Some mechanistic insights into the action of facilitating agents on gas permeation through glassy polymeric membranes

Abstract

Incorporation of facilitating agents is one of the promising strategies being researched in recent years to cross the Robeson bounds for gas separations using polymeric membranes. The ways in which such inclusions modify the performance of membranes are not always clear. Here, we study the performance of two glassy membranes, Polyfurfuryl alcohol and Polysulfone, in O 2 /N 2 and CO 2 /N 2 separations, with Cobalt phthalocyanine in insoluble and solubilized forms as the facilitating agent. The results show that in general, three effects are important: (1) a barrier effect, (2) a facilitation effect, and (3) morphological effects on the polymer matrix due to an incompatibility between the particles and the polymer. These results provide some insight into the action of facilitating agents in soluble and insoluble form, when used as membrane additives.

Enhanced O2/N2 Separation of Mixed-Matrix Membrane Filled with Pluronic-Compatibilized Cobalt Phthalocyanine Particles

“…When CoPCMP loading increased from 3% to 5 wt.%, the O2/N2 selectivity further increased from 14.5% to 31.6%, respectively. This is possibly attributed to the barrier effect caused by the agglomeration of CoPCMPs (Figure 4a), as reported in previous work [38]. In contrast, the…”

“…The permeability of Matrimid ® 5218 needs improvement for fabricating a high-performance MMM out of it. As observed by Midda and coworkers using the polysulfone-CoPC system [38], non-selective voids forming between the polymer matrix and carriers might enhance gas permeability. Nevertheless, non-selective voids might lead to the formation of more substantial defects, causing a dramatic reduction in selectivity performance as well [39].…”

“…Pure Matrimid membrane was fabricated by dissolving 0.5 g of polymer in 2.3 g of DMF. The dope solutions containing CoPCMPs were prepared by mixing the required amounts of Matrimid, CoPCMPs, and/or Pluronic inside glass vials, which was followed by the addition of DMF, according to the literature, with slight modifications [38,42]. For instance, the composite membrane containing 85 wt.% Matrimid, 5 wt.% CoPCMPs, and 10 wt.% Pluronic was prepared by adding 0.4 g of Matrmid, 0.05 g of CoPCMPs, and 0.05 g of Pluronic into 2.3 g of DMF.…”

“…Therefore, it is imperative to compatibilize CoPC particles with the polymer matrices very well. To this end, the surface modification of CoPC particles with tert-butyl groups, for example, is a viable strategy [34,38]. However, an additional step for chemical modification is typically necessary.…”

Development of ternary-component mixed-matrix membranes for advanced gas separations

“…The permeability of Matrimid® 5218 needs improvement for fabricating a high-performance MMM out of it. As observed by Md and co-workers using the polysulfone-CoPc system, non-selective voids forming between the polymer matrix and carriers might enhance the permeability [71]. However, non-selective voids might lead to the formation of more substantial defects, causing dramatic reductions in selectivity performance, as well [60].…”