Post-combustion carbon dioxide separation is an emergency topic. Polymeric membrane based separation technics are attractive. There are two parameters to evaluate membrane performance, i.e. permeability and selectivity. It is known that there is a trade-off between those two parameters that results in the “upper bound”.1 A few approaches have been made to enhance the membrane performance to surpass the upper bound. Most of these efforts increase one parameter at the expense of reducing another. We developed an approach to modify metal-organic framework (MOF) nanoparticle surface by grafting polymer.2 This enlightens us to build up a novel architecture of CO2 separation membranes system. Predicted by the Maxwell model, if the MOF core was completely sealed by a polymer layer, the incorporation of this particle into a polymeric matrix would improve both membrane permeability and selectivity. Practically, as shown in Fig. 1, the MOF nanoparticles were firstly functionalized with initiators, and then a layer of polymer grew from these initiation sites to seal the MOF core, resulting in P@MOF nanoparticles (P@MOF1 and P@MOF2 are prepared at different conditions). The gas adsorption results showed that the P@MOF1 is not completely sealed while P@MOF2 is. P@MOF samples were introduced into a polymer matrix to obtain mixed-matrix membrane (MMM). The gas separation performance of the membranes is plotted in Fig. 2. As seen, the P@MOF2 can enhance the permeability and selectivity simultaneously while P@MOF1 can only reduce the selectivity. This study thus opens up new avenues for intelligent modifications on porous filters towards MMM technology.

Polymer/Metal-organic-framework composite nanoparticle for gas separation: Rational design and theoretical analysis of core-shell structure

253rd National Meeting (2017)

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