Efficient Purification of Ethylene from C₂ Hydrocarbons with an C₂H₆/C₂H₂-Selective Metal-Organic Framework

The separation of ethylene (C₂H₄) from C₂ hydrocarbons is considered as one of the most difficult and important processes in the petrochemical industry. Heat-driven cryogenic distillation is still widely used in the C₂ hydrocarbons separation realms, which is an energy intensive process and takes up immense space. In response to a greener, more energy-efficient sustainable development, we successfully synthesized a multifunction microporous Mg-based MOF [Mg₂(TCPE)(μ₂-OH₂)(DMA)₂]·solvents (NUM-9) with C₂H₆/C₂H₂ selectivity based on a physical adsorption mechanism, and with outstanding stability; especially, it is stable up to 500 °C under an air atmosphere. NUM-9a (activated NUM-9) shows good performances in the separation of C₂H₆/C₂H₂ from raw ethylene gases. In addition, its actual separation potential is also examined by IAST and dynamic column breakthrough experiments. GCMC calculation results indicate that the unique structure of NUM-9a is primarily conducive to the selective adsorption of C₂H₆ and C₂H₂. More importantly, compared with C₂H₄, NUM-9a prefers to selectively adsorb C₂H₆ and C₂H₂ simultaneously, which makes NUM-9a as a sorbent have the capacity to separate C₂H₄ from C₂ hydrocarbon mixtures under mild conditions through a greener and energy-efficient separation strategy.