(169d) A Comparison of Mesopore Templating Methods for Ceria-Zirconia-Yttria Catalysts

High surface area mesoporous ceria and zirconia based oxides continue to be in great demand for applications that include emissions abatement, solid oxide fuel cells, electronics, sensors and catalysis. To date, the most cost effective methods for preparing mesoporous materials is via techniques that employ templates or structure directing agents. These templates can be divided into two groups: endo-templates (i.e., soft templates, such as surfactants, dendrimers, and block copolymers) and exo-templates (i.e., hard templates, such as porous carbons and resins). We prepared mesoporous ceria-zirconia-yttria mixed oxides from sol-gel mixtures of metal salts using all of the templates listed above and compared the resulting oxide structures using nitrogen physisorption (BET surface area and BJH Pore Volume), TEM, SEM, TGA, DSC, elemental analysis, and catalytic testing. For materials prepared using soft templates it was found that the nature of the metals precursors heavily influenced the rate of metal insertion into the growing oxide frameworks, and thus, significantly affected the final composition of the resulting mesoporous oxides. The influence of the templating scheme on the thermal stability of the resulting mesoporous oxides was also explored using TGA and DSC, where samples were heated in air and nitrogen up to 1000 °C. It was observed that the thermal stability (and surface area retention) of the oxides was influenced by the method of templating.