湿法纺丝工艺制备Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)中空纤维陶瓷透氧膜及其改性研究

Preparation and Modification of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ) Hollow Fiber Membranes for Oxygen Permeation by Wet Spinning Process

采用固相反应法合成Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)(BSCF)粉,并以其为原料,采用湿法纺丝工艺及烧结处理制备出外径为3 mm、壁厚为400μm的BSCF中空纤维膜,通过涂覆法,在中空纤维膜的外表面负载BSCF多孔层,以进一步改善其透氧性能。利用X射线衍射对BSCF粉末与中空纤维膜的相组成进行分析,采用扫描电子显微镜对中空纤维膜的微观组织进行观测,对修饰后BSCF膜的透氧性能进行测试。结果表明:采用固相反应法可制备出具有单一钙钛矿相的BSCF粉体,湿法纺丝所制备的BSCF中空纤维膜具有非对称结构;在空气/真空梯度下,未经表面修饰的BSCF膜在700和900℃时的透氧速率分别为0.382和1.284 m L/(cm2·min)。表面负载Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3–δ)多孔层后,其700和900℃的透氧速率分别增加到1.250和2.426 m L/(cm2·min)。表面负载使BSCF的中空纤维透氧膜的透氧表观活化能从49.23降低至24.74 k J/mol。

Ba0.5Sr0.5Co0.8Fe0.2O3-δ（BSCF） powders were synthesized by a solid-state reaction method. The BSCF hollow fiber membranes with a diameter of 3 mm and a thickness of 400 μm were prepared by wet spinning and subsequently sintering processes. A BSCF porous layer was coated onto the outer surface of the BSCF hollow fiber membrane to modify the performance of oxygen permeation. The phase compositions of synthesized powders and hollow fiber membranes were analyzed by X-ray diffraction. The microstructure of the hollow fiber membrane was observed by scanning electron microscopy. The oxygen permeability of hollow fiber membranes were examined at different temperatures. The results indicate that the BSCF synthesized powders have a single perovskite phase. The BSCF hollow fiber membranes prepared by the wet spinning process have an asymmetric structure. The oxygen permeations of BSCF hollow fiber membrane in air/vacuum gradient are 0.382 and 1.284 mL/（cm2 min） at 700 and 900℃, respectively. After the surface modification, the oxygen permeation increases to 1.250 and 2.426 mL/（cm2·min）, respectively. The activation energy of oxygen permeation decreases nearly a half after the surface modification, i.e., decreasing from 49.23 to 24.74 kJ/mol at 800-900 ℃.