Suitability of a diamine functionalized metal-organic framework for direct air capture.

The increase in the atmospheric carbon dioxide level is a significant threat to our planet, and therefore the selective removal of CO from the air is a global concern. Metal-organic frameworks (MOFs) are a class of porous materials that have shown exciting potential as adsorbents for CO capture due to their high surface area and tunable properties. Among several implemented technologies, direct air capture (DAC) using MOFs is a promising strategy for achieving climate targets as it has the potential to actively reduce the atmospheric CO concentration to a safer levels. In this study, we investigate the stability and regeneration conditions of ,'-dimethylethylenediamine (mmen) appended Mg(dobpdc), a MOF with exceptional CO adsorption capacity from atmospheric air. We employed a series of systematic experiments including thermogravimetric analysis (TGA) coupled with Fourier transformed infrared (FTIR) and gas chromatography mass spectrometer (GCMS) (known as TGA-FTIR-GCMS), regeneration cycles at different conditions, control and accelerated aging experiments. We also quantified CO and HO adsorption under humid CO using a combination of data from TGA-GCMS and coulometric Karl-Fischer titration techniques. The quantification of CO and HO adsorption under humid conditions provides vital information for the design of real-world DAC systems. Our results demonstrate the stability and regeneration conditions of mmen appended Mg(dobpdc). It is stable up to 50% relative humidity when the adsorption temperature varies from 25-40 °C and the best regeneration condition can be achieved at 120 °C under dynamic vacuum and at 150 °C under N.