Surface structure of silicalite-1 crystals with modified morphology, studied by high-resolution transmission electron microscopy

COLL 462

Isabel Díaz, Instituto de Catálisis y Petroleoquímica, CSIC, Campus Cantoblanco, Madrid, 28049, Spain, Osamu Terasaki, Arrhenius Laboratory, Stockholm University, Stockholm, S-106 91, Sweden, and Michael Tsapatsis, Department of Chemical Engineering and Material Science, University of Minnesota, 421 Washington Avenue SE, Minneapolis, MN 55455-0132.
Silicalite-1 crystals with a modified shape have been synthesized using organic polycations (dimer or trimer TPA) as zeolite shape modifiers to enhance the relative growth rate along the b-axis (straight channels). Therefore, the purpose here is first to identify the new crystallographic axis of the oval-shaped silicalite-1 crystals, using selected area electron diffraction (SAED). Second, to analyze the surface microstructure based on high resolution transmission electron microscopy (HRTEM) images. The obtained images provide evidences of the different expression of crystallographic faces when morphology changes, even more, give further insights for the understanding of the growth process of silicalite-1 crystals.