SDS-promoted methane hydrate growth in presence of a superhydrophobic substrate

Zhang, Xiaolai; Zhao, Jiatao; Chen, Chen; Yuan, Haoyu; Zhang, Yonghao; He, Yan; Wang, Fei

doi:10.1016/j.ces.2023.118761

Cited by 7 publications

(6 citation statements)

References 43 publications

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“…The transition from slow to rapid hydrate generation, as witnessed at a mesoscopic scale by the generation of hydrate crystals at the water/guest interface and at a macroscopic scale by the meniscus displacement (or water conversion), is observed to occur with both anionic surfactants, AOT and SDS, and with SDS for the two subcoolings investigated, Δ T ≈ 2 and 4 °C. These observations are consistent with those by Zhang et al of methane hydrate promotion by SDS (with concentrations from 0.5 to 4 mmol/l, or from 144 to 1152 ppmw) at the water/methane interface, either in a thin glass capillary or in droplets of the SDS solution under pressurized methane in conditions close to ours. These authors report an aqueous phase/methane interface transitioning from an early regime of “slight fluctuations” to a regime of violent fluctuations or “boiling” …”

Section: Resultssupporting

confidence: 94%

“…These observations are consistent with those by Zhang et al of methane hydrate promotion by SDS (with concentrations from 0.5 to 4 mmol/l, or from 144 to 1152 ppmw) at the water/methane interface, either in a thin glass capillary or in droplets of the SDS solution under pressurized methane in conditions close to ours. These authors report an aqueous phase/methane interface transitioning from an early regime of “slight fluctuations” to a regime of violent fluctuations or “boiling” …”

Section: Resultssupporting

confidence: 94%

“…These authors report an aqueous phase/methane interface transitioning from an early regime of “slight fluctuations” to a regime of violent fluctuations or “boiling”. 50 …”

Section: Resultsmentioning

confidence: 99%

“…The experimental setup and procedures are very similar to those recently used for examining various gas hydrate properties in our − and other ,− laboratories. The optical cell is a round glass capillary with its internal radius r well below the millimeter ( r = 100 μm in this study), filled with a column of a few millimeters of aqueous solution and then flame-sealed at one end.…”

Section: Experimental Setup and Proceduresoutline Of The Studymentioning

confidence: 99%

“…Enhanced presence of the hydrate former in the bulk aqueous solution has been observed concomitant to SDS-promoted hydrate growth. 47 As pointed out above, some substrates favor the growth of porous hydrates, 48 − 50 even though the hydrate crystals are generated at aqueous solution/gas interfaces, 51 − 55 in a manner not yet fully understood.…”

Section: Introductionmentioning

confidence: 99%

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Growth Kinetics and Porous Structure of Surfactant-Promoted Gas Hydrate

Samar,

Venet,

Desmedt

et al. 2024

ACS Omega

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Surfactants present in tiny amounts in the aqueous phase are known to be efficient gas hydrate promoters; yet, the promotion mechanisms are still not fully understood. Understanding and directing those mechanisms is key to the implementation of gashydrate-based applications such as gas storage and separation, secondary refrigeration or water treatment, and desalination. In this work, the growth at the water/gas interface and the porous structure of surfactant-promoted methane hydrate are observed by optical microscopy and Raman imaging in glass capillaries used as optical cells. Hollow crystals are continuously generated and expelled from the methane/water meniscus into the water or surfactant solution, where they ultimately form the skeleton of a porous medium filled with the solution. Unprecedented information is gathered over a range of scales from the molecular scale (crystal structure and cage filling) to the mesoscale (crystal morphologies, growth habits and pore sizes) and macroscale (rates and amounts of water and gas converted into hydrate and hydrate porosity). Following an early steady-state growth regime, a sudden order-of-magnitude increase of the conversion rate occurs, which is related to gaseous methane microbubbles being directly incorporated across the meniscus in the aqueous solution and later converted to methane hydrate. An assessment and comparison are made of the mechanisms and performance of two common anionic surfactants known to be efficient gas hydrate promoters, SDS (sodium dodecyl sulfate) and AOT (dioctylsulfosuccinate sodium or AerosolOcTyl). AOT provides a quicker but more limited conversion into hydrate than SDS, suggesting that it is more appropriate for continuous flow processes while SDS is better suited for gas storage applications. Raman spectra reveal that cage filling by methane of structure I methane hydrate is not affected by surfactants.

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Section: Resultssupporting

confidence: 94%

Section: Resultssupporting

confidence: 94%

“…These authors report an aqueous phase/methane interface transitioning from an early regime of “slight fluctuations” to a regime of violent fluctuations or “boiling”. 50 …”

Section: Resultsmentioning

confidence: 99%