Micro-nano Regulation Of Ceria-based Catalysts For Toluene Catalytic Oxidation

Toluene,as a specific type of VOCs,is harmful to the environment and human health.The catalytic oxidation is considered as one of the most promising technologies to remove it.The transition-metal oxides are treated as the most promising catalysts in this field,and mainly because of their low cost when compared with noble catalysts.Therefore,it is of great significance to develop new high-efficiency non-noble catalysts.Rare earth ceria-based catalysts are a class of VOCs oxidation catalysts with good performance,but their micro-and nano-structures are still poorly understood.Hence,it is highly possible to controllably design and synthesize specific structures of ceria-based catalysts in order to achieve excellent catalytic performance.Herein,in this dissertation,the main goal is to control the micro-and nanostructures of ceria-based catalysts from the simple system to the complex system,then the performance and properites of toluene oxidation is systematically investigated and explored on these catalysts.The main innovative research results are as follows:1.Three different CeO₂ nanocatalysts self-assembled by nanocrystallines,namely,0D nanosphere,1D nanotube and 2D nanosheet were successfully prepared for the oxidation of toluene.CeO₂ nanosheet showed significantly higher catalytic activity than nanosphere and nanotube.The nanosheet CeO₂ catalyst could reach 50%toluene conversion even as low as 202°C.The outstanding catalytic activity of CeO₂ nanosheet could be attributed to the self-assembled 2D sheet-like structure with abundant active oxygen species.2.The hierarchical porous CeO₂-HS was prepared by a hydrothermal-driven assembly method.The hierarchical structure of catalyst was self-assembled by nanowire.The high activities was attributed to the porous structures leading large amounts of surface oxygen vacancies.The T₅₀0 of catalyst was 195°C under a high space velocity.3.A series of different shapes Co/Ce nanocatalysts was prepared fot toluene oxidation.The different of ceria nanosupports could result in the big difference in toluene oxidation behavior,that the?T₅₀ could be as high as 60°C.The low content of CoO_x was formed as either nanoparticles or highly dispersed species on the surfaces of different CeO₂ nanostructures.Highly dispersed CoO_x species and the increased surface active oxygen on the?111?CeO₂ surface led to the excellent performance of toluene oxidation.4.A series of porous ternary Cu-Mn-Ce doped catalysts were prepared by surfactant modification coprecipitation approach.It was found that the“competitive dissolution”of the third element copper can increase the degree of solid solution and further have a significant effect on the oxidation of toluene.The appropriate amount of Cu doping can promote the directional migration of Mn into the CeO₂ unit cell to form a more solid solution of Mn_0.5Ce_0.5O_x structure,resulting in a high concentration of active oxygen on the surface,which is beneficial to the catalytic oxidation of toluene.