Enhanced methane hydrate formation with cyclopentane hydrate seeds

Baek, Seungjun; Ahn, Young‐Ho; Zhang, Junshe; Min, Jae; Lee, Huen; Lee, Jae Woo

doi:10.1016/j.apenergy.2017.05.108

Cited by 82 publications

(43 citation statements)

References 46 publications

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“…Alternatively, mechanical stirring can significantly decrease the nucleation time; however, it increases the complexity of the high-pressure reactor in terms of plugging and requires energy input. ,, Thermodynamic promoters, which alter the hydrate equilibrium curve, can also influence the induction time for hydrate nucleation. − Thermodynamic promoters are often combined with kinetic promoters to enhance hydrate formation. − However, these promoters again involve the use of chemicals such as tetra- n -butylammonium bromide (TBAB) or tetrahydrofuran (THF), which are often required in large quantities and not considered environmentally friendly. Other methods, such as utilizing hydrate seeds, supersaturation, ice melts, amino acids, electronucleation, and acoustics have also been studied to facilitate the nucleation of hydrates. − Electronucleation has been studied by the authors of this study: even though it can enable fast nucleation, it introduces additional complexities in the reactor …”

Section: Introductionmentioning

confidence: 99%

Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates

Kar

Acharya

Bhati

et al. 2021

ACS Sustainable Chem. Eng.

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Gas hydrates offer solutions in areas like CO 2 sequestration and desalination. However, their formation is severely limited by long induction (wait) times for nucleation, which range from hours to days. Many existing nucleation promotion techniques involve chemical additives, which invite environmental and process-related concerns. Here, we report a simple, passive, and environmentally friendly technique to significantly promote the nucleation of CO 2 hydrates: magnesium (in pure and alloy forms) triggers nucleation almost instantaneously. We report induction times of less than 1 min, which is the fastest induction time reported for any gas hydrate under stagnant conditions. This translates to Mg-promoted nucleation rates being 3000 times higher than the baseline. Statistically meaningful measurements of nucleation kinetics (in milliliter and liter-scale reactors), direct visualization of nucleation, and X-ray photoelectron spectroscopy (XPS)/Fourier-transform infrared spectroscopy (FTIR) analysis uncover several chemistry-related insights associated with Mg-based promotion. Importantly, the three-phase line of magnesium−water−CO 2 gas is key to promotion. Porous oxide layers, generation of H 2 nanobubbles, and chemisorption of CO 2 on Mg surfaces are other factors responsible for accelerated nucleation. Interestingly, Mg alloys exhibit faster nucleation promotion than pure Mg, which is significant in salt water medium. Overall, our work opens up pathways for faster synthesis of hydrates, which is critical to realizing applications.

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Section: Introductionmentioning

confidence: 99%

Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates

Kar

Acharya

Bhati

et al. 2021

ACS Sustainable Chem. Eng.

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“…In addition, CP forms hydrates at relatively mild conditions. Therefore, CP is frequently used as a hydrate-former (guest molecule) for hydrate formation and dissociation research [4,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Morphology Investigation on Cyclopentane Hydrate Formation/Dissociation in a Sub-Millimeter-Sized Capillary

Sun

et al. 2019

Crystals

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The formation, dissociation, and reformation of cyclopentane (CP) hydrate in a sub-millimeter-sized capillary were conducted in this work, and the morphology of CP hydrate was obtained during above processes, respectively. The influences of the supercooling degree, i.e., the hydrate formation driving force, on CP hydrate crystals’ aspect and growth rate were also investigated. The results demonstrate that CP forms hydrate with the water melting from ice at the interface between the CP and melting water at a temperature slightly above 273.15 K. With the action of hydrate memory effect, the CP hydrate in the capillary starts forming at the CP-water interface or CP–water–capillary three-phase junction and grows around the CP–water interface. The appearance and growth rate of CP hydrate are greatly influenced by the supercooling degree. It indicates that CP hydrate has a high aggregation degree and good regularity at a high supercooling degree (or a low formation temperature). The growth rate of CP hydrate crystals greatly increases with the supercooling degree. Consequently, the temperature has a significant influence on the formation of CP hydrate in the capillary. That means the features of CP hydrate crystals in a quiescent system could be determined and controlled by the temperature setting.

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“…THF is miscible with water, and CP is immiscible. A previous study revealed that CP should be excluded during the hydrate formation because of its immiscibility, and CH 4 was dominantly stored in sI hydrate, which was originated from the free water phase . However, the water miscibility of THF contributes to inducing a “tuning effect” in gas hydrates: Small-cage-specific guests can be stored in large cages stabilizing the overall hydrate structures when a concentration of hydrate promoter is lower than the stoichiometric concentration .…”

Section: Results and Discussionmentioning

confidence: 99%

“…However, moderate operating conditions and removing the energy-intensive stirring or the preparation of powder process would be strong advantages in terms of safety and economy. The hydrate seed concept, where a small amount of solid hydrate of a large guest molecule + liquid water solution is utilized, was proposed to induce the immediate nucleation of gas hydrates in a non-stirred reactor system, and methane hydrate formation was immediately induced with 0.0556 mol % of the CP hydrate seed solution under moderate pressure without stirring . The surface of hydrate crystals offers nucleation sites for heterogeneous nucleation and decreases the metastable zone for methane hydrate nucleation …”

Section: Introductionmentioning

confidence: 99%

Rapid Formation of Hydrogen-Enriched Hydrocarbon Gas Hydrates under Static Conditions

Lee

Kang

Ahn

et al. 2021

ACS Sustainable Chem. Eng.

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This work introduces a "hydrate seed solution", a surfactant solution containing pre-constructed structure II (sII) hydrate crystals, for the rapid formation of hydrogen-enriched hydrocarbon mixed hydrates. We observed the instantaneous nucleation and fast growth of mixed gas hydrates for both CH 4 − H 2 and C 2 H 6 −H 2 mixtures with the cyclopentane (CP) hydrate seed. The CP hydrate seed, which is immiscible with water, dominantly induces the growth of CH 4 −H 2 and C 2 H 6 −H 2 mixed gas hydrates with thermodynamically favorable sI structure. However, the THF hydrate seed, which is miscible with water, induced the formation of seed-templated sII CH 4 −H 2 or C 2 H 6 − H 2 hydrate, and the overall reaction was much slower than the CP hydrate seed case. For the C 2 H 6 −H 2 gas mixture, C 2 H 6 molecules could not occupy the small cage of hydrates, but H 2 mainly occupied the small cage. The THF hydrate seed provided a higher storage ratio of H 2 than the CP hydrate seed because the seed-templated sII C 2 H 6 −H 2 gas hydrates have a larger number of small cages than does the structure I (sI) hydrate. As the CP hydrate seed concentration decreased from 2.78 to 0.278 mol %, the growth of the mixed gas hydrates was extremely accelerated, and the overall conversion was completed within 1 h. The growth kinetics of hydrogen-enriched hydrocarbon mixed hydrates in the non-stirred system was much faster than that in prior agitation-applied studies. These findings suggest a way forward to an enhanced formation of hydrogen−natural gas clathrates for sustainable energy gas storage.

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Enhanced methane hydrate formation with cyclopentane hydrate seeds

Cited by 82 publications

References 46 publications

Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates

Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates

Morphology Investigation on Cyclopentane Hydrate Formation/Dissociation in a Sub-Millimeter-Sized Capillary

Rapid Formation of Hydrogen-Enriched Hydrocarbon Gas Hydrates under Static Conditions

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