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Интеллектуальная Система Тематического Исследования НАукометрических данных |
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Towards understanding of the mechanism of zeolites recrystallization into micro/mesoporous materialsтезисы доклада
- Авторы: Kasyanov I.A., Maerle A.A., Ivanova I.I.
- Сборник: 6th International FEZA conference ‘Porous Materials: from Novel Materials to Sustainable Solutions’, Universitat Leipzig, Germany. Book of Abstracts
- Тезисы
- Год издания: 2014
- Место издания: Leipzig, Germany
- Первая страница: 329
- Аннотация: Micro/mesoporous materials obtained by recrystallization have emerged as an important class of catalytic materials, which has significant number of advantages with respect to both zeolites and ordered mesoporous materials. Nevertheless, the detailed information on the mechanisms of synthesis of these materials is still unclear. The aim of this work was to clarify the mechanism of mordenite (MOR) recrystallization into mesostructured material. Dealuminated mordenite (MOR) with Si/Al = 48,5 supplied by Zeolyst was used as a starting material. Composite micro/mesoporous materials were obtained by two step procedure including partial destruction of zeolite in NaOH aqueous solution, followed by its hydrothermal treatment in the presence of cethyltrimethylammonium bromide (CTAB) at 373 K. The process was interrupted after different periods of time; samples were cooled down to the room temperature, filtered and dried at 110º C for 24 hours. All the samples were characterized by XRD, XRF, TEM, NMR, nitrogen adsorption, TG-DTA, TPD of ammonia. Two series with different NaOH/zeolite ratio were studied. The results pointed to dissolution/re-assembling mechanism involving i) fast ion exchange of protons with sodium cations, zeolite desilication and formation of mesopores; ii) diffusion of CTAB in zeolite voids formed by desilication and ion exchange of sodium with CTA-cations; iii) formation of micelles by CTA-cations, condensation of silicious species around micelles and ingrowth and overgrowth of mesoporous phase on a zeolite. Depending on the degree of zeolite dissolution and the extent of mesoporous phase overgrowth, two different types of materials have been obtained: coated mesoporous zeolites and micro/mesoporous nanocomposites.
- Добавил в систему: Касьянов Иван Алексеевич