The Molding Of Siderite Catalyst And Its Application In Flue Gas SCR Denitration

Selective Catalytic Reduction method(SCR)is the most widely used flue gas denitration technology of which catalyst is the core.V2O5-WO3/TiO2 catalyst is widely used commercially nowadays,but the active temperature range and price of the catalyst is too high and its main active ingredient vanadium is poisonous.Therefore,it is very important to develop a new type of SCR catalyst with high efficiency,low temperature activity and non-toxic.It was found that the siderite has excellent low temperature SCR denitration activity by our research group,and moreover it has a wide range of sources and low price.However,it is necessary to study the molding process of siderite catalyst for applying it into industrial practice.The low temperature SCR denitration activity of pelleting forming siderite catalyst was studied considering the effects of calcining temperature,calcining time and calcination order on the low temperature catalytic denitration activity of the siderite catalyst.The experimental results show that siderite calcined 5 hours under 450? after pelleting has the highest SCR denitration activity.Its catalytic denitration efficiency reaches 95.2%at 180 ?.Furthermore,its catalytic denitration efficiency is higher than 98%under the reaction temperature from 210? to 330 ?.The SCR denitration activities of siderites from different locations were compared.Moreover,the surface properties and components of the siderite catalysts were investigated with the help of BET,XRD and XRF and other characterization methods.It is found that siderite located in Hunan province contains more iron and manganes.The existence and interaction of iron and manganes make the SCR denitration activity of the siderite located in Hunan province obviously superior to that of the siderite located in Guizhou province.The sulfur resistance experiment of siderite catalyst was conducted.It reveals that ammonium sulfate salt produced by the reaction between SO2 and NH3 covers the surface of catalyst and reduces the SCR denitration efficiency of catalyst accordingly when the reaction temperature is 210?.However,ammonium sulfate salt has decomposed when the reaction temperature is 270?.So the increase of the reaction temperature is benificial for promoting the sulfur resistance performance of the siderite catalyst.The spark plasma sintering(SPS)technology was introduced to make pelleting forming siderite catalyst successfully and the experimental results show that the SCR denitration activity of siderite catalyst made by SPS is slightly better than that of siderite catalyst made by traditional pelleting forming.The molding process and formula of honeycomb low temperature siderite catalyst were studied.The honeycomb siderite catalyst was prepared by proportioning,kneading,pugging,ageing,extrusion molding,drying and calcining process with siderite powder and titanium dioxide as substrate and montmorillonite,stearic acid,lactic acid,glass fiber,paper pulp,polyoxyethylene and hydroxypropyl methyl cellulose as additives.The honeycomb catalyst has a smooth surface and a certain strength.The SCR denitration activity experiment of honeycomb siderite catalyst shows that the addition of forming additives weakens the SCR denitration activity of the honeycomb low temperature siderite catalyst,but the polyporous characteristic of the honeycomb catalyst can improve the surface area of the catalyst thus improving the SCR denitration efficiency.The catalytic denitration efficiency of the honeycomb catalyst is more than 90%when the reaction temperature ranging from 180? to 280? which can meet the needs of the low temperature SCR denitration and lay a foundation for applying siderite low temperature catalyst into industrial practice.