Hernandez-Tamargo, Carlos E., Roldan Martinez, Alberto ![]() ![]() |
Preview |
PDF
- Published Version
Available under License Creative Commons Attribution. Download (5MB) | Preview |
Abstract
The characterization of the acidity of zeolites allows a direct correlation with their catalytic activity. To this end, probe molecules are utilized to obtain a ranking of acid strengths. Trimethylphosphine oxide (TMPO) is a widely used probe molecule, which allows the sensing of solid acids by using 31P NMR. We have performed calculations based on the density functional theory to investigate the Brønsted acid (BA) sites in zeolite MFI by adsorbing TMPO as a probe molecule. We have considered the substitution of silicon at the T2 site by aluminum, both at the internal cavity and at the external surface. The different acid strengths observed in the zeolite MFI when probed by TMPO (very strong, strong, and weak) may depend on the basicity of the centers sharing the acid proton. If the proton lies between the TMPO and one of the framework oxygen atoms binding the Al, the acidity is strong. When the framework oxygen atom is not directly binding the Al, it is less basic and a shortening of the TMPO–H distance is observed, causing an acid response of very strong. Finally, if two TMPO molecules share the proton, the TMPO–H distance elongates, rendering a weak acid character.
Item Type: | Article |
---|---|
Date Type: | Published Online |
Status: | Published |
Schools: | Advanced Research Computing @ Cardiff (ARCCA) Chemistry |
Subjects: | Q Science > QD Chemistry |
Publisher: | ACS Publications |
ISSN: | 1932-7447 |
Funders: | EPSRC and Royal Society |
Date of First Compliant Deposit: | 14 September 2016 |
Date of Acceptance: | 8 August 2016 |
Last Modified: | 03 May 2023 23:27 |
URI: | https://orca.cardiff.ac.uk/id/eprint/94530 |
Citation Data
Cited 20 times in Scopus. View in Scopus. Powered By Scopus® Data
Actions (repository staff only)
![]() |
Edit Item |