Performance of Mn-Ce/TiO_2 Low-temperature SCR Catalysts for NO_x Reduction with NH_3

【Author】

Liangjing Zhang;Suping Cui;HongxiaGuo;Xiaoyu Ma;

【Abstract】

<正>Nitrogen oxides(NO,NO_2,and N_2O) resulting from combustion remain a major source for air pollution.They are major causes for acid rain,smog,ozone depletion,and green horse effects at present,the emission of NOx from cement industry every year in China is about 2.2 million tons,approximately one-tenth of national NOx emission.The cement industry is the third-largest NOx emission source following thermal power plant and automobile exhaust.There is huge dust in Cement kiln,the alkaline substance in the smoke causes catalyst poisoning.Selective catalytic reduction(SCR) of NOx with NH3 is an effective technologies for the removal of NOx from stationary sources.When the flue fas has high concentrations of particles,such a catalyst would be installed downstream of the desulfurizer devices and electrostatic precipitator where the temperature is below 150 V.According to research results,MnOx-CeO_2/TiO_2 is one of the most promising catalytic material for low temperative SCR technology.The MnOx-CeO/TiO_2 catalytic material for low temperature SCR of NOX with NH3 was prepared by sol-gel,impregnation,hydro-thermal methodThe performance of the catalytic materials were characterized by mean of XRD,BET,FT-IR techniques respectively.Based on the results,in the laboratory stage,the denitrification effect of the sol-gel method is the best in the low-temperature.impregnation method is widely used to industry because of simple process and better nox-reduction rate in the low-temperature,but the capable of alkali resistant poisoning is less.Therefore seek a higher low temperature denitration rate also has anti-alkaline catalyst is essential. Originality At present,Catalysts based on MnOx/TiO_2 were prepared by sol-gel,impregnation,and coprecipitation methods for low-temperature selective catalytic reduction(SCR) of NO with NH_3.Among the catalysts,the sample prepared by sot-gel method had the best performance on both activity and SO_2 resistance.(Boqiong Jiang et al.2009)Cu-Mn mixed oxides were prepared by a co-precipitation method and applied for low temperature NO reduction with NH_3 in the presence of excess oxygen.Cu-Mn oxide catalysts containing small amounts of copper showed the complete NOx conversion in a wide range of reaction temperature from 323 to 473 K.This catalyst showed a reversible deactivation due to the presence of water vapor and SO_2.(Min Kang et al,2006) Can be seen,the search of DeNOx catalyst denitrification performance on the low-temperature and resistance to sulfur and water intoxication have been many at home and abroad,but relatively few studies of the catalyst alkali metal poisoning prepared for different methods.Cement kilns relative SO_2,alkali metal poisoning has an greater impact,this study is that in cement kilns this particular environment,through low-temperature catalysts prepared by different methods denitration with anti-alkaline comparative study,looking the best anti-alkaline low-temperature DeNOx catalyst.

【Keywords】

low-temperature SCR;;DeNOx of flue gas;;Mn-Ce/TiO_2;;alkali resistance

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