Preparation And Optimization Of Denitration Catalyst With Wide Activiy Temprature Window For Flu Gas

NOx are one of the major pollutant which are harmful to the atmosphere，Slective catalytic reduction（SCR） is one of effective methods of NOx removal ofstationary source emissions. The SCR catalyst with high performance is located in thecore of the denitration process. As the catalyst carrier, ultra-fine titanium-tungstenpowder is the key material for the high active catalyst development. Unfortunately,our country has no independent intellectual property rights of the carrier production.Meanwhile, in order to obtain wide activity temperature of the denitration catalyst, thethesis is focus on the synthesis of ultra-fine titanium-tungsten powder and modifiedcommercial titanium and titanium-tungsten, and further to preparation SCR catalyst.The main conclusions are as follows:（1）Nano meter-sized titaniu-tungsten powder have prepared by ways ofhydrolysis using titanyl sulfate as raw material and ammonium paratungstate astungsten source. The further prepared V2O₅-WO₃/TiO₂catalyst, which realized68%NO conversion at300℃, by impregnation method using this support. While usingthe prepared F-WO₃/TiO₂as support by doped ammonium fluoride in the hydrolysisrealized78%NOx conversion at250℃.The characterizations of the catalyst provedthat Fluoride ion which might enter the lattice of titanium dioxide with variation ofthe composition of charge around the catalyst to strengthen the NH₃adsorption andreduce the carrier specific surface area.（2）Aseries of V2O₅-WO₃-TiO₂/SO₄2-catalysts were prepared by impregnationmethod using nono TiO₂as supporter with different sulfating order and acid amount.Sulfuric acid treatment when it load WO₃can greatly enhance the SCR activitytemperature window, the NO conversion can reach80%at250℃.The best catalystis V（1%）-WO₃（5%）/TiO₂-SO₄2-（10%）。The characterization of the catalyst provedthat sulfating treatment promotes the catalytic activity greatly for the increase ofcatalyst’s acidity from120-500℃.（3）A series V2O₅-WO₃-TiO₂catalysts with doping some metal oxides and itssulfate have been prepared using commercial titanium-tungsten powder as support.The results of experimental show that doping Fe,Co and Nb metal oxide and sulfatehas a high catalytic activity temperature window form250to450℃.In the case ofultra-low vanadium loading （0.5%）, Cobalt sulfate and ferrous sulfate play an important role in denitrification activity. The best catalysts are V（0.5）-CoSO₄（5）-W/Tand V（0.5）-FeSO₄（3）-W/Ti. the NO conversion can reach60%at250℃；Thecharacterization of the catalysts proved that specific surface area and the acidity of thecatalyst surface showed downward trend with the increase in sulfate loading.However, the in-suit IR characterization shows a significant increase of Br nst andLewis acidic on catalyst surface.