New insights on the autocatalytic nucleation in zeolite A synthesis

Palčić, Ana; Bronić, Josip; Brlek, Đurđica; Subotić, Boris

doi:10.1039/c0ce00102c

Cited by 29 publications

(9 citation statements)

References 24 publications

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“…They are similar to the curves of the systems crystallized at static conditions. 7 The major difference between the systems done under static and dynamic conditions of the synthesis is the time of transformation, and consecutively, different values of kinetics' parameters and distributions of nuclei within gel matrix.…”

Section: Resultsmentioning

confidence: 99%

“…4,6 In this paper, we have studied the ageing of amorphous precursor and the way it affects the zeolite A nucleation process at dynamic conditions and compared the results with the data obtained from the systems in static conditions. 7 The proposed model of autocatalytic nucleation is the one that describes the basic processes of zeolite crystallization and is applicable to all systems which have hydrothermal transformation of the gel into relatively low soluble crystals without using structure directing agents. It is based on the assumption that potential crystal nuclei are formed within the alumosilicate gel matrix during its precipitation and during ageing time.…”

Section: Introductionmentioning

confidence: 99%

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Zeolite A Synthesis under Dynamic Conditions, after Hydrogel Ageing

Palčić¹,

Sekovanić²,

Subotić³

et al. 2012

Croat. Chem. Acta

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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 Na 2 O × 2 SiO 2 × 1.05 Al 2 O 3 × 250 H 2 O were heated in stainless steel reactor at 80 °C under dynamic conditions, after ageing for t A = 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.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Zeolite A Synthesis under Dynamic Conditions, after Hydrogel Ageing

Palčić¹,

Sekovanić²,

Subotić³

et al. 2012

Croat. Chem. Acta

Self Cite

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show abstract

“…After aging for the given time, systems were put at 80 °C for crystallization under static and dynamic conditions. Transformation of the all systems ends with pure zeolite A phase, 6 but of different crystal's size distributions (consequently, specific number of crystals is also different).…”

Section: Methods Of Samples Characterization (Pxrd Dtg Ftir Pals mentioning

confidence: 99%

“…Aluminosilicate hydrogels studied in this paper were prepared as described in our previous paper. 6 Dissolving the needed amounts of fumed silica (SiO 2 -99.8 wt%, Sigma), sodium hydroxide (NaOH reagent grade, >98 wt%, Kemika) and sodium aluminate (NaAlO 2 -41 wt% Na 2 O, 54 wt% Al 2 O 3 , Riedel de Haën) in demineralised water, alkaline sodium silicate and alkaline sodium aluminate solutions were prepared. The sodium aluminate solution was centrifuged to remove the impurities and only supernatant was used for further experiments.…”

Section: Precursors Preparation and Hydrothermal Synthesis Of Zeolmentioning

confidence: 99%

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Relation of the Aged Gels Microstructure on the Product (zeolite A) Particulate Properties

Palčić

Bosnar

et al. 2015

ACSi

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The microstructure of the starting hydrogel has extremely important role in the synthesis of the microporous materials. Due to the fact that very limited number of experimental methods (techniques) can be used for gel analysis, there are still a lot of missing information about the processes on molecular level, which occur before and during the nuclei formation. In this paper, various methods were used in characterization of pretreated (aged) hydrogel before the process of its hydrothermal transformation to zeolite A. The results obtained from different techniques (FTIR, PALS, BET, DTG) show the changes in chemical composition and in microstructure of the solid phase, indicating that the structure of the ordered phase (potential nuclei) within gel matrix (completely amorphous according to PXRD patterns) is rather of different structural units typical for FAU and SOD (or their mixture) than the final product (LTA) only!

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Nanozeolites and Nanoporous Zeolitic Composites: Synthesis and Applications

Vuong

2015

Mesoporous Zeolites

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New insights on the autocatalytic nucleation in zeolite A synthesis

Cited by 29 publications

References 24 publications

Zeolite A Synthesis under Dynamic Conditions, after Hydrogel Ageing

Zeolite A Synthesis under Dynamic Conditions, after Hydrogel Ageing

Relation of the Aged Gels Microstructure on the Product (zeolite A) Particulate Properties

Nanozeolites and Nanoporous Zeolitic Composites: Synthesis and Applications

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