Development of Potassium-Modified Mordenite Catalyst for Soot Oxidation via Treatment Method and Impregnation Method

Abstract

Soot oxidation catalysts are prepared by treatment and impregnation of Na- and H-mordenite with potassium-containing solutions (KOH, KCl, KNO₃, and K₂CO₃). Treatment with KOH increased the soot oxidation activity of Na-mordenite, which is attributed to an increase in alkali content. The presence of macropores of the sample improved soot–catalyst contact by increasing the surface over which soot and active sites can be in good contact, and thus also contributed to the increase in activity. The activity of H-mordenite was influenced by treatment with high KOH concentration, but not with low KOH concentration. Impregnations with potassium increased the activity of Na-mordenite, with KNO₃ impregnation yielding the highest activity. The combination of treatment with KOH and impregnation with KNO₃ further increased the activity of samples. The improvement in activity is attributed to the presence of the alkali element and NO₃^– species, and of macropores that promoted good soot-active sites contact.