The Preparation And Properties Of De-NOx Catalysts Of Red Mud Supported With Mn And/or Ce

In recent years, hazards of nitrogen oxides are becoming increasingly serious with large emissions from fossil fuel combustion and the exhaust. At present, selective catalytic reduction (NH3-SCR) of NOx is the most promising technology to remove NOx, and the commercialized catalysts of V2O5-WO3/TiO2have been applied widely, but there are some defects, such as the low activity at high temperature, high cost, active component of vanadium oxides with highly toxic, and so on. So much effort has been focused on the development of catalysts with high efficient at low-temperature, lower cost, non-toxic and environmental friendly for NOx elimination.It cannot be ignored because of the environmental problems from red mud which was a major waste of aluminum plant. The development of red mud catalysts for NOx removal, mainly based on the rich composition itself. Red mud mainly contains active oxides of iron, aluminum, titanium and silica for de-NOx. Iron oxides in red mud showed catalytic denitration activity, alumina and silica oxides were extensively studied as de-NOx catalyst supports. Consequently, it is feasible for red mud used as de-NOx catalysts. The component of Na and Ca in red mud inhibit its application, so activation to raw red mud material is necessary.In this paper, red mud catalysts were prepared by loading active ingredients like MnOx and/or CeOx on the activate red mud for eliminating NOx, for achieving the purpose of treating waste with waste. Activated red mud and derived catalysts were studied, and the results indicate that:(1) Activation of red mud slag, the results showed that successful removal of high alkaline substances in red mud was achieved, and the surface area of red mud were greatly increased. It was to the benefit of dispersing the active components and effective and feasible in catalysis using activated red mud.(2) For the Mn/ARM and Ce/ARM catalysts, the SCR activity of Mn/ARM catalysts at low temperature is much higher than that of Ce/ARM. Under the low temperature conditions (<250℃), NO conversions approached to100%, and when the reaction temperature is high (>250℃), the activity of Ce/ARM catalysts were higher than Mn/ARM, NO removal efficiencies are close to100%at300℃. Denitration catalyst of red mud supported with manganese and cerium posses the active window width, its NOx conversions are close to100%at about200℃.(3) The results of multiple analysis and test technology demonstrate that:Ce can greatly reduce the loss of surface area and pore volume in calcined process, increase the surface activity oxygen concentration, improve the capacity of redox; Mn and Ce oxides will interact each other, addition of Ce is favor for uniformly dispersing on red mud of Mn, and interact with iron oxide in red mud, which enhance the acid and surface alkaline, improve catalyst activation in absorption of NH3and NOx.