(498g) Glass Catalysts for Diesel Particulate Filter Applications

The promotion effect of alkali metals on the oxidation of diesel soot has been reported by many researchers. [1] Unfortunately, if the potassium is not bound within a crystalline lattice it may be lost during carbon oxidation (e.g. through evaporation, sublimation) at the elevated combustion temperatures. This has limited the usefulness of some alkali metal containing compounds. To accommodate such losses of potassium, the approach developed in our lab is to take advantage of ion-exchange in a glass, in particular, to use the slow release of potassium from a silicate glass as a source of potassium for catalyzing soot oxidation. A simple potash glass (35K2O:52SiO2:13CaO) was synthesized and examined for activity for diesel soot combustion by thermogravimetric analysis (TGA) under various contact and atmospheric conditions. [2] The glass powder was found to be an effective soot oxidation catalyst. As seen in Figure 1(left), ignition temperatures under loose soot-catalyst contact conditions under 400oC are observed. Figure 2 (right) shows that an isothermal hold at 400oC is sufficient to remove all of the soot. Leaching of potassium from the glass is thought to mitigate the effect of potassium loss during soot combustion, offering an effective means to maintain the surface activity of the glass catalyst. Additional TGA characterization suggests the glass has good activity stability based on repeated regeneration cycling. Further work is needed to optimize composition and define the preferred route to apply the glass to various substrates. REFERENCES [1] H.M. An, P.J. McGinn, Appl. Catal. B-Environ. 62, 46 (2006). [2] H.M. An, C.S. Su, P.J. McGinn, Catal. Comm. 10, 508 (2009).