Study On SCR Catalyst For The Flue Gas Denitration

With the rapid economic development, the emission of nitrogen oxides has been increasing every year in our country. NOx is associated with a host of environmental issues, including the photochemical smog, the acid rain,the hole in the ozone layer and the greenhouse effect. Selective catalytic reduction(SCR) of NOx with NH3 has been getting more and more attention what is an effective control method for NOx. The key of SCR is preparation of high selectivity and activity SCR catalysts. In this thesis,vanadium titanium catalysts were prepared by impregnation method. The effects of the SCR operating parameters including O2 concentration,space velocity,SO2 concentration on the activities of vanadium titanium catalysts were investigated. The preparation of the catalysts was studied in details on the composition and calcination temperature, which significantly influenced the activities of the catalysts.The conversion percentage of NOx reached 99.0% on the V2O5(1.5)-WO3/TiO2 catalyst under the condition:ammonia ratio=1, concentration of 02=1%, temperature=450℃, SV=10000h-1. In this thesis,manganese titanium catalysts were also prepared by sol-gel, impregnation and coprecipitation methods for low-temperature SCR of NOx with NH3. The effects of the preparation method, catalyst composition and preparation conditions on the activities of manganese titanium catalysts were investigated. The experimental results showed that the manganese titanium catalysts modified by Nb in impregnation enhanced resistance of catalyst towards high concentration steam and SO2. The conversion percentage of NOx reached 82.8% on the Nb(0.1)-Mn-Ce-TiO2 catalyst under the condition:ammonia ratio=1, concentration of 02=1%, concentration of SO2=1000ppm, temperature=160℃, SV=10000h-1, concentration of steam=12%.