Density functional theory-based analyses on selective gas separation by β-PVDF-supported ionic liquid membranes

Area of Science:

• Materials Science
• Computational Chemistry
• Chemical Engineering

Background:

• Developing efficient polymer-supported ionic liquid (IL) membranes for gas separation is crucial but challenging.
• Understanding the adsorption properties of ILs and support materials is key to optimizing membrane performance.

Purpose of the Study:

• To investigate the quantum chemical perspective of selective gas adsorption in α- and β-polyvinylidene fluoride (PVDF)-supported IL membranes.
• To evaluate the adsorption efficiency of CO2, CO, CH4, and H2 mixtures on these membranes.
• To elucidate the role of IL/support interactions and gas adsorption on the support material.

Main Methods:

• Dispersion-corrected density functional calculations were employed.
• Analyses included interaction energies, nonbonding interactions (SAPT), NBO, QTAIM, RDG, frontier orbitals, DOS, and thermochemical analyses.
• Both α- and β-PVDF supported imidazolium- and pyridinium-based ILs were studied.

Main Results:

• β-PVDF demonstrated superior binding with ILs and better gas affinity compared to α-PVDF.
• Gas adsorption occurred via weak hydrogen bonds, indicating physisorption with favorable adsorption energies.
• All β-PVDF/IL systems showed the highest affinity for CO2 and the lowest for H2.

Conclusions:

• β-PVDF is a more suitable membrane component than α-PVDF for IL-based gas separation.
• The studied membranes exhibit effective selective adsorption of CO2 and H2 from gas mixtures.
• Quantum chemical calculations provide detailed insights into gas adsorption mechanisms in these advanced materials.