New Coating Techniques for Composite Membranes

膜扩散本质上是一个缓慢的过程。 因此，只有使用极薄、无缺陷的膜，基于膜的分离过程才具有经济可行性。 通过目前可用的技术可以制造选择性渗透层厚度低至约0.5μm的薄膜复合膜。 具有比这更薄的选择性渗透层的膜将显着提高膜分离的经济性。 该项目的目标是开发制造工业规模复合膜的技术，其选择性渗透层厚度低至0.1微米或更小。 这些膜将通过修改用于施加薄选择性渗透层的溶液涂覆工艺来制造。 所使用的涂料溶液的特征在于在低聚合物浓度下具有高粘度。 先前的实验数据表明，与传统技术相比，使用此类解决方案可以涂覆更薄的无缺陷涂层。 如果该技术可以应用于许多不同的聚合物，那么它将能够制造出经济可行的基于膜的分离系统，并将其应用于广泛的气体分离问题。 通过所提出的工艺制造的膜可能对许多工业气体分离产生重大影响，例如氧气/氮气分离、从流出物流中去除酸性气体或从许多来源回收氢气。 工艺经济性可能具有足够的吸引力，使膜系统在这些和其他应用中与传统分离方法相比具有竞争力。

Membrane diffusion is an inherently slow process. Consequently, membrane-based separation processes can only be economically viable if extremely thin, defect-free membranes are used. Thin-film composite membranes with a permselective layer thickness down to about 0.5 um can be made by presently available techniques. Membranes with permselective layers thinner than this would dramatically improve the economics of membrane separation. The goal of this program is to develop the technology for making industrial-scale composite membranes with permselective layer thicknesses down to 0.1 um or below. The membranes will be made by modifying the solution coating process used to apply the thin permselective layer. The coating solutions to be used will be characterized in having high viscosity at low polymer concentration. Previous experimental data indicate that the use of such solutions enables a much thinner defect-free coating to be applied than is possible with conventional techniques. If the technique can be applied to many different polymers, it will enable economically viable membrane-based separation systems to be made and applied to a broad range of gas separation problems. Membranes made by the proposed process could have a significant impact on many industrial gas separations, for example, oxygen/nitrogen separation, removal of acid gases from effluent streams, or hydrogen recovery from many sources. The process economics could be sufficiently attractive to make membrane systems competitive with conventional separation methods in these and other applications.