Study on gas separation by facilitated transport liquid membranes

与聚合物膜相比，通过促进扩散机制传输气体的液膜具有更高的选择性。本文研究了以~lt；AgNO_3&gt；为载体的支撑液膜(SLM)中乙烯的传递机理。此外，还提出了一种比SLM具有更高渗透率和稳定性的流动液膜，并对其性能进行了评价。在SLM分离乙烷和乙烯的过程中，分离因子&lt；(C2H4/C2H6)3&gt；随着载体浓度的增加而增大，当[&lt；AgNO3&gt；]为4mol/dm时，分离系数达到1000左右。提出了一种计算伴随瞬时可逆反应的促进输运速率的近似方法。即使在载体和络合物的扩散系数彼此不同的情况下，该方法也适用。实验观测到的乙烯通量与用近似方法计算的通量吻合较好。研制了一种三通道进气、载液(&lt；AgNO3&gt；溶液)和反萃取气的流动液膜池。通过疏水微孔膜分离通道。在载液流量较大时，气体的渗透率约为SLM的5倍。在乙烯和乙烷的分离中，没有观察到由于溶剂挥发而造成的膜污染。然而，当使用聚丙烯膜时，沉淀物可能覆盖在膜上，导致低渗透性。通过向载体溶液中添加硝酸可以避免这种结垢。当使用特氟龙膜时，即使在没有硝酸的情况下，FLM也可以稳定11d以上。SLM带侧抽真空后，乙烯产率可达98%。用渗透模型和设计方程对实验结果进行了令人满意的模拟。

Liquid membranes through which gases are transported by the facilitated diffusion mechanism have higher selectivity compared with polymer membranes. In the present study, the transport mechanism of ethylene through supported liquid membrane (SLM) containing <AgNO_3> as a carrier was elucidated. Furthermore, a flowing liquid membrane (FLM), which has higher permeability and stability compared with SLM, was proposed, and its performance was evaluated.In the separation of ethylene from ethane by SLM, the separation factor <(C_2H_4/C_2H_6)_3> increased with increasing carrier concentration, reaching about 1000 when [ <AgNO_3> ] was 4 mol/dm. An approximate method for caclulating the rate of facilitated transport accompanied by instantaneous reversible reaction was proposed. This method is applicable even to the case where the diffusivities of the carrier and the complex differ from each other. The experimentally observed flux of ethylene agreed well with the flux calculated by the approximation method.A flowing liquid membrane cell with three channels for feed gas, carrier solution( <AgNO_3> solution) and strip gas was developed. The channels were separated by hydrophobic microporous membrames. The permeability of gas at high flow rate of carrier solution was about 5 times that of SLM. In the separation of ethylene from ethane, membrane fouling due to the evaporation of the solvent was not observed. When polypropylene membrane was used, however, precipitates, presumably <Ag_2O> , covered the membrane, resulting in low permeability. This fouling was avoided by adding nitric acid to the carrier solution. When Teflon membrane was used, FLM was stable for more than 11 days even without nitric acid. By evacuating strip side of SLM, 98% ethylene was produced. The experimental result was satisfactorily simulated by a permeation model and design equations.