Molecular gate membrane for CO₂ capture

Membrane separation holds promise as a cost saving process of CO₂ capture. To extend the membrane application, improving performance and reducing costs of membranes are desired. Composite membrane has a great possibility for future standard of preparing gas separation membranes because of its low cost and potential performance. This chapter presents a study in which composite hollow fiber membrane of highly CO₂ selective molecular gate was formed by the in situ modification technique. An active layer of poly (amidoamine) (PAMAM) dendrimer, which has shown the property of high CO₂-selective molecular gate, was prepared on the surface of a hollow fiber substrate by using modification technique of surface coating. For the substrate, a polysulfone (PSF) hollow fiber membrane was used. The PSF hollow fiber itself has no selectivity of CO₂ on N₂, on the other hand, the CO₂/N₂ selectivity of composite membrane treated by PAMAM attained to 67. Membrane systems of CO₂ and H₂ separation from a hypothetical integrated gasification combined cycle (IGCC) process gas were also investigated. Potential CO₂/H₂ selectivity of 100 in the molecular gate membrane would offer the reasonable separation of CO₂ from H₂.