Korean Chemical Engineering Research, Vol.57, No.1, 11-16, February, 2019
산소 분리를 위한 La0.6Sr0.4Ti0.3Fe0.7O3-δ가 코팅된 Ba0.5Sr0.5Co0.8Fe0.2O3-δ 이온전도성 분리막에서 Cr 불순물의 온도 의존성
Temperature Dependence of Cr Impurity in La0.6Sr0.4Ti0.3Fe0.7O3-δ Coated Ba0.5Sr0.5Co0.8Fe0.2O3-δ Ion Conducting Membrane for oxygen Separation
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초록
높은 산소 분리 특성과 CO2에 대한 안정성을 보인 La0.6Sr0.4Ti0.3Fe0.7O3-δ(LSTF)가 코팅된 Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) 분리막을 bench 규모의 장치에 적용하여 산소 투과 실험을 수행 하였다. 또한 실험실 규모 장치와 bench 규모 장치의 분리막 반응기 내 온도 구배에 따라서 분리막을 3영역으로 나누어 각각 비교 분석하였다. 900 °C까지 온도 범위에서 산소 투과 실험을 진행하면서 Cr 침적의 온도 의존성을 조사하였다. 그 결과 실험실 장치에서 측정한 산소 투과율인 3.79 ml/min·cm2에 비해 현저히 낮은 2.37 ml/min·cm2를 확인했다. 이와 같은 산소 투과율의 감소는 XRD와 SEM/EDS 분석을 통하여 분리막 반응기의 합금 재질에서 방출되어 나온 기상 Cr의 분리막 표면 침적에 의한 것임을 밝혀냈다. 특히 중온 영역에서 많은 양의 Cr이 발견되었다.
La0.6Sr0.4Ti0.3Fe0.7O3-δ(LSTF) coated Ba0.5Sr0.5Co0.8Fe0.2O3-δ(BSCF) membranes which has properties of high oxygen permeability and stability to CO2 were applied to a bench scale apparatus to conduct oxygen permeation experiments. Also, the membranes of the laboratory and the bench scale device were divided into three regions according to the temperature gradient in the membrane reactor for comparative analysis. While oxygen permeation experiment were conducted up to 900 °C, temperature dependence of Cr deposition was investigated. As a result, it was confirmed that the oxygen permeability was 2.37 ml/min·cm2, which was significantly lower than 3.79 ml/min·cm2 measured in the laboratory apparatus. It was found through XRD and SEM/EDS analysis that the decrease in oxygen permeability was originated from the deposition of gaseous Cr on the membrane surface released from the alloy material of the housing. In particular, a large amount of Cr was found in the medium temperature region.
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