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

Abstract

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.