Scalable and Depurative Zirconium Metal–Organic Framework for Deep Flue-Gas Desulfurization and SO₂ Recovery

Abstract

Deep SO₂ removal and recovery as industrial feedstock are of importance in flue-gas desulfurization and natural-gas purification, yet developing low-cost and scalable physisorbents with high efficiency and recyclability remains a challenge. Herein, we develop a viable synthetic protocol to produce DUT-67 with a controllable MOF structure, excellent crystallinity, adjustable shape/size, milli-to-kilogram scale, and consecutive production by recycling the solvent/modulator. Furthermore, simple HCl post-treatment affords depurated DUT-67-HCl featuring ultrahigh purity, excellent chemical stability, fully reversible SO₂ uptake, high separation selectivity (SO₂/CO₂ and SO₂/N₂), greatly enhanced SO₂ capture capacity, and good reusability. The SO₂ binding mechanism has been elucidated by <i>in situ</i> X-ray diffraction/infrared spectroscopy and DFT/GCMC calculations. The single-step SO₂ separation from a real quaternary N₂/CO₂/O₂/SO₂ flue gas containing trace SO₂ is implementable under dry and 50% humid conditions, thus recovering 96% purity. This work may pave the way for future SO₂ capture-and-recovery technology by pushing MOF syntheses toward economic cost, scale-up production, and improved physiochemical properties.