Enhanced Brönsted acidity created upon Al-grafting of porous clay heterostructures ia aluminium acetylacetonate adsorption

Abstract

Montmorillonite-PCH (porous clay heterostructure) and saponite-PCH are inorganic silica-like materials with large surface areas (∽1000 m² g⁻¹) and pore volumes (0.7 cm³ 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 Brönsted acid sites are created, remaining even after thermal treatment as high as 300°C. Evaluation of this acidity has been performed by NH₃ and acetonitrile-d₃ (CD₃CN) adsorptions.