Separation of methane/ethylene gas mixtures efficiently by using ZIF-67/water-ethylene glycol slurry

By using Zeolitic imidazolate framework-67(ZIF-67)/water-ethylene glycol slurry, we separated methane/ethylene gas mixtures by the absorption-adsorption method. The influences of temperature, mass fraction of ZIF-67 in ZIF-67/water-ethylene glycol slurry, pressure, and gas-slurry ratio on the separation performance were studied systematically. We found lower temperature, mass fraction of ZIF-67 of 0.15, higher gas–liquid ratio, and higher operation pressure are suitable for separation of methane/ethylene mixture. The experimental results show by using the slurry we synthesized, the mole fraction of ethylene in gas phase decreases from 74.8 to 53.0%, the selectivity coefficient reaches 10 (much higher than that of solid ZIF-67), and more than 68% of C2H4 can be recovered after one stage of the absorption-adsorption process. Sorption enthalpy of methane and ethylene at low loading is only 11 and 17 kJ/mol, respectively. In addition, the crystal structure of ZIF-67 remains intact after 20 adsorption/desorption cycles.