Vermiculites intercalated with Al2O3 pillars and modified with transition metals as catalysts of DeNOx process

Vermiculites intercalated with alumina pillars and modified with transition metals (Cu, Fe) were studied as catalysts of selective reduction of NO with ammonia. Prior to the pillaring process, a raw vermiculite was treated with a solution of nitric acid and then citric or oxalic acid in order to reduce the overall charge of layers. This modification was necessary for a successful pillaring of the clay. Transition metals (Fe, Cu) were deposited on the surface of the modified vermiculites by an ion-exchange method. The obtained samples were characterized with respect to composition (EPMA), structure (XRD), texture (BET) and chemical nature of deposited transition metal species (UV–vis–DRS). The vermiculite based materials have been found to be active and selective catalysts of the DeNOx process. The Cu-containing samples were catalytically active at lower temperatures than the pillared clays modified with iron. A side reaction of ammonia oxidation by oxygen decreased the effectiveness of the DeNOx process in the high temperature range.