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混合导体透氧膜是一类同时具有电子和氧离子两类导电性的陶瓷膜 .在高温下 ,氧会以氧离子的形式透过透氧膜 ,因此在膜表面存在丰富的氧物种 (O- ,O-2 ,O2 -2 和O2 - ) ,这些氧物种能够提高甲烷氧化偶联 (OCM )反应的C2 选择性 .采用挤压的方法制备出致密的Ba0 5Sr0 5Co0 8Fe0 2 O3-δ(BSCFO)透氧膜管 ,并考察了此透氧膜管对OCM反应的催化性能 .发现BSCFO的C2 生成速率比La0 6 Sr0 4Co0 8Fe0 2 O3-δ(LSCFO)和La Ba Co Fe O(LBCFO)要高得多 ,其原因主要是由于BSCFO中的氧空缺浓度比较高 .高的氧空缺浓度不仅能够加速氧离子的传输 ,而且能够提高甲烷分子的活化速度 ,所以BSCFO具有比LSCFO和LBCFO更好的催化性能 .C2 生成速率随着反应温度及原料气中甲烷浓度的升高而升高 ,C2 选择性取决于氧离子结合与OCM反应竞争的结果 ,高的氧离子结合速率会降低C2 选择性 .甲烷转化率随着富氧侧氧分压的升高而升高 ,但C2 选择性则随着氧分压的升高而降低 .这说明在OCM过程中气相反应起着重要的作用
Mixed-conductor oxygen-permeable membranes are a class of ceramic membranes that have both types of electrical and oxygen ions. At high temperatures, oxygen permeates oxygen-permeable membranes in the form of oxygen ions and thus forms abundant oxygen species (O -, O-2, O2-2 and O2-), these oxygen species can improve the C2 selectivity of the reaction of methane oxidative coupling (OCM) .The compact Ba0 5 Sr0 5 Co0 8 Fe0 2 O3-δ BSCFO) was used to investigate the catalytic performance of the oxygen-permeable membrane tube for OCM reaction.The results show that the C2 formation rate of BSCFO is higher than that of La0 6 Sr0 4 Co0 8 Fe0 2 O3-δ (LSCFO) and La Ba Co Fe O (LBCFO) Much higher is due to the higher concentration of oxygen vacancies in BSCFO, which not only accelerates the transport of oxygen ions but also increases the activation rate of methane molecules, so BSCFO is better than LSCFO and LBCFO The C2 selectivity increases with the reaction temperature and the methane concentration in the feed gas. The C2 selectivity depends on the competition between oxygen ion binding and OCM reaction, and the high oxygen ion binding rate decreases the C2 selectivity Methane conversion is as oxygen enriched side oxygen Temperature increased, C2 selectivity but with the increasing partial pressure of oxygen decreases. This shows that plays an important role in a gas phase reaction process OCM