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Confinement effects and acid strength in Zeolites

Emanuele Grifoni1,2*, GiovanniMaria Piccini1,2*, Johannes Lercher3,4*, Vassiliki-Alexandra Glezakou3*, Roger Rousseau3*, Michele Parrinello1,2,5*

1 Department of Chemistry and Applied Biosciences, ETH Zurich, c/o USI Campus, Via Giuseppe Buffi 13, CH-6900 Lugano, Ticino, Switzerland.

2 Institute of Computational Science, Università della Svizzera italiana (USI), Via Giuseppe Buffi 13, CH-6900, Lugano, Ticino, Switzerland.

3 Institute for Integrated Catalysis, Pacific Northwest National Laboratory, Richland Washington, USA.

4 Department Chemie and Catalysis Research Center, TU München, Lichtenbergstr. 4, 85747 Garching, Germany

5 Italian Institute of Technology, Via Morego 30, 16163 Genova, Italy.

* Corresponding authors emails: emanuele.grifoni@phys.chem.ethz.ch, g.piccini@phys.chem.ethz.ch, Johannes.Lercher@pnnl.gov, vanda.Glezakou@pnnl.gov, roger.rousseau@pnnl.gov, parrinello@phys.chem.ethz.ch
DOI10.24435/materialscloud:m8-97 [version v1]

Publication date: Jan 26, 2021

How to cite this record

Emanuele Grifoni, GiovanniMaria Piccini, Johannes Lercher, Vassiliki-Alexandra Glezakou, Roger Rousseau, Michele Parrinello, Confinement effects and acid strength in Zeolites, Materials Cloud Archive 2021.20 (2021), doi: 10.24435/materialscloud:m8-97.

Description

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 conversion 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.

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Files

File name Size Description
MD_simulations.zip
MD5md5:5b777689c5d87151927f28c6863e6387
502.5 MiB input files for MD and WT-MetaD simulations
data.zip
MD5md5:d21b506bac7da37b26b141a57fa0c258
84.8 KiB other data files
script_files.zip
MD5md5:33c83d476e0bd0ae08d9d3e624a78630
1.4 MiB script files and plots
clusters.zip
MD5md5:1c3837e5f1431cb56be2ec2fa31d2dfe
348.4 KiB files and scripts for water clusters analyses
plumed2_development.zip
MD5md5:9f563e7d52fb5b56b15c552d2a476642
100.4 MiB PLUMED2 development version code
README.txt
MD5md5:aab7af3303af48e00b04017a20a255c0
691 Bytes README file

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Preprint
E. Grifoni, G. Piccini, J. Lercher, V.-A. Glezakou, R. Rousseau, M. Parrinello, Confinement Effects and Acid Strength in Zeolites. Res. Sq. 2020. doi:https://doi.org/10.21203/rs.3.rs-79664/v1

Keywords

Zeolites acid-base metadynamics molecular dynamics

Version history:

2021.20 (version v1) [This version] Jan 26, 2021 DOI10.24435/materialscloud:m8-97