Experimental Evidence of Confined Methane Hydrate in Hydrophilic and Hydrophobic Model Carbons

Casco, Mirian Elizabeth; Zhang, En; Grätz, Sven; Krause, Simon; Bon, Volodymyr; Wallacher, Dirk; Grimm, Nico; Többens, Daniel M.; Hauß, Thomas; Borchardt, Lars

doi:10.1021/acs.jpcc.9b06366

Cited by 67 publications

(77 citation statements)

References 40 publications

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“…Apparently, methane physical adsorption in micropores contributes to methane uptake in the first stage, which is almost nil because of steric restriction. However, it significantly depends on the chemical properties of the AC surface, and since strong water molecule–AC surface interaction enhances steric restriction, hydrophobic carbon materials were known as adsorbing more methane (Casco et al, 2019 ), and some porous materials were even reported to have no influence on methane physical adsorption (Casco et al, 2016 ). Subsequently, when pressure exceeds a threshold value, i.e., equilibrium pressure, drastic methane uptake occurs that associates with hydrate formation at large pores or pore mouths.…”

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

“…However, because of complicated surface properties and pore texture, the micronature behind the macromechanisms is still unclear. One of the most appreciated factors was reported to be the chemical properties of AC surface, e.g., surface defect (Pirzadeh and Kusalik, 2013 ) and hydrophobic or hydrophilic properties (Casco et al, 2017 , 2019 ; Nguyen et al, 2017 ), which can change the interaction between water molecules and AC surface. Water molecules are known to assemble at the sites which are occupied by surface-deflecting and oxygen-containing functional groups to form clusters, which may provide potential nucleation sites and constitute a hydrate precursor.…”

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

“…It is well-known that the nanoconfinement effect equals high pressure, the so-called quasi-high-pressure effect (Urita et al, 2011 ; Fujimori et al, 2013 ), so solid water was observed in such a pore space because of low activity of water molecules, presenting an ice-like structure, which are thought to enhance hydrate nucleation. Nevertheless, non-freezing water was also reported in a confined nanopore space, which cannot contribute to hydrate formation (Casco et al, 2019 ; Cuadrado-Callados et al, 2019 ). Therefore, how the confined pore space influences hydrate nucleation and growth is still unclear due to lack of effective characterization methods at a molecular scale.…”

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

“…For hydrophobic AC, water molecules commonly occupy the center of a pore space, so the adsorbed methane molecules penetrate into the inner pore through the channel between the pore wall and the water molecules. In addition, methane adsorption in micropores was reported to induce an outward migration of water molecules (Casco et al, 2019 ), so two-way convection of water and methane molecules in a pore space occurs as shown in Figure 1D , and the enhanced molecular fluidity in a confined pore space significantly increases gas–liquid contact at the molecular scale, which further drastically increases nucleation sites. More details can be found in Zhang et al ( 2020 ).…”

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

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Promotion of Activated Carbon on the Nucleation and Growth Kinetics of Methane Hydrates

et al. 2020

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Due to the hybrid effect of physical adsorption and hydration, methane storage capacity in pre-adsorbed water-activated carbon (PW-AC) under hydrate favorable conditions is impressive, and fast nucleation and growth kinetics are also anticipated. Those fantastic natures suggest the PW-AC-based hydrates to be a promising alternative for methane storage and transportation. However, hydrate formation refers to multiscale processes, the nucleation kinetics at molecule scale give rise to macrohydrate formation, and the presence of activated carbon (AC) causes this to be more complicated. Although adequate nucleation sites induced by abundant specific surface area and pore texture were reported to correspond to fast formation kinetics at macroperspective, the micronature behind that is still ambiguous. Here, we evaluated how methane would be adsorbed on PW-AC under hydrate favorable conditions to improve the understanding of hydrate fast nucleation and growth kinetics. Microbulges on AC surface were confirmed to provide numerous nucleation sites, suggesting the contribution of abundant specific surface area of AC to fast hydrate nucleation and growth kinetics. In addition, two-way convection of water and methane molecules in micropores induced by methane physical adsorption further increases gas–liquid contact at molecular scale, which may constitute the nature of confinement effect of nanopore space.

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Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

Section: How Methane Would Be Adsorbed On Pw-acmentioning

confidence: 99%

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Promotion of Activated Carbon on the Nucleation and Growth Kinetics of Methane Hydrates

et al. 2020

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“…Several approaches have been tested to increase the gas-liquid contact area, and consequently the rate of MH formation (Linga et al 2009;Mel'nikov et al 2016;Park and Kim 2013). Nanoporous materials have proven to be an excellent platform for hosting and promoting the formation of MHs in a matter of minutes (Borchardt et al 2018;Casco et al 2019). Still, there is little known on how surfaces can be used to facilitate MH growth.…”

Section: Vapor/gas Sorptionmentioning

confidence: 99%

Non-porous organic crystals and their interaction with guest molecules from the gas phase

et al. 2020

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Some organic molecules encapsulate solvents upon crystallization. One class of compounds that shows a high propensity to form such crystalline solvates are tetraaryladamantanes (TAAs). Recently, tetrakis(dialkoxyphenyl)-adamantanes have been shown to encapsulate a wide range of guest molecules in their crystals, and to stabilize the guest molecules against undesired reactions. The term ‘encapsulating organic crystals’ (EnOCs) has been coined for these species. In this work, we studied the behavior of three TAAs upon exposition to different guest molecules by means of sorption technique. We firstly measured the vapor adsorption/desorption isotherms with water, tetrahydrofuran and toluene, and secondly, we studied the uptake of methane on dry and wet TAAs. Uptake of methane beyond one molar equivalent was detected for wet crystals, even though the materials showed a lack of porosity. Thus far, such behavior, which we ascribe to methane hydrate formation, had been described for porous non-crystalline materials or crystals with detectable porosity, not for non-porous organic crystals. Our results show that TAA crystals have interesting properties beyond the formation of conventional solvates. Gas-containing organic crystals may find application as reservoirs for gases that are difficult to encapsulate or are slow to form crystalline hydrates in the absence of a host compound. Wet tetraaryladamantane crystals take up methane in form of methane hydrate structure I, even though they appear non-porous to argon.

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Effect of surface roughness on methane hydrate formation and its implications in nucleation design

Fan

Wang

et al. 2023

AIChE Journal

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As a new form of energy with substantial potential, natural gas hydrate will play a crucial strategic role in the future due to its vast reserves and broad industrial application prospects. To better comprehend the nucleation and growth mechanism of clathrate hydrate, an enhanced thermodynamic model was proposed based on the wall roughness model and nucleation theory. In general, we discovered that the nucleation of hydrate on a smooth wall surface conforms to the conclusion of classical nucleation theory. However, curvature and surface roughness are frequently characterized by hydrophilicity's inhibition of hydrate and hydrophobicity's enhancement.The specific situation is more complex and requires specific analysis and discussion.Nonetheless, this also explains the uneven distribution of hydrate nucleation induction time. Our research reveals a fundamental method for designing or manipulating the heterogeneous nucleation of hydrates. We foresee promising applications in hydrate-related technologies based on the fractal structure of the substrate's surface.

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Experimental Evidence of Confined Methane Hydrate in Hydrophilic and Hydrophobic Model Carbons

Cited by 67 publications

References 40 publications

Promotion of Activated Carbon on the Nucleation and Growth Kinetics of Methane Hydrates

Promotion of Activated Carbon on the Nucleation and Growth Kinetics of Methane Hydrates

Non-porous organic crystals and their interaction with guest molecules from the gas phase

Effect of surface roughness on methane hydrate formation and its implications in nucleation design

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