Micro-mesoporous metal-organic framework temperature-dependent CO2/NO2 selectivity in static and dynamic conditions: a structural insight

CO2 and N2O are among the most worrying greenhouse gases in the atmosphere. Synthesis and study of specifically designed adsorbents for their efficient capture is mandatory. The MOF [Zr6O4(OH)6(H2O)2(TBAPy)2(PhTz)]Br obtained incorporating [PhTz]Br in [Zr6O4(OH)8(H2O)4(TBAPy)2] (NU-1000) [1] and having the same 3D framework shows temperature-dependent selectivity, adsorbing more N2O at 298 K, more CO2 at lower temperatures. GCMC simulations of its adsorption isotherms suggest that CO2 and N2O interact with PhTz+ in end-on and side-on mode, respectively. In situ PXRD on both MOFs at different temperatures a) dosing CO2 or N2O in static conditions will allow clarifying the role of PhTz+ suggested by the calculations and rationalizing the observed temperature-dependent selectivity; b) flowing a CO2/N2O mixture with the atmosphere v/v ratio and coupling MS on the exit flow will allow establishing if PhTz+ is involved and the selectivity is temperature-dependent also in dynamic conditions.