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Title: Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite

Abstract

Aqueous phase dehydration of 1-propanol over H-ZSM-5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulation of the mimicking aqueous phase H-ZSM-5 zeolite unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol-propanol, the propanol-water complex, and the trimeric propanol-propanol-water are formed at high propanol concentrations, which provide a kinetically feasible dehydration reaction channel of 1-propanol to propene. However, calculation results also indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration reaction. This work was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computationalmore » catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research.« less

Authors:
 [1];  [2]
  1. Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352
  2. Pacific Northwest National Laboratory, Physical and Computational Sciences Directorate & Institute for Integrated Catalysis, Richland WA 99352; Dept. of Chemistry and Catalysis Research Institute, TU München, Lichtenbergstrasse 4 Garching 85748 Germany
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1339800
Report Number(s):
PNNL-SA-117505
Journal ID: ISSN 0001-1541; 48810; KC0302010
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
AIChE Journal
Additional Journal Information:
Journal Volume: 63; Journal Issue: 1; Journal ID: ISSN 0001-1541
Publisher:
American Institute of Chemical Engineers
Country of Publication:
United States
Language:
English
Subject:
Alcohol; Dehydration; Zeolite; Reaction mechanism; Density functional theory; Environmental Molecular Sciences Laboratory

Citation Formats

Mei, Donghai, and Lercher, Johannes A. Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite. United States: N. p., 2016. Web. doi:10.1002/aic.15517.
Mei, Donghai, & Lercher, Johannes A. Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite. United States. doi:10.1002/aic.15517.
Mei, Donghai, and Lercher, Johannes A. Thu . "Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite". United States. doi:10.1002/aic.15517.
@article{osti_1339800,
title = {Mechanistic insights into aqueous phase propanol dehydration in H-ZSM-5 zeolite},
author = {Mei, Donghai and Lercher, Johannes A.},
abstractNote = {Aqueous phase dehydration of 1-propanol over H-ZSM-5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulation of the mimicking aqueous phase H-ZSM-5 zeolite unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol-propanol, the propanol-water complex, and the trimeric propanol-propanol-water are formed at high propanol concentrations, which provide a kinetically feasible dehydration reaction channel of 1-propanol to propene. However, calculation results also indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration reaction. This work was supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. Computing time was granted by the grand challenge of computational catalysis of the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL). EMSL is a national scientific user facility located at Pacific Northwest National Laboratory (PNNL) and sponsored by DOE’s Office of Biological and Environmental Research.},
doi = {10.1002/aic.15517},
journal = {AIChE Journal},
issn = {0001-1541},
number = 1,
volume = 63,
place = {United States},
year = {2016},
month = {10}
}