Acid- and base-treated Fe3+-TiO2-pillared clays for selective catalytic reduction of NO by NH3

Fe3+-ion-exchanged delaminated pillared clays (PILCs) have been found previ ously to be more active than the vanadia-based catalysts for selective cata lytic reduction (SCR) of NO by NH3. The effects of acid treatment of the cl ay (before pillaring) and base treatments of the TiO2-PILC (before ion exch ange) on the activities of the Fe-TiO2-PILC catalysts were studied. It was found that the acid treatment increased the activity (by 33%), but the base treatments decreased the activity (although they increased the cation exch ange capacity of the pillared clay and, hence, the Fe content). The activit ies of the catalysts were directly related to their surface Bronsted acidit ies as identified by FT-IR of chemisorbed NH3.