An indium-based ethane-trapping MOF for efficient selective separation of C2H6/C2H4 mixture

Abstract

The purification of ethylene (C2H4) from the cracking gas ethane/ethylene mixture (1:15, v/v) is a typical energy-intensive process in the chemical industry. As an alternative, adsorptive separation with much lower energy consumption and operational cost has attracted escalating attention. In this work, we reported an interesting C2H6-trapping adsorbent, In-soc-MOF-1, an indium-based metal-organic framework exhibiting the preferential adsorption of C2H6 over C2H4. Single-component adsorption isotherms showed that the C2H6 adsorption capacities were higher than those of C2H4 under measured temperatures (288, 298 and 308 K). For example, the uptakes of C2H6 and C2H4 were 4.04 and 3.72 mmol/g at 298 K and 100 kPa, respectively. The calculated IAST selectivity of C2H6/C2H4 (1:15) on In-soc-MOF-1 was in the range of 1.4–4.8. Moreover, the dynamic separation performance of In-soc-MOF-1 toward the C2H6/C2H4 binary mixture was evaluated by the breakthrough experiments, the result of which suggests that In-soc-MOF-1 could achieve efficient separation by trapping the impurity C2H6 molecules out of the C2H6/C2H4 binary mixture. Notably, In-soc-MOF-1 not only showed good water and moisture stability but also exhibited excellent recyclability, where negligible decrease in C2H6 adsorption capacity was observed during five cycles of adsorption-desorption tests. These properties suggest that In-soc-MOF-1, as a C2H6-trapping adsorbent, could be considered as a potential candidate in the practical application of separating the cracking gas mixture.