Syngas Production by Partial Oxidation of Methane with Oxygen Permeable Membrane

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In this study, oxygen permeability was improved by three methods (1)Preparation of asymmetric membranes, (2)Optimization of preparation methods, and (3)Investigation of new materials. (1)We investigated the preparation of SrFeCo_<0.5>O_x(SFC2) asymmetric membranes on porous α-alumina substrates. Though gas-tight membranes were obtained by repeating the preparation, these membranes did not show high oxygen flux due to solid-state reaction between membrane materials and substrates or due to differences of compositions from SFC2. To prevent such problems, we established a new preparation method. The dense layer was prepared with SFC2 powder, and the porous support layer was prepared using SFC2 powder mixed with ethyl cellulose. The SFC2 powder and the mixture were simultaneously pressed and calcined. The minimum thickness of the dense layer prepared by this method was 0.1 mm. The asymmetric membranes gave greater oxygen flux than the symmetric membrane. And the oxygen fluxes through these membranes increased with decreasing the thickness of dense layer. (2)SFC2 membranes were synthesized with powders prepared by three different methods, (a)a solid-state reaction method, (b)an evaporation-to-dryness method, and (c)a combined citrate and EDTA. Complexing method. Oxygen fluxes increased in the order of (a)<(b)<(c). Influence of preparation conditions on oxygen flux was investigated. The oxygen flux could be improved by repeated calcination and grinding of parent powder or by sintered at a higher temperature. (3)La in La_<0.4>Ba_<0.6>Fe_<0.8>Co_<0.2>O_<3-δ> was substituted by another rare earth element such as Pr, Nd, Sm. The higher oxygen flux than La_<0.4>Ba_<0.6>Fe_<0.8>Co_<0.2>O_<3-δ> membrane, however, was not obtained. Now we evaluating membranes prepared in this study by applying to a membrane reactor.