具有“无阻力”区域的聚合物/PEO中空纳米微球混合基质膜构建及其CO2分离性能研究

The membrane separation is attractive for CO2 capture because of the inherently low energy requirement. The developments of membrane materials and membranes with outstanding performances are keys to future growth. In order to escape the restriction of Robeson upper boundary and obtain high CO2 permeability and high CO2/light gases selectivity simultaneously, the “non-resistance” region will be constructed in membranes based on hollow PEO nanoparticles. The gas tends to permeate to the permeate-side through the “non-resistance” region due to the lower transfer resistance. The hollow structures in nanoparticles, forming the “non-resistance” regions in membranes, shorten mass transfer path and reduce mass transfer resistance, and finally increase gas permeability. In this proposal, the polymer/hollow PEO nanoparticle mixed matrix membranes will be synthesized to strengthen mass transfer process and improve permeation-separation performance. The hollow nanoparticles with dense shell filled in traditional polymer materials for CO2 separation will be synthesized by PEO monomers and multi-functional cross-linkers both containing acrylate groups. The dual-layer asymmetric composite membranes will be fabricated by simultaneous casting technique and co-extrusion technique. The construction methods and the implementation methods of hollow PEO nanoparticles and “non-resistance” regions will be discussed. Comprehensive discussions will be presented about the regulation mechanism of the structure and performance in mixed matrix membranes. The method to confine hollow PEO nanoparticles to dense skins of membranes will be established. The effects of the “non-resistance” region in membranes on the mass transfer will be investigated, which will provide an effective way to develop the polymer/hollow PEO nanoparticle mixed matrix membranes with excellent CO2 permeability and selectivity.

膜分离是碳捕集技术热点之一，开发具有优异性能的膜材料和分离膜是关键。为解决传统聚合物膜材料难以同时实现高气体渗透性与高选择性的难题，项目基于中空纳米微球内部为空腔的结构特点，从缩短传质途径角度出发提出新思路：将具有高CO2渗透分离性能的PEO交联聚合物构建成具有致密壳层的中空纳米微球，填充于传统聚合物膜中；微球内部空腔在膜内形成“无阻力”区域，由于气体倾向于通过“无阻力”区域向低压侧渗透，气体传质途径缩短，传质阻力降低，膜内传质过程得到强化，进而提高CO2渗透分离性能。研究PEO中空纳米微球及“无阻力”区域的可控构建方式与实现途径；探索双层非对称混合基质复合膜结构和性能的调控机制，建立一套将中空纳米微球禁锢于致密皮层中的方法；揭示基于中空纳米微球构建的膜内“无阻力”区域对膜内传质过程的影响与作用规律，为研究开发具有高CO2渗透性与选择性的聚合物/PEO中空纳米微球混合基质膜提供有效途径。

膜分离是碳捕集技术热点之一，开发具有优异性能的膜材料和分离膜是关键。为解决传统聚合物膜材料难以同时实现高气体渗透性与高选择性的难题，项目基于中空纳米微球内部为空腔的结构特点，制备了聚合物/聚合物中空纳米微球混合基质膜，用于提高渗透性能。我们制备了多个系列的中空纳米微球，包括橡胶态和玻璃态微球；包括壳层致密、壳层带微孔及壳层带介孔的微球。主要研究微球的引入对膜结构和性能的影响。研究表明：微球和基质的匹配是本项研究最重要的问题，因为它全方位的影响膜的结构和性能。（1）只有匹配得当，中空纳米微球中的空腔结构才能在混合基质膜内保留，进而形成“无阻力”通道；（2）只有匹配得当，膜内空腔才能被高度利用，进而实现减小阻力的目的；（3）基质含量决定了混合基质膜的性能是由基质还是填料决定：如我们基于高负载硅橡胶中空微球制备的混合基质材料渗透性能是硅橡胶的10倍，CO2渗透系数高达44200 Barrer，而分离系数也趋于硅橡胶的分离系数；基于低负载的聚酰胺微球制备的混合基质膜，渗透性是基质渗透性的2倍，高达1890 Barrer，分离系数趋近于基质材料（CO2/N2：~44）。基于抗塑化和抗老化的需求，我们采用橡胶态基质，制备了复合膜，并考察了制膜条件对膜结构和性能的影响。.我们还将中空微球的理念引入到N2/CH4分离体系中，制备了混合基质膜和共聚膜，借助分子筛的中空化，提高了渗透性的同时，还提高了吸附选择性；聚合物中空纳米微球还可应用于纳滤膜领域，我们制备了聚哌嗪酰胺/中空纳米微球混合基质膜和聚哌嗪酰胺-中空纳米微球共聚膜，在保证分离性能的同时（实质上略有提升），均实现了渗透性的提高。.中空填料有助于提高分离膜的渗透性能，在某些特定的分离体系，还能提高分离性能，是极具发展前景的填料。