Unusual Pathway of Crystallization of Zeolite ZSM-5 in a Heterogeneous System: Phenomenology and Starting Considerations
| Autor: | Boris Subotić, Sanja Bosnar, Tatjana Antonić Jelić, Tea Mišić Radić, Nan Ren, Vesna Svetličić, Yi Tang, Maja Dutour Sikirić, Josip Bronić |
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| Rok vydání: | 2012 |
| Předmět: |
Materials science
Scanning electron microscope General Chemical Engineering Zeolte ZSM-5 Unusual crystallization pathway “Worm-like” particles Condensed aggregates Polycrystalline aggregates Heterogeneous system Analytical chemistry General Chemistry law.invention Amorphous solid Crystallography Dynamic light scattering Electron diffraction law Transmission electron microscopy Materials Chemistry ZSM-5 Crystallization Zeolite |
| Zdroj: | Chemistry of Materials. 24:1726-1737 |
| ISSN: | 1520-5002 0897-4756 |
| Popis: | Crystallization of zeolite ZSM-5 from a diluted heterogeneous system (12.5Na2O-Al2O3-8TPABr-60SiO2-4000H2O) was investigated by various experimental methods such as, X-ray diffraction (XRD), electron diffraction (ED), infrared spectroscopy (FTIR), X-ray fluorescence (XRF), scanning-electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), thermo-gravimetric analysis (TG-DTG), particle size analysis (PSA) and Inductive Coupling Plasma (ICP) Emission Spectrometry. The crystallization process is characterized by a very long “induction period” (95 % of the entire reaction time) and very fast transformation (5 % of the entire reaction time) of amorphous to crystalline phase (zeolite ZSM-5) at the end of crystallization process. Analysis of the obtained results have shown that the crystallization process takes place by a chain of processes: (i) formation of “primary” amorphous aluminosilicate precursor (gel) at room temperature, (ii) formation of “secondary” amorphous aluminosilicate precursor (“worm-like” particles – WLPs), (iii) formation of “tertiary” amorphous aluminosilicate precursor (condensed aggregates – CAs) by aggregation of the WLPs and densification (condensation) of aggregates and (iv) formation of nuclei and their growth in the matrixes of CAs ; these processes result in the formation of fully crystalline zeolite ZSM-5 in the form of polycrystalline aggregates. |
| Databáze: | OpenAIRE |
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