Characterization of Zeolite L Nanoclusters

Zeolite L (structure code LTL) crystals are synthesized starting from homogeneous potassium aluminosilicate solutions. Particle size and shape of the formed zeolite L are examined by high-resolution transmission electron microscopy, field emission-scanning electron microscopy, X-ray diffraction, and dynamic light scattering. The synthesis conditions reported lead to nanoclusters of aligned zeolite crystalline domains of dimensions ~40 nm in the channel direction and ~15 nm in the direction perpendicular to the zeolite channels. The nanoclusters have sizes of ~60 nm. Electron microscopy of the nanoclusters reveals the presence of inhomogeneities (intercrystalline porosity) on length scales ranging from 2 to 60 nm. The N₂ and cyclohexane adsorption capacities and the thermal stability of the crystals synthesized are correlated with their microstructure. The preparation of colloidal suspensions of the zeolite L nanoclusters in water is described along with their use in seeded growth and film formation.