Synthesis of lta type zeolites from georgian clinoptilolite
Generally, the microporous structure of synthetic zeolite is affected by the nature of used reactants and their pretreatments, as well as by composition of the reaction mixture. Our recent investigation of hydrothermal transformation of natural Georgian clinoptilolite demonstrated possibility of pre...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Chuiko Institute of Surface Chemistry of NAS of Ukraine
2017-09-01
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| Series: | Хімія, фізика та технологія поверхні |
| Subjects: | |
| Online Access: | https://cpts.com.ua/index.php/cpts/article/view/437 |
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| Summary: | Generally, the microporous structure of synthetic zeolite is affected by the nature of used reactants and their pretreatments, as well as by composition of the reaction mixture. Our recent investigation of hydrothermal transformation of natural Georgian clinoptilolite demonstrated possibility of preparation of zeolites with high silicon content (mordenite-like materials) without organic template, directly from aged gels having suitable chemical composition and prepared by acid treatment of raw material. The aim of present work was preparation of zeolites with high aluminium content on the same basis without organic templates. The study tested possibility of synthesis of the LTA type zeolites in following steps: treatment of the natural clinoptilolite ((Na3.3K1.15Ca0.75Mg0.25[Me]0.55)(Al7.0Si29.3O72)22.5H2O, where Me = Cu, Zn, Ba, etc.) in HCl water solution; gel preparation by suspension in NaOH solution; its hydrothermal crystallization to the sodalite structure (SOD) with Si/Al=1, and then re-crystallization of the sodalite into the NaA zeolite (LTA). Chemical elemental analyses confirm a good accordance with the UPAC SOD and LTA chemical formulas for prepared materials having nearly monocationic composition (Na – 78 % SOD and 89 % LTA). In XRD patterns there are no additional peaks from zeolitic or other impurities, prepared materials have high crystallinity, their FTIR spectra are typical for SOD and LTA structures, developed zeolitic crystal microporous structure is confirmed by comparatively high averaged value of water adsorption capacity (0.08 cm3/g for SOD, and of 0.24 cm3/g for LTA at p/pS = 0.4). SEM images show uniform LTA micrometric crystallites (average diameter 4 ?m) with fairly narrow distribution of sizes produced by lasting (> 10 h) low temperature crystallization, as well as nanoscale spherical zeolites (0.2 ?m) and fibrous aggregates (0.08 ?m) produced at low temperature, that can be used for preparation of composite and hierarchical structures for various catalytic and adsorptive applications. |
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| ISSN: | 2079-1704 2518-1238 |