Tuning the Adsorption Selectivity of ZIF‐8 by Amorphization.

Amorphous metal–organic frameworks (amMOFs) with a partially collapsed structure are a new category of porous hybrid materials. Here, solid‐state amorphization of ZIF‐8 was achieved by mechanical compression at 0.75 GPa. The compression‐induced amorphous ZIF‐8 (amZIF‐8) had a collapsed structure, but retained partial porosity. Benefiting from the deformed channel, the resultant amZIF‐8 exhibited preferable adsorption of C3H6, resulting in higher thermodynamic adsorption selectivity of C3H6/C3H8 (6.72) than the crystalline counterparts (1.06). Further, amZIF‐8 achieved complete separation of an equimolar C3H6/C3H8 mixture with the first breakthrough of C3H8. amZIF‐8 also displayed an enhancement in CO2/N2 and CO2/CH4 adsorption selectivities. More importantly, a self‐standing amZIF‐8 membrane with boundary‐free microstructure was constructed for the first time, and exhibited separation potential for H2/CH4, CO2/N2, CO2/CH4, and C3H6/C3H8 with ideal selectivities of 14.79, 12.83, 16.23, and 2.67, respectively. [ABSTRACT FROM AUTHOR]