The effect of Ca(2+) and Al(3+) additions on the stability of potassium disilicate glass as a soot oxidation catalyst

Potassium disilicate (K(2)Si(2)O(5)) glasses substituted with additions of Ca(2+) and Al(3+) have been prepared, characterized and tested as diesel soot oxidation catalysts. Ca and Al modify the silicate glass network, resulting in improved stability for catalyzing oxidation of diesel soot. TGA and water immersion studies showed that substituting K(2)O with CaO can improve the chemical stability with a small loss of catalytic activity. (K(2)O)(0.5)(CaO)(0.5)(SiO(2))(2) had a soot ignition temperature (T(ig)) around 410 degree C and also excellent catalytic stability with repeated soot oxidation cycling. Similarly, substituting with Al(3+) gave improved stability, with(K(2)O)(0.7)(Al(2)O(3))(0.3)(SiO(2))(2) exhibiting a T(ig) around 370 degree C and betterstability than K(2)O 2Si(2)O(2). The activity results are interpreted with insights gained from FTIR characterization.