Path-dependent morphology of CH hydrates and their dissociation studied with high-pressure microfluidics.

Methane hydrates (MHs) have been considered a promising future energy source due to their vast resource volume and high energy density. Understanding the behavior of MH formation and dissociation at the pore-scale and the effect of MH distribution on the gas-liquid two phase flow is of critical importance for designing effective production strategies from natural gas hydrate (NGH) reservoirs. In this study, we devised a novel high-pressure microfluidic chip apparatus that is capable of direct observation of MH formation and dissociation behavior at the pore-scale.

Enhanced formation of methane hydrate from active ice with high gas uptake.

Gas hydrates provide alternative solutions for gas storage & transportation and gas separation. However, slow formation rate of clathrate hydrate has hindered their commercial development. Here we report a form of porous ice containing an unfrozen solution layer of sodium dodecyl sulfate, here named active ice, which can significantly accelerate gas hydrate formation while generating little heat.

Sodium Dodecyl Sulfate Preferentially Promotes Enclathration of Methane in Mixed Methane-Tetrahydrofuran Hydrates.

Methane storage in mixed hydrates is advantageous due to faster kinetics and added stability. However, capacity needs to be improved. Here we study mixed hydrates of methane (CH) and tetrahydrofuran (THF), in the presence of sodium dodecyl sulfate (SDS) as a kinetic promoter for hydrate formation.

CH Hydrate Formation between Silica and Graphite Surfaces: Insights from Microsecond Molecular Dynamics Simulations.

Microsecond simulations have been performed to investigate CH hydrate formation from gas/water two-phase systems between silica and graphite surfaces, respectively. The hydrophilic silica and hydrophobic graphite surfaces exhibit substantially different effects on CH hydrate formation. The graphite surface adsorbs CH molecules to form a nanobubble with a flat or negative curvature, resulting in a low aqueous CH concentration, and hydrate nucleation does not occur during 2.

What are the key factors governing the nucleation of CO hydrate?

Microsecond molecular dynamics simulations were performed to provide molecular insights into the nucleation of CO hydrate. The adsorption of sufficient CO molecules around CO hydration shells is revealed to be crucial to effectively stabilize the hydrogen bonds formed therein, catalyzing the hydration shells into hydrate cages and inducing the nucleation. Moreover, a high aqueous CO concentration is found to be another key factor governing the nucleation of CO hydrate, and only above a critical concentration can the nucleation of CO hydrate occur.

High pressure rheology of gas hydrate formed from multiphase systems using modified Couette rheometer.

Conventional rheometers with concentric cylinder geometries do not enhance mixing in situ and thus are not suitable for rheological studies of multiphase systems under high pressure such as gas hydrates. In this study, we demonstrate the use of modified Couette concentric cylinder geometries for high pressure rheological studies during the formation and dissociation of methane hydrate formed from pure water and water-decane systems. Conventional concentric cylinder Couette geometry did not produce any hydrates in situ and thus failed to measure rheological properties during hydrate formation.

Thermodynamic and kinetic verification of tetra-n-butyl ammonium nitrate (TBANO3) as a promoter for the clathrate process applicable to precombustion carbon dioxide capture.

In this study, tetra-n-butyl ammonium nitrate (TBANO3) is evaluated as a promoter for precombustion capture of CO2 via hydrate formation. New hydrate phase equilibrium data for fuel gas (CO2/H2) mixture in presence of TBANO3 of various concentrations of 0.5, 1.

A new porous material to enhance the kinetics of clathrate process: application to precombustion carbon dioxide capture.

In this work, the performance of a new porous medium, polyurethane (PU) foam in a fixed bed reactor for carbon dioxide separation from fuel gas mixture using the hydrate based gas separation process is evaluated. The kinetics of hydrate formation in the presence of 2.5 mol % propane as thermodynamic promoter was investigated at 4.

Medium-pressure clathrate hydrate/membrane hybrid process for postcombustion capture of carbon dioxide.

This study presents a medium-pressure CO2 capture process based on hydrate crystallization in the presence of tetrahydrofuran (THF). THF reduces the incipient equilibrium hydrate formation conditions from a CO2/N2 gas mixture. Relevant thermodynamic data at 0.

The clathrate hydrate process for post and pre-combustion capture of carbon dioxide.

One of the new approaches for capturing carbon dioxide from treated flue gases (post-combustion capture) is based on gas hydrate crystallization. The basis for the separation or capture of the CO(2) is the fact that the carbon dioxide content of gas hydrate crystals is different than that of the flue gas. When a gas mixture of CO(2) and H(2) forms gas hydrates the CO(2) prefers to partition in the hydrate phase.