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Title: Theoretical Investigation of the Hydrodeoxygenation of Levulinic Acid to γ-Valerolactone over Ru(0001)

Abstract

The reaction mechanism of the hydrodeoxygenation (HDO) of levulinic acid (LA) to γ-valerolactone (GVL) has been investigated over a Ru(0001) model surface by a combination of plane-wave density functional theory (DFT) calculations and mean-field microkinetic modeling. Catalytic pathways involving the direct hydrogenation of LA to GVL with and without formation of the experimentally proposed 4-hydroxypentanoic acid (HPA) intermediate have been considered. In the low reaction temperature range of 323–373 K, the activity of the model Ru(0001) surface is low, owing to a very small number of free sites available for catalysis. As a result, it is unlikely that Ru(0001) is the active site for the experimentally observed catalysis at low temperatures. In contrast, in the medium- to high-temperature range (423–523 K), the HDO of LA is facile over Ru(0001) and we predict at 423 K a turnover frequency, apparent activation barrier, and forward reaction orders that are fairly close to prior experimental observations, leading us to suggest that Ru(0001) sites might constitute the active site for high-temperature catalysis. Finally, our microkinetic analysis suggests that the HDO of LA occurs by LA adsorption, hydrogenation of LA to an alkoxy intermediate, surface ring closure, and –OH group removal: i.e., it does notmore » occur via HPA production as previously suggested. The first hydrogenation step of LA toward the formation of an alkoxy intermediate is the most rate controlling step over Ru(0001).« less

Authors:
ORCiD logo [1];  [1];  [2];  [3]; ORCiD logo [1]
  1. Department of Chemical Engineering, University of South Carolina, 301 South Main Street, Columbia, South Carolina 29208, United States
  2. Department of Chemical Engineering, University of South Carolina, 301 South Main Street, Columbia, South Carolina 29208, United States; Department of Chemical Engineering, University of Engineering &, Technology, Lahore 54890, Pakistan
  3. Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1485140
DOE Contract Number:  
SC0007167
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Catalysis; Journal Volume: 7; Journal Issue: 1
Country of Publication:
United States
Language:
English

Citation Formats

Mamun, Osman, Walker, Eric, Faheem, Muhammad, Bond, Jesse Q., and Heyden, Andreas. Theoretical Investigation of the Hydrodeoxygenation of Levulinic Acid to γ-Valerolactone over Ru(0001). United States: N. p., 2016. Web. doi:10.1021/acscatal.6b02548.
Mamun, Osman, Walker, Eric, Faheem, Muhammad, Bond, Jesse Q., & Heyden, Andreas. Theoretical Investigation of the Hydrodeoxygenation of Levulinic Acid to γ-Valerolactone over Ru(0001). United States. doi:10.1021/acscatal.6b02548.
Mamun, Osman, Walker, Eric, Faheem, Muhammad, Bond, Jesse Q., and Heyden, Andreas. Mon . "Theoretical Investigation of the Hydrodeoxygenation of Levulinic Acid to γ-Valerolactone over Ru(0001)". United States. doi:10.1021/acscatal.6b02548.
@article{osti_1485140,
title = {Theoretical Investigation of the Hydrodeoxygenation of Levulinic Acid to γ-Valerolactone over Ru(0001)},
author = {Mamun, Osman and Walker, Eric and Faheem, Muhammad and Bond, Jesse Q. and Heyden, Andreas},
abstractNote = {The reaction mechanism of the hydrodeoxygenation (HDO) of levulinic acid (LA) to γ-valerolactone (GVL) has been investigated over a Ru(0001) model surface by a combination of plane-wave density functional theory (DFT) calculations and mean-field microkinetic modeling. Catalytic pathways involving the direct hydrogenation of LA to GVL with and without formation of the experimentally proposed 4-hydroxypentanoic acid (HPA) intermediate have been considered. In the low reaction temperature range of 323–373 K, the activity of the model Ru(0001) surface is low, owing to a very small number of free sites available for catalysis. As a result, it is unlikely that Ru(0001) is the active site for the experimentally observed catalysis at low temperatures. In contrast, in the medium- to high-temperature range (423–523 K), the HDO of LA is facile over Ru(0001) and we predict at 423 K a turnover frequency, apparent activation barrier, and forward reaction orders that are fairly close to prior experimental observations, leading us to suggest that Ru(0001) sites might constitute the active site for high-temperature catalysis. Finally, our microkinetic analysis suggests that the HDO of LA occurs by LA adsorption, hydrogenation of LA to an alkoxy intermediate, surface ring closure, and –OH group removal: i.e., it does not occur via HPA production as previously suggested. The first hydrogenation step of LA toward the formation of an alkoxy intermediate is the most rate controlling step over Ru(0001).},
doi = {10.1021/acscatal.6b02548},
journal = {ACS Catalysis},
number = 1,
volume = 7,
place = {United States},
year = {Mon Dec 05 00:00:00 EST 2016},
month = {Mon Dec 05 00:00:00 EST 2016}
}