The catalysts of three-dimensionally ordered macroporous Ce1−xZrxO2-supported gold nanoparticles for soot combustion: The metal–support interaction

Abstract

Three-dimensionally ordered macroporous (3DOM) Ce1−xZrxO2-supported gold nanoparticle catalysts were successfully synthesized by the gas bubbling-assisted membrane reduction (GBMR) method. Au nanoparticles with similar sizes are well dispersed and supported on the inner walls of uniform macropores. The active oxygen species (O2-, O−) over 3DOM Au/Ce1−xZrxO2 catalysts are derived from the two approaches: one is direct activation of oxygen on the surface of gold nanoparticles and the other is derived from strong metal–support interaction in which Ce-based supports serve as a reservoir for oxygen in the oxidation reaction. 3DOM Au/Ce1−xZrxO2 catalysts exhibited good catalytic performance for soot combustion, which is strongly related to the role of supports including the structures, the Ce/Zr ratios and the active oxygen supply pathways. The reaction pathways of soot combustion can be classified by two regions. At the low temperature, the soot particles are direct oxidized by active oxygen species migrated from the surface of supported Au catalysts. At the relatively high temperature, the catalytic activity for soot combustion is strongly related to intermediate reactant of NO2 derived from NO oxidation.