Surface redox characters and synergetic catalytic properties of macroporous ceria-zirconia solid solutions.

Macroporous CeO2-ZrO2 (CZ) solid solutions with gradually changing ceria content were prepared through the EISA method. Pore sizes of the samples are about 100 nm-1 μm and pore walls are 100 nm-1.5 μm. The surface and near surface reduction bands of Ce4+ below 600 °C were maximized for the Ce0.5Zr0.5O2 sample (C5) according to the quantitative de-convolution to the acquired TPR curves. The area percentage of the O2-2p6 → Ce3+3d94f2 electronic transition band on XPS spectra, which related to the concentration of the Ce3+, was found to be a function of the ceria content. The oxygen storage capacity showed a positive relationship with the chemical compositions. Redox reactions below 600 °C play a key role in determining the reduction performances of ceria based TWCs. Three-way catalytic performances of the Pd + Rh + Pt /C5 sample showed an ignition temperature for CO and NOx at about 240 °C, and finished before 300 °C. The ignition of C3H8 started at 270 °C while finished at differed samples. The maximum catalytic efficiencies of CO, NOx, and C3H8 on C5 sample were revealed to 100%, 98%, and 97%, respectively. The performances showed that porous CZ solid solutions are suitable for high performance catalytic applications.