Preparation and Characterization of Inner-pressure Hollow Fiber Composite Membrane via Two-way Coating Technique for CO2/CH4 Separation

High-selectivity inner-pressure hollow fiber composite (HFC) membrane for CO2/CH4 separation was prepared through the Two-way coating (TWC) technique. The blends of poly(vinylamine) (PVAm)/polyvinyl alcohol (PVA) were coated onto porous hollow fiber pplysulfone (PSF) ultrafiltration (UF) membrane with an effective membrane area of 0.4 m(2). The effects of fabrication parameters on the permselectivity of the resultant HFC membrane were investigated and the optimum preparation conditions were obtained as follows: coating time for 30 min and air blowing time for 30 min after the coating. The prepared HFC membrane showed the typical characteristic of fixed carrier membrane with a high selectivity of CO2 and CH4: the separation factor of CO2/CH4 (40 vol% CO2 at 25 degrees C and 0.2 MPa) was 36.6 and the CO2 permeability was 56.3 GPU. Field emission scanning electron microscopy (FESEM) images indicated that the HFC membrane prepared by TWC technique had a uniform coating layer along the whole hollow fiber. Membrane permselectivity showed almost no difference between different membrane sections. The HFC membrane showed a good stability during the continuous testing process of 540 h. And the HFC membrane preserved at 30 degrees C and 40 % humidity exhibited a good durability with a basically unchanged separation factor after 30 days.