Collect. Czech. Chem. Commun. 1998, 63, 321-337

Sorption and Transport of Species in Silicalite Study of Binary Systems Containing Iodine

Vladimír Masaříka, Pavel Nováka, Arlette Zikánováa, Jan Kornatowskib, Jaroslav Maixnerc and Milan Kočiříka

a J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 182 23 Prague 8, Czech Republic
b Institute of Technical Chemistry and Heterogeneous Catalysis, Technical University of Rheinland-Westfalen, D-52074 Aachen, Germany, and Faculty of Chemistry, N. Copernicus University, PL-87-100 Toruñ, Poland
c Prague Department of Institute of Chemical Technology, 166 28 Prague 6, Czech Republic


Sorption of iodine from both the vapour phase and iodine solutions in organic solvents on large Silicalite-1 crystals was investigated. The single component sorption of iodine and sorption from binary mixtures under co-diffusion conditions led to a uniform colouring of the crystals. Under counter-diffusion conditions with crystals saturated initially with vapour of a selected solvent, the sorption kinetics of iodine was 2 or 3 orders of magnitude slower as compared with the corresponding co-diffusion experiment. Colouring of crystals was always, at least in its initial stage, non-uniform with visualized pyramids at crystal basal planes. This finding together with the nature of outer and inner crystal morphology suggests that our Silicalite-1 crystals are 90°-intergrowths which have only pore mouth openings of sinusoidal channels in the crystal surface. The process of crystal colouring under counter-diffusion conditions seems to proceed via diffusion along the boundaries of crystal sections.

Keywords: Silicalite-1; Iodine; Binary sorption; Diffusion; Zeolites.