Simultaneous Capture of N2O and CO2 from a N2O/N2/CO2/O2 Mixture with a Ni(II)-Pyrazolecarboxylate Framework

Nitrous oxide (N2O) is a potent greenhouse gas and a major contributor to ozone depletion. Its primary industrial emission source is tail gas from adipic acid production, which typically comprises a mixture of N2O, CO2, N2, and O2. Current technologies for the removal of N2O and CO2 from tail gas are energy-intensive and operationally complex. Herein, for the first time, simultaneous capture of N2O and CO2 from the quaternary mixture is achieved using a Ni(II)-pyrazolecarboxylate framework, BUT-167. This material demonstrated an exceptional adsorption capacity (135.8 cm3 cm-3 at 40 kPa) and a high packing density (790 mg cm-3) for N2O, outperforming reported sorbents. Moreover, BUT-167 also exhibits a remarkable CO2 adsorption capacity (101.5 cm3 cm-3 at 4 kPa), achieving simultaneously high selectivity values of 257.6 for CO2/N2 (4:96, v/v) and 135.7 for N2O/N2 (40/60). Importantly, BUT-167 exhibits robust and outstanding dual-gas removal performance across multiple adsorption-desorption breakthrough cycles under both dry and humid conditions. The strong affinity toward CO2 and N2O could be attributed to multiple hydrogen bonding interactions facilitated by its highly confined channel structure, as confirmed through single-crystal X-ray diffraction analysis.