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- Title
H-D Exchange of Simple Aromatics as a Measure of Brønsted-Acid Site Strengths in Solids.
- Authors
Wang, Cong; Li, Sha; Mao, Xinyu; Caratzoulas, Stavros; Gorte, Raymond J.
- Abstract
The relative Brønsted-acid strengths of H-[Al]ZSM-5, H-[Fe]ZSM-5, H-[B]ZSM-5, silicalite, P-SPP, tungstated zirconia, ZrO2, and γ-Al2O3 were studied using H-D exchange with toluene and chlorobenzene. Temperature programmed desorption (TPD) of toluene-h8 and chlorobenzene-h5 from the deuterated forms of H-[Al]ZSM-5, H-[Fe]ZSM-5, and P-SPP demonstrated that the temperature at which H-D exchange rates become significant change with the proton affinity of the aromatic molecule and the strength of the Brønsted sites. The steady-state, gas-phase reaction between D2O and the aromatic molecules were consistent with the TPD results and allowed the Brønsted-acid site strengths to be ordered as follows: H-[Al]ZSM-5 > H-[Fe]ZSM-5 > tungstated zirconia > P-SPP > H-[B]ZSM-5. H-D exchange was also observed at high temperatures with ZrO2 and γ-Al2O3 but it appears that the reaction mechanism with these Lewis acids is different because reaction with toluene and chlorobenzene occur at nearly the same temperature. It is suggested that the H-D exchange reaction with simple aromatic molecules is a useful way to probe Brønsted acidity in solids.Graphical Abstract:
- Subjects
AROMATIC compounds; SOLIDS; HYDROGEN-deuterium exchange; ZIRCONIUM oxide; SILICALITE; CHLOROBENZENE
- Publication
Catalysis Letters, 2018, Vol 148, Issue 11, p3548
- ISSN
1011-372X
- Publication type
Article
- DOI
10.1007/s10562-018-2563-5