Effect Of Microwave Field On Catalytic Behavior Of Activated Carbon Desulfurization And Denitrification

At present,the emission of sintering flue gas SO₂ and NO_X in our country’s iron and steel industry production processes accounts for 2/3 of the whole process.The emission of these pollutants will not only endanger the human body health,but also cause serious pollution to ecological environment.In our country,for the content of SO₂and NO_X emitted from industrial production,a very strict standard was set.Therefore,it is a common goal for the low emission of pollutants in the sintering flue gas workers to achieve the common goal,also was a necessary way to realize the green development of the iron and steel industry.The non-thermal effect of microwave field was used to optimize the adsorption performance of activated carbon on low concentration pollutants in sintering flue gas,further reducing the concentration of pollutants in sintering flue gas after desulfurization and denitration treatment,which can alleviate the contradiction between the development of iron and steel industry and natural environment to a certain extent,and has a significant practical significance in the realization of green industry development of our iron and steel industry.In this thesis,industrial activated carbon was selected as the carrier,and three metal oxides of Mn,Ce and Fe were added through the method of ultrasonic impregnation,and the activated carbon was calcined by conventional tube furnace and microwave calcining.The influence law of different catalysts on the behavior of removing SO₂ and NO_x from activated carbon under two calcining conditions was studied.Then,the catalysts which are more suitable for desulfurization and denitrification of activated carbon are selected.In this thesis,the influences of loading,calcination temperature,microwave power and reaction temperature on the desulfurization and denitrification behavior of activated carbon were compared and analyzed.A variety of methods including phase composition,valence state of elements,surface microstructure,pore parameters and kinetic analysis were used to analyze the experimental results in depth.（1）By comparing the influence of conventional tubular furnace calcination and microwave calcination on the adsorption behavior of activated carbon,it is found that the adsorption effect of activated carbon after microwave calcination is better.The reason is that the specific surface area of activated carbon particles decreases,the average pore size and the number of surface functional groups increase significantly after microwave calcination,so as to optimize the desulfurization and denitrification efficiency of activated carbon.By comparing the adsorption behavior of activated carbon under different metal oxide loading conditions,it is found that adding Mn-Ce-Fe catalyst with composite support can make activated carbon show the best adsorption performance in the process of desulfurization and denitrification.（2）The optimal parameters of microwave calcination activated carbon are as follows:10%load,400℃calcination temperature,2000 W microwave power,160℃reaction temperature.Under these conditions,the time required for the desulfurization and denitrification efficiency of activated carbon to reach 60%is 10 min and 3 min,respectively.By analyzing the desulfurization and denitrification reaction of activated carbon under microwave calcination,it can be seen that the coupling effect of different metal oxides can catalyze the adsorption of SO₂ and NO on activated carbon to the greatest extent,improve the oxidation and reduction capacity of metal ions,increase the oxygen-containing functional groups on the surface of activated carbon,and reduce the damage to the surface microstructure of activated carbon particles during calcination.The adsorption efficiency of activated carbon on SO₂ and NO in flue gas was significantly improved.（3）Under the optimal activated carbon adsorption conditions,the maximum adsorption capacity of SO₂ was 0.50 mg·g^-1,and that of NO was 0.09 mg·g^-1;The fit degree of the second-order kinetic model for adsorption of SO₂ by activated carbon is0.971,which is smaller than that of the internal diffusion model.The fit degree of the second-order kinetic model for the adsorption of NO by activated carbon was 0.955,which was smaller than that of the internal diffusion model.Compared with the second-order kinetic model,the internal diffusion model has a higher fitting degree,indicating that the diffusion rate of SO₂ and NO in activated carbon is the limiting link in the desulfurization and denitrification reactions of activated carbon.