Study On Preparation And Forming Properties Of SCR Low Temperature Denitration Catalyst

At present,nitrogen oxides get the attention of country and government as an important factor in air pollution in the case of controlling the environmental pollution.The vanadium titanium series denitration catalysts can not used at low temperature（<200℃）because of the limitation of itself,thus its application is limited.In this paper,denitration activity improvement and integral honeycomb denitration catalyst preparation of manganese based low temperature SCR denitration catalyst were explored with a large number of experiments.First of all,MnO_x powder catalysts were prepared by redox precipitation method with a series of Fe and Ce doped.With the help of XRD,SEM,H₂-TPR,XPS,BET,and other characterization measurements,the performance and reaction mechanism of doping MnO_x were systematically analyzed.The results showed that:the dispersibility was promoted,the surface area and pore size were increased,and more and more chemisorbed oxygen were appeared with the doping of Fe and Ce,which can enhance denitrification reaction.The whole denitration performance can be maintained at more than 90%between 100℃and 200℃with the ratio was0.10 of Fe and Ce doping.What is more,the surface reaction mechanism of0.10Fe-MnO_x and 0.10Ce-MnO_x catalyst mainly followed the L-H mechanism.NH₃had a strong adsorption capacity on the catalyst surface and the NH₃ existed mainly by adsorbed states on Lewis acid sites.The presence of NO was a large number of nitrates and amide base materials in the case of existing of O₂.And then N₂ and H₂O were produced on the surface of catalyst.Secondly,the cordierite powder and active components as the main raw material,the integral honeycomb denitration catalyst was prepared by blending method using extrusion.And the relationship between compressive strength and forming additive type and content was explored.the best content of external addition were oleic acid 6%,silica sol 40%,methyl cellulose 4.5%,maltose 3%,glass fiber（11μm/3mm）8%after acid treatment respectively.The integral honeycomb denitration catalyst was prepared using 0.10Fe-MnOx as active component with the content was 45%,which has a better comprehensive performance.And the compressive strength can reach 2.26 MPa and the denitration Performance can reach above 80%at 180℃.Finally,the performance at actual working conditions of integral honeycomb catalyst was studied.It was found that the SO2 poisoning resistance of Fe doped MnOx was obviously better than the undoped sample.The denitration rate remained at 40.1%after 9 hours with exist of SO₂ gas,while the undoped performance was just 13%.Under the same experimental conditions,the space velocity had a certain influence on the denitration catalyst performance,the smaller the space velocity,the better denitration performance.