Increasing the Catalytic Activity of Clays

Smectite clays have three important properties related to catalytic activity, intercalation, swelling and cation exchange capacity. When smectites are immersed in water, both intercalation of water molecules and swelling occur. The suspended clay can also freely exchange its interlayer cations for other cations in solution. Interlayer water molecules are dissociated producing protons and exhibit Bronsted acidity (Reaction l).8 

The higher the electronegativity of the interlayer metal cation M + the stronger the acid sites. When montmorillonite is ion-exchanged with Al3+ ions, it displays a very high activity towards several Bronsted acid catalysed reactions, comparable to that of 98% H2S04.9 

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