Mixed Matrix Membranes

CTS-0107488 Eva MarandVirginia Polytechnic Institute and State University混合基质膜的开发摘要膜分离代表了一个不断增长的技术领域，由于低能量需求和膜模块化设计的容易放大，具有潜在的高经济回报。膜技术的进步，特别是新型膜材料的进步，将使该技术与传统的、高能耗的和昂贵的工艺（如低温蒸馏和吸附）相比更具竞争力。特别地，需要大规模的气体分离膜系统，其可以完成诸如氮和氧富集、氢回收、从天然气中去除酸性气体（CO2、H2S）和捕获温室气体以及分离各种烃混合物的过程。这些应用中采用的材料必须提供耐用性、生产率和高度选择性的分离性能，才能在经济上可行。目前，聚合物和某些无机膜是唯一的候选人，这两类都有局限性，本研究的目标是开发结构化的复合沸石/聚酰亚胺薄膜膜，将表现出气体分离性能上级的现有聚合物为基础的膜，并将保留其加工的多功能性和耐用性相比，无机膜。本工作将各向异性ETS-4，ZSM-2，LTL和MFI板状分子筛在混合基质膜。 这些沸石可以以受控的纳米级尺寸分布和表面官能化来生产。 混合基质材料的成功在于消除了分子筛/聚合物界面的缺陷，并将膜的微观结构控制在亚纳米水平。这可以通过使用具有官能化表面的沸石纳米颗粒来促进与聚合物基质的结合来实现。一系列新的，良好的表征聚酰亚胺已开发与侧羧基官能团作为膜基质。这些聚酰亚胺已经对各种气体混合物具有优异的分离性能，并且在400 ℃以上的空气中具有热稳定性。通过在聚酰亚胺链和官能化沸石纳米颗粒之间形成氢键或直接共价键来实现无缺陷的聚合物-沸石界面。

CTS-0107488Eva MarandVirginia Polytechnic Institute and State UniversityThe Development of Mixed-Matrix MembranesAbstractMembrane separations represent a growing technological area with potentially high economic reward due to low energy requirements and facile scale-up of membrane modular design. Advances in membrane technology, especially in novel membrane materials, will make this technology even more competitive with traditional, highly energy-intensive, and costly processes such as low-temperature distillation and adsorption. In particular, there is need for large-scale gas-separation-membrane systems that can accomplish processes such as nitrogen and oxygen enrichment, hydrogen recovery, acid gas (CO2, H2S) removal from natural gas, and capture of greenhouse gases as well as separation of various hydrocarbon mixtures. Materials employed in these applications must offer durability, productivity, and highly selective separation performance if they are to be economically viable. Currently, polymers and certain inorganic membranes are the only candidates, and each of these two classes has limitations.The goal of this research is to develop structured composite zeolite/polyimide thin-film membranes that will exhibit gas-separation performance superior to that of existing polymer-based membranes and which will retain their processing versatility and ruggedness compared to inorganic membranes. This work incorporates anisotropic ETS-4, ZSM-2, LTL and MFI plate-like molecular sieves in mixed-matrix membranes. These zeolites can be produced with controlled nanometer-scale size distribution and surface functionalization. The success of the mixed-matrix materials lies in the elimination of defects at the molecular sieve/polymer interface and in the control of the film's microstructure at the sub-nanometer level. This can be achieved by employing zeolite nanoparticles with functionalized surfaces to promote bonding with the polymer matrix. A series of new, well-characterized polyimides has been developed with pendant carboxylic functional groups to serve as the membrane matrix. These polyimides already have excellent separation properties for various gas mixtures and are thermally stable above 400oC in air. A defect-free polymer-zeolite interface is achieved by forming hydrogen bonds or direct covalent linkages between the polyimide chains and the functionalized zeolite nano-particles.