C2H2/CH4 and CO2/CH4 separations on a ethoxyl-functionalized Cobalt(II)–Organic framework with open metal sites

A water-stable porous cobalt(II)–organic framework functionalized by ethoxyl groups with a chemical formula, {[Co 6 (5-EIA) 5 (tmbpy)(OH) 2 (H 2 O) 2 ]∙4(H 2 O)} n ( 1 ) (5-H 2 EIA = 5-ethoxy-isophthalic acid; tmbpy = 3,3′-dimethyl-4,4′-bipyridine) has been constructed and studied in terms of structure and performance. 1 shows a 3D framework, and has a 1D channel of 8.1 × 6.0 Å 2 along the a axis. The framework 1 exhibits high humid and thermal stability according to PXRD and TGA results. The C 2 H 2 and CO 2 uptakes of the activated 1 ( 1a ) were up to 2.07 mmol g −1 and 1.89 mmol g −1 at 273 K (100 kPa), respectively. More importantly, 1a shows excellent C 2 H 2 /CH 4 (1:1) and CO 2 /CH 4 (1:1) separations with IAST selectivity of 23.7 and 11.4 at 298 K (100 kPa), respectively. Furthermore, 1a showed good reuse performance, suggesting that 1a could be applied to the separation of C 2 H 2 /CH 4 or CO 2 /CH 4 .