GAS PERMEATION OF POROUS ORGANIC-INORGANIC HYBRID MEMBRANES

Selective gas permeation of porous organic/inorganic hybrid membranes via sol-gel route and its thermal stability are described. Separation performance of the hybrid membrane was improved compared with porous m embranes governed by the Knudsen flow, and gas permeability was still much higher than that through nonporous membranes. Additionally, it wa s shown that these membranes were applicable at higher temperatures th an organic membranes. SEM observation demonstrated that the thin membr ane was crack-free. Nitrogen physisorption isotherms showed the pore s ize was in the range of nanometers. Gas permeability through this memb rane including phenyl group was in the range of 10(-8) [cc(STP) cm/(cm (2) s cmHg)] at 25 degrees C. The ratios of O-2/N-2 and CO2/N-2 were 1 .5 and 6.0, respectively, showing the permeation was not governed by t he Knudsen flow. The permeability decreased as the temperature increas ed. Furthermore, the specific affinity between gas molecules and surfa ce was observed not only in the permeation data of the hybrid membrane s but in the physisorption data. These results suggested that the gas permeation through the hybrid membrane was governed by the surface flo w mechanism. Thermal analysis indicated that these functional groups w ere still stable at higher temperatures. The phenyl group especially r emained undamaged even at 400 degrees C.