Preparation Of Modified ZnO And Removal Of NO At Low Temperature

In this paper,microwave assisted sol-gel method for the preparation of nano-ZnO.Different modified ZnO catalysts were used in visible light catalytic removal experiments and selective catalytic reduction（SCR）experiments of NO,to investigate the effects of different microwaves,different surfactants and different doping elements on the catalytic removal of NO by modified ZnO,and explore its anti-poisoning ability,the number of continuous use,reaction kinetics,reaction mechanism.The experimental results show that:with the first process at 300W,the second process at 600W prepared conditions,the doping SDS（1%）-ZnO had the best photocatalytic activity,the photocatalytic activity of NO at a concentration of 600μg/m³ was as high as 95.6%.When the NO concentration is 2600 ug/m³,the visible light photocatalytic efficiency can still reach about 69.2%.When the concentration of NO is 1900μg/m³,the efficiency is 84.9%,about 20%higher than pure ZnO.Anti-poisoning ability has also been improved,proved by SDS modified ZnO photocatalytic performance is good.Process I at 200W,process II at 900W under the conditions of preparation,The effect of selective catalytic removal of NO by Cr（1%）-PEG6000（2%）-ZnO is best and most stable,about 20%higher than that of pure ZnO.It is proved that the doping of surfactant PEG6000 and metal Cr can promote the selective catalytic reduction of NO by the modified catalyst.The modified ZnO catalysts prepared were characterized by BET,XRD,SEM,EDS,UV-Vis,NH₃-TPD,XPS,TG and IR.The results show that the sol-gel method after adding microwave assisted heating system is uniform,the reaction is sensitive,the heating rate is fast,the preparation period of the catalyst can be shortened,and the yield of the catalyst can be increased.Surfactants can reduce the surface tension and reduce the surface energy,thereby reducing the degree of aggregation of the solid particles in the dispersion system,keeping the dispersion relatively stable and effectively controlling the size and morphology of the nanoparticles.The selective catalytic reduction of NO by modified ZnO with chromic nitrate as chromic source has been improved because the surface acidity and acidity of the catalyst are all increased and the performance of adsorbed NH₃ is further enhanced at low temperature,The reduction effect.Photocatalytic removal of NO at room temperature in the experiment,the ammonia nitrogen ratio of about 1:1,NO removal efficiency of the highest.The catalytic performance of SDS（1%）-ZnO can reach 70.7%after 5consecutive uses.The reaction kinetics analysis shows that it is in accordance with L-H first order reaction kinetics.