Strong Acidity of Silanol Groups of Zeolite Beta: Evidence from the Studies by IR Spectroscopy of Adsorbed CO and 1H MAS NMR
Научная публикация
| Общее |
Язык:
Английский,
Жанр:
Статья (Full article),
Статус опубликования:
Опубликована,
Оригинальность:
Оригинальная
|
| Журнал |
Microporous and Mesoporous Materials
ISSN: 1387-1811
, E-ISSN: 1873-3093
|
| Вых. Данные |
Год: 2010,
Том: 131,
Номер: 1-3,
Страницы: 210-216
Страниц
: 7
DOI:
10.1016/j.micromeso.2009.12.025
|
| Ключевые слова |
1H MAS NMR, Acid-form and Zn- and Ga-modified zeolite, Acidic silanol groups, BEA, IR spectroscopy |
| Авторы |
Gabrienko Anton A.
1
,
Danilova Irina G.
1
,
Arzumanov Sergei S.
1
,
Toktarev Alexander V
1
,
Freude Dieter
2
,
Stepanov Alexander G.
1
|
| Организации |
| 1 |
Институт катализа им. Г.К. Борескова СО РАН
|
| 2 |
Universität Leipzig
|
|
Информация о финансировании (1)
|
1
|
Российский фонд фундаментальных исследований
|
07-03-00136
|
Acidic OH groups of acid-form and Zn and Ga-modified zeolite beta (BEA) have been characterized with 1H MAS NMR and by IR spectroscopy of adsorbed carbon monoxide. It is demonstrated that OH groups, which exhibit a vibration band at 3740 cm−1, reveal acidity, which is similar to that of the OH groups with the band at 3610 cm−1 according to the value of the low frequency shift of OH vibrations with adsorbed CO (ΔνOH/CO = 300 cm−1). The IR band 3740 cm−1 corresponds to the signal at ca. 2.1 ppm in 1H MAS NMR spectrum. The OH groups with signal 2.1 ppm are involved in H/D exchange with methane-d4 similar to acidic OH groups with the signals 4.0–5.1 ppm. The signals at 2.1 ppm in 1H MAS NMR and at 3740 cm−1 in IR are attributed to the strongly acidic silanol groups of the faulted structure of the zeolite. The silanols with the signals at 1.8 ppm and 3745 cm−1 are weakly acidic (ΔνOH/CO = 85 cm−1) and are not involved in the H/D exchange. Loading of the zeolite with Zn affords a notable decrease of the concentration of strongly acidic SiOHAl groups, whereas the quantity of these groups does not decrease upon loading the zeolite with Ga.