| The mixed ionic and electronic conducting (MIEC) oxides can transport oxygen ion and electron simultaneously at high or intermediate temperatures. The dense membranes based on MIEC materials can separate oxygen from air selectively under the oxygen partial pressure gradient through them and without external circuit. This novel oxygen separation technology is suitable to meet the requirement of oxygen production at the small and middle scales. This thesis systemically conducted some basic research in this field.Firstly, it reviewed the recent development of materials and the principles about transport for oxygen permeable membrane of MIEC, as well as the development of industrial processes involving oxygen, such as the membrane reactor for syngas from methane. Moreover, this thesis aimed to solve the problems of bottle-neck in the field of oxygen separation with MIEC membrane.Secondly, it introduced the preparation and characterization of as-prepared membranes. The phase compositions of as-prepared membranes were investigated by XRD method, the microstructure of them was investigated using SEM and metalloscope techniques, and the oxygen permeability of them was measured in steady method.Thirdly, the preparation and oxygen permeability of La1-xSrxCo0.2Fe0.8O3-δ disk membranes were investigated. It was found that the contents of oxygen vacancy were increased with the decrease of tervalent La ions, which were partially substituted by bivalent Sr ions. It led to the increment of oxygen permeability and the degradation of thermal stability of LSCF disk membranes as the Sr contents increased. In them, La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF6428) had the promising behavior of oxygen permeation and stability.LSCF6428 tubular membranes were prepared by plastic extrusion, and the dependence of its properties on the sintering temperature was investigated systematically. The properties included the phase composition, microstructure, and oxygen permeability. The oxygen permeability of LSCF6428 tubular membrane sintered at 1300oC was a magnitude higher than that sintered at 1250oC, and it was due to that the rise of sintering temperature can reduce the contents of the impurities in membranes, The relative density of resulting LSCF6428 tubular membrane sintered at 1300oC was 98%, and its permeability was 1.25×10-7 mol.cm-2.s-1 at 1010oC.At last, this thesis conducted the preparation of SrCo0.8Fe0.1Sn0.1O3-δ(SSCF) hollow fiber membranes using the method of phase inversion. The impact of producing conditions on the quality and properties of SSCF hollow fiber membranes was investigated. At 25oC, the optimal preparing conditions were 1) nitrogen pressure being 1.5atm, and 2) the mass ratio of PESf to SSCF being 1:11 for the green compact. The outside diameter of the green compact for SSCF hollow fiber is 2.3mm, and its wall thickness is 0.3mm. The structure of as prepared SSCF hollow fiber membrane was asymmetrical, and contained a thin dense layer sandwiched by two porous layers. This structure can improve the oxygen permeability of SSCF membranes.
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