Thermodynamic stability and characterization of double clathrate hydrate with carbon dioxide + cyclopentane + deuterium oxide.

[Display omitted] • The phase equilibrium conditions for gas hydrates formed in CO 2 + cyclopentane + deuterium oxide system. • Temperature and pressure ranges were from 285.35 K to 293.65 K and from 0.279 MPa to 2.735 MPa, respectively. • Powder X-ray diffraction analysis were performed for both CO 2 + cyclopentane + D 2 O hydrate and CO 2 + cyclopentane + H 2 O hydrate. This paper reports characterization of clathrate hydrate formed in CO 2 + cyclopentane + deuterium oxide (D 2 O) system with the phase equilibrium determination and the powder X-ray diffraction (PXRD) measurements towards the development of hydrate-based tritium separation technology. Four-phase (CO 2 gas + liquid cyclopentane + liquid D 2 O + hydrate) equilibrium conditions were measured using the isochoric procedure in the pressure range from 0.279 MPa to 2.735 MPa and the temperature range from 285.35 K to 293.65 K. The equilibrium temperature of CO 2 + cyclopentane + D 2 O system is always higher by 2.0 K to 2.4 K compared to that of CO 2 + cyclopentane + H 2 O system. The detailed crystallographic properties of both CO 2 + cyclopentane + D 2 O hydrate and CO 2 + cyclopentane + H 2 O hydrate including the lattice constants, the radii and volumes of each cage and the cage occupancy were estimated by the PXRD analysis. Based on the obtained results, implications for the development and operation of D 2 O-hydrate-based process are discussed. [ABSTRACT FROM AUTHOR]