Synthesis of Multivariate Indolo[3,2- <i>b</i> ]carbazole-Based Zr-MOFs via <i>In Situ</i> Synthetic Modification for Propane Recovery from Simulated Natural Gas

Adsorptive separation using metal-organic frameworks (MOFs) displays significant potential for propane (C₃H₈) recovery from natural gas, and the key lies in the synthesis of high-performance MOFs of proper pore environments. In this study, we employed an <i>in situ</i> synthetic modification strategy to successfully integrate chlorine (Cl) from metal salts into indole[3,2-<i>b</i>]carbazole-based organic ligands, thereby synthesizing a multivariate zirconium-based MOF (NUT-162) for C₃H₈ recovery from simulated natural gas. This material shows exceptional chemical stability across a broad pH spectrum (1.0-12.0) in aqueous environments. Featuring a high surface area and an ordered pore structure, NUT-162 demonstrates significantly higher adsorption capacities for C₃H₈ compared to ethane (C₂H₆) and methane (CH₄) at 298 K. Grand Canonical Monte Carlo simulation suggests the zirconium clusters, aromatic benzene rings, and the ICZ motifs perform synergistically to achieve good selectivity. Dynamic breakthrough experiments further validate its outstanding separation performance in mixed-gas streams, and the performance can be well-maintained over multiple cycles. The material combines good durability and separation efficiency, offering a robust and practical solution for advancing the C₃H₈ recovery technologies.