(27c) Highly Selective Hollow Fiber Membranes for Carbon Capture Via in-Situ Layer-By-Layer Surface Functionalization

Authors: 
Mishra, N. K., Texas A& M University
Grunlan, J. C., Texas A&M University
Wilhite, B., Texas A&M University
Recent developments in the field of carbon sequestration have generated a renewed effort for efficient separation of CO2, which can be sent to a aquifers or depleted reservoirs for a long-term storage. However, current CO2 capture technologies, including absorption and pressure swing adsorption, are expensive and contribute 70-80% to the total cost of overall carbon capture and sequestration process. In the past two decades, cost effective membrane technology for CO2 separation has gained significant attention because of inherently low energy consumption, small carbon footprint and passive operation.

Homogenous polymeric membranes currently studied for separation of O2 from air and CO2 from natural gas possess an intrinsic trade-off between permeability and selectivity [1], while industrial application demands membranes with both high permeability and selectivity. Poly(ethylene oxide) (PEO) is a potential candidate for CO2 selective membranes owing to the unique interaction of the dipole-quadrupole of polar ether groups. In Our past work, we employed layer-by-layer (LbL) technique to fabricate Polymethacrylic acid (PMAA)/polyethylene oxide (PEO) films on polystyrene which demonstrated high CO2:N2 (~ 135) selectivity [2]. However, these membranes had but low CO2 permeability (0.011 barrer).

This works aims to demonstrate a cost-effective approach of deposition of highly CO2 selective membranes via LbL route on hollow fibers (HF), provided by our collaborator at NETL. These HFs were first potted inside a set-up and polyelectrolyte solution though the setup to deposit functional thin film. After addition of 20 bi-layers of PEO/PMAA on HF substrate, the selectivity of CO2 over N2 increased by 3 orders of magnitude exceeding the Robeson’s upper bound for homogenous polymeric films [3]. This work for the first time reports a thin deposition of membranes on HF with high selectivity (~1000) of CO2 over N2 as well as significant permeability (~50 barrer). The LbL technique on low-cost and mass-producible HF substrate has a potential use in carbon dioxide capture in power plants and refinery flue gases.

  1. Freeman, B.D., Basis of permeability/selectivity tradeoff relations in polymeric gas separation membranes. Macromolecules, 1999. 32(2): p. 375-380.
  2. Song, Y., et al., Highly selective multilayer polymer thin films for CO2/N2 separation. Journal of Polymer Science Part B: Polymer Physics, 2017. 55(23): p. 1730-1737.
  3. Robeson, L.M., The upper bound revisited. Journal of Membrane Science, 2008. 320(1-2): p. 390-400.