Gas hydrates have been proposed as a potential technology for a number of applications, such as separation of gas mixtures, CO2 capture, transportation, and sequestration, methane storage and transport, and seawater desalination. Most of these applications will benefit from reduced induction time of hydrate nucleation, enhanced hydrate growth rate, and maximum water-to-hydrate conversion. The addition of surfactants to the gas–water system serves this purpose in a very effective manner. This review focuses on different surfactants that were utilized for gas hydrate formation studies; insights have been provided on the possible mechanisms of action through which these surfactants affect hydrate formation kinetics. A thorough analysis of the existing literature on surfactants suggests that enhanced rate of hydrate nucleation and growth kinetics may not be directly linked to micelle formation. Conversely, reduced surface tension in the presence of surfactants not only enhances the mass transfer but also changes the morphology of hydrate formation, which in turn enhances gas–water interactions for faster hydrate growth rate.

The emergence of natural gas as a key player in the current energy landscape tenders a rare opportunity for the development of new, robust gas storage technologies. Gas hydrate or...

In the present study, CO 2 sequestration by hydrate formation in porous sediments has been discussed. Two siliceous materials with high porosities, pumice and fire hardened red clay (FHRC), have been used as packing materials in a fixed bed setup to study hydrate formation kinetics. The results obtained using the aforementioned materials were compared with those obtained using silica sand and quartz. Carbon dioxide hydrate formation kinetics was studied at 3.0 MPa pressure and 274 K temperature. Two different types of experiments were conducted: (a) using a constant volume of water and (b) maintaining a constant bed height. These experiments were conducted using the different porous media individually as packing materials. It was observed that pumice as the porous medium showed better hydrate formation kinetics resulting in 46 mol % water to hydrate conversion in 5 h. Moreover, kinetics was enhanced with decrease in the bed height of pumice; this suggests that at field scale adaptation of CO 2 sequestration in geological formations, mass transfer limitations would be significant. The effects of particle size on hydrate formation kinetics were also investigated. It was observed that hydrate formation kinetics was enhanced with decrease in the particle size fraction.

Gas hydrates are viewed as a potential process enabler for several critical technological applications such as methane storage, hydrogen storage, gas separation, desalination, carbon dioxide capture and sequestration, etc. Hydrate based technological applications almost always require rapid hydrate formation along with high gas uptake to be economically viable. One possible approach to achieve the same is the introduction of particular additives into the system. These additives which are known as kinetic hydrate promoters (KHPs) either reduce the time required for hydrate nucleation or enhance the rate of hydrate growth or both. In recent times, amino acids, which are essential components of the human diet and thus ecofriendly materials, have emerged as a highly effective class of KHPs and unlike surfactants (traditional KHP molecules) promise a clean mode of kinetic action, i.e., no foam formation. Here we review the application of amino acids as KHPs for gas hydrate formation thus far and present perspectives on the mechanism of action for the same.

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