Integration of air separation and partial oxidation of methane in the La 0.4Ba 0.6Fe 0.8Zn 0.2O 3− δ membrane reactor

Abstract

A disc-membrane made of the La 0.4Ba 0.6Fe 1− x Zn x O 3− δ (LBFZ- x) perovskite oxide with x = 0.2 was used to carry out air separation. The oxygen permeation through the membrane was driven by either He sweeping or partial oxidation of methane (POM) at the permeate side of membrane. Both operation temperature and thickness of the LBFZ-0.2 membrane impact oxygen permeation flux under a permeation gradient. Oxygen permeation flux increases with the decrease in the thickness of membrane and the trend gradually levels off. A much greater oxygen flux through the LBFZ-0.2 membrane was achieved when the POM reaction instead of the He sweeping was used to drive oxygen permeation. It could reach 12 cm 3 cm −2 min −1 through a 0.5 mm-thick LBFZ-0.2 membrane. The most influential property exhibited by the LBFZ-0.2 membrane lies in its chemical stability under the reducing atmosphere of POM. The membrane remains intact and supplies oxygen to maintain almost quantitative CH 4 conversion and CO selectivity through a 500 h testing period at 900 °C. The chemical stability of LBFZ-0.2 was also verified by the retention of perovskite structure.