Effects Of Doping Rare-earth Oxides On The Structure And The Performance Of SCR Catalysts

The Nitrogen oxide （NOx） is the formation culprit of acid rain and smogphotochemical, which heavily destroy the environment and damage to human bodyhealth.Selective Catalytic Reduction （SCR） technology is an important flue gas denitrationtechnology, and Catalyst is the core of the SCR system, which is accounting for20to30percent of the cost. Its core technology mainly mastered by some developed countries andthe SCR catalyst technology urgently need to improve and enhance in some places. thestudy of independent intellectual property rights, a cost-effective SCR DeNOx catalyst has avery important practical significance.In this paper, we use nano TiO₂as the carrier, load different proportion of the V₂O₅andWO₃as the active components.Through extrusion molding technology, the SCR catalystswere prepared.The catalyst’s denitration efficiency was measured by the self-built testequipment.The loading of the active component including V₂O₅and WO₃were studied indetail.and get the active component proportion of the best performancecatalyst.Second,Vanadium-Titanium catalysts were modified by adding of rare earth oxides,which load different content of Cerium Oxide, Lanthanide Oxide and Erbium Oxidation,and research effects of doping Rare-earth Oxides on the performance of Vanadium-titaniumCatalysts. Using SEM,EDS,XRD,BET, Strength Tester and other methods, catalysts werecharacterized.By homemade test device,study the performances on reaction temperature,space velocity （SV）, NO concentration, O₂concentration, ammonia ratio （NH3/NO） andcalcination temperature. Finally, reaction kinetics of SCR was analyzed through the data ofdenitration reaction using the Catalyst1%V-10%W and the Catalyst1%Ce–V.The best performance of Vanadium-titanium catalyst is Catalyst1%V-10%W, whosehighest denitration efficiency reached94.51%;As loading different amount of rare earthoxides have different effects on denitration performances of Vanadium-titanium catalysts,thebest performance of Catalysts Ce-V is the catalyst loading1%CeO₂,and the bestperformance of Catalysts La-V is the catalyst loading1.5%La₂O₃; Calcining temperature ofcatalysts has great influence on the specific surface area. The specific surface area of TiO₂as the carrier is89.46m²g^-1. the specific surface area of Catalyst1%V-10%W which wassinted at600℃reduce to74.32m²g^-1,while the specific surface area of Catalyst1%V-10%W which was sinted at750℃reduce to43.49m²g^-1; At the same time,the calcining temperature has effect on the strength of the catalysts,and when the calciningtemperature were600℃and750℃, the strength of the Catalyst1%V-10%W are1.58and2.00MPa; The strength of the catalyst loading rare earth are bigger than the catalys thatdidn’t contant rare earth, when the calcining temperature were600℃and750℃, thestrength of the Catalyst1%Ce-V are2.97and3.50MPa. When the temperature is250℃,thedenitration efficiency of Catalyst1%Ce-V reach90%, showing good low-temperaturecatalytic effect, In the range of300℃to450℃, its denitration efficiency is more than97%;The most denitration efficiency of catalysts is Catalyst1%La-V with97.45%at350℃.The catalytic activity enhances about7%when rare-earths were loaded.In the range of200³50℃, with the reaction temperature rise, the catalysticdenitration efficiency is increasing quickly, reaches maximum when reaction temperature is350℃, decrease after400℃; At the same temperature, the denitration efficiency of catalystsreduce with airspeed increased; when the ammonia nitrogen less than1, the catalystdenitration efficiency increased with ammonia nitrogen increased significantly, when theammonia nitrogen is larger than1, denitration efficiency almost unchanged; When theconcentration of O₂is less than2%, denitration efficiency is very low,but when theconcentration of O₂is more than4%, denitration efficiency tend to be the best, whenconcentration of O₂continue to increase, denitration efficiency tend to gently; Thedeveloped for removal of nitrogen oxide catalyst concentration area is broad; Catalyst1%V-10%W appropriate calcining temperature is600℃, when the burning temperatureishigher than600℃, the crystal of TiO₂which was used in Catalyst1%V-10%W change tored petrochemical, serious reduce NOx denitration efficiency and temperaturewindow;appropriate calcining temperature of Catalyst1%Ce-V can be both600℃and750℃, Catalyst1%Ce-1%V which was calcined by600℃has higher denitrationperformance;Catalyst1%Ce-V which was calcined by750℃has higher mechanicalproperties.Activation energy Ea of reaction by Catalyst1%V-10%W is33435.9709J/moland Ea of reaction by Catalyst1%Ce-1%V-10%W is21924.0408J/mol.When Ea issmaller,the catalytic reaction is more easily reacted and denitration efficiency improve more.