Organic Vapor Separation with Super-Glassy Polymer Membranes

本研究将考察由聚（三甲基硅丙炔）(PTMSP； ıC（CH3)=C(SiCH3)3!n）制成的各向同性聚合物膜的渗透性和气体输输选择性。先前对PTMSP膜的研究表明，由于其自由体积大，气体分子通过膜的溶解度和扩散率非常大，这就导致了非常高的透气性。高渗透率伴随着相对较低的选择性（即一种物质的通量与另一种物质的通量之比）。这种选择性的缺乏可以再次归因于大的自由体积大小，这使得各种大小的分子都很容易通过。因此，到目前为止，PTMSP膜在气体分离中还没有实际价值。然而，研究指出，在相同的驱动条件下，通过纯气体通过膜并取通量比来测量选择性。最近的实验表明，该膜在共渗透中表现出选择性：特别是MTR实验表明，在24℃的正丁烷/甲烷混合物中，正丁烷的选择性为27:1。如果成功，将通过研究PTMSP中纯气体和混合气体与一系列永久性气体（如甲烷或空气）以及密切相关的有机溶剂蒸气（CCl4, CF4，一系列氟利昂）和碳氢化合物蒸气（如丁烷和戊烷）的输运来建立这项研究的结果。这项研究将导致分离丁烷和甲烷（在天然气工业中很重要）以及空气中的有机蒸汽（在许多环境问题中很重要的分离）的膜。

This study will examine the permeability and selectivity for gas transport of isotropic polymeric membranes made of poly(trimethyl silylpropyne) (PTMSP; ıC(CH3)=C(SiCH3)3!n). Previous research on PTMSP membranes have shown that because of their large free volume, the solubility and diffusivity of gas molecules through the membrane is very large, and this results in a very high gas permeability. The high permeability is accompanied by relatively low selectivity (i.e. the ration of the flux of one species to that of the other). This lack of selectivity can be attributed again to the large free volume size which facilitates the easy passage of molecules of all sizes. Consequently, to date PTMSP membranes have not been of practical value in gas separations. The research points out, however, that the selectivity has been measured by passing pure gases through the membrane and taking the flux ratio under identical driving conditions. Recent experiments have shown that the membrane exhibits selectivity in co-permeation: In particular experiments at MTR demonstrate a 27:1 selectivity on n-butane in an n- butane/methane mixture at 24oC. The result of this research will be built by studying pure and mixed gas transport in PTMSP with a series of permanent gases such as methane or air, and closely related organic solvent vapors (CCl4, CF4, a series of freons and with hydrocarbon vapors such as butane and pentane if successful, the research will lead to membranes which can separate butane from methane (important in the natural gas industry), and organic vapors from air (an important separation in many environmental concerns).