Research On Catalytic Direct Decomposition Of Nitric Oxide Over RE-Attapulgite Catalyst

With the development of modern industry and the increasing of vehicles, air pollution has become a serious global problem. As the one of main atmosphere pollutants, Nitrogen oxide has huge threat to human health and ecological balance by its excessive emissions. Therefore, effectively elimination of nitrous oxide, especially the catalytic elimination, is present hot issue in environmental protection research area.In this study, attapulgite, yttrium oxide, the lanthanum oxide and the carbonated cerium were choosed as raw materials. A series of RE-Attapulgite catalysts for NO decomposition were prepared by chemical blending method and their catalytic performance was evaluated in a fixed bed flow reactor.La-Ce-Attapulgite and Ce-Y-Attapulgite catalysts were prepared in this study. Meanwhile, the effects of preparation conditions, including the rare earth content, ratio of La/Ce, pH value of the chemical blending, calcination treatment temperature of the catalysts, on catalytic activity of the catalysts for NO decomposition were investigated. After the single factor experiments, response surface experiment and orthogonal experiment methods were applied to optimize the preparation condition of La-Ce-Attapulgite and Ce-Y-the Attapulgite catalyst, respectively.The obtained results indicated that the optimal conditions of La-Ce-Attapulgite catalyst preparation were 2%, x=0.55, pH 7 and 400℃for the rare earth content, LaxCe(1-X), pH value of the chemical blending and alcination treatment temperature, respectively. And the denitration rate could be up to 66.58% under reaction conditions of 400℃, gas space velocity of 5000 h-1, the flue gas of 0.08% NO and 5.0% O2 balancing by N2. The optimal conditions of Ce-Y-Palygorskite catalyst preparation were 3%, x=0.8,7 and 375℃for the rare earth content, CexY(1-x), pH value of the chemical blending and calcination treatment temperature, respectively, and the denitration rate could be up to 69.89%.The effects of reaction temperature, airspeed, NO and O2 density of waste gas on NO catalytic decomposition were investigated. Based on the above experiments, the catalytic reaction dynamics were preliminary discussed. The results indicated that the react model has the second-level characteristic. NO adsorption on catalyst activeness bits is reversible; the surface reaction of two adsorbed NO molecules is the control speed step.X-ray diffractometer, scanning electron microscope, infrared spectrometer and thermogravimetric technology were used to analysis the elements, surface morphology and the characteristic structure of the catalysts, respectively.