open access

https://hdl.handle.net/2115/97227

Characterization of acid sites on Hf-Beta zeolite by CD3CN IR-TPD

英語

TPD

2024-07-07

Elsevier

Microporous and mesoporous materials

378

113246

To identify Hf species and quantitatively evaluate their acid properties, combined measurement of infrared (IR) and temperature-programmed desorption (TPD) with deuterated acetonitrile (CD 3 CN) as probe molecule was performed on Hf-Beta and HfO 2 /Si-Beta. IR spectra of CD 3 CN adsorbed on Hf-Beta showed five types of Hf species including framework open and closed Hf sites, extra-framework HfO 2 , and two types of Hf species bearing hydroxy groups. IR measurement showed structural change in Hf-Beta upon exposing to water vapor with generation of the two types of Hf species bearing hydroxy groups. Integrated molar extinction coefficients for C - -- N stretching vibration of CD 3 CN adsorbed on these Hf species were estimated and the number of each Hf acid site was calculated. Acid strength of these Hf species was estimated from CD 3 CN-TPD measurement in combination with IR; the acid strength of the open and closed Hf sites, extra-framework HfO 2 species, and the other Hf species was found to be strong, moderate, and weak, respectively.

学術雑誌論文

Accepted Manuscript

Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International

© 2024. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

1387-1811

AA11160707