Indolo[3,2-b]carbazole-based Hyper-Crosslinked organic polymers for adsorptive separation of C₃H₆/C₂H₄

Propylene (C₃H₆) and ethylene (C₂H₄) play a vital role in chemical production processes. The separation of C₂H₄ and C₃H₆ is of great importance for their practical application. Hyper-crosslinked polymers (HCPs), which have the merits of abundant pore structures, exceptional stability, and the simplicity of synthesis, have the potential for the adsorptive separation C₃H₆/C₂H₄. Herein, two novel HCPs, namely NUT-17 and NUT-17-Me were synthesized based on indolo[3,2-b]carbazole-based monomers and rigid crosslinks. For the first time, these materials were applied to separate C₃H₆/C₂H₄ mixtures. NUT-17 and NUT-17-Me with abundant porous structure and exceptional thermal stability (470 °C), can preferentially adsorb C₃H₆ rather than C₂H₄. In particular, the two HCPs reveal high C₃H₆/C₂H₄ (v/v 50/50) selectivity up to 9.3 for NUT-17 and 9.5 for NUT-17-Me under atmospheric conditions, which are higher than most reported high-performance C₃H₆-selective materials. Density functional theory (DFT) calculation results show stronger adsorption interactions for C₃H₆ compared to C₂H₄ in the optimized configurations of NUT-17 and NUT-17-Me. Furthermore, NUT-17 and NUT-17-Me demonstrate excellent repeatability, and their C₃H₆ storage capacities remain relatively stable after five cycles. Moreover, the dynamic breakthrough studies conducted at various C₃H₆ to C₂H₄ ratios demonstrate that both NUT-17 and NUT-17-Me exhibit high-efficiency separation capacities for C₃H₆/C₂H₄, indicating their promising potential for industrial adsorptive separation.