Device Design For Photocatalystic Oxidation Of NO From Flue Gas With ZnO And Research On Catalytic Performance Of ZnO

In recent years, with more importance attached to the air pollution and more stringentnational emission standards set for air pollutants, removal technology of NOx from flue gasis becoming increasingly important for the power plant. Photocatalytic oxidation technologyis attracting more and more attention because of its excellent virtues, such as being friendlyto environment, strong oxidation ability, and relatively low cost. Catalysts like TiO2, ZnOand so on have an outstanding performance. Gas-phase photocatalytic performance of ZnOnano materials and subsequent removal effect of NOx was studied, in terms of preparingand characterizing of ZnO, designing and assembling of photocatalytic reactor, experimentsand tests, and analytical aspects.Through optimizing the experimental conditions and reagents’ dose, ZnO powder, on thelevel of nanometer, was prepared by hydrothermal method. Characterized by SEM, XRD,the homemade ZnO, of which crystal shape was found being nanorod, had a betterdispersion property than purchased one. Under the UV light, photocatalytic experimentaltest on degradation of Rhodamine B with suspension made of the homemade ZnO wascarried out. Degradation rate reached96.13%in1h, indicating its liquid-phasephotocatalytic performance is good.Quartz tube photocatalytic reactor with illumination on both upside and downside wasadopted. Catalyst was loaded on glass fiber cloth which was put in the reactor, for it couldhelp increase the adsorption area. Loaded ZnO was achieved by dipping, followed bydrying.In this paper, process law of photocatalytic oxidation of NO was observed byphotocatalytic experiments with homemade ZnO, the results showed that photocatalytic reaction was a process from transient state to steady state, and stable state was achieved at40min and remained unchanged after that. The higher inlet concentration of NO, the lowerconversion efficiency, for example,92ppm NO was with an efficiency of27%, but660ppmonly got9.7%. The conversion efficiency of NO increased along with the rise of O2, and itschange was no longer obvious after10%. Experimental temperature (60~95oC) andhumidity (temperature of water heater60~80oC) had little effect on the conversionefficiency of NO. No more increasing in photocatalytic efficiency when residence time wasbeyond15s. With NO concentration=272ppm, the conversion efficiency of NO and removalefficiency of NOx through liquid-phase absorption were14.9%and26.9%.Photocatalytic oxidation effect for NO with nano-ZnO, prepared under laboratoryconditions, was4%higher than that in references(conversion efficiency of NO neared11%).In turn, higher removal efficiency of NOx could ahieve.