Fluorinated MOF platform for selective removal and sensing of SO ₂ from flue gas and air

Abstract

Conventional SO ₂ scrubbing agents, namely calcium oxide and zeolites, are often used to remove SO ₂ using a strong or irreversible adsorption-based process. However, adsorbents capable of sensing and selectively capturing this toxic molecule in a reversible manner, with in-depth understanding of structure–property relationships, have been rarely explored. Here we report the selective removal and sensing of SO ₂ using recently unveiled fluorinated metal–organic frameworks (MOFs). Mixed gas adsorption experiments were performed at low concentrations ranging from 250 p.p.m. to 7% of SO ₂. Direct mixed gas column breakthrough and/or column desorption experiments revealed an unprecedented SO ₂ affinity for KAUST-7 (NbOFFIVE-1-Ni) and KAUST-8 (AlFFIVE-1-Ni) MOFs. Furthermore, MOF-coated quartz crystal microbalance transducers were used to develop sensors with the ability to detect SO ₂ at low concentrations ranging from 25 to 500 p.p.m.

Abstract

Removal of SO ₂ from flue gas is of prime importance to avoid its poisoning of CO ₂-seperating agents. Here, the authors demonstrate that two fluorinated metal–organic frameworks selectively remove SO ₂ from synthetic flue gas and can sense SO ₂ with p.p.m.-level detection using quartz crystal microbalance transducers.