Temperature dependence of gas sorption and permeation in PIM-1

• Sorption, diffusion and permeation isotherms for PIM-1 were measured.
• Temperature and pressure dependence of P, D, and S were evaluated.
• Energies of sorption, diffusion and permeation were quantified.

In a prior paper gas sorption, permeation and diffusion coefficients were determined for He, H2, N2, O2, CH4, CO2, C2H4, C2H6, C3H6 and C3H8 in PIM-1, a polymer of intrinsic microporosity, at 25 °C over a range of pressures. Here similar measurements and analyses were made at temperatures from 25 to 55 °C over a wide range of pressure. In all cases, the sorption isotherms were generally consistent with the form of the dual-sorption model. For He, H2, N2, O2, CH4 and CO2, the effects of plasticization were minimal and the results could be effectively analyzed by the dual sorption-dual mobility model, and the temperature dependence of the model parameters were analyzed to obtain the energetic parameters for the sorption and diffusion processes. However, for C2H4, C2H6, C3H6 and C3H8, plasticization was quite significant and temperature dependent; as a result, a similar analysis in terms of the dual sorption-dual mobility model could not be meaningfully carried out. For all gases, a more phenomenological analysis of P, D and S was made in terms of simple Arrhenius and van't Hoff relations to obtain energetic parameters that subsequently depend on pressure because of some combination of dual mode and/or plasticization effects.

Diffusivity and permeability of hydrocarbons in PIM-1 have an inverted temperature dependence due to plasticization.Figure optionsDownload high-quality image (121 K)Download as PowerPoint slide