Fabrication of ceramic membrane tubes for direct conversion of natural gas

摘要

Several perovskite-type oxides that contain transition metals on the B-site show mixed (electronic/ionic) conductivity. These mixed conducting oxides are promising materials for oxygen permeating membranes that can operate without the need of electrodes or external electrical circuitry. SrCo(sub 0.8)Fe(sub 0.2)O(sub x) perovskite is known to exhibit very high oxygen permeabilities and one could use this material for producing value added products by direct conversion of methane, the most abundant component of natural gas. This paper deals with the processing and fabrication by plastic extrusion of long lengths ((approx)30 cm) of hollow SrCo(sub 0.8)Fe(sub 0.2)O(sub x) ceramic tubes. These tubes are characterized by scanning electron microscopy, X-ray diffraction (XRD) and their thermodynamic stability is evaluated using room temperature XRD on samples equilibrated at high temperatures in different gas environment.