ZIF-8 nanoparticles with tunable size for enhanced CO2 capture of Pebax based MMMs

By Wenji Zheng, R. Ding, Kai Yang, Yan Dai, Xiaoming Yan, G. He. Separation and Purification Technology, 2019

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Abstract Poly (ether-block-amide) (Pebax) based mixed matrix membranes (MMMs) were prepared by using size-tunable ZIF-8 nanoparticles as fillers. ZIF-8 nanoparticles with sizes of 40, 60, 90 and 110 nm (ZIF-8-40, ZIF-8-60, ZIF-8-90 and ZIF-8-110) were synthesized in microemulsion by controlling the ratio of Zn2+ to Hmim (1:16, 1:8, 1:5, 1:2). And they were distributed uniformly in Pebax matrix without obvious agglomerations and defects at the loading of 0–20 wt.%, which was confirmed by field-emission scanning electron microscopy (FE-SEM). The incorporation of ZIF-8 resulted in a significant improvement in CO2 permeability and the CO2/N2 selectivity increased with the BET surface area of ZIF-8 increasing. The enhanced permeability is attributed to an improvement in the free volume of the polymer induced by larger sized ZIF-8, while the increased selectivity results from the high specific surface area of large sized ZIF-8, which can provide more active sites for CO2 capture and great mass transfer resistance for N2. At 5 wt.% loading of ZIF-8-90, the MMM presents the best separation performance with CO2 permeability of 99.7 Barrer and CO2/N2 selectivity of 59.6, both of which are increased by about 25% by comparison to the pure Pebax membrane. The present study provides an effective way to obtain size-controlled ZIF-8 fillers and high separation performances of Pebax based MMMs.

Subfields: Inorganic Chemistry, Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/21d677249b1136424a4db6d2b8154f2f307226a9