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 CuII 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.