In situ generated 2,5-pyrazinedicarboxylate and oxalate ligands leading to a Eu-MOF for selective capture of C 2 H 2 from C 2 H 2 /CO 2 .

The separation of C 2 H 2 /CO 2 mixtures is a very important but highly challenging task due to their comparable physical natures and relative sizes. Herein, we report a europium-based 3D microporous MOF with a 4-connected two-nodal net with {4·5 3 ·6 2 } 2 {4 2 ·6 2 ·8 2 } topology, {[Eu 2 (pzdc)(ox) 2 (H 2 O) 4 ]·5H 2 O} n (1) (H 2 pzdc = 2,5-pyrazinedicarboxylic acid, H 2 ox = oxalic acid), prepared by a hydrothermal method involving in situ generation of 2,5-pyrazinedicarboxylate and oxalate ligands. Two different temperatures were utilized to create two porous materials (1a and 1b) with channels of 4.8 × 5.4 Å and 4.1 × 6.3 Å, and 4.8 × 5.4 and 4.6 × 8.7 Å 2 , respectively. 1b shows a superior ability to selectively capture C 2 H 2 from C 2 H 2 /CO 2 as compared with 1a. At 1 bar and 298 K, 1b takes up 4.10 mmol g -1 C 2 H 2 and 1.84 mmol g -1 CO 2 , respectively. In addition, at 298 K and 1 bar, 1b has a high selectivity for C 2 H 2 over CO 2 , with an IAST selectivity of 12.7 while the value for 1a is 3.2. The separation of C 2 H 2 /CO 2 with 1b also exhibits good reusability.