Influence of the Alumina Precursor on the Activity of Structured Fe–K/Al₂O₃ Catalysts Towards the Simultaneous Removal of Soot and NO_x

Fe–K/Al₂O₃ catalysts supported on cordierite monoliths were prepared using four washcoating suspensions containing different dispersible boehmites. The influence of the inherent properties of these alumina precursors on the textural properties, morphology and mechanical integrity of the catalytic layer were studied together with the activity of the monolithic catalyst in the simultaneous removal of soot and NO_x. The textural and structural properties of the washcoat strongly determine the mobility of potassium species and therefore the activity of the different catalyst prepared. Calcination at 650 °C and complete removal of such mobile potassium nitrate species results in similar activity that no longer depends on the textural and morphological properties of the catalytic layer, determined by the type of alumina precursor used.