engleski

The synthesis of high surface area mesoporous ceria and investigations into its surface and bulk properties

Ceria (cerium oxide, Ce02) has found widespread use in the materials industry including use in the automotive industry as a catalytic support component. Its use is due not only to its oxygen storage/release capabilities but also due to its ability to stabilise and disperse catalytically active noble metals such as platinum and rhodium. Many of these properties are closely related to the available surface area, with enhanced activity being displayed with increasing surface area. The preparation of a new form of this material of high surface area known as mesoporous ceria was attempted, and its structural and surface properties investigated with a view to improving its properties. Mesoporous materials are those which contain a regular 3D array of pores, and whose pore diameter lies in the range 2-10 nm. Their usefulness lies in the ease of manipulating the pore dimensions to form tailored materials of extremely high surface area. Doped cerias were prepared by a number of different routes, viz. anionic, neutral and cationic surfactant-assisted approaches. Materials were aged at various temperatures and their structure and phase content monitored by Powder X-Ray Diffraction. Surface morphology was probed using Scanning Electron Microscopy and nitrogen adsorption measurements. Varying the preparation route gave materials with different surface and bulk properties, viz. mesoporosity, particle size and homogeneity. Mesoporosity was observed up to 600°C for pure ceria, and to still higher temperatures after doping with lanthanum. Barium-doped samples also exhibited enhanced stability at elevated temperatures, while those doped with boron showed a marked decrease in stability, with pore collapse being observed around 500°C.

Mesoporous ; Lanthanide ; Ceria ; Stability ; Catalyst

nije evidentirano