Study On The Crystal-plane-effects Of CeO₂-based Nanomaterials For The Selective Catalytic Reduction Of NO With NH₃

The selective catalytic reduction of NO_x by NH3?NH3-SCR?is one of the most important technique for the deNO_x of coal-fired flue gas.For NH3-SCR reaction,CeO₂ has played an important role in the new non-vanadium-based catalysts due to its own excellent high oxygen storage-release capacity and redox ability.It is well-known that the catalytic elimination of environmental pollutants is mainly belonged to heterogeneous catalysis,in which the surface structures of catalysts play an important role.In recent years,with the rapid development of the characterization techniques and controlled synthesis for different-shaped nanocrystals,the understanding of the relationship between the structures and catalytic properties of nanocrystals at the molecular level has become possible,which will provide an significant theoretical gudiance for the design of highly efficient and environmentally friendly catalysts.In this thesis,we focus on studying the issue about the crystal-plane-effects of cerium oxide?CeO₂?for the selective catalytic reduction of NO with NH3.The details about our research are as follows:?I?Differernt-shaped WO₃/CeO₂ nanomaterials,including nanorod?111??100?,octahedron?111?and nanocube?100?,were prepared by hydrothermal method.The samples are characterized by XRD?TEM?XPS?TPR?Raman and in situ DRIFTS systematically.The crystal-plane-effects of CeO₂ has made the surface WO₃ existing in a different way.Through studying the surface acid amount and redox ability of the catalyst,we consider the isolated WO₃ may have the better catalytic activity for NH3-SCR.???Differernt-shaped MnO_x/CeO₂ nanomaterials,including nanorod?110??100?,octahedron?111?and nanocube?100?,are prepared by hydrothermal method.The samples are characterized by XRD?TEM?XPS?TPR and in situ DRIFTS systematically.we found the MnO_x/CeO₂-C catalyst which exposed?100?crystal plane exhibit the best NH3-SCR activity at low temperature.Through the analysis,we consider the high content of Ce4+on the surface may activate NH3 and NO more easily,the in situ generation of NO₂ can accelerate the reaction following the "Fast-SCR" approach.