The Preparation Of Copper-titanium-based Oxide And Its Catalytic Ammonia Selective Reduction Of NO

As one of the main air pollutants,nitrogen oxides?NO_x?are harmful to the health of human and the environment.Thus,how to eliminate the emission of NO_x effectively has become the concerned problem for the scientists all over the world.Among the way of removing NO_x,selective catalytic reduction by NH₃?NH₃-SCR?is considered as an efficient technique to remove NO_x emissions which come mainly from the stationary sources such as coal-fired power plants,industrial boilers and so on.Though V2O5-WO3?MoO3?/TiO2 as a commercial catalyst has been used for denitrification of flue gas in large coal-fired power plants,there are still many disadvantages to be resolved such as the narrow operation temperature window?300-400 ^oC?,high conversion of SO₂ to SO₃ at high temperature and the biotoxicity of V₂O₅ for human and environment.Thus,the oxidability and the surface acidity were modulated by doping proper Cu in the system of Ni-Ti and Ce-Ti,which obtained the catalysts of NH₃-SCR for denitrification with high catalytic activity and broad temperature window.A series of Cu_mNi_0.1-mTiO_x?m=0,0.01,0.015,0.02,0.03 and 0.1?and Cu_mCe_0.1-mTiO_x?m=0,0.005,0.01,0.02,0.03 and 0.1?catalysts were synthesized by the sol-gel method.Various characterizations including XRD,H₂-TPR,NH₃-TPD,XPS and in situ DRIFTS are used to investigate the effect of Cu doping on the structure and properties of the catalyst.The results suggest that the doping of Cu increase the low-temperature activity of the catalysts.The Cu_0.015Ni_0.085TiO_x catalyst shows excellent performance?NO conversion>90%?at the temperatre range of 205-425 ^oC at GHSV of40 000 h^-1.In addition,the Cu_0.01Ce_0.09TiO_x catalyst exhibits superior performance at the temperatre range of 170-425 ^oC?NO conversion>90%?at GHSV of 40 000 h^-1.In situ DRIFTS results indicate that the NH₃-SCR reaction for Ni_0.1TiO_x and Cu_0.015Ni_0.085TiO_x catalysts as well as Ce_0.1TiO_x and Cu_0.01Ce_0.09TiO_x catalysts mainly proceed through between the surface adsorbed NH₃ species and the surface absorbed nitrogen oxides,which follows the L-H mechanism.