REACTIVITY OF USY EXTRAFRAMEWORK ALUMINA IN ALKALINE-MEDIUM

Two ultrastable Y zeolites with different degrees of dealumination wer e treated with NaOH solution al various temperatures and contact limes . Filtrate analysis showed the transference of the solubilized nonfram ework aluminum species to the solid phase, at a rate that increases wi th both increasing temperature and dealumination degree. The reinserti on of this aluminum in the lattice was verified by the reduction in th e structural silica-to-alumina ratios (SAR) determined by Si-29 n.m.r. and FT i.r. The mesoporosity reduction points to a reinsertion in the structural defects, An estimate of the activation energy for the rein sertion process was obtained from the data fitting to a basic zeolite crystallization model.