Molecular dynamics insights into tetrahydrofuran-assisted formation of CH, CO, and H gas hydrates.

Gas hydrates, also known as clathrate hydrates, are crystalline compounds formed when water molecules organize into cage-like structures that encapsulate gas molecules under conditions of high pressure and low temperature. These hydrates occur naturally in permafrost regions and deep-sea sediments and have gained significant interest as potential energy sources and for applications in gas storage, transportation, and sequestration. Here, we deploy molecular dynamics (MD) simulations to investigate the molecular-level mechanisms governing the formation and stabilization of CH, CO, and H hydrates in the presence of tetrahydrofuran (THF).

Interfacial behavior of the decane + brine + surfactant system in the presence of carbon dioxide, methane, and their mixture.

Molecular dynamics simulations are carried out to get insights into the interfacial behavior of the decane + brine + surfactant + CH + CO system at reservoir conditions. Our results show that the addition of CH, CO, and sodium dodecyl sulfate (SDS) surfactant at the interface reduces the IFTs of the decane + water and decane + brine (NaCl) systems. Here the influence of methane was found to be less pronounced than that of carbon dioxide.

Bulk and interfacial properties of decane in the presence of carbon dioxide, methane, and their mixture.

Molecular dynamics simulations were performed to study the bulk and interfacial properties of methane + n-decane, carbon dioxide + n-decane, and methane + carbon dioxide + n-decane systems under geological conditions. In addition, theoretical calculations using the predictive Peng-Robinson equation of state and density gradient theory are carried out to compare with the simulation data. A key finding is the preferential dissolution in the decane-rich phase and adsorption at the interface for carbon dioxide from the methane/carbon dioxide mixture.

Clathrate hydrates in interstellar environment.

Clathrate hydrates (CHs) are ubiquitous in earth under high-pressure conditions, but their existence in the interstellar medium (ISM) remains unknown. Here, we report experimental observations of the formation of methane and carbon dioxide hydrates in an environment analogous to ISM. Thermal treatment of solid methane and carbon dioxide-water mixture in ultrahigh vacuum of the order of 10 mbar for extended periods led to the formation of CHs at 30 and 10 K, respectively.

Effect of Sodium Dodecyl Sulfate Surfactant on Methane Hydrate Formation: A Molecular Dynamics Study.

In experimental studies, it has been observed that the presence of sodium dodecyl sulfate (SDS) significantly increases the kinetics of hydrate formation and the final water-to-hydrate conversion ratio. In this study, we intend to understand the molecular mechanism behind the effect of SDS on the formation of methane hydrate through molecular dynamics simulation. Hydrate formation conditions similar to that of laboratory experiments were chosen to study hydrate growth kinetics in 1 wt % SDS solution.