Influence of Polymeric Excipient Properties on Crystal Hydrate Formation Kinetics of Caffeine in Aqueous Slurries

Sodium dodecyl sulfate (SDS) is a well-known surfactant, which can accelerate methane hydrate formation. In this work, methane hydrate formation kinetics were studied in the presence of SDS using a rocking cell apparatus in both temperature-ramping and isothermal modes. Ramping and isothermal experiments together suggest that SDS concentration plays a vital role in the formation kinetics of methane hydrate, both in terms of induction time and of final gas uptake. There is a trade-off between growth rate and gas uptake for the optimum SDS concentration, such that an increase in SDS concentration decreases the induction time but also decreases the gas storage capacity for a given volume. The experiments also confirm the potential use of the rocking cell for investigating hydrate promoters. It allows multiple systems to run in parallel at similar experimental temperature and pressure conditions, thus shortening the total experimentation time. Understanding methane hydrate formation and storage using SDS can facilitate large-scale applications such as natural gas storage and transportation.

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Modelling hydrate formation kinetics of a hydrate promoter–water–natural gas system in a semi-batch spray reactor

Chemical Engineering Science ◽

10.1016/j.ces.2004.06.009 ◽

2004 ◽

Vol 59 (18) ◽

pp. 3849-3863 ◽

Cited By ~ 26

Author(s):

Nimalan Gnanendran ◽

Robert Amin

Keyword(s):

Natural Gas ◽

Hydrate Formation ◽

Formation Kinetics ◽

Gas System ◽

Natural Gas System ◽

Kinetics Of

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Chemically Influenced Self-Preservation Kinetics of CH4 Hydrates below the Sub-Zero Temperature

Energies ◽

10.3390/en14206765 ◽

2021 ◽

Vol 14 (20) ◽

pp. 6765

Author(s):

Jyoti Shanker Pandey ◽

Saad Khan ◽

Nicolas von Solms

Keyword(s):

Amino Acids ◽

Natural Gas ◽

Pure Water ◽

Hydrate Formation ◽

The Self ◽

Gas Uptake ◽

Formation Kinetics ◽

Preservation Property ◽

And Storage ◽

Kinetics Of

The self-preservation property of CH4 hydrates is beneficial for the transportation and storage of natural gas in the form of gas hydrates. Few studies have been conducted on the effects of chemicals (kinetic and thermodynamic promoters) on the self-preservation properties of CH4 hydrates, and most of the available literature is limited to pure water. The novelty of this work is that we have studied and compared the kinetics of CH4 hydrate formation in the presence of amino acids (hydrophobic and hydrophilic) when the temperature dropped below 0 °C. Furthermore, we also investigated the self-preservation of CH4 hydrate in the presence of amino acids. The main results are: (1) At T < 0 ℃, the formation kinetics and the total gas uptake improved in the presence of histidine (hydrophilic) at concentrations greater than 3000 ppm, but no significant change was observed for methionine (hydrophobic), confirming the improvement in the formation kinetics (for hydrophilic amino acids) due to increased subcooling; (2) At T = −2 °C, the presence of amino acids improved the metastability of CH4 hydrate. Increasing the concentration from 3000 to 20,000 ppm enhanced the metastability of CH4 hydrate; (3) Metastability was stronger in the presence of methionine compared to histidine; (4) This study provides experimental evidence for the use of amino acids as CH4 hydrate stabilizers for the storage and transportation of natural gas due to faster formation kinetics, no foam during dissociation, and stronger self-preservation.

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Formation Kinetics of the Mixed Cyclopentane—Carbon Dioxide Hydrates in Aqueous Sodium Chloride Solutions

Energies ◽

10.3390/en13174388 ◽

2020 ◽

Vol 13 (17) ◽

pp. 4388

Author(s):

Xuebing Zhou ◽

Ye Zhang ◽

Xiaoya Zang ◽

Deqing Liang

Keyword(s):

Carbon Dioxide ◽

Mass Fraction ◽

Hydrate Formation ◽

Initial Pressure ◽

Diffusion Resistance ◽

X Ray Diffraction ◽

Sodium Chloride Solutions ◽

Formation Kinetics ◽

Initial Stage ◽

Kinetics Of

Hydrate formation from cyclopentane (CP) and carbon dioxide was measured at 281 K by powder X-ray diffraction (PXRD) and macroscopic methods. The effect of initial pressure and CP mass fraction in liquid phase was analyzed. The results showed that hydrate formation was assumed to start with the nucleation of the mixed CP-CO2 hydrate with small fraction of CO2 followed by a large continuous CO2 adsorption. Initial pressure was found to have a positive correlation with the total CO2 consumptions when the initial pressure was below 2.5 MPa. However, the total CO2 consumptions dropped by over a half as the initial pressure was 3.0 MPa. PXRD revealed that all the hydrate samples formed at different initial pressures were structure II. The CO2 consumptions were assumed to be inhibited by the competitive occupation of 51264 cages between CP and CO2 molecules when the initial pressure was above 2.5 MPa. The CO2 consumptions were also found to be reduced as the CP mass fraction was above 0.25. An excess of CP molecules was not assumed to strengthen the formation of the mixed CP-CO2 hydrates at the initial stage, but increased the thickness of liquid CP film at aqueous brine and hydrate particles, which increased the diffusion resistance of CO2 molecules. Therefore, the suitable initial pressure and the CP mass fraction for the mixed CP-CO2 hydrate formation should be around 2.5 MPa and 0.2, respectively.

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