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CO₂–CH₄ permeation in high zeolite 4A loading mixed matrix membranes

Adams, Ryan T., Lee, Jong Suk, Bae, Tae-Hyun, Ward, Jason K., Johnson, J.R., Jones, Christopher W., Nair, Sankar, Koros, William J.
Journal of membrane science 2011 v.367 no.1-2 pp. 197-203
adhesion, artificial membranes, carbon dioxide, composite materials, feeds, gases, methane, natural gas, permeability, polymers, separation, temperature, zeolites
Mixed matrix membranes (MMMs) with low particle loadings have been shown to improve the properties of pure polymers for many gas separations. Comparatively few reports have been made for high particle loading (≥50vol.%) MMMs. In this work, CO₂–CH₄ feeds were used to study the potential of 50vol.% zeolite 4A-poly(vinyl acetate) (PVAc) MMMs for natural gas separations. A low CO₂ partial pressure mixed feed probed MMM performance below the plasticization pressure of PVAc and a high CO₂ partial pressure mixed feed probed MMM performance at industrially relevant conditions above the plasticization pressure. Under both mixed feed conditions at 35°C, substantial improvements in overall separation performance were observed. At low CO₂ partial pressures, CO₂ permeability roughly doubled with a nearly 50% increase in selectivity versus pure PVAc under the same conditions. For the high CO₂ partial pressure feed, CO₂ permeability remained effectively unchanged with a 63% increase in selectivity versus pure PVAc. Surprisingly, the performance of these PVAc based MMMs approached the properties of current “upper bound” polymers. Overall, this work shows that significantly improved performance MMMs can be made with traditional techniques from a low cost, low performance polymer without costly adhesion promoters.