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Title: Dehydration pathways of 1-propanol on HZSM-5 in the presence and absence of water

Abstract

The Brønsted acid-catalyzed gas-phase dehydration of 1-propanol (0.075-4 kPa) was studied on zeolite H-MFI (Si/Al = 26, containing minimal amounts of extraframework Al moieties) in the absence and presence of co-fed water (0-2.5 kPa) at 413-443 K. It is shown that propene can be formed from monomeric and dimeric adsorbed 1-propanol. The stronger adsorption of 1-propanol relative to water indicates that the reduced dehydration rates in the presence of water are not a consequence of the competitive adsorption between 1-propanol and water. Instead, the deleterious effect is related to the different extents of stabilization of adsorbed intermediates and the relevant elimination/substitution transition states by water. Water stabilizes the adsorbed 1-propanol monomer significantly more than the elimination transition state, leading to a higher activation barrier and a greater entropy gain for the rate-limiting step, which eventually leads to propene. In a similar manner, an excess of 1-propanol stabilizes the adsorbed state of 1-propanol more than the elimination transition state. In comparison with the monomer-mediated pathway, adsorbed dimer and the relevant transition states for propene and ether formation are similarly, while less effectively, stabilized by intrazeolite water molecules. This work was supported by the US Department of Energy, Office of Science, Officemore » of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, and was performed in part using the Molecular Sciences Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located and the Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for DOE.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1252852
Report Number(s):
PNNL-SA-110810
Journal ID: ISSN 0002-7863; 48810; KC0302010
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 137; Journal Issue: 50; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
Alcohol dehydration; biomass conversion; zeolite H-MFI; water; 1-propanol; transition states; Environmental Molecular Sciences Laboratory

Citation Formats

Zhi, Yuchun, Shi, Hui, Mu, Linyu, Liu, Yue, Mei, Donghai, Camaioni, Donald M., and Lercher, Johannes A. Dehydration pathways of 1-propanol on HZSM-5 in the presence and absence of water. United States: N. p., 2015. Web. doi:10.1021/jacs.5b09107.
Zhi, Yuchun, Shi, Hui, Mu, Linyu, Liu, Yue, Mei, Donghai, Camaioni, Donald M., & Lercher, Johannes A. Dehydration pathways of 1-propanol on HZSM-5 in the presence and absence of water. United States. https://doi.org/10.1021/jacs.5b09107
Zhi, Yuchun, Shi, Hui, Mu, Linyu, Liu, Yue, Mei, Donghai, Camaioni, Donald M., and Lercher, Johannes A. 2015. "Dehydration pathways of 1-propanol on HZSM-5 in the presence and absence of water". United States. https://doi.org/10.1021/jacs.5b09107.
@article{osti_1252852,
title = {Dehydration pathways of 1-propanol on HZSM-5 in the presence and absence of water},
author = {Zhi, Yuchun and Shi, Hui and Mu, Linyu and Liu, Yue and Mei, Donghai and Camaioni, Donald M. and Lercher, Johannes A.},
abstractNote = {The Brønsted acid-catalyzed gas-phase dehydration of 1-propanol (0.075-4 kPa) was studied on zeolite H-MFI (Si/Al = 26, containing minimal amounts of extraframework Al moieties) in the absence and presence of co-fed water (0-2.5 kPa) at 413-443 K. It is shown that propene can be formed from monomeric and dimeric adsorbed 1-propanol. The stronger adsorption of 1-propanol relative to water indicates that the reduced dehydration rates in the presence of water are not a consequence of the competitive adsorption between 1-propanol and water. Instead, the deleterious effect is related to the different extents of stabilization of adsorbed intermediates and the relevant elimination/substitution transition states by water. Water stabilizes the adsorbed 1-propanol monomer significantly more than the elimination transition state, leading to a higher activation barrier and a greater entropy gain for the rate-limiting step, which eventually leads to propene. In a similar manner, an excess of 1-propanol stabilizes the adsorbed state of 1-propanol more than the elimination transition state. In comparison with the monomer-mediated pathway, adsorbed dimer and the relevant transition states for propene and ether formation are similarly, while less effectively, stabilized by intrazeolite water molecules. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, and was performed in part using the Molecular Sciences Computing Facility (MSCF) in the William R. Wiley Environmental Molecular Sciences Laboratory, a DOE national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located and the Pacific Northwest National Laboratory (PNNL). PNNL is operated by Battelle for DOE.},
doi = {10.1021/jacs.5b09107},
url = {https://www.osti.gov/biblio/1252852}, journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 50,
volume = 137,
place = {United States},
year = {Wed Dec 23 00:00:00 EST 2015},
month = {Wed Dec 23 00:00:00 EST 2015}
}