Self-assembly of Metal-organic Framework Particles into Hierarchical Porous Structures

Abstract

The present study focused on the self-assembly of porous metal-organic framework (MOF) particles into spherical superstructures and characterization of structural and adsorption properties of fabricated superstructures, aiming at practical applications of MOFs in separation processes. Self-assembly was conducted by mixing MOF particles dispersed in MeOH-water mixture with fluorinated oil to make suspension droplets, followed by the drying. Spherical superstructures formed at a MeOH-water mixture volume ratio of 1 : 1 possibly because both the droplet and dispersion stabilities are enhanced. Porosity of superstructures was approximately 0.3, indicating that the structure is close to the close-packed one. Adsorbed amount in superstructures was less than in MOF power, although the adsorption rate is larger for a superstructure-packed bed than powder-packed one because gaps between superstructures act as meso/macro pores to promote mass transfer.

Graphical Abstract

Schematic of experimental setup.