TY - JOUR
T1 - Crystal structure, stability and spectroscopic properties of methane and CO2 hydrates
AU - Martos-Villa, Ruben
AU - Francisco-Márquez, Misaela
AU - Mata, M. Pilar
AU - Sainz-Díaz, C. Ignacio
N1 - Funding Information:
Funding for this work came from Junta de Andalucía RNM-3581 CADHYS project . Authors are thankful to H. Heinz for his useful discussions and for facilitating the force fields, M. V. Fernández-Serra, M. Pruneda for their useful discussions, W. Kuhs for the availability of crystal atomic data of methane hydrate, and to the Junta de Andalucía for the financial support, to the Supercomputational Center of the Granada University (UGRGRID), to the Centro Técnico de Informática del CSIC.
PY - 2013
Y1 - 2013
N2 - Methane hydrates are highly present in sea-floors and in other planets and their moons. Hence, these compounds are of great interest for environment, global climate change, energy resources, and Cos-mochemistry. The knowledge of stability and physical-chemical properties of methane hydrate crystal structure is important for evaluating some new green becoming technologies such as, strategies to produce natural gas from marine methane hydrates and simultaneously store CO2 as hydrates. However, some aspects related with their stability, spectroscopic and other chemical-physical properties of both hydrates are not well understood yet. The structure and stability of crystal structure of methane and CO2 hydrates have been investigated by means of calculations with empirical interatomic potentials and quantum-mechanical methods based on Hartree-Fock and Density Functional Theory (DFT) approximations. Molecular Dynamic simulations have been also performed exploring different configurations reproducing the experimental crystallographic properties. Spectroscopic properties have also been studied. Frequency shifts of the main vibration modes were observed upon the formation of these hydrates, confirming that vibration stretching peaks of C-H at 2915cm -1 and 2905 cm-1 are due to methane in small and large cages, respectively. Similar effect is observed in the CO2 clathrates. The guest-host binding energy in these clathrates calculated with different methods are compared and discussed in terms of adequacy of empirical potentials and DFT methods for describing the interactions between gas guest and the host water cage, proving an exothermic nature of methane and CO2 hydrates formation process.
AB - Methane hydrates are highly present in sea-floors and in other planets and their moons. Hence, these compounds are of great interest for environment, global climate change, energy resources, and Cos-mochemistry. The knowledge of stability and physical-chemical properties of methane hydrate crystal structure is important for evaluating some new green becoming technologies such as, strategies to produce natural gas from marine methane hydrates and simultaneously store CO2 as hydrates. However, some aspects related with their stability, spectroscopic and other chemical-physical properties of both hydrates are not well understood yet. The structure and stability of crystal structure of methane and CO2 hydrates have been investigated by means of calculations with empirical interatomic potentials and quantum-mechanical methods based on Hartree-Fock and Density Functional Theory (DFT) approximations. Molecular Dynamic simulations have been also performed exploring different configurations reproducing the experimental crystallographic properties. Spectroscopic properties have also been studied. Frequency shifts of the main vibration modes were observed upon the formation of these hydrates, confirming that vibration stretching peaks of C-H at 2915cm -1 and 2905 cm-1 are due to methane in small and large cages, respectively. Similar effect is observed in the CO2 clathrates. The guest-host binding energy in these clathrates calculated with different methods are compared and discussed in terms of adequacy of empirical potentials and DFT methods for describing the interactions between gas guest and the host water cage, proving an exothermic nature of methane and CO2 hydrates formation process.
KW - CO2 hydrates
KW - Clathrates
KW - Methane hydrate
KW - Molecular-dynamics
UR - http://www.scopus.com/inward/record.url?scp=84880858523&partnerID=8YFLogxK
U2 - 10.1016/j.jmgm.2013.06.006
DO - 10.1016/j.jmgm.2013.06.006
M3 - Artículo
SN - 1093-3263
VL - 44
SP - 253
EP - 265
JO - Journal of Molecular Graphics and Modelling
JF - Journal of Molecular Graphics and Modelling
ER -