Planar and tubular perovskite-type membrane reactors for the partial oxidation of methane to syngas

Dense planar and tubular oxygen separation membranes of La0.6Ca0.4Fe0.75Co0.25O3-delta were investigated as reactors for the partial oxidation (POX) of methane to syngas. Their permeation properties were measured in an air/argon pO(2) gradient as a function of temperature. At 900degreesC, the oxygen flux through a 1.26-mm-thick membrane was 0.075 mumol/cm(2).s and through a 0.25-mm-thick tube, 0.24 mumol/cm(2).s. For the POX measurements, a catalyst was added to the membrane and methane was introduced on the argon side. This resulted in a gradual increase of the oxygen flux with increasing concentration of methane, reaching 2 mumol/cm(2).s at 900degreesC with pure methane. For the planar reactor, the CO selectivity reached 99% and the CH4 conversion 75% at 918degreesC with pure methane. For the tubular reactor, the CO selectivity and CH4 conversion were 83 and 99%, respectively, under the same conditions. After 1,400 h of operation in a tubular POX reactor, the membrane was examined revealing phase demixing and local decomposition.