Transition-metal oxide pillared clays

Abstract

Manganese(iii) pillared montmorillonite samples have been prepared by intercalating the trinuclear manganese(iii) acetate complex {[Mn ₃ O(COOCH ₃ ) ₆ (H ₂ O) ₃ ] ⁺ CH ₃ COO ^- } between the silicate layers of both Na-exchanged (NaMont) and acid-activated montmorillonite (HMont), and characterised by different techniques. As far as the intercalation is concerned, the multistep ion-exchange process gave better loading of the complex in comparison to the single-step process. FTIR analysis shows the presence of a bidentate acetate group inside the silicate layer which decomposes at 300 °C. Materials prepared from both clays are thermally stable up to 500 °C, with basal spacings of 17.1 and 16.9 Å and surface areas of 280 and 268 m ² g ^-1 , (NaMont, HMont respectively). Although the acid-activated pillared montmorillonite shows low uptake of the complex and low surface area, the resultant material has higher pore volume and acidity in comparison to the product from the Na-exchanged material. Samples prepared from acid-activated clays possess both micropores and mesopores (average pore diameter 41 Å) while those prepared from Na-exchanged clays show predominately uniform small pores with an average pore diameter of 33 Å.