Halogen-modified metal–organic frameworks for efficient separation of alkane from natural gas

Abstract

As a rich green energy source, natural gas is widely used in many fields such as the chemical industry, automobile energy, and daily life. However, it is very challenging to separate and recover C₂H₆ and C₃H₈ from natural gas. Metal–organic frameworks (MOFs) as an emerging type of multi-pore porous materials show huge potential in gas adsorption separation. Herein, we report pillar-layered MOFs, Ni (BDC)(DABCO)_0.5 (DMOF-X), modified by halogen atoms (F, Cl, Br), and investigate their CH₄/C₂H₆/C₃H₈ separation performance. The experimental results show that DMOF-Cl exhibited a extremely high adsorption capacity for C₃H₈ and C₂H₆. Under the conditions of 298 K and 100 kPa, the adsorption capacities for C₃H₈ and C₂H₆ on DMOF-Cl are as high as 6.23 and 4.94 mmol g⁻¹, which are superior to the values for most of the porous materials that have been reported. In addition, DMOF-Cl also shows high C₃H₈/CH₄ (5: 85, V/V) and C₂H₆/CH₄ (10: 85, V/V) separation selectivities, with values of 130.9 and 12.5, respectively. Finally, DMOF-Cl also demonstrated great potential as an adsorbent for separating C₃H₈/C₂H₆/CH₄.