Experiments And Mechanisms Study Of Simultaneous Control Of SO₂ And NO_x Emissions With Mg-Al Composite Oxide

In China, coal-fired power plants are the main sources of sulfur dioxide and nitrogen oxides. Reducing emissions of air pollutants is the way to realize sustainable development of power industry and national economy. Removing SO2 and NOX respectively need large areas and investment. Researching and developing a technology of simultaneous control of SO2 and NOX emissions to save resources are hot topics. Because of rich source and low cost, Mg-Al oxides as absorbents have a lot of applications and great potential in the desulfurization and denitration. Reducing the grain size to improve the removal efficiency of Mg-Al composite oxide is a breakthrough. In this paper, Mg-Al composite oxides of different Mg/Al molar ratio were prepared by the solid state reaction synthesis process and molten salt synthesis process respectively, and were used to carry out experiments of simultaneous removing SO2 and NOX in the reactor. Found that when Mg in the samples is more than Al, the removal effects are better. Samples prepared by molten salt synthesis process have significantly higher removal efficiency than samples prepared by the solid state reaction synthesis process. When samples were prepared by the solid state reaction synthesis process, The influence of preparation temperature on removal efficiency of SO2 is greater than that on removal efficiency ofNOx. Low temperature of preparing sample is advantageous to the removing of SO2. The sample in which Mg/Al molar ratio is 6:1 has the best removal effect. The highest removal efficiency of SO2 can reach 99%, and highest removal efficiency of NOx can reach 45%. And after 60 minutes, removal efficiency of SO2 fell by 3.4% and removal efficiency of NOx fell by 1.5%. When samples were prepared by the molten salt synthesis process, the sample in which Mg/Al molar ratio is 4:1 has the best removal efficiency. The highest removal efficiency of SO2 can reach 100%, and highest removal efficiency of NOx can reach 71%. And the maximum removal efficiency can maintain 150 min. The maintain time is 2.5 times than that of samples prepared by the solid state reaction synthesis process. Further research shows that the adsorption process is controlled by surface adsorption reaction. Particle diffusions on and inside the surface also have roles, but not the leading factors.