The Influence of Silica Template Aging Temperature on the Properties and Catalytic Activity of Nanocast Mesoporous Zirconium-Doped Ceria

KIT-6 samples were prepared at hydrothermal aging temperatures of 60, 100, and 140 °C, and used as templates for nanocasting of zirconium-doped ceria. In nanocast samples, the ordered 3D structure collapsed, leaving behind nanorods with a diameter roughly in concordance with the corresponding KIT-6 template pore diameter. In addition to nanocrystalline ceria, a small amount of cubic zirconia is present in the doped samples, but the formation of a solid solution was confirmed by the decrease in the ceria lattice parameter relative to bulk ceria. The specific surface areas of the nanocast samples decreased with the increase in KIT-6 template aging temperature. Ceria bandgap values were slightly blueshifted in comparison with bulk ceria, which was attributed to quantum confinement. No difference between samples concerning lattice ceria defects has been noted. Conversion curves show apparent three-stage conversion with stagnation at temperatures in the range between 250 °C and 300 °C, which is a consequence of abundant adsorption of toluene below 250 °C and desorption above 250 °C. Slight differences in catalytic activity are only due to a difference in the amount of adsorbed toluene caused by differences in the specific surface area of the samples.