Sr1−xKxTiO3 catalysts for diesel soot combustion

Strontium titanates partially substituted with potassium (Sr1−xKxTiO3, x = 0.1–0.5) were prepared by sol–gel citric method. The obtained materials were characterized by XRD, SBET and cyclohexanol (CHOL) decomposition measurements, their catalytic activity in soot combustion was determined. It has been shown that substitution of strontium by potassium lowers temperature of soot ignition temperature by 270 °C in a 10% O2 in Ar atmosphere and ca 400 °C in a 1500 ppm of NO2, 10% O2 in Ar atmosphere for Sr0.2K0.2TiO3. The potassium promoting effect is discussed in terms of surface basicity and creation of oxygen vacancies where molecular oxygen or (NO, NO2) is adsorbed forming basic surface oxygen species active for soot oxidation.