Fine-Tuning Porosity of In-Mofs with Ncb Topology Based on Reticular Chemistry for One-Step Purification C2h4 from Ternary C2h6/C2h4/C2h2 Mixtures

Abstract

One-step purification of C2H4 from ternary C2H6/C2H4/C2H2 mixtures by single adsorbent is of great industrial significance, but few adsorbents can achieve this purpose. Herein, four isoreticular In-MOFs, In-BDC-AINA, In-ATC-INA, In-Fum-INA, and In-Fum-AINA (H2BDC, H2ATC, H2Fum, HINA and HAINA are 1,4-benzenedicarboxylic acid, 2-amino-terephthalic acid, fumaric acid, isonicotinic acid and 3-amino-isonicotinic acid, respectively), were designed and synthesized by the guidance of reticular chemistry, using the known In-BDC-INA as the platform, through amino modification and shorten ligand approaches. In-ATC-INA and In-BDC-AINA were amination of H2BDC and HINA, respectively. In-Fum-INA is replacing H2BDC to shorter H2Fum. In-Fum-AINA is obtained by further amination of In-Fum-INA. Due to the molar ratio of isoniacic and dicarboxylic ligand in this series structure is 2/1, they exhibit different site number, site distribution, pore size and pore volume after regulation. These frameworks without open metal sites provided the ability of C2H6/C2H4 inversion adsorption. The amino modification and shorten ligand approaches successfully improved the selectivity of C2H2/C2H4, and the equimolar C2H2/C2H4 selectivitivies of In-ATC-INA (1.82) and In-Fum-INA (2.81) were higher than that of In-BDC-INA (1.73) calculated by IAST method. The breakthrough results show that In-BDC-INA, In-ATC-INA and In-Fum-INA can achieve one-step separation of the ternary C2 mixtures and C2H4 yields were 0.08, 0.13 and 0.09 mmol/g, respectively, demonstrating that the two approaches successfully improved the gas separation performance. In addition, these materials possess exceptional thermal and chemical stability, the low-cost ligand used in In-Fum-INA synthesis further enhances its potential application for industrial gas separation.

Keywords: MOFs, Reticular chemistry, amino modification, shorten ligand, gas separation, C2H4 purification.