Confinement of Ag(I) Sites within MIL-101 for Robust Ethylene/Ethane Separation

Effective utilization of Ag(I) π-complexation adsorbents for practical C 2 H 4 /C 2 H 6 separation urges both good separating performances and high stabilities. In this work, we incorporated AgNO 3 onto a typical metal–organic framework (MOF) of MIL-101 to obtain efficient Ag(I) π-complexation adsorbents. It was found that the separation performances were highly dependent on the location of the AgNO 3, which could be at the interior or the exterior of nanoporous MIL-101. Confining AgNO 3 inside the nanopores of MIL-101 was achieved through employing a double-solvent approach. The resulting AgM-DS adsorbents exhibited superior performances compared with not only pristine MIL-101 but also other modified samples with AgNO 3 at the exterior of MIL-101. To be specific, the optimal 1.6AgM-DS adsorbent secured good C 2 H 4 /C 2 H 6 separation, which is C 2 H 4 uptake (75.5 cm 3 ·g –1 ) and C 2 H 4 /C 2 H 6 selectivity (9.5) at 100 kPa. For comparison, the C 2 H 4 uptakes for MIL-101, 1.6AgM-WI, and 1.6AgM-SG were merely 48.1, 56.0, and 19.4 cm 3 ·g –1, and the corresponding IAST selectivity was only 1.1, 8.1, and 1.8, respectively. It was further indicated that the 1.6AgM-DS adsorbent maintained good stability for 3 weeks, alleviating the light sensitivity of AgNO 3 . This work opens an avenue for constructing stable Ag(I) sites on MOFs to develop π-complexation adsorbents.