A separation MOF with O/N active sites in nonpolar pore for One-step C2H4 purification from C2H6 or C3H6 mixtures

Abstract

Here, a 2-fold interpenetrated metal–organic framework (MOF) was synthesized by imidazole derivative and carboxyl co-ligands, which features nonpolar pore environment with accessible N/O sorption sites, resulting in the suitable pore sizes (8.78 Å × 11.45 Å) to optimally interact with C2H6 and C3H6 compared to C2H4. The C3H6- and C2H6-selective phenomena were rigorously studied by combining pure-component sorption isotherms, ideal adsorbed solution theory (IAST) calculations, molecular simulations and breakthrough curves. The MOF exhibits high C3H6 uptake (53.6 cm3 g−1 at 10 kPa and 298 K) and benchmark C3H6/C2H4 selectivity (17.1), surpassing all of the reported porous materials for C3H6/C2H4 separation. Molecular simulations revealed both nonpolar pore environment and accessible O/N sites synergistically “match” better with C3H6 and C2H6 to provide stronger multiple interactions than C2H4. Experimental breakthrough curves and transient breakthrough simulations revealed that the MOF not only can realize one-step C2H4 purification (purity ≥ 99.9%) from various ratios of C2H6/C2H4 and C3H6/C2H4 mixtures with great recyclability, but also greatly increase the purity of C3H6 (such as from 28.5% to 87.7% for 2/5 C3H6/C2H4 mixture).