LAUSR

Abstract The separations of C2/C1 hydrocarbons are significant but challenging processes in petrochemical industry. Metal-organic frameworks (MOFs) have been considered as energy-efficient porous materials for gas separations owing to their moderate interactions with gas molecules. The incorporation of heterocycles can help to adjust the C2/C1 separation properties of MOFs. In this work, a large collection of heterocycles was screened for improving C2/C1 adsorption and separations via comparing their binding energies using ab-initio method. Besides, in order to further understand the interaction mechanisms between heterocycles and C2/C1 molecules, the symmetry-adapted perturbation theory (SAPT) was applied to analyze the components of interaction energies. The selected heterocycles were then grafted to UiO-67 to evaluate their influence on C2/C1 adsorption and separation performances with GCMC method. The results show that the 1,2,3-triazole is the best heterocycle for improving C2H6 and C2H2 adsorption in UiO-67. The 1,2,4-triazole and imidazole are the most suitable heterocycles for facilitating adsorptions of CH4 and C2H6 in UiO-67. In terms of C2/C1 separations in UiO-67, the 1,2,3-triazole, pyrrole and imidazole are recommended as the most potential heterocycles for improving the selective adsorption of C2H2/CH4, C2H4/CH4 and C2H6/CH4, respectively. The C2H2/CH4 selectivity of 1,2,3-triazole@UiO-67 can reach up to 70, much higher than that of the parent UiO-67 (only about 3) at 298 K.