Flue gas CO2 capture with hybrid ultramicroporous materials (HUMs)

One of the biggest drawbacks of solid physisorbents for CO2 is their poor performance at high temperatures. This is due to their relatively low heat of CO2 sorption, which drives the adsorption/desorption equilibrium to favor desorption at above ambient temperatures. We show here that Hybrid Ultramicroporous Materials (HUMs), comprised of metals coordinated to organic ligands, and inorganic pillars, are highly effective physisorbents for capture CO2 in particular at very low partial pressure and even at moderate temperatures. We fine-tuned the HUM structure using various inorganic pillars and metal centers and produced a HUM NbOFFIVE-1-Cu that can effectively physisorb CO2 at 100 °C with CO2 uptake capacity comparable to at that 30 °C. NbOFFIVE-1-Cu is also highly stable even after 45 sorption cycles with no change in its CO2 capture properties.