Preparation and catalytic activity of K4Zr5O12 for the oxidation of soot from vehicle engine emissions

Pure phase K4Zr5O12 is synthesized via solid state method in the present work. Various K/Zr ratios and temperatures are applied, and the synthesis process is investigated in detail by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Its catalytic activity for soot oxidation is studied by temperature programmed oxidation with different types of soot/catalyst contacts. It is revealed that K4Zr5O12 is very active in the presence of 2–10% O2 for both tight and loose contacts (Tp(tight) = 335 °C, Tp(ethanol) = 355 °C and Tp(shaking) = 370 °C). Thermal stability study shows that K4Zr5O12 is highly stable up to at least 900 °C.