N-doped Co3O4 and then oxidize Hg0. It is considered that nitrogen atoms in polycrystalline N-doped Co304 are responsible for the significant enhancement of Hg0 removal ability. Different NH4Cl or NH4Br adulteration values have been tested, and the results show that 50 mol % NH4Cl or 40 mol % NH4Br doped Co3O4 have the highest Hg0 removal ability. Compared with Co3O4, N-doped Co3O4 has a longer breakthrough time and better SO2 antipoisoning ability. On the basis of the above analyses, possible Hg0 oxidation mechanisms of N-doped Co3O4 are provided.