The Evaluation of the Temperature Dependence of Gate-Opening Phenomena in ZIF-8

The onset of gate-opening behavior in ZIF-8 is evaluated through a detailed gas adsorption study. The sharp increase of adsorbent loading at threshold pressures in ZIFs occurs through a structural deformation of the flexible imidazolate linkers at the pore mouth, with potential applications to selective adsorption processes.  Increases in temperature show an expected decrease in adsorbent loading along with a transition from Type IV isotherms to Type I isotherms. The adsorbate pressures and loadings at gate-opening are evaluated as a function of adsorbate nature, and the disappearance of the phenomena is related to system variables.  Various gas isotherms are presented in a wide temperature range to investigate the thermodynamics of adsorption and structural deformation of ZIF-8.