Enhanced Bronsted acidity created upon Al-grafting of porous clay heterostructures via aluminium acetylacetonate adsorption

Montmorillonite-PCH (porous clay heterostructure) and saponite-PCH are inorganic silica-like materials with large surface areas (similar to 1000 g(-1)) and pore volumes (0.7 cm(3) g(-1)). They are obtained by introducing a surfactant template in-between the clay plates and subsequently polymerizing a silica source around them. The acidity of porous clay heterostructures has been improved. Based on the 'molecular designed dispersion' method, the Al-grafting onto the PCH surface using aluminium acetylacetonate complex is carried out, involving interaction between the surface silanol groups of the PCH-support and the complex, followed by a calcination step. In this way, stable Bronsted acid sites are created, remaining even after thermal treatment as high as 300 degreesC. Evaluation of this acidity has been performed by NH3 and acetonitrile-d(3) (CD3CN) adsorptions.