Probing the Limits of Mechanical Stability of the Mesoporous Metal-Organic Framework DUT-76(Cu) by Hydrocarbon Physisorption.

The mechanical robustness of MOFs is crucial in most adsorption-related applications. Herein, we investigated the interaction of the mesoporous metal-organic framework DUT-76(Cu) with various C1-C4 hydrocarbons at their boiling points. During adsorption, the pore structure partially collapsed into an amorphous phase while retaining a residual porosity. We employed a combination of multicycle physisorption experiments using different hydrocarbons (methane, ethane, ethylene, propane, propylene, -butane, and 1,3-butadiene) along with X-ray diffraction, scanning electron microscopy, and total scattering to examine this transition. This methodology allowed us to gain a comprehensive understanding of the effects on the crystal structure, local structure, and macroscopic behavior of the material. Furthermore, we identified specific correlations among the chain length, number of double bonds, and adsorption/desorption cycle stability, which are influenced by adsorption-induced stress. These multicycle adsorption experiments served as semiquantitative tools for assessing the mechanical stability of mesoporous frameworks.