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

Abstract

A water-stable porous cobalt(II)–organic framework functionalized by ethoxyl groups with a chemical formula, {[Co6(5-EIA)5(tmbpy)(OH)2(H2O)2]∙4(H2O)}n (1) (5-H2EIA = 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 Å2 along the a axis. The framework 1 exhibits high humid and thermal stability according to PXRD and TGA results. The C2H2 and CO2 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 C2H2/CH4 (1:1) and CO2/CH4 (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 C2H2/CH4 or CO2/CH4.