Selective adsorption of ethane over ethylene through a metal–organic framework bearing dense alkyl groups

Metal-organic frameworks (MOFs) have been widely applied as adsorbents for the purification of C2H4. Selective adsorption of C2H6 from C2H6/C2H4 mixture can be expected to directly achieve high purity C2H4 in a single separation step, but it remains a daunting challenge. Here, we fabricated a MOF-based adsorbent with ethane-philic environment, Ni-MOF-BD, by incorporation of dense alkyl groups into its pores. Experimental results show that the adsorption capacity of C2H6 on such adsorbent can be reached up to 88.9 cm3·g−1 at 298 K and 1 bar, and offering a C2H6/C2H4 adsorption capacity ratio of 137%. Corresponding ideal adsorption solution theory (IAST) calculation revealed that the adsorption selectivity reaches 2.0. Molecular simulation study indicates that the alkyl groups inside the pores is poised to bind with C2H6 through strong van der Waals interactions, rendering Ni-MOF-BD an enhanced C2H6 selectivity. The present work successfully demonstrated another strategy of improving adsorption affinity for C2H6 by developing MOF-based adsorbent with dense alkyl groups, thereby providing a new C2H6-selective adsorbent for purifying C2H4.