Parametric Study of Transport Properties of Hollow Fiber Membranes Containing Ionic Liquids for Pre-Combustion CO2 Capture

Gasification of coal and biofuels with carbon dioxide capture and storage is a promising technology for low emission electric power production.  In a typical gasification scheme with CO₂ capture, carbonaceous fuel is gasified to produce hydrogen and carbon monoxide, followed by a water-gas shift reaction to convert carbon monoxide into carbon dioxide. The high partial pressure of CO₂ produced after the water-gas shift reaction makes this process particularly amenable for membrane separations.  However, traditional polymer membranes are limited by the separation characteristics of the polymer and often suffer from low permeability and selectivity.  Several research groups have attempted to overcome these limitations by using supported ionic liquid membranes (SILMs) in which an ionic liquid (IL) is suspended within the pores of a membrane support and serves as the active gas separation medium of the membrane.  For industrial applications, hollow fibers are preferred over flat membranes due to their smaller footprint, ease of high efficiency module design and low fabrication cost. In the current work, polymeric hollow fiber SILMs were fabricated from several dope compositions, and the effect of fiber wall morphology on transport properties was studied. The morphology of the fiber wall was characterized by measuring the volume fraction of the polymer, macro-voids, and micro-voids for each type of fiber.  The calculated porosities of both the bulk fiber and the micro-porous region of the fiber were then related to the transport properties of the fibers.