Performance of a mixed-conducting ceramic membrane reactor with high oxygen permeability for methane conversion

A mixed-conducting perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCFO) cer amic membrane reactor with high oxygen permeability was applied for the act ivation of methane. The membrane reactor has intrinsic catalytic activities for methane conversion to ethane and ethylene. C-2 selectivity up to 40-70 % was achieved, albeit that conversion rate were low, typically 0.5-3.5% at 800-900 degreesC with a 50% helium diluted methane inlet stream at a flow rate of 34 ml/min. Large amount of unreacted molecular oxygen was detected in the eluted gas and the oxygen permeation flux improved only slightly com pared with that under non-reactive air/He experiments. The partial oxidatio n of methane to syngas in a BSCFO membrane reactor was also performed by pa cking LiLaNiO/gamma -Al2O3 with 10% Ni loading as the catalyst. At the init ial stage, oxygen permeation flux, methane conversion and CO selectivity we re closely related with the state of the catalyst. Less than 21 h was neede d for the oxygen permeation flux to reach its steady state. 98.5% CH4 conve rsion, 93.0% CO selectivity and 10.45 ml/cm(2) min oxygen permeation flux w ere achieved under steady state at 850 degreesC. Methane conversion and oxy gen permeation flux increased with increasing temperature, No fracture of t he membrane reactor was observed during syngas production. However, H-2-TPR investigation demonstrated that the BSCFO was unstable under reducing atmo sphere, yet the material was found to have excellent phase reversibility. A membrane reactor made from BSCFO was successfully operated for the POM rea ction at 875 degreesC for more than 500h without failure, with a stable oxy gen permeation flux of about 11.5 ml/cm(2) min. (C) 2001 Elsevier Science B .V. All rights reserved.