Experimental Study On Removal Of SO₂ And NO From Coal-fired Flue Gas By Catalytic Oxidation Of Bimetallic Oxides

A large number of pollutants such as SO2 and NOx discharged by coal combustion have caused a series of ecological environment and human health problems,and have received extensive attention from all over the world.Chinese energy structure determines that the pattern of energy-based coal is difficult to change for a long time in the future.Therefore,the control of conventional atmospheric pollutants such as SO2 and NOx will be a long-term work in the energy and environmental field.At present,SO2 control generally adopts limestone-gypsun process,while NOx control often adopts selective catalytic reduction technology(SCR).These traditional methods are hierarchical treatment methods,which has problems such as equipment investment and high operating cost.From the perspective of efficient and low-cost control of pollutants,it is urgent to develop SO2 and NOx while removing theory and new technologies.Based on extensive data research,it is found that the use of metal catalysts,especially bimetallic oxide catalysts,can achieve high-efficiency oxidation of NOx in coal-fired flue gas,thereby achieving the simultaneous removal of SO2 and NOx.In this paper,a double metal oxide catalyst(M=Co.Ni.Cu.Zn)with a spinel structure of MFe2O4 was prepared by water/solvent thermal method.NiFe2O4 was selected as the best catalyst for simultaneous oxidation and SO2 removal.The effects of various influencing factors on simultaneous oxidative removal of NO and SO2 were investigated by experiments.The experimental results show that when the simulated flue gas velocity is 1.3L/min.the Na2S2O8 solution concentration is 0.03mol/L.the catalyst dosage is 0.45g/L.the initial concentration of NO is 400mg/m3.and the initial concentration of SO2 is 1500mg/m3 and when the pH of the absorption liquid is 6.0 and the reaction temperature is 60?.the simultaneous removal effects of NO and SO2 can reach 48.73%and 98%.respectively.The prepared catalysts were characterized by X-ray diffraction and scanning electron microscope.The surface characteristics of NiFe2O4 were revealed.The infrared spectroscopic scanning and photoelectron spectroscopy analysis confirmed that the main forms of iron and nickel on the surface of the catalyst were Fe(?).Fe(?)and Ni(?).By ion chromatography analysis of the reaction product,it was confirmed that NO and SO2 were finally oxidized to NO3-and SO42-.Based on the above characterization and product analysis,the catalytic oxidation mechanism is preliminarily inferred.Fe(?)and Ni(?)on the surface of the catalyst activate S2O82-to generate SO4·-firee radicals,which can react with H2O to produce HO· free radicals.Under the action of a strong oxidizing free radical.NO and SO2 are oxidized and absorbed.