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The hydrate morphology pattern plays a critical role in the reactor design for hydratebased gas storage/separation technology. This work investigated the morphology of mixed methane− THF hydrate formation using salt water (3.5 wt % NaCl) instead of pure water at 288.2 K and 8 MPa. The result indicated that the nucleation occurred at the gas/liquid interface and then the hydrates grew along the wall of the crystallizer column. After a specific time interval, the hydrates gradually grew downward until they completely covered the bulk solution. This work applied 500 ppm of copromoters, including sodium dodecyl sulfate (SDS) and three amino acidsvaline, leucine, and methionine to improve the kinetics of mixed hydrate formation. The presence of SDS in the system resulted in distinct mixed hydrate formation patterns. After hydrate nucleation at the gas/liquid interface, most of the hydrates predominantly grew downward and enveloped the solution within a few minutes. Moreover, the mushy hydrates gradually transformed into stiff hydrates over time. Three amino acids resulted in the same hydrate patterns as those formed in the absence of a co-promoter, but the formation was completed more rapidly. The kinetic data indicated that using salt water for the formation of mixed methane−THF hydrates resulted in low hydrate formation kinetics. The presence of SDS significantly enhanced the kinetics of hydrate formation but decreased the final gas uptake by about one-half. Additionally, it was discovered that the presence of amino acids accelerated the hydrate formation kinetics while having a negligible effect on the final methane uptake.

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Solidified natural gas is an appealing option for storing natural gas in the form of clathrate hydrates. However, it has some limitations, particularly the slow rate of hydrate formation and the requirement for severe operating conditions. To overcome these constraints, one approach is to introduce promoters into the system to enhance the hydrate formation rate. Amino acids have been reported as kinetic promoters with the potential to improve the methane hydrate formation. In this work, the effect of three different side-chain amino acids (L-methionine, L-leucine, and L-valine) on methane hydrate formation and dissociation was investigated in terms of kinetics and morphology. The experiments were conducted at 8 MPa and 277.2 K using a hybrid combinatorial reactor approach at various amino acid concentrations (0.10 to 1.00). The results showed that the presence of amino acids significantly decreased the induction time and increased the rate of methane hydrate formation. In addition, L-methionine was shown to be the most effective as a kinetic promoter in this work. However, the final methane uptake and the water to hydrate conversion were the same in all experiments. For all the investigated experiments, the morphology of methane hydrate formation exhibited a similar pattern, including methane bubbles and capillary channels. In terms of hydrate dissociation, methane recovery was greater than 95% in all studies, and no foam was generated during hydrate dissociation, which is favorable for large-scale applications.