Textural characterization of montmorillonite pillared with aluminum/lanthanum polyoxycations

This study compares the porosity created in montmorillonites pillared with aluminum/lanthanum pillars with that of a sample pillared only with aluminum. Studies of the pore size distribution indicate that the Al/La-pillared samples have a new porous system, with a pore size at the limit between microporosity and mesoporosity. The presence of larger pores in the Al/La-pillared samples is due to the intercalation of inorganic polyoxycations between the clay layers. These polyoxycations are larger than the Keggin ion intercalated in the sample pillared only with aluminum. After successive thermal treatments the micropore volume is still high in the Al/La-pillared samples, whereas the thermal stability of the micropore volume, developed after the pillaring process, is lower in the Al-pillared sample, being reduced practically to zero after thermal treatment at the same temperature. Moreover, this work distinguishes and analyzes the different thermal evolution of both types of pores and compares them with the thermal evolution of the one single type of pores generated in the Al-pillared sample.

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