| The rapid development of industry has promoted the progress of human society and science and technology,but but it has brought about the destruction of the ecological environment,and mankind has also paid a high price for this.The atmospheric environment is the basis for human survival.Nitrogen oxides（NOx）emitted from industrial flue gas is one of the atmospheric pollutants,and it is also the focus and difficulty of current air pollutant control.The NH3 selective catalytic reduction method（NH3-SCR）is the most mature and effective method for removing NOx,and its core is the catalyst system.This article focuses on the current mainstream commercial denitration catalysts（V2O5-WO3/Ti O2 catalyst）at home and abroad.Due to its high active window temperature（300-420℃）,it is not suitable for low-temperature（60-150℃）flue gas denitration in the steel industry.There are certain difficulties in the application of low-temperature flue gas treatment.The development of high-efficiency denitration catalysts with a low active window temperature is an important aspect of promoting low-temperature flue gas denitration in the iron and steel industry.This paper first studied in detail the effect of doping Ru Ox in the Ce Ox-Mn Ox/Ti O2 catalyst on the low-temperature denitration activity and reaction mechanism,and then studied the effect of calcination temperature on the low-temperature denitration activity and catalytic mechanism of the Ce Ox-Mn Ox-Ru Ox/Ti O2 mixed oxide catalyst.The main conclusions drawn in this article are as follows:（1）The Ce Ox-Mn Ox/Ti O2（CMT）catalyst（calcined at 600°C）was prepared by the step-by-step impregnation method,and then the CMT catalyst was used as a carrier to continue to support different contents of Ru Ox to prepare Ru Ox-Ce Ox-Mn Ox/Ti O2（R-CMT）catalyst（calcined at 400°C）.The results showed that with the increase of Ru Oxcontent,the low-temperature denitration performance of R-CMT gradually improved,and Ru Ox（2%）was the most suitable addition amount.The denitrification activity of R（2%）-CMT is 72%higher than CMT at 120℃,and reaches 91-99%at 120-140℃.Ru Ox can promote the low-temperature denitrification activity of CMT catalyst,mainly because the monodentate nitrate of NO activation product adsorbed on the surface of R-CMT catalyst gradually increases with the increase of Ru Ox.In addition,Ru Ox can also promote the conversion of inactive bidentate nitrates on the surface of R-CMT catalysts to active monodentate nitrates.（2）The Ce Ox-Mn Ox-Ru Ox/Ti O2（CMRT）mixed oxide catalyst was prepared by wet co-impregnation method with Ti O2 as the carrier at different calcination temperatures.The results show that the optimal calcination temperature of CMRT catalyst is 350℃,mainly because CMRT-350 has the strongest NO activation performance and moderate NH3 activation performance,and the reaction rate of NO activation product and NH3 activation product on the catalyst surface is the best fast.（3）Both parts of the experiment show that the oxidation-reduction mechanism（Mars-van Krevelen;M-K mechanism）is the fundamental mechanism for the catalytic action of the R-CMT series of catalysts.Ru content,optimal calcination temperature and lattice oxygen content can all increase the redox performance of the R-CMT catalyst further promotes the SCR reaction fundamentally.Lattice oxygen(O2-)is the medium for a series of R-CMT catalysts to generate M-K cycle.The entire M-K cycle connects the catalyst,reaction gas,activation product and reaction product through lattice oxygen.In addition,M-K,Langmuir-Hinshelwood（L-H）and Eley-Rideal（E-R）mechanisms exist on the surface of R-CMT series catalysts.The three mechanisms work together to complete the SCR reaction.（4）The main reason why the activity of R-CMT series catalysts will decrease at high temperature is the intensification of the side reaction,namely the NH3 oxidation reaction.In addition,it was found that the catalyst with the highest low-temperature denitration activity has the strongest resistance to SO2 poisoning. |
