Selective Hysteretic Sorption of Light Hydrocarbons in a Flexible Metal–Organic Framework Material

Porous MFM-202a (MFM = Manchester Framework Material, replacing the NOTT designation) shows an exceptionally high uptake of acetylene, 18.3 mmol g–1 (47.6 wt %) at 195 K and 1.0 bar, representing the highest value reported to date for a framework material. However, at 293 K and 10 bar C2H6 uptake (9.13 mmol g–1) is preferred. Dual-site Langmuir-Freundlich (DSLF)- and Numerical Integration (NI)-based IAST methods have been used to analyze selectivities for C1 to C3 hydrocarbons. MFM-202a exhibits broadly hysteretic desorption of acetylene; such behavior is important for practical gas storage since it allows the gas to be adsorbed at high pressure but stored at relatively low pressure. Stepwise uptake and hysteretic release were also observed for adsorption of other unsaturated light hydrocarbons (ethane and propene) in MFM-202a but not for saturated hydrocarbons (methane, ethane, and propane). MFM-202a has been studied by in situ synchrotron X-ray powder diffraction to reveal the possible phase transition ...