A Molecular Dynamics Study on Xe/Kr Separation Mechanisms Using Crystal Growth Method.

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• Xenon (Xe) and krypton (Kr) gas separation is crucial but difficult due to similar molecular properties.
• Hydrate-based gas separation offers a promising method for separating these noble gases.

Purpose of the Study:

• To investigate the efficacy of hydrate-based gas separation for xenon/krypton mixtures.
• To analyze the influence of temperature and pressure on guest molecule occupancy within hydrate cages using molecular dynamics simulations.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model hydrate formation and guest molecule encapsulation.
• Examined the occupancy of xenon and krypton in different hydrate cage structures (5¹², 5¹²6⁴) under varying temperature and pressure conditions.

Main Results:

• Increased temperature and pressure enhanced xenon occupancy in both 5¹² and 5¹²6⁴ cages.
• Elevated pressure improved krypton occupancy in 5¹²6⁴ cages, with minimal impact on 5¹² cage occupancy.
• Higher temperatures and pressures reduced the number of empty hydrate cages, indicating more efficient guest molecule filling.

Conclusions:

• Hydrate-based separation is a viable strategy for xenon/krypton mixtures.
• Xenon preferentially occupies larger 5¹²6⁴ cages, while krypton favors smaller 5¹² cages.
• Optimizing temperature and pressure conditions can enhance separation efficiency by influencing guest molecule distribution within hydrate cages.