Revisiting Acidity of SnBEA Catalysts by Combined Application of FTIR Spectroscopy of Different Probe Moleculesстатья
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 июля 2017 г.
Аннотация:The Lewis and Brønsted acid properties of SnBEA zeolites as well as SnO2 supported on silica BEA have been examined by means of IR spectroscopy of adsorbed pyridine, 2,6-ditertbutylpyridine and deuterated acetonitrile. Three types of surface sites have been detected and assigned to: i) framework Sn centers possessing Lewis acid properties; ii) weak Brønsted acid sites associated with framework tin atoms and iii) non-framework SnO2 particles which possess Lewis acidity. The total amount of Lewis sites can be determined using pyridine as a probe molecule, while the type of Lewis sites can be distinguished by FTIR of adsorbed acetonitrile. The band at 2316 cm-1 is attributed to strong framework sites, whereas the band at 2287 cm-1 – to non-framework sites. Brønsted acid sites can be characterized using 2,6-ditertbutylpyridine (bands at 3363, 1613 and 1530 cm-1) and deuterated acetonitrile (band at 2308 cm-1). The relative amount of Lewis and Brønsted acid sites on SnBEA can be varied by treatment in hydrogen at different temperatures.