Original scientific paper

https://doi.org/10.5562/cca2055

Zeolite A Synthesis under Dynamic Conditions, after Hydrogel Ageing

Ana Palčić orcid.org/0000-0002-1092-4739 ; Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
Lavoslav Sekovanić ; Geotechnical Faculty, University of Zagreb, Hallerova aleja 7, 42 000 Varaždin, Croatia
Boris Subotić ; Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
Josip Bronić orcid.org/0000-0001-5846-0235 ; Ruđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia

Abstract

Zeolites are crystalline, microporous, alumo-silicate materials (around 400 types) which are used in many applications. Each field of usage (catalysis, ion exchange, sorption, molecular sieving, etc.) has demands regarding crystals’ structural and particulate properties. Detailed understanding of the mechanisms of crystals’ formation and growth enables the control of these properties. Hydrogels of the starting composition 3.2 Na2O × 2 SiO2 × 1.05 Al2O3 × 250 H2O were heated in stainless steel reactor at 80 °C under dynamic conditions, after ageing for tA = 0–209 h at 25 °C. Solid phase samples were characterized using microscopy (OM, SEM), PXRD and laser light scattering (LLS). Specific number of zeolite A crystals was calculated from particle size distributions. It was shown that the some particulate properties: specific number of crystals and crystal size distribution, are changing towards higher number of crystals and wider size distribution while the morphology of the crystals remains the same. Also, the crystal growth rate is higher in the systems which are treated under dynamic conditions. Obtained results were compared with data of systems crystallized under static conditions and commented on the grounds of the autocatalytic nucleation theory. (doi: 10.5562/cca2055)

Keywords

zeolite A; autocatalytic nucleation; crystal size distribution; hydrogel ageing

Hrčak ID:

92098

URI

https://hrcak.srce.hr/92098

Publication date:

31.10.2012.

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