Fine-Tuning MOFs with Amino Group for One-Step Ethylene Purification from the C2 Hydrocarbon Mixture.

Due to the similar kinetic diameters of C 2 H 2 , C 2 H 4 , and C 2 H 6 , one-step purification of C 2 H 4 from a ternary C 2 H 2 /C 2 H 4 /C 2 H 6 mixture by adsorption separation is still a challenge. Based on a C 2 H 6 -trapping platform and crystal engineering strategy, the N atom and amino group were introduced into NTUniv-58 and NTUniv-59 , respectively. Gas adsorption testing of NTUniv-58 showed that both the C 2 H 2 and C 2 H 4 uptake capacities and the C 2 H 2 /C 2 H 4 separation ability were boosted compared with the original platform. However, the C 2 H 4 uptake value exceeds the C 2 H 6 adsorption data. For NTUniv-59 , the C 2 H 2 uptake at low pressure increased and the C 2 H 4 uptake decreased; thus, the C 2 H 2 /C 2 H 4 selectivity was enhanced and the one-step purification of C 2 H 4 from a ternary C 2 H 2 /C 2 H 4 /C 2 H 6 mixture was realized, which was supported by the enthalpy of adsorption ( Q st ) and breakthrough testing. Grand canonical monte carlo (GCMC) simulation indicated that the preference for C 2 H 2 over C 2 H 4 originates from multiple hydrogen-bonding interactions between amino groups and C 2 H 2 molecules.