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

One-stepethylene purification from a C2 hydrocarbon mixturewas realized in NTUniv-59 with a densely decorated aminogroup. Due to the similar kinetic diameters of C2H2, C2H4, and C2H6, one-steppurification of C2H4 from a ternary C2H2/C2H4/C2H6 mixture by adsorption separation is still a challenge. Based ona C2H6-trapping platform and crystal engineeringstrategy, the N atom and amino group were introduced into NTUniv-58 and NTUniv-59, respectively. Gas adsorption testingof NTUniv-58 showed that both the C2H2 and C2H4 uptake capacities and theC(2)H(2)/C2H4 separation abilitywere boosted compared with the original platform. However, the C2H4 uptake value exceeds the C2H6 adsorption data. For NTUniv-59, the C2H2 uptake at low pressure increased and the C2H4 uptake decreased; thus, the C2H2/C2H4 selectivity was enhanced and the one-steppurification of C2H4 from a ternary C2H2/C2H4/C2H6 mixture was realized, which was supported by the enthalpy of adsorption(Q (st)) and breakthrough testing. Grandcanonical monte carlo (GCMC) simulation indicated that the preferencefor C2H2 over C2H4 originatesfrom multiple hydrogen-bonding interactions between amino groups andC(2)H(2) molecules.