Jump to main content
Jump to site search

Issue 34, 2014
Previous Article Next Article

Reactive molecular simulations of protonation of water clusters and depletion of acidity in H-ZSM-5 zeolite

Author affiliations

Abstract

Using reactive molecular dynamics (RMD), we present an atomistic insight into the interaction between water molecules and acidic centers of H-ZSM-5 zeolite. The reactive force field method, ReaxFF, was used to evaluate the adsorption and diffusion of water as well as to study the protonation of water molecules inside zeolite channels. The existing Si/Al/O/H parameters were refitted against DFT calculations to improve the ReaxFF description of interaction between water molecules and the acidic sites of zeolites. The diffusion coefficient of water in the zeolite obtained from refitted parameters is in excellent agreement with experimental results. The molecular dynamics (MD) simulations indicate that protonation of water molecules and acidity of the zeolite catalyst depend on water loadings and temperature and the observed trends compare favorably with existing experimental and theoretical studies. At higher water loadings, protonation of water molecules is more frequent leading to formation and growth of protonated water clusters inside zeolite channels. From the analysis of various reaction channels that were observed during the simulations, we found that such water clusters have relatively short life due to frequent interchange of protons and water molecules among the water clusters. Such proton hopping events play a key role in moving the protons between different acidic centers of zeolite. These simulations show the capability of ReaxFF in providing atomistic details of complex chemical interactions between the water phase and solid acid zeolites.

Graphical abstract: Reactive molecular simulations of protonation of water clusters and depletion of acidity in H-ZSM-5 zeolite

Back to tab navigation

Supplementary files

Publication details

The article was received on 13 Jun 2014, accepted on 15 Jul 2014 and first published on 16 Jul 2014


Article type: Paper
DOI: 10.1039/C4CP02612H
Author version
available:
Download author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2014,16, 18433-18441
  •   Request permissions

    Reactive molecular simulations of protonation of water clusters and depletion of acidity in H-ZSM-5 zeolite

    K. L. Joshi, G. Psofogiannakis, A. C. T. van Duin and S. Raman, Phys. Chem. Chem. Phys., 2014, 16, 18433
    DOI: 10.1039/C4CP02612H

Search articles by author

Spotlight

Advertisements