Highly efficient helium purification through a dual-membrane system: insights from molecular dynamics simulations

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Helium is primarily sourced from natural gas, necessitating efficient recovery technologies.
• Developing advanced separation methods is crucial for helium purification from natural gas mixtures.

Purpose of the Study:

• To propose and investigate a novel dual membrane system for helium separation from He/N2/CH4 mixtures.
• To evaluate the system's performance using molecular dynamics simulations under varying pressures and compositions.

Main Methods:

• Utilized molecular dynamics (MD) simulations to model gas permeation through C2N and graphdiyne membranes.
• Analyzed the effects of applied pressure (up to 2 MPa) and feed composition on separation efficiency.
• Investigated gas transport mechanisms using density maps, van der Waals interactions, and potential of mean force calculations.

Main Results:

• The C2N membrane selectively allowed He and N2 permeation while rejecting CH4.
• The graphdiyne membrane further purified helium by allowing He passage and blocking N2.
• The dual membrane system demonstrated high helium permeance (2.5 × 10^6 GPU) and ultrahigh selectivity.
• Simultaneous separation of all three components was achieved at 2 MPa.

Conclusions:

• The proposed dual membrane system exhibits outstanding performance for helium purification from natural gas.
• This technology offers a promising solution for efficient helium recovery and resource conservation.