Chemical immobilization of amino acids into robust metal–organic framework for efficient SO₂ removal

Adsorptive removal of trace SO₂ emissions from flue-gases can significantly reduce energy and water consumption and minimize the amount of unmanageable waste, however, this remains a great challenge. Herein, we report a universal strategy of chemical immobilization of amino acids into a robust metal–organic framework to enhance deep desulfurization. The grafted amino acid resulted in the formation of pores with compatible pore sizes and created abundant N-containing moieties for selective SO₂ adsorption. MOF-808-His (His = l-histidine) exhibited a top-ranking SO₂ uptake (10.4 mmol g⁻¹) with an excellent SO₂/CO₂ selectivity (90.5) under ambient conditions; furthermore, MOF-808-His could be easily regenerated. Breakthrough curves verified its excellent separation performances with water vapor and real flue-gas compositions. Computational simulations confirmed the vital role of immobilized amino acids in improving the SO₂ capture ability and selectivity. As a proof-of-concept, five natural amino acids were immobilized into MOF-808; all samples displayed improved adsorptive desulfurization performances.