A robust aluminum-octacarboxylate framework with scu topology for selective capture of sulfur dioxide

The high structural diversity and porosity of metal-organic frameworks (MOFs) promote their applications in selective gas adsorption. The development of robust MOFs that are stable against corrosive SO₂ remains a daunting challenge. Here, we report a highly robust aluminum-based MOF (HIAM-330) built on a 4-connected Al₃(OH)₂(COO)₄ cluster and 8-connected octacarboxylate ligand with a (4,8)-connected scu topology. It exhibits a fully reversible SO₂ uptake of 12.1 mmol g^-1 at 298 K and 1 bar. It is capable of selective capture of SO₂ over other gases (CO₂, CH₄, and N₂) with high adsorption selectivities of 60, 330, and 3537 for equimolar mixtures of SO₂/CO₂, SO₂/CH₄, and SO₂/N₂, respectively, at 298 K and 1 bar. Breakthrough measurements verified the capability of HIAM-330 for selective capture of SO₂ (2500 ppm) over CO₂ or N₂. High-resolution synchrotron X-ray powder diffraction of SO₂ loaded HIAM-330 revealed the binding domains of adsorbed SO₂ molecules and host-guest interactions.