| Mercury is a volatile global environmental pollutant,which can spread all over the world by means of atmosphere and hydrosphere,enriched in higher organisms through the food chain.Selective Catalytic Reduction(SCR)is the most widely used and most effective technology for flue gas denitrification at present.Previous studies have shown that modified SCR catalyst can not only remove NOx,but also oxizide some part of the insoluble Hg0 to soluble Hg2+,which can be removed by the Wet Flue Gas Desulfurization unit.Among them,the modification effect of cerium is best.Based on the existing research,the formulation and production process of V2O5-Ce O2-WO3/Ti O2 catalysts were studied.The structure and composition of the catalysts were analyzed by characterization equipment.The mercury oxidation rate of the catalysts was tested by the mercury oxidation efficiency test bench.The main works of this paper are as follows:(1)On the basis of commercial V2O5-WO3/Ti O2 catalyst formula,the formula of Ce O2-V2O5-WO3/Ti O2 catalyst was put forward;By adjusting the parameters of the production process of the catalysts,such as p H,moisture content,adhesive dosage,drying time and calcination temperature,the preparation process of Ce O2-V2O5-WO3/Ti O2 catalyst was obtained.In order to solve the problems during the trial production,the formula of the catalyst was optimized.Two groups of Ce O2-V2O5-WO3/Ti O2 catalysts with different cerium gradients were prepared by Ce(NO3)3 method and Ce O2 method respectively.(2)Using BET,XRD,ESEM and XRF to analyze the specific surface area,crystallinity,morphology,element types and content of the catalysts.(3)In order to study the influence of active substances,space velocity and temperature on catalytic activity,The mercury oxidation efficiency of 5 groups of catalysts were tested under simulated flue gas.(4)The influence of flue gas components on mercury oxidation efficiency was analyzed.The main conclusions of this paper are as follows:(1)Under the condition of the same cerium content,the mercury oxidation efficiency of the catalyst prepared by Ce(NO3)3 was higher than that of the Ce O2.With the increase of the content of vanadium and cerium,the mercury oxidation efficiency of the catalyst increase.The Ti WV0.8Ce6 catalyst prepared by Ce(NO3)3 has the highest efficiency of 92.13% at the temperature of 250?,and still has an efficiency of 76.49% at the temperature of 300?.(2)Specific surface area of the catalyst prepared by Ce O2 method was less than that of Ce(NO3)3 method.There was no significant difference in the composition and content of elements in the two groups of catalysts which were prepared by Ce(NO3)3 method and Ce O2 method.They were all consistent with the design value.(3)The Ti O2 in the two groups of catalysts mainly existed in the form of anatase.The cerium in Ce(NO3)3 catalyst existed in the form of dispersion,while in the Ce O2 catalyst existed in the form of crystalline state;ESEM analysis showed that the morphology of the catalyst was good,and no obvious sintering phenomenon occurred.(4)HCl and O2 could promote the mercury oxidation ability of the catalyst.In the presence of O2,low concentration of SO2 could promote the oxidation of mercury,while high concentration of SO2 could inhibit the oxidation of mercury.NH3 has an inhibitory effect on the mercury oxidation capacity of the catalyst,while the effect of NO on mercury oxidation of catalyst was not obvious.In all components of flue gas,the temperature of 300? and the airspeed of 20000h-1,after 12 h of reaction,the Ti WV0.8Ce6 catalyst's mercury oxidation rate was still more than 80%. |
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