A new and highly robust light-responsive Azo-UiO-66 for highly selective and low energy post-combustion CO2 capture and its application in a mixed matrix membrane for CO2/N2 separation

A new and robust generation-2 light-responsive MOF with UiO-66 topology applicable for post combustion CO2 capture has been successfully synthesized and is described in this article. Azo-UiO-66 shows a satisfactory performance for CO2/N2 separation as observed through high CO2/N2 selectivity. Furthermore, due to the presence of azobenzene groups, Azo-UiO-66 also exhibits a very efficient CO2 photoswitching uptake, a characteristic that has never been observed in any generation-2 light-responsive MOF. Combined together with its robust character, this makes Azo-UiO-66 a promising candidate for highly selective and low energy CO2 capture applications. To further apply this material, Azo-UiO-66 was incorporated in Matrimid to form mixed matrix membranes (MMM). Composites with up to 20 wt% of Azo-UiO-66 were fabricated and tested. The resulting MMM showed increased performance in terms of CO2 permeability and CO2/N2 selectivity compared with the similar MOF-based MMM composites. This then shows another promising application of Azo-UiO-66 as a filler to enhance polymeric membrane performance for CO2 separation.