(366f) Inhibition Effect of Various Surfactants On CO2 Hydrate Formation

The effect of an ionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethylammonium bromide, CTAB), and non-ionic (fatty alcohol EO/PO derivative, LS54) surfactant on unsteady-state CO2 absorption in the metastable region of CO2 hydrates and CO2 enclathration with cyclopentane (CP) was investigated in an unstirred batch reactor. These surfactants have no significant effect on the CO2 absorption rate; however, they retard CO2 enclathration and this inhibition becomes significant at 200 ppm SDS and 100 ppm LS54 or CTAB. A layer of clathrate hydrates is visually detected if charging CO2 and CP sequentially. Even though this layer cannot be macroscopically observed when swapping the order of CO2 and CP charge, the existence of this layer is inferred from the unchanged pressure profile. This layer prevents CO2 from contacting with water and thus it delays CO2 enclathration. The habit of clathrate hydrates growing along the reactor wall without agitation is discussed based on the magnitude of temperature spikes at the very early stage of the enclathration.