Y zeolite depolymerization–recrystallization: Simultaneous formation of hierarchical porosity and Na dislodging

The effect of the depolymerization–recrystallization (DR) process upon Na dislodging on Y zeolites was studied. A Na–Y zeolite was depolymerized with glycerol at 200 and 250 °C and partially recrystallized in presence of either a structure directing agent (CTAB) or ammonium ions (NH4NO3/NH4OH). The DR process produced a recrystallized Y zeolite and a non-crystalline mesoporous material acting as a support of zeolite. When recrystallization was carried out with CTAB, the pore size distribution in the support was narrower than in samples where ammonium was used. In both cases, sodium was dislodged away from its exchange sites, yielding a NH4–Y zeolite after recrystallization. Depending on the DR conditions, it is possible to modulate the amount of exchanged sodium of the recrystallized Y zeolite as well as the textural properties of the mesoporous alumino-silicate support.