Enhanced chemical activity and wettability at adjacent Brønsted acid sites in HZSM-5
Journal Article
·
· Catalysis Today
- Univ. of Oklahoma, Norman, OK (United States); University of Oklahoma
- Univ. of Oklahoma, Norman, OK (United States)
The adjustable acid sites in zeolites and its well-defined pore structure allows for a fine-tuning of the catalytic performance. The activity and selectivity of several reactions have been shown to be dependent on the location and distribution of the acid sites in the zeolite. However, the underlying mechanisms responsible for this dependence remain to be explored. Here, we report density functional theory calculations, through which we investigate the impact of proximity of Brønsted acid sites in the HZSM-5. We find that Brønsted sites with close spatial proximity can significantly strengthen the adsorption of water, which is used as a molecular probe for the local activity. We find that a water molecule can form H-bonds with two adjacent sites with increased adsorption energy. This increase is attributed to enhanced polarization of the water molecule through pronounced interfacial charge transfer. In some case, we observe that the proton becomes detached from the zeolite framework and forms a hydronium ion. Here, we further show that hybrid functional calculations are essential for accurately describing the structural stability when two sites are located in close proximity of each other. Both, the enhanced polarization and proton delocalization may affect activity and selectivity for zeolite-catalyzed reactions.
- Research Organization:
- Univ. of Oklahoma, Norman, OK (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0018284
- OSTI ID:
- 1775282
- Alternate ID(s):
- OSTI ID: 1538071
OSTI ID: 1591655
- Journal Information:
- Catalysis Today, Journal Name: Catalysis Today Vol. 312; ISSN 0920-5861
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Quantification of Brønsted Acid Sites in Zeolites by Water Desorption Thermogravimetry
Genesis and Stability of Hydronium Ions in Zeolite Channels
Atomistic Investigations of the Effects of Si/Al Ratio and Al Distribution on the Adsorption Selectivity of n -Alkanes in Brønsted-Acid Zeolites
Journal Article
·
Mon Apr 06 20:00:00 EDT 2020
· European Journal of Inorganic Chemistry
·
OSTI ID:1774788
Genesis and Stability of Hydronium Ions in Zeolite Channels
Journal Article
·
Tue Jan 29 23:00:00 EST 2019
· Journal of the American Chemical Society
·
OSTI ID:1507391
Atomistic Investigations of the Effects of Si/Al Ratio and Al Distribution on the Adsorption Selectivity of n -Alkanes in Brønsted-Acid Zeolites
Journal Article
·
Tue Jan 02 19:00:00 EST 2018
· Journal of Physical Chemistry. C
·
OSTI ID:1571101