Evaluation of the Permeation of Syngas and Its Components through a Synthesized Matrimid Asymmetric Hollow-Fiber Membrane

Bioconversionof syngas (H-2-CO-CO2) to organicsis an excellent means of carbon recycling. Membrane-basedgas-delivery systems can overcome the challenge of syngas'slow solubility in water. However, to maintain syngas conversion stoichiometry,it is crucial to have a membrane that delivers gases at high rateswithout selectivity toward any component. We synthesized an asymmetric,high-flux, low-selectivity hollow-fiber membrane, "small-defect-engineered",to prevent bubble formation in future bioreactors. We created sixsets of Matrimid membranes and screened their He/N-2 selectivityand permeances. We compared the pressure-normalized flux of the setwith the highest He/N-2 permeance against a commercial symmetricmembrane for a syngas mixture and its individual purified components.Under equal pressure, the asymmetric membrane exhibited 300-fold higherH(2)-flux, 80-fold higher CO-flux, and 100-fold higher CO2-flux than the symmetric membrane for pure gases. For themixture, the asymmetric membrane had a 45-fold greater H-2-flux, 100-fold greater CO-flux, and 400-fold greater CO2-flux than those of the symmetric membrane. Although the asymmetricmembrane's selectivity (H-2:CO:CO2, 1:5.2:12)exceeded that of the commercial membranes (1:3:1.7), the asymmetricmembrane possesses highly desirable traits for bioconversion of syngas,as its gas fluxes greatly exceed those of commercial membranes.