Synthesis and characterization of new promoters based on CeO2–ZrO2–Bi2O3 for automotive exhaust catalysts

New oxidation catalysts based on CeO2–ZrO2–Bi2O3 solid solutions were synthesized for the effective oxidation of the soot particulates in the automotive emissions. Temperature programmed reduction and O2 pulses experiments have been performed to examine the redox behavior of the CeO2–ZrO2–Bi2O3 catalysts. The CeO2–ZrO2–Bi2O3 solid solution showed both oxygen release below 300 °C and high oxygen storage capacity (OSC) over 1000 μmol O2 g−1, while those of the conventional CeO2–ZrO2 were 594 °C and 482 μmol O2 g−1, respectively. Furthermore, the low temperature reduction behavior of the CeO2–ZrO2–Bi2O3 solid solution was promoted by the addition of silver, which is an oxygen permeable component. The mechanism of the behavior was attributed to the synergetic effects of the partial solution of silver into the CeO2–ZrO2–Bi2O3 lattice and the surface deposition of silver on the solid solution. The reactivity of oxygen in the bulk of the catalyst greatly improves the soot combustion activities at low temperatures.