Highly selective adsorption of light hydrocarbons in a HKUST-like MOF constructed from spirobifluorene-based octacarboxylate ligand by a substitution strategy

Metal-organic frameworks(MOFs)with HKUST-like tbo structures have been paid specific attention for gas sorption and separation because of their specific pore features.According to the geometric similarity of spirobifluorene and[Cu_(2)(O_(2)CR)_(4)]paddlewheel secondary building units(Cu_(2)SBUs)in HKUST-1,we attempted to rationally construct a HKUST-like MOF by a substitution strategy.Using a judiciously designed octatopic carboxylate ligand,a copper-organic framework,JUC-220,was synthesized.The crystals of JUC-220 exhibited characteristic features in cubic with disorder,possibly due to the disorder substitution and high symmetry of tbo topology.Two related HKUST-like structure models were considered.Thanks to the suitable pore size and specific pore shapes,the adsorption selectivities of JUC-220 for C_(3)H_(8)/CH_(4)(5/85)and C_(2)H_(6)/CH_(4)(10/85)gas mixtures were as high as 736 and 46 respectively at 298 K and 1 bar.Specially,JUC-220 exhibited excellent trace adsorption performance of C_(3)H_(8)and C_(2)H_(6)as well as reverse adsorption behavior of C_(2)H_(6)/C_(2)H_(4).Thus,JUC-220 serves as an example of HKUST-like MOF with disorder for light hydrocarbons separation and the implementation of substitution which can be used to explore more porous MOFs.

Construction of hierarchically porous metal-organic framework particle by a facile MOF-template strategy

Increasing the mass diffusion efficiency is a major challenge in the realm of metal-organic frameworks(MOFs).Construction of hierarchically porous,typically microporous MOF adsorbents or catalysts is crucial for enhancing both mass transfer and molecular accessibility.Many strategies have been proposed for the synthesis of hierarchically porous MOFs(HP-MOFs),with some striking results.In this paper,we proposed a facile and versatile strategy,termed the MOF-Template strategy,for fabricating hierarchical pores in MOF particle.The highly controlled crystalline sizes and morphologies of the unstable Cu-MOFs Cu_(3)(BTC)_(2) and Cu(Qc)_(2) have been exploited in their utilization as sacrificial agents by uniformly dispersing them during the shaping process of ZIF-8.Through a facile treatment with alkaline solution,tunable mesopores and macropores could be easily introduced in the shaped ZIF-8 spheres.This strategy could effectively improve the adsorption kinetics and separation productivity of MOF materials while maintaining high mechanical stability,offering promising prospects for industrial application.