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 selfassembled 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 & PLUSMN; 0.86) x 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 & PLUSMN; 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.