Amino-Functionalized Microporous MOFs for Capturing Greenhouse Gases CF 4 and NF 3 with Record Selectivity.

The capture and separation of fluorinated gases (F-gases) from N 2 has the potential to not only reduce greenhouse gas emissions but also provide economic benefits for the semiconductor industry. In this work, two Ni-based metal-organic frameworks (MOFs), Ni-MOF (Ni(ina) 2 , ina = isonicotinic acid) and amine-functionalized NH 2 -Ni-MOF (Ni(3-ain) 2 , 3-ain = 3-aminoisonicotinic acid), were constructed for capturing F-gases (CF 4 and NF 3 ). At ambient conditions, both materials exhibit very high CF 4 sorption capacities (2.92 mmol g -1 for Ni-MOF and 2.69 mmol g -1 for NH 2 - Ni-MOF) . In addition, NH 2 -Ni-MOF exhibited a record selectivity of 46.3 for the CF 4 /N 2 mixture at 298 K and 100 kPa, surpassing all benchmark adsorbents, including Ni-MOF (34.7). The kinetic adsorption tests demonstrated that Ni-MOF and NH 2 -Ni-MOF performed well for CF 4 /N 2 and NF 3 /N 2 mixtures. According to grand canonical Monte Carlo (GCMC) simulations, CF 4 or NF 3 interacts with NH 2 -Ni-MOF by multiple van der Waals interactions, resulting in stronger interaction than N 2 . More importantly, dynamic breakthrough experiments verified the practical separation potential of the two materials for CF 4 /N 2 and NF 3 /N 2 mixtures.