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Title: Density Functional Theory (DFT) Study To Unravel the Catalytic Properties of M-Exchanged MFI, (M = Be, Co, Cu, Mg, Mn, Zn) for the Conversion of Methane and Carbon Dioxide to Acetic Acid

Abstract

The conversion of greenhouse gases, such as CO 2 and CH 4, to value chemicals is a major challenge, because of the high stability of both molecules. In this study, density functional theory (DFT) calculations with long-range corrections and ONIOM were used to analyze the reaction mechanism for the conversion of CO 2 and CH 4 to acetic acid with MFI zeolite exchanged with Be, Co, Cu, Mg, Mn, and Zn cations. Our results demonstrate that (a) the highest reaction barrier on the reaction mechanism is CH 4 dissociation, and the transition state energy in that step is directly related to the energy of the lowest unoccupied molecular orbital and the electronegativity of the metal exchanged zeolites; (b) a charge transfer between CH 4 and the metal cation occurs simultaneously to CH 4 dissociation; (c) CO 2 insertion has a low energy barrier, and the protonation of the acetate species is spontaneous; (d) dispersion interactions are the main contributions to CH 4 adsorption energies, whereas, in the rest of the steps of the reaction mechanism, the contribution of dispersion to the energies of reaction is almost negligible; (e) desorption of acetic acid could be promoted by the coadsorption of water;more » and (f) CH 4 dissociation on Cu-MFI has an apparent activation energy of 11.5 kcal/mol, and a forward rate constant of 1.1 s–1 at 398 K.« less

Authors:
 [1];  [1];  [1]; ORCiD logo [1]
  1. Univ. of Puerto Rico, Mayaguez (Puerto Rico). Dept. 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:
1485301
Grant/Contract Number:  
AC02-05CH11231; AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 7; Journal Issue: 10; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Montejo-Valencia, Brian D., Pagán-Torres, Yomaira J., Martínez-Iñesta, María M., and Curet-Arana, María C. Density Functional Theory (DFT) Study To Unravel the Catalytic Properties of M-Exchanged MFI, (M = Be, Co, Cu, Mg, Mn, Zn) for the Conversion of Methane and Carbon Dioxide to Acetic Acid. United States: N. p., 2017. Web. doi:10.1021/acscatal.7b00844.
Montejo-Valencia, Brian D., Pagán-Torres, Yomaira J., Martínez-Iñesta, María M., & Curet-Arana, María C. Density Functional Theory (DFT) Study To Unravel the Catalytic Properties of M-Exchanged MFI, (M = Be, Co, Cu, Mg, Mn, Zn) for the Conversion of Methane and Carbon Dioxide to Acetic Acid. United States. doi:10.1021/acscatal.7b00844.
Montejo-Valencia, Brian D., Pagán-Torres, Yomaira J., Martínez-Iñesta, María M., and Curet-Arana, María C. Wed . "Density Functional Theory (DFT) Study To Unravel the Catalytic Properties of M-Exchanged MFI, (M = Be, Co, Cu, Mg, Mn, Zn) for the Conversion of Methane and Carbon Dioxide to Acetic Acid". United States. doi:10.1021/acscatal.7b00844. https://www.osti.gov/servlets/purl/1485301.
@article{osti_1485301,
title = {Density Functional Theory (DFT) Study To Unravel the Catalytic Properties of M-Exchanged MFI, (M = Be, Co, Cu, Mg, Mn, Zn) for the Conversion of Methane and Carbon Dioxide to Acetic Acid},
author = {Montejo-Valencia, Brian D. and Pagán-Torres, Yomaira J. and Martínez-Iñesta, María M. and Curet-Arana, María C.},
abstractNote = {The conversion of greenhouse gases, such as CO2 and CH4, to value chemicals is a major challenge, because of the high stability of both molecules. In this study, density functional theory (DFT) calculations with long-range corrections and ONIOM were used to analyze the reaction mechanism for the conversion of CO2 and CH4 to acetic acid with MFI zeolite exchanged with Be, Co, Cu, Mg, Mn, and Zn cations. Our results demonstrate that (a) the highest reaction barrier on the reaction mechanism is CH4 dissociation, and the transition state energy in that step is directly related to the energy of the lowest unoccupied molecular orbital and the electronegativity of the metal exchanged zeolites; (b) a charge transfer between CH4 and the metal cation occurs simultaneously to CH4 dissociation; (c) CO2 insertion has a low energy barrier, and the protonation of the acetate species is spontaneous; (d) dispersion interactions are the main contributions to CH4 adsorption energies, whereas, in the rest of the steps of the reaction mechanism, the contribution of dispersion to the energies of reaction is almost negligible; (e) desorption of acetic acid could be promoted by the coadsorption of water; and (f) CH4 dissociation on Cu-MFI has an apparent activation energy of 11.5 kcal/mol, and a forward rate constant of 1.1 s–1 at 398 K.},
doi = {10.1021/acscatal.7b00844},
journal = {ACS Catalysis},
number = 10,
volume = 7,
place = {United States},
year = {2017},
month = {9}
}

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