A microporous zinc–organic framework with Lewis basic pyridyl sites for highly selective C2H2/CH4 and C2H2/CO2 gas separation
A new Zn-based metal–organic framework with 8-connected hex topology constructed from bipyridine and carboxylate ligands, namely, [Zn(cpna)3(tmbpy)]n•4DMF (1) (H2cpna = 6-(4-carboxylphenyl)nicotinic acid; tmbpy = 3,3’-dimethyl-4,4’-bipyridine) has been synthesized under solvothermal condition. The Zn-MOF was structurally characterized, and remains good crystal structure after activation (1a), an indication of permanent porosity. 1a exhibits a BET surface of 770 m2•g-1 and the maximum aperture of 8.60 Å. Single component adsorption isotherm measurements of C2H2, CO2, CH4, CO and N2 on 1a were performed both at 273 K and 298 K, and the selectivities of C2H2/CH4, C2H2/CO2, CO2/CO, CO2/CH4 and CO2/N2, were estimated on the basis of ideal adsorbed solution theory (IAST). 1a shows the uptake of C2H2 (3.89 mmol/g) and CO2 (3.52 mmol/g) at 273 K and 100 kPa, respectively. Due to the Lewis basic pyridyl sites inside the channel of the framework, 1a showed good adsorption selectivities of C2H2/CH4(50:50), and C2H2/CO2(50:50) at 298 K(100 kPa).