Structure-H hydrate of mixed gases: Phase equilibrium modeling and experimental validation

CO2 Hydrate Formation Kinetics and Morphology Observations Using High-Pressure Liquid CO2 Applicable to Sequestration

“…Ripmeester and Ractliff reported a lower limit of 7.0 for the CO 2 hydrate hydration number . The cage occupancy or the fraction of each cage occupied by the guest molecule for CO 2 hydrate using experimental approaches has been reported to be >90% for the large cage, whereas measurements and predictions for the small cage occupancy vary significantly. − Fractional cage occupancy of CO 2 in sI hydrate in this work is predicted (at 6.5 MPa and 1.5 °C) using the model by Dhamu et al, which is estimated as 6.95% for small cages and 92.7% for large cages . We used a hydration number of 7.03 for pure CO 2 hydrate, consistent with our earlier work. , …”

“…59−61 Fractional cage occupancy of CO 2 in sI hydrate in this work is predicted (at 6.5 MPa and 1.5 °C) using the model by Dhamu et al, which is estimated as 6.95% for small cages and 92.7% for large cages. 62 We used a hydration number of 7.03 for pure CO 2 hydrate, consistent with our earlier work. 49,63 The batch reactor (Figure 4) consists of three thermocouples or temperature sensors at three different locations: bottom (T1), interface between water and liquid CO 2 (T2), and top of the reactor (T3).…”

The Development of Clathrate Hydrate Science

“…Str.H with its ability to contain larger hydrocarbons along with CH 4 was soon of interest to the oil and gas community, and studies of phase equilibria and kinetics of formation and decomposition followed. ,,− The occurrence of str.H in nature was confirmed in the early 21st century (see below).…”

Modeling of Structure H Carbon Dioxide Clathrate Hydrates: Guest–Lattice Energies, Crystal Structure, and Pressure Dependencies

“…54,55 A majority of studies have concentrated on enclathration of the CO 2 as a co-guest in the sH structure, such as those with CO 2 + N 2 gas mixtures, to explore cagespecific guest distributions and structural transitions in the process of CO 2 capture and sequestration. 56 Despite the above-mentioned motivations, there is no theoretical study for the CO 2 @sH clathrate, with most of the research focused on sH structures with methane (CH 4 ), hydrogen (H 2 ), nitrogen (N 2 ), or mixed-binary sH clathrates, 54,57−68 investigating thermodynamic stability, 69,70 investigating the storage capacity of different hydrocarbon molecules, 62 or predicting hydrate phase equilibrium and formation conditions 71 or mechanical, acoustic, and thermal properties for sH hydrate structures using first-principles methods 72 and combinations of approaches such as hybrid density functional theory and forcefield methods. 73 Following our recent studies on CO 2 clathrates, our present study seeks to determine the stability of sH clathrates of CO 2 , as its storage capacity could make such clathrates good candidates for CO 2 sequestration.…”

“…On the other hand, experimental studies have focused on the synthesis of clathrate hydrates and on structural and spectroscopic measurements by means of X-ray and neutron diffraction, solid-state nuclear magnetic resonance (NMR), and Raman and infrared spectroscopic analysis with various guest molecules. − To understand the effect of size, type, and flexibility of guest molecules on lattice structure sH and stability, X-ray diffraction measurements have been carried out. , A majority of studies have concentrated on enclathration of the CO 2 as a co-guest in the sH structure, such as those with CO 2 + N 2 gas mixtures, to explore cage-specific guest distributions and structural transitions in the process of CO 2 capture and sequestration . Despite the above-mentioned motivations, there is no theoretical study for the CO 2 @sH clathrate, with most of the research focused on sH structures with methane (CH 4 ), hydrogen (H 2 ), nitrogen (N 2 ), or mixed-binary sH clathrates, ,− investigating thermodynamic stability, , investigating the storage capacity of different hydrocarbon molecules, or predicting hydrate phase equilibrium and formation conditions or mechanical, acoustic, and thermal properties for sH hydrate structures using first-principles methods and combinations of approaches such as hybrid density functional theory and force-field methods …”