Enhancing oxygen permeation through hierarchically-structured perovskite membranes elaborated by freeze-casting
Enhancing oxygen permeation through hierarchically-structured perovskite membranes elaborated by freeze-casting
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DOI：
10.1039/c3ta14069e
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发表时间：
2014-01-01
影响因子：
11.9
通讯作者：
Serra, Jose M.
中科院分区：
文献类型：
--
作者：
Gaudillere, Cyril;Garcia-Fayos, Julio;Serra, Jose M.
创新的不对称氧传输膜结构的制备相结合的冷冻浇铸和薄膜沉积技术。冷冻浇铸能够通过产生分级孔隙率来优化通过载体的气体输送，同时通过丝网印刷在该载体上涂覆30 μ m的致密顶层。该技术的多功能性通过制备由快离子导体（例如钙钛矿和掺杂的氧化铈萤石）制成的高度多孔体来证明，其在催化、电化学和气体分离中具有大量应用。使用全La 0. 6Sr 0. 4Co 0. 2Fe 0. 8 O3-δ非对称膜的渗透测试证明了这种多孔载体对O-2通量的有益效果，在1000 ℃下的最大值为6.8 mL min（-1）cm（-2），明显高于迄今为止使用常规制备技术所获得的结果。通过多孔冷冻铸造支持的气体渗透研究表明，特定的孔结构允许气体传输阻力最小化。发现与常规多孔载体（例如流延载体）相比，相关压降非常低，例如对于400 mL min（-1）cm（-2）的入口流量，在800 ℃下氩气仅为0.59 bar mm（-1）。最后，在CO2气氛下和900 ℃下评估了非对称膜的稳定性48小时。膜被发现是稳定的，没有失活，也没有减少的O-2渗透通量。
Innovative asymmetric oxygen-transport membrane architectures were prepared by combining freeze-casting and film deposition techniques. Freeze-casting enabled the optimization of the gas transport through the support by creating a hierarchical porosity while a dense top-layer of 30 mu m was coated over this support by screen printing. The versatility of this technique was demonstrated by preparing highly porous bodies made of fast ionic conductors, e.g. perovskites and doped ceria fluorites, with a large number of applications in catalysis, electrochemistry and gas separation. Permeation tests using an all-La0.6Sr0.4Co0.2Fe0.8O3-delta asymmetric membrane proved the beneficial effect of such porous supports over the O-2 fluxes with a maximum value of 6.8 mL min(-1) cm(-2) at 1000 degrees C, markedly above the results achieved so far with conventional preparation techniques. Gas permeance study through the porous freeze-cast support showed that the particular pore structure allows the gaseous transport resistance to be minimized. The related pressure drop is found to be very low in comparison with conventional porous supports, e.g. tape-cast supports, with for example only 0.59 bar mm(-1) with argon at 800 degrees C for an inlet flow of 400 mL min(-1) cm(-2). Finally, the stability of the asymmetric membrane has been evaluated under CO2 atmosphere during 48 hours and at 900 degrees C. The membrane is found to be stable without deactivation nor decrease in the O-2 permeation flux.