Structural and Dynamic Analysis of Sulphur Dioxide Adsorption in a Series of Zirconium-Based Metal-Organic Frameworks

We report reversible high capacity adsorption of SO₂ in robust Zr-based metal-organic framework (MOF) materials. Zr-bptc (H₄ bptc=biphenyl-3,3',5,5'-tetracarboxylic acid) shows a high SO₂ uptake of 6.2 mmol g^-1 at 0.1 bar and 298 K, reflecting excellent capture capability and removal of SO₂ at low concentration (2500 ppm). Dynamic breakthrough experiments confirm that the introduction of amine, atomically-dispersed Cu^II or heteroatomic sulphur sites into the pores enhance the capture of SO₂ at low concentrations. The captured SO₂ can be converted quantitatively to a pharmaceutical intermediate, aryl N-aminosulfonamide, thus converting waste to chemical values. In situ X-ray diffraction, infrared micro-spectroscopy and inelastic neutron scattering enable the visualisation of the binding domains of adsorbed SO₂ molecules and host-guest binding dynamics in these materials at the atomic level. Refinement of the pore environment plays a critical role in designing efficient sorbent materials.