Experimental Study Of Low-Temperature Flue Gas Desulfurization And Denitrification Based On H₂O₂ Decomposition Modified Attapulgite Catalyst

Nitrogen oxides and sulfur oxides emitted by coal-fired flue gas are important atmospheric pollutants that seriously endanger human health.Although the selective catalytic reduction denitration technology and the wet flue gas desulfurization technology are widely used in the industry to efficiently remove nitrogen oxides and sulfur oxides in flue gas,there are still disadvantages such as high cost,high operating cost and high reaction temperature.Therefore,the development of an efficient,low-cost simultaneous desulfurization and denitrification process has important engineering and economic significance.The research group proposed a new method for simultaneous desulfurization and denitrification.The method first mixes the atomized H₂O₂ with the flue gas,and then passes through the catalytic reactor.The gas phase H₂O₂ decomposes on the surface of the catalyst to produce·OH,and the NO is oxidized to a high-valent nitrogen oxide,and then the ammonia solution is used to absorb nitrogen oxides and sulfur oxides in the flue gas.Based on this new process,the subject uses iron-based catalysts to simulate the desulfurization and denitrification of flue gas on a self-designed fixed-bed test bench.The oxidized denitrification experiment of H₂O₂ was carried out by using attapulgite as catalyst.The results of denitrification experiments show that the attapulgite catalyst can significantly improve the denitration efficiency of flue gas;the flue gas denitration efficiency is close to 70%under the conditions of flue gas preheating temperature of 140?,H₂O₂ vaporization temperature of 160?,catalytic reaction temperature of 140?,H₂O₂ concentration of 4 mol/L,and H₂O₂ flow rate of 5 mL/h.With the increase of H₂O₂ concentration,the flue gas denitration efficiency increases.The flue gas preheating temperature has no significant effect on the flue gas denitration efficiency.As the H₂O₂ vaporization temperature increases,the flue gas denitration efficiency increases.The catalytic reaction temperature is an important factor affecting the denitrification efficiency of flue gas,with the increase of catalytic reaction temperature,the flue gas denitration efficiency first increases and then decreases.When the catalytic reaction temperature changes from 180?to 220?,the flue gas denitration efficiency is basically becoming steady.On the basis of the experimental parameters experiment,according to the liquid product analysis,it can be inferred that:the oxidation of·OH is the main removal mechanism of NO.The results of XRD,FTIR,BET and SEM showed that the structure,composition and pore structure parameters of the attapulgite catalyst remained unchanged at different reaction time.The optimum pickling conditions for the attapulgite are:the concentration of the sulfuric acid solution is 60%,and the solid-liquid ratio of the attapulgite to the sulfuric acid solution is 1:4.The acid modification treatment of the attapulgite can effectively remove the dolomite from the sample,and the specific surface area of the acid-modified attapulgite gradually increases with the increase of the sulfuric acid concentration,and the change of solid-liquid ratio of attapulgite and sulfuric acid solution has little effect on this.Under the optimal pickling conditions,different ratios of Fe₂O₃ were loaded on the acid-treated attapulgite to modify.The denitrification performance and physical properties of catalysts with different loadings were studied and characterized.The experimental results show that with the increase of Fe₂O₃ loading in the catalyst sample,the denitrification efficiency of flue gas increases first and then decreases,and the optimal loading of Fe₂O₃ is 40%.The characterization results show that the specific surface area of the catalyst sample tends to decrease with the increase of Fe₂O₃ loading in the catalyst sample.When the Fe₂O₃ loading is 50%,the Fe₂O₃ particles on the surface of the carrier agglomerate.In the catalyst screening experiment,the modified attapulgite with Fe₂O₃ loading of 40%was used as a catalyst to carry out the oxidized desulfurization and denitrification experiments of H₂O₂.The experimental results show that under different experimental conditions,SO₂ in flue gas can reach nearly98%removal efficiency.With the increase of H₂O₂ concentration,the flue gas denitration efficiency increases.The flue gas preheating temperature has no significant effect on the flue gas denitration efficiency.As the H₂O₂ vaporization temperature increases,the flue gas denitration efficiency increases.The catalytic reaction temperature is an important factor affecting the denitrification efficiency of flue gas,with the increase of catalytic reaction temperature,the flue gas denitration efficiency first increases and then decreases.The optimum catalytic reaction temperature is between 180?and 220?.The results of XRD,FTIR,BET and SEM showed that the structure,composition and pore structure parameters of the modified attapulgite catalyst remained unchanged at different reaction time.