Modeling molecular transport in slit pores

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Understanding gas transport in porous materials is crucial for applications like gas storage and separation.
• Microporous carbons are widely used due to their tunable pore structures and high surface areas.
• Accurate modeling of methane transport in these materials is essential for optimizing their performance.

Purpose of the Study:

• To investigate methane transport in microporous carbon using molecular dynamics simulations.
• To develop and validate models for predicting methane diffusion coefficients.
• To determine the applicability of different transport models across a range of fluid densities.

Main Methods:

• Equilibrium and nonequilibrium molecular dynamics simulations were performed.
• Simulations covered various pore sizes, densities, and temperatures.
• Two models, molecular flow and slip flow, were used to interpret simulation results.

Main Results:

• The molecular flow model accurately predicted methane diffusion at low densities (up to 0.1-1 nm⁻³).
• The slip flow model, incorporating hydrodynamic theory and slip conditions, was effective at higher densities.
• A combined model using molecular flow for slip conditions also showed good agreement with simulations.

Conclusions:

• Both molecular flow and slip flow models provide reliable estimations of methane transport coefficients in microporous carbon.
• The choice of model depends on the fluid density within the pores.
• These validated models can aid in the design and optimization of carbon-based materials for gas transport applications.