Local structure analysis of low-temperature neutron pair distribution function coupled with molecular dynamics simulations of CH4 and CO2 hydrates from 2 to 210 K

Bernadette R. Cladek; S. Michelle Everett; Marshall T. McDonnell; Dayton G. Kizzire; Matthew G. Tucker; David J. Keffer; Claudia J. Rawn

doi:10.1016/j.fuel.2021.120908

Local structure analysis of low-temperature neutron pair distribution function coupled with molecular dynamics simulations of CH₄ and CO₂ hydrates from 2 to 210 K

Bernadette R. Cladek, S. Michelle Everett, Marshall T. McDonnell, Dayton G. Kizzire, Matthew G. Tucker, David J. Keffer, Claudia J. Rawn

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

CH₄ hydrates occur naturally and are an abundant potential fuel source with a corresponding risk of potent greenhouse gas release, due to their stability conditions at low temperature and high pressure. Byproduct CO₂ can be exchanged with CH₄ in these natural deposits and can potentially stabilize the hydrates at higher temperatures. CH₄, CO₂, and mixed CH₄-CO₂ hydrates are studied with in situ neutron pair distribution function experiments from 2 to 210 K to investigate the impact of varying the CH₄-CO₂ guest composition in the gas hydrate structure. These experiments combined with Reverse Monte Carlo analysis allow for the characterization of intermolecular CH₄ and CO₂ interactions with the water molecules which form the hydrate lattice and how they impact the local structure of the lattice itself. Results indicate that when CH₄ and CO₂ co-occupy the hydrate, the host is more strongly distorted than in the pure CH₄ and CO₂ hydrates, but this becomes less defined with increasing temperature. The presence of CO₂ in mixed hydrate increases the stability range and creates a barrier for CH₄ to completely leave the structure.

Original language	English
Article number	120908
Journal	Fuel
Volume	299
DOIs	https://doi.org/10.1016/j.fuel.2021.120908
State	Published - Sep 1 2021

Funding

This research used resources at the Spallation Neutron Source (SNS), a US Department of Energy (DOE) Office of Science User Facility operated by Oak Ridge National Laboratory (ORNL). BRC has been partially supported by the Center for Materials Processing, a Tennessee Higher Education Commission (THEC) Center of Excellence located at the University of Tennessee, Knoxville, a University of Tennessee Chancellor's Fellowship, and the Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for DOE. Research at SNS was sponsored by the DOE Office of Basic Energy Sciences. The ICE-MAN software suite used for this work was funded by the ORNL Laboratory Directed Research and Development program. The data that support the findings of this study are available from the corresponding author upon request. The codes used in this study are primarily cited. RMCProfile version 6.7.4.3 was used to fit the neutron data and is available at RMCProfile.org. PyStog version 0.1.3 is available at https://pystog.readthedocs.io/en/latest/. The code to calculate the radial distribution function from data fits and simulations is found at http://utkstair.org/clausius/docs/mse614/text/examples.html. MD simulations were performed with LAMMPS, documented at https://lammps.sandia.gov/doc/Manual.html. This research used resources at the Spallation Neutron Source (SNS), a US Department of Energy (DOE) Office of Science User Facility operated by Oak Ridge National Laboratory (ORNL). BRC has been partially supported by the Center for Materials Processing, a Tennessee Higher Education Commission (THEC) Center of Excellence located at the University of Tennessee, Knoxville, a University of Tennessee Chancellor’s Fellowship, and the Office of Science Graduate Student Research (SCGSR) program. The SCGSR program is administered by the Oak Ridge Institute for Science and Education for DOE. Research at SNS was sponsored by the DOE Office of Basic Energy Sciences. The ICE-MAN software suite used for this work was funded by the ORNL Laboratory Directed Research and Development program.

Keywords

Crystallography
Methane hydrate
Mixed methane-carbon dioxide hydrates
Molecular dynamics simulation
Neutron diffraction
Reverse Monte Carlo simulation

