MOF-74(Zn) Metal Organic Frameworks (MOFs) Powder for Gas Absorption and Separation, CGASMOF74Zn

MOF-74(Zn) (also known as Zn-MOF-74 or CPO-27-Zn, with chemical formula Zn2(DOBDC), where DOBDC = 2,5-dioxido-1,4-benzenedicarboxylate}$) is the zinc-based archetypal member of the MOF-74 family. It is constructed from infinite helical chains of edge-sharing ZnO5(OH2) octahedra bridged by 2,5-dihydroxyterephthalate linkers into a honeycomb-like network with 1D hexagonal channels. Upon thermal activation, coordinated solvent molecules are desorbed to expose a high density of coordinatively unsaturated open Zn^{2+} metal sites (OMS).

The critical structural and functional features of the MOF-74(Zn) are shown below: (1) 1D Hexagonal Honeycomb Channels: Channel Diameter: ~11.0–12.0 Å (accessible pore aperture ~ 10.5 Å. Open Metal Site Density: Every Mg^{2+} ion in the coordination backbone points an open coordination site directly into the channel interior upon solvent removal, yielding a theoretical active site density of ~ 6.3 mmol/g. (2) Moderate Binding Energy & Low Regeneration Penalty: Compared to the strongly polarizing Mg^{2+} cation, Zn^{2+} has a lower charge density and larger ionic radius (0.74 Å vs 0.72 Å for Mg^{2+}. This results in a more moderate isosteric heat of adsorption, significantly reducing the thermal energy required for desorption and regeneration during Pressure/Vacuum Swing Adsorption (PSA/VSA).

References:

1. H. Yang, et al., Ligand Charge Separation To Build Highly Stable Quasi-Isomer of MOF-74-Zn, Journal American Chemical Society (2019) 141 (25): 9808–9812.
2. W. Zhu, et al., Bimetallic MOF-74-based mixed matrix membrane for efficient CO2 separation, Microporous and Mesoporous Materials, 2024, 379, 113288