(54c) Toward Cryogenic Membrane Gas Separations: Insights from Molecular Simulation and Statistical Mechanics

Membrane gas separations at cryogenic temperatures rely on the relative permeability of gaseous components through polymeric materials. Although gas separations have been widely studied at ambient temperatures, there is limited data and simulation results at cryogenic conditions. With limited experimental data, molecular simulation offers a powerful tool to analyze the transport and thermodynamic properties of these gases within polymers. Additionally, advanced equations of state, such as PC-SAFT, can accurately predict thermodynamic properties across a wide temperature range.

In this study, we embark on a systematic study of the diffusivity and solubility of various gases within polymer films using molecular dynamics simulations. To complement these simulations, we employ an extended version of Widom’s Potential Distribution Theory (PDT) to determine the chemical potential. Additionally, we will use regularization method, known as QCT-PDT, to evaluate the work required to create cavities within the material.

By combining diffusivity and chemical potential calculations, we aim to derive the necessary data for permeability assessments across polymer films. Through these calculations, we can estimate the exchange of gaseous species within the film. Our methodology will be validated against experimental data, and we will demonstrate the efficacy of PC-SAFT in fitting molecular simulation results for the chemical potential of gaseous components in the polymer. This fitting will enable us to interpolate and extrapolate molecular simulation findings effectively.

Overall, this research promises to shed light on the intricate dynamics of gas transport within polymer films at cryogenic temperatures, offering valuable insights for various industrial applications.