Tolerance of Flexible MOFs toward Repeated Adsorption Stress.

The adsorption/desorption cyclability of four flexible MOFs, namely, MIL-53(Al), ELM-11, DUT-8(Ni), and SNU-9, was studied at 298 K using n-butane as adsorptive. The detailed analysis of thermal response curves, physisorption isotherm data, powder X-ray diffraction patterns, as well as SEM images revealed the highly stable switching performance of MIL-53(Al) and ELM-11 materials during 100 adsorption/desorption cycles. In contrast, for DUT-8(Ni) and SNU-9, the multiple adsorption/desorption stress leads to the reduction of crystallite size, causing changes in the switching behavior in the initial 10 physisorption runs, and a characteristic shift of the "gate-opening" pressure to higher values is observed.