TUB41: A Robust MOF for Industrial Gas Separation

Herein, we report on the thermal and chemical stability and CO2 and water vapor adsorption of a mixed linker phosphonate-MOF [Cu(4,4’‐bpy)0.5(1,4‐NDPAH2)], namely TUB41 (bpy = bipyridine and NDPAH4 = naphthalenediphosphonic acid). TUB41 exhibits reversible phase transitions upon heating until 330 °C. TUB41 is a very stable MOF across a pH range of 1 to 11 and after two years of repeated adsorption experiments and activation at 80 °C and ambient humidity. While gases with larger kinetic diameter do not access the narrow pores of TUB41, it can efficiently adsorb CO2 and water vapor, which have smaller kinetic diameter compared to other atmospheric gases. TUB41 exhibits a moderate enthalpy of adsorption for CO2, which is favorable compared to water vapor at low pressure, indicating its potential for selective CO2 separation in the presence of water vapor. TUB41 has an estimated optical band gap between 2.7 and 3.0 eV, which is within the bluish-violet range.