Preparation of poly(ether-block-amide)/attapulgite mixed matrix membranes for CO₂/N₂ separation

Mixed matrix membranes (MMMs) made from selective inorganic fillers and polymers are very attractive in the field of gas separation. But only few of inorganic fillers can simultaneously enhance both gas permeability and selectivity for the pristine polymer membrane. In this work, composite membranes made from poly(ether-block-amide) (Pebax^®1657) and attapulgite (ATP) were fabricated. The interaction between ATP nanorods and Pebax matrix were characterized by XRD and FTIR, and the adhesion of MMMs was also examined by SEM. Single gas permeation measurements showed that both the CO₂ permeability and CO₂/N₂ selectivity increased at low ATP loadings (<6.3wt%). Compared with the pristine Pebax membrane, the addition of 1.7wt% ATP/Pebax MMMs enhanced the CO₂ permeability from 56 to 77 Barrer and the CO₂/N₂ selectivity of from 40 to 52, respectively. In addition, the CO₂ permeability and the CO₂/N₂ selectivity of 1.7wt% ATP/Pebax MMMs can be further increased to 104Barrer and 84, respectively, as the feeding pressure was increased to 10bar. The ATP/Pebax MMMs exhibit well stability, even under the humidified feeding. Overall, ATP/Pebax composite membranes provide a potentially promising alternative for CO₂ separation from N₂.