| The results of transport and separation characterization studies of supported polyfurfuryl alcohol-based (PFFA) carbon molecular sieve membranes (CMSMs) have been presented and discussed. Polyfurfuryl alcohol was used as the polymeric precursor for forming the carbogenic selective layer, due to its relatively high carbon content and amorphous structure that makes it an ungraphitizable polymeric precursor. The membranes were prepared by dip-coating of the tubular support substrates, gamma-alumina USFilter tubes, in the appropriate solution followed by controlled carbonization in an inert atmosphere. The membranes were tested using single gases H2, CO 2, CO, CH4 and Ar as well as binary mixtures of CO2 /CH4 and a four-gas mixture consisting of CO2/CO/H 2/CH4. Separation factors for CO2/CH4 in the range of 34--37 were obtained for the binary and the four-gas mixtures. The permeance of CH4, Ar, and CO increased by increasing the temperature. However, the increase in the temperature decreased the permeance of CO2, indicating that CO2 permeates mainly by surface diffusion through the membrane. The membrane permeance decreased slowly during continuous testing with the four-gas mixture. This decline in performance was found, however, to be reversible. The initial membrane permeance was recovered by heating the membrane in an inert atmosphere of Ar. |
