The upper bound revisited
The upper bound revisited
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DOI：
10.1016/j.memsci.2008.04.030
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发表时间：
2008-07-15
影响因子：
9.5
通讯作者：
Robeson, Lloyd M.
中科院分区：
文献类型：
--
作者：
Robeson, Lloyd M.
目前可用的无数数据，对1991年最初发表的气体的膜分离的经验上限关系进行了审查。上限相关性遵循关系p-i = ka（ij）（n），其中p-i是快速气的渗透性，alpha（ij）（p-i/p-j）是分离因子，k被称为“前一个因子” “ n是著名关系的日志图图的斜率。在Log Aij与Log P-I的图上，在此行下方，实际上所有实验数据点都存在。尽管进行了严格的研究，导致奇迹比原始相关性大得多，但对于许多气体，对于许多气体，上限位置的位置只有很小的变化。如果观察到更重要的变化，它们几乎完全是由于文献中有关一系列全氟聚合物的数据，并且涉及包括HE的许多气体对。观察到的转移主要是由于前一个因子的变化，而所得的上限关系的斜率仍然与先前的数据相关性相似。这表明与碳氢化合物/芳族聚合物相比，全氟化聚合物的溶解度选择性不同，如文献中所述。此分析中包括另外两个上限关系； CO2/N-2和N-2/CH4。除了完全氟化的聚合物导致明显的上限移位外，还观察到很小的偏移，主要是由于聚合物表现出刚性玻璃状结构，包括梯子型聚合物。上结合的相关性可用于定性确定渗透率从溶液扩散到诺森扩散的位置。 （c）2008 Elsevier B.V.保留所有权利。
The empirical upper bound relationship for membrane separation of gases initially published in 1991 has been reviewed with the myriad of data now presently available. The upper bound correlation follows the relationship P-i = ka(ij)(n), where P-i is the permeability of the fast gas, alpha(ij) (P-i/P-j) is the separation factor, k is referred to as the "front factor" and n is the slope of the log-log plot of the noted relationship. Below this line on a plot of log aij versus log P-i, virtually all the experimental data points exist. In spite of the intense investigation resulting in a much larger clataset than the original correlation, the upper bound position has had only minor shifts in position for many gas pairs. Where more significant shifts are observed, they are almost exclusively due to data now in the literature on a series of perfluorinated polymers and involve many of the gas pairs comprising He. The shift observed is primarily due to a change in the front factor, k, whereas the slope of the resultant upper bound relationship remains similar to the prior data correlations. This indicates a different solubility selectivity relationship for perfluorinated polymers compared to hydrocarbon/aromatic polymers as has been noted in the literature. Two additional upper bound relationships are included in this analysis; CO2/N-2 and N-2/CH4. In addition to the perfluorinated polymers resulting in significant upper bound shifts, minor shifts were observed primarily due to polymers exhibiting rigid, glassy structures including ladder-type polymers. The upper bound correlation can be used to qualitatively determine where the permeability process changes from solution-diffusion to Knudsen diffusion. (C) 2008 Elsevier B.V. All rights reserved.