Study On The Preparation And Performance Of SCR Catalyst Based On Bauxite Residue (Red Mud)

Aluminum is an indispensable strategic metallic material during a country’s national economic development and defense construction.While the alumina is the main raw material of aluminum, red mud(RM) is a hazardous waste generated from alumina refining industries. China generates 6000 t of RM annually. Long time of stockpiling in vast amounts of RM not only occupies a quantity of land, but also became an important issue of alumina refining industries’ sustainable development because of its hazardous pollution to the environment, so the management and the utilization of RM continues to be a global concern puzzle.Nitrogen oxide(NOx) is one of critical hazards to the atmospheric environment and human health. Facing with the growing resource constraint and the pressure of emission reduction, how to reduce energy consumption and NOx emission at the same time is a serious problem to achieve sustainable development.In this study, RM was used as the main raw material to prepare the catalyst carrier, and different active components, such as BaZrO3, TiO2,V2O5, WO3, M0O3, Mn and Ce, were supported on the catalyst carrier by impregnation method. The SCR catalysts obtained were conducted under simulated flue gas to observe which kind of catalyst has the best catalytic performance, and the influences of different conditions such as calcining temperature, calcining time, active component content, molar ratio,reaction temperature, space velocity, oxygen content, H2O content and SO2 content were observed. The major studies are as follows:(1) The main chemical composition and mineral composition of red mud were studied by XRF and XRD analysis. RM contains a variety of metal oxides, such as Al2O3,Fe2O3, CaO,SiO2, and the mineral composition of red mud is very complicated, such as gibbsite, goethite,Calcium diaspore, anatase, hematite, edc. The surface area of RM is 65.8149 m2/g by BET test.(2) The BaZr03/RM, Ti02/RM, V2O5/RM, V2O5-MoO3-WO3/RM,Mn/RM, Ce/RM, Mn-Ce/RM catalysts were prepared by impregnation method. The SCR catalysts obtained were conducted under simulated flue gas, and Mn-Ce/RM catalysts showed the best catalytic performance.(3) Experimental results showed that when the reaction conditions were at temperature of 92 ℃, balanced with N2 space velocity 16200 h-1,and NO 250 ppm, O2 5%, 10%Mn10%Ce/RM produced conversion ratio of NO was about 58.2%. The Mn-Ce/RM catalyst showed poor water resistance, but the catalyst showed more excellent catalytic performance while there is SO2 in the flue gas, which reached a higher catalytic efficiency even at room temperature.(4) Mn-Ce/RM catalyst was analyzed by XRD, SEM, EDS, XPS,BET and other methods. The results shows that Mn in the catalyst mainly in the form of Mn3+ and Ce mainly in the form of Ce4+, and both of them have high dispersion, which is helpful to improve the catalytic activity.The surface area of the catalyst was reduced after two calcination process during the preparation of the catalyst.