Access to Document

10.1016/j.fuel.2021.120908

Cite this

@article{aa32e981c8384070b9798141d01af4b8,

title = "Local structure analysis of low-temperature neutron pair distribution function coupled with molecular dynamics simulations of CH4 and CO2 hydrates from 2 to 210 K",

abstract = "CH4 hydrates occur naturally and are an abundant potential fuel source with a corresponding risk of potent greenhouse gas release, due to their stability conditions at low temperature and high pressure. Byproduct CO2 can be exchanged with CH4 in these natural deposits and can potentially stabilize the hydrates at higher temperatures. CH4, CO2, and mixed CH4-CO2 hydrates are studied with in situ neutron pair distribution function experiments from 2 to 210 K to investigate the impact of varying the CH4-CO2 guest composition in the gas hydrate structure. These experiments combined with Reverse Monte Carlo analysis allow for the characterization of intermolecular CH4 and CO2 interactions with the water molecules which form the hydrate lattice and how they impact the local structure of the lattice itself. Results indicate that when CH4 and CO2 co-occupy the hydrate, the host is more strongly distorted than in the pure CH4 and CO2 hydrates, but this becomes less defined with increasing temperature. The presence of CO2 in mixed hydrate increases the stability range and creates a barrier for CH4 to completely leave the structure.",

keywords = "Crystallography, Methane hydrate, Mixed methane-carbon dioxide hydrates, Molecular dynamics simulation, Neutron diffraction, Reverse Monte Carlo simulation",

author = "Cladek, {Bernadette R.} and Everett, {S. Michelle} and McDonnell, {Marshall T.} and Kizzire, {Dayton G.} and Tucker, {Matthew G.} and Keffer, {David J.} and Rawn, {Claudia J.}",

note = "Publisher Copyright: {\textcopyright} 2021",

year = "2021",

month = sep,

day = "1",

doi = "10.1016/j.fuel.2021.120908",

language = "English",

volume = "299",

journal = "Fuel",

issn = "0016-2361",

publisher = "Elsevier",

}

TY - JOUR

T1 - Local structure analysis of low-temperature neutron pair distribution function coupled with molecular dynamics simulations of CH4 and CO2 hydrates from 2 to 210 K

AU - Cladek, Bernadette R.

AU - Everett, S. Michelle

AU - McDonnell, Marshall T.

AU - Kizzire, Dayton G.

AU - Tucker, Matthew G.

AU - Keffer, David J.

AU - Rawn, Claudia J.

PY - 2021/9/1

Y1 - 2021/9/1

N2 - CH4 hydrates occur naturally and are an abundant potential fuel source with a corresponding risk of potent greenhouse gas release, due to their stability conditions at low temperature and high pressure. Byproduct CO2 can be exchanged with CH4 in these natural deposits and can potentially stabilize the hydrates at higher temperatures. CH4, CO2, and mixed CH4-CO2 hydrates are studied with in situ neutron pair distribution function experiments from 2 to 210 K to investigate the impact of varying the CH4-CO2 guest composition in the gas hydrate structure. These experiments combined with Reverse Monte Carlo analysis allow for the characterization of intermolecular CH4 and CO2 interactions with the water molecules which form the hydrate lattice and how they impact the local structure of the lattice itself. Results indicate that when CH4 and CO2 co-occupy the hydrate, the host is more strongly distorted than in the pure CH4 and CO2 hydrates, but this becomes less defined with increasing temperature. The presence of CO2 in mixed hydrate increases the stability range and creates a barrier for CH4 to completely leave the structure.

AB - CH4 hydrates occur naturally and are an abundant potential fuel source with a corresponding risk of potent greenhouse gas release, due to their stability conditions at low temperature and high pressure. Byproduct CO2 can be exchanged with CH4 in these natural deposits and can potentially stabilize the hydrates at higher temperatures. CH4, CO2, and mixed CH4-CO2 hydrates are studied with in situ neutron pair distribution function experiments from 2 to 210 K to investigate the impact of varying the CH4-CO2 guest composition in the gas hydrate structure. These experiments combined with Reverse Monte Carlo analysis allow for the characterization of intermolecular CH4 and CO2 interactions with the water molecules which form the hydrate lattice and how they impact the local structure of the lattice itself. Results indicate that when CH4 and CO2 co-occupy the hydrate, the host is more strongly distorted than in the pure CH4 and CO2 hydrates, but this becomes less defined with increasing temperature. The presence of CO2 in mixed hydrate increases the stability range and creates a barrier for CH4 to completely leave the structure.

KW - Crystallography

KW - Methane hydrate

KW - Mixed methane-carbon dioxide hydrates

KW - Molecular dynamics simulation

KW - Neutron diffraction

KW - Reverse Monte Carlo simulation

UR - http://www.scopus.com/inward/record.url?scp=85105018523&partnerID=8YFLogxK

U2 - 10.1016/j.fuel.2021.120908

DO - 10.1016/j.fuel.2021.120908

M3 - Article

AN - SCOPUS:85105018523

SN - 0016-2361

VL - 299

JO - Fuel

JF - Fuel

M1 - 120908

ER -