A Copper-Based Metal-Organic Framework for Selective Separation of C2 Hydrocarbons from Methane at Ambient Conditions: Experiment and Simulation.

C2 hydrocarbon separation from methane represents a technological challenge for natural gas upgrading. Herein, we report a new metal-organic framework, [Cu 2 L(DEF) 2 ]·2DEF ( UNT-14 ; H 4 L = 4,4',4″,4‴-((1 E ,1' E ,1″ E ,1‴ E )-benzene-1,2,4,5-tetrayltetrakis(ethene-2,1-diyl))tetrabenzoic acid; DEF = N , N -diethylformamide; UNT = University of North Texas). The linker design will potentially increase the surface area and adsorption energy owing to π(hydrocarbon)-π(linker)/M interactions, hence increasing C2 hydrocarbon/CH 4 separation. Crystallographic data unravel an sql topology for UNT-14 , whereby [Cu 2 (COO) 4 ]···[L] 4- paddle-wheel units afford two-dimensional porous sheets. Activated UNT-14a exhibits moderate porosity with an experimental Brunauer-Emmett-Teller (BET) surface area of 480 m 2 g -1 (vs 1868 m 2 g -1 from the crystallographic data). UNT-14a exhibits considerable C2 uptake capacity under ambient conditions vs CH 4 . GCMC simulations reveal higher isosteric heats of adsorption ( Q st ) and Henry's coefficients ( K H ) for UNT-14a vs related literature MOFs. Ideal adsorbed solution theory yields favorable adsorption selectivity of UNT-14a for equimolar C 2 H n /CH 4 gas mixtures, attaining 31.1, 11.9, and 14.8 for equimolar mixtures of C 2 H 6 /CH 4 , C 2 H 4 /CH 4 , and C 2 H 2 /CH 4 , respectively, manifesting efficient C2 hydrocarbon/CH 4 separation. The highest C2 uptake and Q st being for ethane are also desirable technologically; it is attributed to the greatest number of "agostic" or other dispersion C-H bond interactions (6) vs 4/2/4 for ethylene/acetylene/methane.