EVOLUTION OF THE MICROPOROUS ACCESSIBILITY WITH THE HYDROLYSIS DEGREE AND THE INTERCALATION SOLUTION AGING TIME CONDITIONS IN ALUMINUM PILLARED CLAYS

The microporous accessibility of two series of aluminium-pillared clays prepared with different OH/Al molar ratios and intercalation solution ageing times has been studied. Nitrogen adsorption data obtained from very low relative pressures were used to obtain a thorough characterization of the microporosity of the intercalated solids. Dubinin-Radushkevich plots and micropore size distributions obtained with the Horvath-Kawazoe model confirmed the existence of two sizes of micropores. The OH/Al molar ratio played a determinant role in the properties of the intercalated samples. For the lower values (0.5 and 1.0), the intercalation process was not successful and a low microporosity was obtained in agreement with X-ray diffraction measurements. On the other hand, it was observed that the ageing time conditions of the intercalation solutions increased the accessibility properties. This behaviour was correlated with the state of hydrolysis of the aged solutions.