Light-responsive metal-organic framework sheets constructed smart membranes with tunable transport channels for efficient gas separation

Exploring a new type of smart membrane with tunable separation performance is a promising area of research. In this study, new light-responsive metal-organic framework [Co(azpy)] sheets were prepared by a facile microwave method for the first time, and were then incorporated into a polymer matrix to fabricate smart mixed matrix membranes (MMMs) applied for flue gas desulfurization and decarburization. The smart MMMs exhibited significantly elevated SO2(CO2)/N-2 selectivity by 184(166)% in comparison with an unfilled polymer membrane. The light-responsive characteristic of the smart MMMs was investigated, and the permeability and selectivity of the Co(azpy) sheets-loaded smart MMMs were able to respond to external light stimuli. In particular, the selectivity of the smart MMM at the Co(azpy) content of 20% for the SO2/N-2 system could be switched between 341 and 211 in situ irradiated with Vis and UV light, while the SO2 permeability switched between 58 Barrer and 36 Barrer, respectively. This switching influence was mainly ascribed to the increased SO2 adsorption capacity in the visible light condition, as verified by adsorption test. The CO2 permeability and CO2/N-2 selectivity of MMMs in the humidified state could achieve 248 Barrer and 103.2, surpassing the Robeson's upper bound reported in 2019.

Automated summary

This study introduces a new type of light-responsive metal-organic framework [Co(azpy)] sheets for smart mixed matrix membranes (MMMs), which exhibit significantly improved selectivity for SO2(CO2)/N-2 gases. The permeability and selectivity of the Co(azpy) sheets-loaded smart MMMs can respond to external light stimuli and achieve high levels of performance. Additionally, in a humidified state, the CO2 permeability and CO2/N-2 selectivity of MMMs surpass the upper bound reported by Robeson in 2019.