Adsorptive capturing and storing greenhouse gases such as sulfur hexafluoride and carbon tetrafluoride using metal–organic frameworks

High pressure excess adsorption isotherms of sulfur hexafluoride (SF6) and tetrafluoromethane (CF4) on metal–organic frameworks Cu3(btc)2 (HKUST-1, btc – benzene-1,3,5-tricarboxylate), Fe3FO(H2O)2(btc)3 (MIL-100), Cr3F(H2O)2O(1,4-bdc)3 (MIL-101, 1,4-bdc – 1,4-benzenedicarboxylate), Co2(1,4-bdc)2(dabco) (dabco-1,4-diazabicyclo[2.2.2]octane), Ni2(2,6-ndc)2(dabco) (DUT-8, 2,6-ndc – 2,6-naphthalenedicarboxylate), Ni2O5(btb)2 (DUT-9, btb – benzene-1,3,5-tribenzoate), Zn4O(btb), and (Zn4O(dmcpz)3) (dmcpz – 3,5-dimethyl-4-carboxypyrazolato) at 298 K were investigated using volumetric methods. Up to 1 bar pressure (at 298 K), microporous MOF with open metal sites HKUST-1 shows the best performance in SF6 adsorption and microporous Zn4O(dmcpz)3 in CF4 adsorption. At high pressure, mesoporous MIL-101 and DUT-9 have the highest storage capacities for both gases among the MOFs investigated.

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► MOFs are promising adsorbents for high global warming potential gases CF4 and SF6.
► Microporous MOFs are efficient for trapping at low pressure.
► Mesoporous MOFs show high uptake in high pressure region.
► The binding energy of CF4 to the adsorbent is lower than that for SF6.