The effect of Ca2+ and Al3+ additions on the stability of potassium disilicate glass as a soot oxidation catalyst

Potassium disilicate (K2Si2O5) glasses substituted with additions of Ca2+ and Al3+ 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 K2O with CaO can improve the chemical stability with a small loss of catalytic activity. (K2O)(0.5)(CaO)(0.5)(SiO2)(2) had a soot ignition temperature (T-ig) around 410 degrees C and also excellent catalytic stability with repeated soot oxidation cycling. Similarly, substituting with Al3+ gave improved stability, with (K2O)O-3(Al2O3)O-3(SiO2)(2) exhibiting a T-ig around 370 degrees C and better stability than K2O center dot 2Si(2)O(2). The activity results are interpreted with insights gained from FTIR characterization. (C) 2013 Elsevier B.V. All rights reserved.