Robust ultramicroporous metal-organic frameworks with benchmark affinity for acetylene

Highly selective separation and/or purification of acetylene from various gas mixtures is a relevant and difficult challenge which currently requires costly and energy intensive chemisorption processes. Herein, we demonstrate that two ultramicroporous metalorganic framework physisorbents, NKMOF-1-M (M = Cu or Ni), offer high hydrolytic stability and benchmark selectivity towards acetylene vs. several gases at ambient temperature. We attribute the performance of NKMOF-1-M to their exceptional acetylene binding affinity as revealed by modeling and several experimental studies: in situ single crystal X-ray diffraction and FT-IR; gas mixture breakthrough tests. NKMOF-1-M exhibit better low pressure uptake than existing physisorbents and possesses the highest selectivities yet reported for C2H2/CO2 and C2H2/CH4. This study introduces a new strategy for the design of porous materials for acetylene separation since the performance of NKMOF-1-M is not driven by the same mechanism as current benchmark physisorbents that rely on pore walls lined by inorganic anions.