TY - JOUR

T1 - Physical properties and characterization of the binary clathrate hydrate with methane + 1,1,1,3,3-Pentafluoropropane (HFC-245fa) + Water

AU - Kodera, Masamichi

AU - Matsueda, Tomoyuki

AU - Belosludov, Rodion V.

AU - Zhdanov, Ravil K.

AU - Belosludov, Vladimir R.

AU - Takeya, Satoshi

AU - Alavi, Saman

AU - Ohmura, Ryo

N1 - Funding Information: We are thankful to the JKA Foundation (grant no. 2018M-170) for support from the Keirin-racing-based research-promotion fund and the Ministry of Education, Culture, Sports, Science, and Technology of Japan (grant no. 17H03122) for financial support. R.V.B. and R.K.Z. are grateful to the crew of the Center for Computational Materials Science and E-IMR center at the Institute for Materials Research, Tohoku University, for continuous support. R.K.Z. and V.R.B. also gratefully acknowledge to the Ministry of Science and Education of Russian Federation within a framework of funding project no. V.44.4.9. Publisher Copyright: © 2020 American Chemical Society Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/9/24

Y1 - 2020/9/24

N2 - This paper reports the thermodynamic and crystallographic properties of the binary clathrate hydrate with methane + 1,1,1,3,3-pentafluoropropane (HFC-245fa) by phase equilibrium measurements, powder X-ray diffraction (PXRD) measurements, and first-principles and thermodynamic calculations. The four-phase (methane gas + water liquid + HFC-245fa liquid + hydrate) equilibrium conditions are lower in pressure by approximately 2−3 MPa than those of the methane + trans-1,3,3,3tetrafluoropropene [HFO-1234ze(E)] hydrates at each temperature from 274.5 to 282.17 K, in spite of the similar molecular structure of HFC-245fa and HFO-1234ze(E). The crystallographic structure of the hydrate with methane + HFC-245fa was identified to be structure II by the PXRD measurement; although because of its molecular length, HFC-245fa would be expected to be encapsulated into a 51268 cage of structure H hydrate. First-principles calculations revealed that these thermodynamic and crystallographic phenomena are the result of two physical factors. First, the total HFC-245fa−water interactions in the cages are stronger than the HFO-1234ze(E)−water interactions due to the presence of more fluorine atoms at the two edge groups in the HFC-245fa molecule and the resulting higher dipole moment of HFC-245fa, and second, the HFC-245fa−HFC-245fa interaction is more greatly enhanced by the presence of methane compared to the HFO-1234ze(E)−HFO-1234ze(E) interactions.

AB - This paper reports the thermodynamic and crystallographic properties of the binary clathrate hydrate with methane + 1,1,1,3,3-pentafluoropropane (HFC-245fa) by phase equilibrium measurements, powder X-ray diffraction (PXRD) measurements, and first-principles and thermodynamic calculations. The four-phase (methane gas + water liquid + HFC-245fa liquid + hydrate) equilibrium conditions are lower in pressure by approximately 2−3 MPa than those of the methane + trans-1,3,3,3tetrafluoropropene [HFO-1234ze(E)] hydrates at each temperature from 274.5 to 282.17 K, in spite of the similar molecular structure of HFC-245fa and HFO-1234ze(E). The crystallographic structure of the hydrate with methane + HFC-245fa was identified to be structure II by the PXRD measurement; although because of its molecular length, HFC-245fa would be expected to be encapsulated into a 51268 cage of structure H hydrate. First-principles calculations revealed that these thermodynamic and crystallographic phenomena are the result of two physical factors. First, the total HFC-245fa−water interactions in the cages are stronger than the HFO-1234ze(E)−water interactions due to the presence of more fluorine atoms at the two edge groups in the HFC-245fa molecule and the resulting higher dipole moment of HFC-245fa, and second, the HFC-245fa−HFC-245fa interaction is more greatly enhanced by the presence of methane compared to the HFO-1234ze(E)−HFO-1234ze(E) interactions.

UR - http://www.scopus.com/inward/record.url?scp=85095914615&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcc.0c05565

DO - 10.1021/acs.jpcc.0c05565

M3 - Article

AN - SCOPUS:85095914615

VL - 124

SP - 20736

EP - 20745

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 38

ER -