Montmorillonite, vermiculite and saponite based porous clay heterostructures modified with transition metals as catalysts for the DeNOx process

Abstract

Porous clay heterostructures (PCHs) were synthesized from natural montmorillonite and vermiculite as well as synthetic saponite using the surfactant directed method. The direct synthesis of PCHs from saponite and montmorillonite was possible, while the pre-treatment of parent vermiculite with acids was necessary prior to the intercalation step. The PCH samples were characterized with respect to their composition (EPMA), structure (XRD, UV–vis-DRS), texture (BET), surface acidity (FT-IR) and chemical nature of the deposited transition metal species (UV–vis-DRS). Porous clay heterostructures as well as their derivatives modified by deposition of transition metal (Cu, Fe) oxides were tested as catalysts for the DeNOx process. The transition metal containing PCH samples were found to be active, selective and stable catalysts of this process. Their catalytic performance depended on the kind of the parent clay used for the PCH synthesis as well as deposited transition metals.