TY - JOUR
T1 - Low-Temperature Thermodynamic Study of the Metastable Empty Clathrate Hydrates Using Molecular Simulations
AU - Cruz, Fernando J. A. L.
AU - Alavi, Saman
AU - Mota, José P. B.
N1 - info:eu-repo/grantAgreement/FCT/5876/147218/PT#
info:eu-repo/grantAgreement/FCT/5876-PPCDTI/127536/PT#
POCI-01-0145-FEDER - 007265.
RE-QUIMTE/BPD/004/2016.
PY - 2019/5/16
Y1 - 2019/5/16
N2 - The thermodynamics of metastable empty sI-clathrate hydrates are probed over broad temperature and pressure ranges, 100 ≤ T (K) ≤ 220 and 1 ≤ p (bar) ≤ 5000, respectively, by large-scale simulations and compared with experimental data at 1 bar. The whole p-V-T surface obtained is fitted by the universal form of the Parsafar and Mason equation of state with an accuracy of 99.7-99.9%. Framework deformation brought about by the applied temperature follows a parabolic law, and there is a critical temperature above which the isobaric thermal expansion becomes negative, ranging from 194.7 K at 1 bar to 166.2 K at 5000 bar. That response to the applied (p, T) field is analyzed in terms of angle and distance descriptors of a classical tetrahedral structure and observed to occur essentially by means of angular alteration for (p, T) > (2000 bar, 200 K). The length of the hydrogen bonds responsible for framework integrity is insensitive to the thermodynamic conditions and its average value is r (O-H)=0.25 nm.
AB - The thermodynamics of metastable empty sI-clathrate hydrates are probed over broad temperature and pressure ranges, 100 ≤ T (K) ≤ 220 and 1 ≤ p (bar) ≤ 5000, respectively, by large-scale simulations and compared with experimental data at 1 bar. The whole p-V-T surface obtained is fitted by the universal form of the Parsafar and Mason equation of state with an accuracy of 99.7-99.9%. Framework deformation brought about by the applied temperature follows a parabolic law, and there is a critical temperature above which the isobaric thermal expansion becomes negative, ranging from 194.7 K at 1 bar to 166.2 K at 5000 bar. That response to the applied (p, T) field is analyzed in terms of angle and distance descriptors of a classical tetrahedral structure and observed to occur essentially by means of angular alteration for (p, T) > (2000 bar, 200 K). The length of the hydrogen bonds responsible for framework integrity is insensitive to the thermodynamic conditions and its average value is r (O-H)=0.25 nm.
KW - Empty clathrate hydrates
KW - isobaric expansivity
KW - isobaric heat capacity
KW - molecular dynamics
KW - p- V- T data
KW - structure
KW - thermodynamics
UR - http://www.scopus.com/inward/record.url?scp=85064130220&partnerID=8YFLogxK
U2 - 10.1021/acsearthspacechem.9b00009
DO - 10.1021/acsearthspacechem.9b00009
M3 - Article
AN - SCOPUS:85064130220
SN - 2472-3452
VL - 3
SP - 789
EP - 799
JO - ACS Earth and Space Chemistry
JF - ACS Earth and Space Chemistry
IS - 5
ER -