Flue gas concerted catalytic denitration and demercuration technology

The invention provides a flue gas concerted catalytic denitration and demercuration technology. The technology realizes simultaneous removal of NOx and Hg<0> without arranging a flue gas purifying device, so the reconstruction cost of present apparatuses is saved, and pollution to atmosphere is reduced, thereby the technology has strong industrial application values. The technology comprises the following steps: 1, injecting ammonia gas fully mixed with air to a boiler flue gas through the nozzle of an ammonia injection grating, fully mixing, and converting NOx in the flue gas into N2 under the action of an upper portion honeycomb Ce-Cu-V-W-TiO2 composite catalyst; 2, introducing treated flue gas obtained in step 2, and carrying out catalytic oxidation on a tiny amount of O2 and HCl and Hg<0> under the action of a lower portion honeycomb Ce-Cu-V-W-TiO2 composite catalyst to generate HgCl2; and 3, allowing a treated gas obtained in step 2 to enter the operating unit of a desulfurization tower, capturing gaseous divalent mercury having high solubility in water by a wet washing system to remove the gaseous divalent mercury, and treating sulfur-containing compounds in the flue gas to recover elemental sulfur.