Studies On Catalysts For NO_x Removal From The Regenerator In FCC Apparatus

As a pollutant in the atmosphere, NOxmainly comes from the exhaust gas of theregenerators of FCC apparatuses, power plants and vehicles. It has been shown that theamount of NOxemitted by FCC apparatus accounts for10%of the total NOxwhich isdischarged into the air. Therefore, it is essential to emphasize on the control of NOxpollution.However, at this stage, SO2in FCC regenerator easily enables the DeNOxcatalysts todeactivate. Therefore, it seems to be a feasible way to investigate a novel catalyst system toresist SO2poisoning so as to solve the demanding difficulty.In this thesis, we aimed to study the properties of different catalysts containing CuOand/or CeO2species in the reaction between CO and NO. Meanwhile, various kinds ofcharacterized methods including in-situ infrared spectroscopy, XRD, N2adsorption-desorption and H2-TPR were utilized to analyze the relationship between thestructure and activity of those prepared catalysts loaded on different supports. Besides,promotors were added into catalytic systems to investigate the influence towards the DeNOxactivity and the resistance towards SO2. Some significant results were obtained during theexperiments.The research indicated that CuO/γ-Al2O3possessed inferior DeNOxactivity at lowreaction temperature. Nevertheless, after ZrO2species being introduced into the catalyticsystem, the catalytic ability positively changed to some extent, which could be attributed tothe advantages of ZrO2species that could effectively inhibit the aggregation of activecomponents and the sintering of the support at high reaction temperature. As to CuO/CeO2catalysts, factors such as preparation methods and temperature exerted tremendous influenceson their DeNOxactivity. The synergistic effect between CuO and CeO2enabled CuO/CeO2 catalysts to show preferable DeNOxactivity at low reaction temperature compared withCuO/γ-Al2O3and CuO/MgAl2O4catalysts. When Co or Mg species were introduced intoCuO/CeO2catalytic system, the DeNOxactivity dropped because of the aggregation of activecomponents on the surface of the catalysts. Compared with CuO/Co3O4/CeO2,CuO/MgO/CeO2possessed higher resistance towards SO2, which was able to be ascribed tothe stronger basicity of MgO that increased its ability to capture SO2in the gaseous phase.When Ce species were added into CuO/γ-Al2O3and CuO/MgAl2O4catalysts, the newcatalysts owned higher DeNOxactivity at low reaction temperature. The interactive effectsbetween CeO2and the active sites with larger surface energy of MgAl2O4lead to theproduction of structure defects on the solid surface of CuO/CeO2/MgAl2O4, supplying activesites for the catalytic reaction. The introduction of Ce species promoted the catalytic reactionbetween CO and SO2, improving the resistance against SO2of the new catalysts at hightemperature.