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Study of the bulk and surface acidity of protonated Y zeolites by TPD and XPS
Author(s) -
Guimon C.,
Boreave A.,
PfisterGuillouzo G.
Publication year - 1994
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740220188
Subject(s) - x ray photoelectron spectroscopy , chemistry , sodalite , desorption , thermal desorption spectroscopy , protonation , adsorption , lewis acids and bases , molecule , pyridine , inorganic chemistry , zeolite , brønsted–lowry acid–base theory , analytical chemistry (journal) , catalysis , organic chemistry , nuclear magnetic resonance , ion , physics
The combined use of temperature programmed desorption (TPD) of nitrogened bases (ammonia, pyridine) and x‐ray photoelectron spectroscopy (XPS) was applied to the study of acidity of HY zeolites with different molar Si/Al ratios (∼ 2.7, 5.8, 24). N 1s binding energies of probe molecules showed two types of sites (Brönsted and Lewis) whose relative proportions varied with pretreatment and desorption temperatures, and a dissociative adsorption of NH 3 for dehydroxylated zeolites. The TPD curves and the XPS quantitative analyses of probe molecule concentration in Zeolites allowed the determination of acid sites distribution in term of strength for the real surface of crystals and for a sub‐surface partially freed of extra‐framework species that cover it. These data showed that the acid sites located in sodalite units are mostly strong and Brönsted type sites.