Continuous Polycrystalline Zeolitic Imidazolate Framework-90 Membranes on Polymeric Hollow Fibers

摘要

The fabrication of advanced molecular separation membranes is attracting great interest because of their potential to significantly increase the energy efficiency, and reduce the cost, of renewable/clean fuel production, bio-based chemical production, greenhouse gas capture, and water purification. Currently available polymeric membranes have the advantage of low cost and high processibility. They can be engineered into different morphologies, such as asymmetric hollow fiber membranes (ca. 100-300 μm in diameter) comprised of mechanically strong macroporous fibers with a thin, dense polymeric layer that performs molecular separation. These fibers are used to fabricate modules with large membrane areas in excess of 1000 m~2m~(-3) of module volume. However, polymeric membranes are limited by an intrinsic trade-off between permeability and selectivity, and higher-performance materials are desired to decisively improve the economics of emerging separation technologies. Inorganic (zeolitic) molecular sieving membranes with very high throughput and high selectivity can be fabricated by hydrothermal processing on flat and tubular ceramic supports, but currently have limited applications. This is due to the high cost of the support materials and difficulties in the scale-up and reliability of hydrothermal growth and high-temperature calcination to remove the organic structure-directing agents.