Simultaneous removal of NO and Hg0 in flue gas over Co-Ce oxide modified rod-like MnO2 catalyst: Promoting effect of Co doping on activity and SO2 resistance

The Co was firstly used as a dopant to improve the NO and Hg-0 removal performance of CeO2 loaded rod-like MnO2 catalyst (Ce/MnO2) and its SO2 resistance. The results showed the doping process effectively improved the relative concentrations of chemisorbed oxygen as well as the contents of surface Ce4+ and Mn4+, enhanced the redox ability of catalyst, which was conducive to the simultaneous removal performance of NO and Hg-0 in flue gas. The Co-Ce/MnO2 catalyst (the mole ratio of Co/Ce = 1.0) had optimal catalytic performance among all prepared catalysts in 160-280 degrees C, its NO and Hg-0 removal efficiencies achieved 99.9% and 91.9% at 200 degrees C and 10,000 h(-1), respectively. In addition, the Co-Ce/MnO2 performed stronger resistance to SO2 in comparison with Ce/MnO2, its catalytic activities decreased slightly when SO2 with a concentration of 500 ppm was added into the gas stream, and then recovered close to the initial value after eliminating of SO2. We considered the excellent SO2 tolerance performance of Co-Ce/MnO2 catalyst is assigned to the fact that the Co-modification restrained the sulfation of CeO2 and MnO2 to CeSO4 and MnSO4, alleviated the decreasing of chemisorbed oxygen, and hindered the chemisorption of SO2 on the catalyst. This work provided a promising prospect of Co-modification on Ce/MnO2 as SO2 resistant catalysts for simultaneous removal of NO and Hg-0 from flue gas.