(326e) Advanced Nanocomposite Membranes for Natural Gas Purification

This presentation discusses preparation and characterization of novel nanocomposite membranes based on recently discovered porous aromatic framework (PAF-1) material in a matrix of a polymer of intrinsic microporosity (PIM-1) for CO₂ removal from natural gas. Both pure and mixed gas permeation and separation properties will be reported, as will pure and mixed gas physical aging data over periods of 1,000 hours. Permeability coefficients decreased over time and selectivity increased. We also characterized the influence of temperature on gas permeability and selectivity properties. We characterized both thick films, as well as thin-film (~2 µm) composite membranes on a porous support. We find evidence of competitive sorption at short (e.g., 24 hours) aging times, with mixed gas CO₂/CH₄ selectivity values being higher than pure gas values. However, at longer aging times (e.g., >200 hours), the mixed gas selectivity is somewhat less than the pure gas selectivity, indicating the influence of CO₂-induced plasticization in the aged membranes. These mixed matrix membranes are, in some cases, more than 10x more permeable than cellulose acetate, a commonly used membrane for natural gas purification. Selectivity of the nanocomposites was somewhat lower than that of cellulose acetate, but it increased as the samples underwent physical aging.