Confinement effects and acid strength in zeolites
OPEN ACCESS
Loading...
Author / Producer
Date
2021-05-11
Publication Type
Journal Article
ETH Bibliography
yes
Citations
Altmetric
OPEN ACCESS
Data
Rights / License
Abstract
Chemical reactivity and sorption in zeolites are coupled to confinement and-to a lesser extent-to the acid strength of Brønsted acid sites (BAS). In presence of water the zeolite Brønsted acid sites eventually convert into hydronium ions. The gradual transition from zeolite Brønsted acid sites to hydronium ions in zeolites of varying pore size is examined by ab initio molecular dynamics combined with enhanced sampling based on Well-Tempered Metadynamics and a recently developed set of collective variables. While at low water content (1-2 water/BAS) the acidic protons prefer to be shared between zeolites and water, higher water contents (n > 2) invariably lead to solvation of the protons within a localized water cluster adjacent to the BAS. At low water loadings the standard free energy of the formed complexes is dominated by enthalpy and is associated with the acid strength of the BAS and the space around the site. Conversely, the entropy increases linearly with the concentration of waters in the pores, favors proton solvation and is independent of the pore size/shape.
Permanent link
Publication status
published
External links
Editor
Book title
Journal / series
Volume
12 (1)
Pages / Article No.
2630
Publisher
Nature
Event
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Heterogeneous catalysis; Molecular dynamics; Thermodynamics