Seeding for Zeolite Membranes
Résumé
The seeding process can be described as a method in which a small piece of a single crystal/polycrystal (seed) is used to act as an active site (nuclei) for growing a larger crystal when exposed to the effect of nutrients (liquids or gas) in a reaction system. The addition of seeds shifts the equilibrium toward crystal formation and avoids the undesirable random nature of spontaneous nucleation. This procedure is typically applied for solutions during recrystallization processes, thus eliminating the need for molecular collision/interaction and decreasing significantly the time required for nucleation. The seeding strategy is also largely applied for growing uniform zeolite membranes on porous supports, starting from a layer of closely packed seed crystals which have been previously nucleated (Julbe 2007). The decoupling of the nucleation step (at high supersaturation) from the crystal growth (at low supersaturation) makes the formation of a zeolite membrane very rapid as compared to...