Montmorillonite-based porous clay heterostructures (PCHs) intercalated with silica-titania pillars-synthesis and characterization

Porous clay heterostructures (PCHs) were synthesized using natural montmorillonite as a raw material. Apart from pure silica pillars also silica-titania pillars were intercalated into the interlayer space of the parent clay. The detailed studies of the calcination process of the as-prepared PCH samples as well as thermal stability of the pillared structure of these materials were performed. The pillared structure of PCHs intercalated with both silica and silica-titania clusters was found to be thermally stable up to temperatures exceeding 600 degrees C. It was found that titanium incorporated into the silica pillars was present mainly in the form of separated tetracoordinated cations. For the samples with the higher Ti loading also small contribution of titanium in the form of the polymeric oxide species was detected. Titanium incorporated into the PCH materials significantly increased their surface acidity forming mainly Bronsted acid sites. (C) 2009 Elsevier Inc. All rights reserved.