Insights into the self-preservation effect of methane hydrate at atmospheric pressure using high pressure DSC

New Insights into the Kinetics and Morphology of CO2 Hydrate Formation in the Presence of Sodium Dodecyl Sulfate

“…The experimental conditions for CO 2 hydrate formation are the same as those used in the literature. ,, The temperature was fixed at 277.15 K while the initial pressure was set at 3.5 MPa. It should be noted that the presence of SDS only improves the kinetics of hydrate formation and has no influence on the phase equilibrium conditions of CO 2 hydrate. , The driving force for hydrate formation is defined as the difference between the initial experimental pressure and the phase equilibrium pressure at the experimental temperature (Δ P = P exp – P eq ). The phase equilibrium pressure for CO 2 hydrate formed in pure water and in SDS solutions is 1.89 MPa at 277.15 K, so the driving force Δ P is 1.59 MPa at 277.15 K .…”

“…It has been found that adding chemical additives to the hydrate formation system is a preferable approach to promote hydrate nucleation and accelerate the hydrate formation process. , Sodium dodecyl sulfate (SDS) is a well-known surfactant that is widely used to improve the hydrate formation kinetics, but it does not affect the thermodynamics of gas hydrate formation (phase equilibrium conditions). , One reason is that the surface tension of the liquid can be reduced by SDS and thus enhance gas dissolution in the liquid phase. Accordingly, the induction time is shortened, and the rate of hydrate formation is increased. , For example, at 274.15 K and 5.0 MPa, the induction time for CO 2 hydrate formed at 500 ppm of SDS is approximately 35 min while that for CO 2 hydrate formed in pure water is 50 min under the same experimental conditions .…”

A Calorimetric Study on the Phase Behavior of Tetra-n-butyl Phosphonium Bromide + CO2 Semiclathrate Hydrate and Evaluation of CO2 Consumption─Impact of a Surfactant

“…The heat flow resolution of the HP μ-DSC is 0.02 μW. A detailed description of HP μ-DSC can be found in the previous paper. , On the other hand, a high pressure transparent reactor was used to measure the gas consumption for TBPB + CO 2 semiclathrate hydrate formation. The schematic diagram of the apparatus is shown in Figure .…”

Review on Hydrate-Based CH4 Separation from Low-Concentration Coalbed Methane in China

“…In comparison to cryogenic liquefaction, the hydrate-based gas separation can be operated at a temperature closer to room temperature if TBAB or cyclopentane is used. , In addition, in comparison to the pressure swing adsorption, the operating pressure for hydrate-based separation is much lower; therefore, the pressure loss during the separation process is smaller, and the purification efficiency is higher. (v) Solidified CH 4 transportation: The self-preservation effect can be used to preserve the CH 4 hydrate under mild conditions (263.15–273.15 K and 0.1–1 MPa); therefore, the transportation of CH 4 hydrate is safe and reliable . It has been found that the self-preservation effect of the CH 4 hydrate is not affected by the surfactant SDS, but whether it will be affected by other additives, such as TBAB and tetra- n -butylammonium chloride (TBAC), is not known.…”

“…(v) Solidified CH 4 transportation: The self-preservation effect can be used to preserve the CH 4 hydrate under mild conditions (263.15–273.15 K and 0.1–1 MPa); therefore, the transportation of CH 4 hydrate is safe and reliable . It has been found that the self-preservation effect of the CH 4 hydrate is not affected by the surfactant SDS, but whether it will be affected by other additives, such as TBAB and tetra- n -butylammonium chloride (TBAC), is not known. Thus, future work should be performed to explore the additive impacts.…”