The initiation of O permeation and POM were studied in mixed conducting ceramic membrane reactors. The membrane material composition, and catalyst-loading mode had an important effect upon the initiation of O permeation and POM reaction. The initiation time for Ba0.5Sr0.5Co0.8Fe0.2O3−δ and BaCo0.4Fe0.4Zr0.2O3−δ were 20 and 2h, respectively. When the catalyst was loaded directly onto the membrane surface, the O permeation flux increased by 8- to 10-fold over that under an air/He gradient. A good POM performance of methane conversion (higher than 96%) and the CO selectivity (higher than 95%) was successfully achieved. However, when the catalyst was loaded away from the membrane surface, or when the catalyst was not loaded, a lower O permeation flux (by 1- to 2-fold) and a poor POM performance (methane conversion lower than 30%) and CO selectivity (lower than 20%) were obtained. Characterization, using X-ray diffraction and SEM-EDS, indicated that the initial process could be finished by initiating the catalyst and adjusting the membrane structure (formation of a thin CoO-containing porous layer with a thickness of about 10μm). A marked increase in O permeation flux could be attributed to a sharp decrease in the O partial pressure and to adjustment of the surface structure.

Initiation of Oxygen Permeation and POM Reaction in Different Mixed Conducting Ceramic Membrane Reactors. J.Tong, W.Yang, H.Suda, K.Haraya: Catalysis Today, 2006, 118[1-2], 144-50