Dense open metal sites in a microporous metal–organic framework for deep desulfurization with record-high sulfur dioxide storage density

Dry desulfurization employing porous adsorbents is industrially preferred but efficient capture of sulfur dioxide (SO₂) at the ultralow concentration (i.e., 2000 ppm) is exceptionally challenging. Metal–organic frameworks with open metal sites (OMSs) can provide sufficient interactions with SO₂, which, in turn, will degrade or compromise the structural robustness. Herein, we reported Cu-ATC that contains dense oppositely positioned Cu OMSs for efficient trace SO₂ removal. Explicitly, Cu-ATC adsorbs a benchmark amount of SO₂ (5.3 mmol g⁻¹) at 0.01 bar with a record-high SO₂ storage density of 2.23 g cm⁻³ at ambient conditions. The critical role of OMSs has been confirmed by the partially desolvated sample with declined uptakes and adsorption enthalpy. The desulfurization performances have been validated by multicycle breakthrough experiments even with mimic flue-gas and water vapor. Computational simulations identify the adsorption sites at the molecular level. Combined with the high stability under various conditions, Cu-ATC is a potent candidate for industrial implementation.