N-doping technology is introduced to improve Co_3O_4's Hg~0 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 Hg~0 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 Co_3O_4 matrix as anions and are thought to substitute for 0 atoms. Anions, such as Cl~- and Br, can be activated by N-doped Co_3O_4 and then oxidize Hg~0. It is considered that nitrogen atoms in polycrystalline N-doped Co_3O_4 responsible for the significant enhancement of Hg~0 removal ability. Different NH_4Cl or NH_4Br adulteration values have been tested, and the results show that 50 mol % NH_4Cl or 40 mol % NH_4Br doped Co_3O_4 have the highest Hg~0 removal ability. Compared with Co_3O_4, N-doped Co_3O_4 has a longer breakthrough time and better SO_2 antipoisoning ability. On the basis of the above analyses, possible Hg~0 oxidation mechanisms of N-doped Co_3O_4 are provided.
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