A Molecular Dynamics Study of Enhanced CO2 Separation via Boron Nitride Nanotubes Embedded in a Silicon Nitride Membrane

In this work, we performed molecular dynamics (MD) simulations to investigate CO2 capture from flue gases with boron nitride nanotubes (BNNTs) and BNNTs embedded inside a silicon nitride (Si3N4) membrane. The CO2 molecules preferentially fill and occupy the BNNTs over N2 molecules. The high selectivity of BNNTs to capture CO2 rather than N2 results in a large separation effect. It was found that the CO2 molecules within the BNNTs form an ordered solid structure. Further to this, we investigated how the separation performance may be enhanced by placing BNNTs inside a silicon nitride (Si3N4) membrane. The presence of the Si3N4 membrane was found to alter the solid CO2 structures. This change is attributed to the resulting non-uniform electric field inside the BNNT. The altered electrostatic and the van der Waals interaction experienced by CO2 due to the presence of the the Si3N4 membrane leads to an enhancement of the previously mentioned separation effect. This work demonstrates the great potential for BNNTs, in particular those embedded in Si3N4 membranes, for use in carbon capture applications.