CERAMIC MEMBRANE REACTOR FOR CONVERTING METHANE TO SYNGAS

Certain perovskite-type oxides (ABO(3)) containing transition metals o n the B-site shaw mixed (electronic/ionic) conductivity. These mixed-c onductivity oxides are promising materials for oxygen-permeating membr anes that can operate without electrodes or external electrical circui try. Oxides in the system Sr-Fe-Co-O permeate large amounts of oxygen, and extruded tubes of these materials have been evaluated in a reacto r operating at approximate to 850 degrees C for direct conversion of m ethane into syngas (CO + H-2) in the presence of a reforming catalyst. Methane conversion efficiencies of > 99% were observed, and some of t he reactor tubes have been operated for more than 1000h. Membrane tube s were fabricated from calcined powders by a plastic extrusion techniq ue. Ceramic powders in the Sr-Fe-Co-O system were made by solid-state reaction of the constituent carbonates, oxides, and/or nitrates. The c hemical-phase behavior of the ceramic powders with varying stoichiomet ries were studied by high-temperature in-situ X-ray diffraction (XRD) as a function of oxygen partial pressure. The sintered extruded tubes were also characterized by XRD and scanning electron microscopy.