Effect of Tungsten on Hg0 Removal by W-Mn-Mo/CNT During Oxy-Fuel Combustion Simulated Flue Gas

A new type of tungsten-doped Mn-Mo/CNT catalyst (CM5Mo5Wx) is prepared by the impregnation method, and their surface properties and mercury removal ability during oxy-fuel combustion simulated flue gas are investigated in this study. It indicated that the addition of tungsten to Mn-Mo/CNT significantly changed the surface structure of the catalyst. The Brunauer-Emmett- Teller surface areas of CM5Mo5 and CM5Mo5W6 are 209 and 172 m(2)/ g, respectively. However, the addition of tungsten expands pore volume of the catalyst. In addition, less Mn4+ is found on the surface of the tungsten-doped catalyst. Mercury removal ability of the tungsten-doped catalyst is stronger than that of CM5Mo5, especially the mercury removal ability of CM5Mo5W6. Its mercury removal efficiency is 98% at 100 degrees C, while that of CM5Mo5 is lower than 70%. Under different flue gas conditions, O-2 and NO can significantly enhance Hg-0 removal, but SO2 decreases mercury removal efficiency. However, H2O slightly suppresses the mercury removal by this catalyst. Moreover, combining the Hg-TPD and kinetic analyses, it was revealed that chemisorption is crucial for Hg-0 removal. Hg-0 is more easily adsorbed by CM5Mo5W6 through the results of kinetic analysis.