Nanocomposite membranes functionalized with facilitated transport and molecular sieving for challenging gas separations

拟议的研究将寻求一种变革性的方法，以开发具有促进传输和分子筛分功能的纳米复合膜，以实现气体分离，这对加拿大的工业很重要，但使用现有技术具有挑战性。具体地说，这项研究的目标是开发具有促进传输和分子筛分功能的尖端混合基质纳米复合膜，专门用于(1)烯烃/烷烃分离(取代或补充传统的能源密集型低温蒸馏)，(2)从烟道气中捕获二氧化碳(用于温室气体排放控制)，以及(3)从甲烷中去除氮气以提升劣质天然气质量。在天然气工业中，烯烃分离和天然气脱氮是最具挑战性的两项操作，而烟气分离是碳捕获以减少温室气体排放的关键。这项工作建立在我们通过纳米结构和功能化在创新膜方面取得的成就的基础上，将导致在推进可向上扩展的膜方面取得突破，用于这些具有挑战性的气体分离，这些都与加拿大的石化、资源和能源部门直接相关。本课程将探讨促进剂、分子筛分材料，以及这两种功能在膜强化分离中的协同作用。为了促进烯烃和二氧化碳的传输，促进剂将起到“载体”的作用，将目标气体分子传输到膜上。银离子和胺分子(包括单体和聚合胺)将分别作为烯烃和二氧化碳的促进剂，以开发特定的烯烃-银和二氧化碳-胺相互作用。对于N_2/CH_4的分离，缺乏合适的促进剂，取而代之的是采用具有微两相分离纳米结构的嵌段共聚物作为基膜，实现基于离散扩散的N_2/CH_4分离。在所有情况下，膜将与适当的MOF/ZIF筛分结合，以通过分子筛分进一步加强分离。由于易于传输和分子筛分(用于烯烃和二氧化碳应用)以及基础聚合物和MOF/ZIF筛分对N_2/CH_4气体对的双重离散扩散系数，最终得到的混合基质纳米复合膜有望表现出优异的性能。将建立组成-纳米结构-渗透选择性关系，以指导这些新型膜的实际应用开发。这项研究具有很高的原创性和创新性；这是第一次将促进转运与膜内的分子筛分相结合。这项工作不仅直接满足了加拿大对先进膜的工业需求，还将极大地促进高素质人才的知识和培训。

The proposed research will pursue a transformative approach to developing nanocomposite membranes functionalized with facilitated transport and molecular sieving to effect gas separations that are important to Canadian industries, but challenging to carry out with current technologies. Specifically, this research aims at developing cutting-edge mixed-matrix nanocomposite membranes with both facilitated transport and molecular sieving functionalities tailored for (1) olefin/paraffin separation (to replace or complement with traditional energy-intensive cryogenic distillation), (2) CO2 capture from flue gas (for greenhouse gas emission control), and (3) removal of N2 from CH4 for upgrading sub-quality natural gas. Olefin separation and natural gas denitrogenation are two most challenging operations in the gas industry, and flue gas separation is critical for carbon capture to mitigate greenhouse gas emission. Built on our accomplishments in innovative membranes via nanostructuring and functionalization, this work will lead to breakthroughs in advancing up-scalable membranes for these challenging gas separations, which are all directly related to Canada's petrochemical, resource and energy sectors. The fundamental aspects of the facilitating agents, the molecular sieving materials, and the synergy of both functions in the membrane for enhanced separation will be investigated. For facilitated transport of olefin and CO2, the facilitating agents will function as a "carrier" to transport the target gas molecules across the membrane. Silver ions and amine molecules (both monomeric and polymeric amines) will be chosen as the facilitating agents for olefin and CO2, respectively, to exploit the specific olefin-silver and CO2-amine interactions. For N2/CH4 separation, suitable facilitating agents are lacking, and instead block copolymers with micro-biphase separated nanostructures will be used as the base membrane to achieve N2/CH4 separation based on discretive diffusion. In all cases, the membranes will be incorporated with appropriate MOF/ZIF sieves to further augment the separation via molecular sieving . The resulting mixed matrix nanocomposite membranes are expected to exhibit superior performance due to combined facilitated transport and molecular sieving (for olefin and CO2 applications) and the double discretive diffusivities of the base polymer and MOF/ZIF sieves towards N2/CH4 gas pair. A composition-nanostructure-permselectivity relationship will be established to guide development of these novel membranes for practical applications. This research is highly original and innovative; this is the first time that facilitated transport is integrated with molecular sieving within a membrane. Not only does this work directly address Canada's industrial needs for advanced membranes, it will also contribute significantly to advancing knowledge and training of highly qualified personnel.