|
ИСТИНА |
Войти в систему Регистрация |
ИСТИНА ЦЭМИ РАН |
||
Mechanism of Zr Incorporation in the Course of Hydrothermal Synthesis of Zeolite BEAстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 12 ноября 2018 г.
- Авторы: Kots Pavel A., Zabilska Anna V., Khramov Evgeny V., Grigoriev Yuriy V., Zubavichus Yan V., Ivanova Irina I.
- Журнал: Inorganic Chemistry
- Том: 57
- Номер: 19
- Год издания: 2018
- Издательство: American Chemical Society
- Местоположение издательства: United States
- Первая страница: 11978
- Последняя страница: 11985
- DOI: 10.1021/acs.inorgchem.8b01548
- Аннотация: The mechanism of Zr-BEA hydrothermal synthesis in fluoride media has been investigated through the detailed characterization of samples obtained at different synthesis times by XRD, XRF, TGA, multinuclear solid-state NMR, FTIR, SEM, TEM with EDS, XAS, and nitrogen sorption. The synthetic procedure involved hydrothermal crystallization of the gel with the following composition: 1SiO2:0.54TEAOH:0.54HF:0.005ZrO2:5.6H2O. The formation of open and closed Lewis acid sites was monitored by FTIR spectroscopy of adsorbed CO, while coordination of Zr was studied by XAS. The results show that the formation of Zr-BEA proceeds by two steps. In the first step, pure silica BEA is crystallized via a solid–solid hydrogel rearrangement mechanism. Zirconium species are occluded in Si-BEA crystals in the form of Zr-rich silicate particles. These particles do not provide for any appreciable Lewis acidity. In the second step, Zr incorporation into T positions of the zeolite structure takes place, leading to the formation of closed Zr sites, which are partially converted into open sites at longer synthesis times. It is demonstrated that the content of open and closed sites can be tuned by variation of the synthesis time.
- Добавил в систему: Коц Павел Александрович