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Title: Computational Investigation on Hydrodeoxygenation (HDO) of Acetone to Propylene on α-MoO3 (010) Surface

Abstract

Density functional theory (DFT) calculations were performed on the multistep hydrodeoxygenation (HDO) of acetone (CH3COCH3) to propylene (CH3CHCH2) on a molybdenum oxide (α-MoO3) catalyst following an oxygen vacancy-driven pathway. First, a perfect O-terminated α-MoO3 (010) surface based on a 4 × 2 × 4 supercell is reduced by molecular hydrogen (H2) to generate a terminal oxygen (Ot) defect site. This process occurs via a dissociative chemisorption of H2 on adjacent surface oxygen atoms, followed by an H transfer to form a water molecule (H2O). Next, adsorption of CH3COCH3 on the oxygen-deficient Mo site forms an O–Mo bond and then the chemisorbed CH3COCH3 forms CH3COCH2 by transfer of an H atom to an adjacent Ot site. The surface bound hydroxyl (OH) then transfers the H atom to the immobilized O atom to form surface-bound enol, CH3CHOCH2. The next step releases CH3CHCH2 into the gas phase, while simultaneously oxidizes the surface back to a perfect O-terminated α-MoO3 (010) surface. The adsorption of H2, and the formation of a terminal oxygen (Ot) vacancy, moves the conduction band minimum (CBM) from 1.2 eV to 0 and 0.3 eV, respectively. Climbing image-nudged elastic band (CI-NEB) calculations using a Perdew–Burke–Ernzerhof (PBE) functional in combination with double-ζmore » valence (DZV) basis sets indicate that the dissociative adsorption of H2 is the rate-limiting step for the catalytic cycle with a barrier of 1.70 eV. Furthermore, the lower barrier for surface-mediated H transfer from primary-to-secondary carbon atom (0.63 eV) compared to that of a concerted direct H transfer to the secondary C atom with simultaneous desorption (2.02 eV) emphasizes the key role played by the surface in H transfer for effective deoxygenation.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Department of Chemical Engineering
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1480471
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 121; Journal Issue: 33; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 42 ENGINEERING

Citation Formats

Shetty, Manish, Buesser, Beat, Román-Leshkov, Yuriy, and Green, William H. Computational Investigation on Hydrodeoxygenation (HDO) of Acetone to Propylene on α-MoO3 (010) Surface. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b02942.
Shetty, Manish, Buesser, Beat, Román-Leshkov, Yuriy, & Green, William H. Computational Investigation on Hydrodeoxygenation (HDO) of Acetone to Propylene on α-MoO3 (010) Surface. United States. doi:10.1021/acs.jpcc.7b02942.
Shetty, Manish, Buesser, Beat, Román-Leshkov, Yuriy, and Green, William H. Thu . "Computational Investigation on Hydrodeoxygenation (HDO) of Acetone to Propylene on α-MoO3 (010) Surface". United States. doi:10.1021/acs.jpcc.7b02942. https://www.osti.gov/servlets/purl/1480471.
@article{osti_1480471,
title = {Computational Investigation on Hydrodeoxygenation (HDO) of Acetone to Propylene on α-MoO3 (010) Surface},
author = {Shetty, Manish and Buesser, Beat and Román-Leshkov, Yuriy and Green, William H.},
abstractNote = {Density functional theory (DFT) calculations were performed on the multistep hydrodeoxygenation (HDO) of acetone (CH3COCH3) to propylene (CH3CHCH2) on a molybdenum oxide (α-MoO3) catalyst following an oxygen vacancy-driven pathway. First, a perfect O-terminated α-MoO3 (010) surface based on a 4 × 2 × 4 supercell is reduced by molecular hydrogen (H2) to generate a terminal oxygen (Ot) defect site. This process occurs via a dissociative chemisorption of H2 on adjacent surface oxygen atoms, followed by an H transfer to form a water molecule (H2O). Next, adsorption of CH3COCH3 on the oxygen-deficient Mo site forms an O–Mo bond and then the chemisorbed CH3COCH3 forms CH3COCH2 by transfer of an H atom to an adjacent Ot site. The surface bound hydroxyl (OH) then transfers the H atom to the immobilized O atom to form surface-bound enol, CH3CHOCH2. The next step releases CH3CHCH2 into the gas phase, while simultaneously oxidizes the surface back to a perfect O-terminated α-MoO3 (010) surface. The adsorption of H2, and the formation of a terminal oxygen (Ot) vacancy, moves the conduction band minimum (CBM) from 1.2 eV to 0 and 0.3 eV, respectively. Climbing image-nudged elastic band (CI-NEB) calculations using a Perdew–Burke–Ernzerhof (PBE) functional in combination with double-ζ valence (DZV) basis sets indicate that the dissociative adsorption of H2 is the rate-limiting step for the catalytic cycle with a barrier of 1.70 eV. Furthermore, the lower barrier for surface-mediated H transfer from primary-to-secondary carbon atom (0.63 eV) compared to that of a concerted direct H transfer to the secondary C atom with simultaneous desorption (2.02 eV) emphasizes the key role played by the surface in H transfer for effective deoxygenation.},
doi = {10.1021/acs.jpcc.7b02942},
journal = {Journal of Physical Chemistry. C},
number = 33,
volume = 121,
place = {United States},
year = {2017},
month = {8}
}

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Figures / Tables:

Figure 1 Figure 1: Optimized $α$-MoO3 supercell with a = 3.961, b = 14.611, and c = 3.683 Å, Mo and O atoms are shown in green and red colors, respectively.

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