Based on adsorption theory of surfactants at solid-liquid interface

promotion effects of three surfactants on formation of methane hydrates were studied in a stainless steel reactor at conditions of 2℃ and 6.6 MPa without stirring. Surfactants were sodium dodecyl sulfate (SDS)

sodium alcohol ether sulphate (AES) and dodecyl alcohol ethoxylates (AEO). The results showed a good correlation between macroscopic morphology of hydrates and molecular morphology of adsorbed surfactants. With directional adsorption of SDS and AES on metal surface

interface hydrophobicity was increased and a porous media environment was formed at solid surface

which promoted bulk water to move through the porous media to gas phase driven by capillarity. Thus

both nucleation rate and sites were increased. However

no AEO adsorption on metal surface resulted in decrease of the promotion effect on hydrate formation. With SDS

AES and AEO solutions at concentration of 300 mg·L-1

hydrate storage capacity were 131.4

128.3 and 12.3 (volume ratio) and average gas storage rates were 5.8

7.6 and 0.07 mmol·min-1

respectively. With concentration increase of SDS (80-1200 mg·L-1) and AES (60-1350 mg·L-1)

hydrate storage capacity first enhanced and then decreased whereas average gas storage rate kept increasing linearly. Therefore

hydrate formation can be significantly promoted by choosing appropriate types and concentrations of surfactants.