Evaluation of the promotion of self-assembly hydrophobic domain on methane hydrate formation

In view of the low solubility of the hydrophobic guest gas in solutions during gas hydrate formations, the self-assembled domains with the hydrophobic core and hydrophilic shell were designed in this research for the purpose of enhancing the methane hydrate formation. Initially, the cationic surfactants n-trimethylammonium bromide (CnTAB, n = 10, 12, 14, 16) with different alky chains and anionic polymer sodium polystyrenesulfonate were linked together by electrostatic interaction to form the nano-aggregates (marked as CnTAB/PSS). In forms of irregular core-shell structures, the nanoaggregate had the particle size of 161–228 nm. Employed as the reaction system for methane hydrates formation, the self-assembled aggregates held higher ability to solubilize methane compared with deionized water. During the hydrate formations, the nanoaggregates-contained systems exerted prominent promotion effects on the hydrate formation. Based on the same neutralized degree of 50 %, the C14TAB/PSS nanoaggregates turned out to facilitate hydrate formations with the maximum formation rate of (1.33 ± 0.86) × 10−3 mmol/(mL.min). Meanwhile, the hydrate formation process was accelerated gradually along with higher DN value, where the final gas storage capacity was improved to 138 ± 16 v/v for C14TAB/PSS with DN value of 75 %. Thereby, the designed self-assembled microdomain was conducive to enhancing methane hydrate formation kinetics, and this may provide significant fundamental guidance on the industrial application of hydrate‐based SNG (solid natural gas) technology.