Reduced Aging in Carbon Molecular Sieve Membranes Derived from PIM-1 and MOP-18
Reduced Aging in Carbon Molecular Sieve Membranes Derived from PIM-1 and MOP-18
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DOI：
10.1021/acs.iecr.1c01727
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发表时间：
2021-07-05
影响因子：
4.2
通讯作者：
Musselman, Inga H.
中科院分区：
文献类型：
--
作者：
Cosey, Whitney K.;Balkus, Kenneth J., Jr.;Musselman, Inga H.
碳分子筛膜（CMSMs）通常由于微孔的坍塌而随着时间的推移而失去渗透性。由于膜的致密化，这种渗透性的下降被称为物理老化。由固有微孔隙度（PIM-1）聚合物制成的cmms受物理老化的影响很大，随着时间的推移，渗透率下降幅度超过60%。据推测，由这种高自由体积聚合物前驱体衍生的cmms的致密化是由大型未连接的石墨烯畴坍塌以达到更稳定的构象（即石墨）的热力学驱动的。本研究描述了一种利用铜纳米颗粒支撑CMSM来缓解物理老化的新策略。将高可溶性金属有机多面体-18 （MOP-18）以高达40 wt/wt的负载引入到PIM-1中，形成混合基质膜（MMM）。在550℃下对MMM进行热解，可以原位形成铜金属纳米颗粒，作为CMSM内石墨烯片的支柱，防止微孔坍塌，从而最大限度地减少CMSM的老化。在35℃和2 bar条件下，对原始聚合物基CMSM和铜柱CMSM进行了CO2和CH4的单次气体渗透性测试，以验证膜的抗物理老化性。在7天的时间里，PIM-1 CMSM的CH4渗透率从64巴勒下降到27巴勒，下降幅度接近60%，而铜柱PIM-1 CMSM的CH4渗透率基本没有下降。本研究展示了一种减少cmms身体衰老的一般方法。
Carbon molecular sieve membranes (CMSMs) commonly lose permeability over time due to the collapse of micropores. This decline in permeability, due to the densification of the membrane, is known as physical aging. CMSMs derived from polymers of intrinsic microporosity (PIM-1) are highly affected by physical aging, with declines in permeability greater than 60% over time. It is hypothesized that the densification of CMSMs derived from this high-free-volume polymer precursor is thermodynamically driven by the collapse of large unconnected graphene domains to reach a more stable conformation (i.e., graphite). This study describes a novel strategy to mitigate physical aging by pillaring the CMSM using copper nanoparticles. Highly soluble metal-organic polyhedra-18 (MOP-18) was introduced into PIM-1 with loadings up to 40 wt/wt to form a mixed-matrix membrane (MMM). Pyrolysis of the MMM at 550 degrees C resulted in the in situ formation of copper metal nanoparticles that acted as pillars for the graphene sheets within the CMSM, preventing the collapse of the micropores, thus minimizing the aging of the CMSM. Single gas permeation measurements of CO2 and CH4 were made on the pristine polymer-derived CMSM and the copper-pillared CMSM at 35 degrees C and 2 bar to confirm the membranes' resistance to physical aging. The CH4 permeability for the PIM-1 CMSM decreased by similar to 60%, from 64 to 27 Barrers, over a period of 7 days, while the copper-pillared PIM-1 CMSM remarkably showed essentially no decline in CH4 permeability. This research demonstrates a general approach to reducing physical aging in CMSMs.