Preparation and catalytic properties of low content Ag-added ZrO₂ for soot oxidation

Abstract

Low content (0.1–3.4 wt %) Ag added ZrO₂ catalysts were synthesized by a hydrothermal method for soot combustion catalysis. The thermal stability and microstructure were characterized by X-ray diffractogram, field emission scanning microscopy, surface area and X-ray Absorption Fine Structure (XAFS) measurement. Soot oxidation temperature of Ag/ZrO₂ catalysts was able to be controlled by changing heat-treatment temperature for starting powders. The mixture of metallic Ag and ionic Ag₂O was observed by the XAFS spectra, and catalysts maintaining thermal stability were modified by active Ag/Ag₂O mixed state on ZrO₂. The catalysts with only 0.9 and 3.4 wt % doping of Ag in ZrO₂ were effective and a better candidate for diesel soot oxidation catalysis.