Metal–Organic Frameworks with Tunable Metal Node for Selective Capture and Separation of CO2 and CO from Ternary Blast Furnace Gas Mixtures

Abstract

The simultaneous capture of carbon dioxide (CO2) and carbon monoxide (CO) from complex industrial gases represents a critical challenge. Designing framework sorbents that combine selective molecular recognition with stability is essential. Herein, a series of anthracene-based metal–organic frameworks (MOFs), M-ABHBs (M = Co, Mg, Mn, and Ni), were successfully synthesized. By regulating metal centers, which leads to different interactions between gases (CO2/CO/N2) and metal–ligand pairs in the framework, excellent CO adsorption selectivity has been discovered. Notably, Mg/Mn-ABHBs allow efficient binary CO2/N2 separation, and Co/Ni-ABHBs enable benchmark ternary CO2/CO/N2 separation by increasing the adsorption affinity toward CO. This unique phenomenon is rare among adsorbents. Such behaviors enable a stepwise separation strategy to selectively capture CO2 and CO from ternary mixtures. Co-ABHB exhibits high selectivity of CO/N2 (13.1), while Mg-ABHB shows high selectivity of CO2/N2 (66.6) and CO2/CO (5.8). In situ DRIFTS and theoretical calculations indicate that the former is the result of the strong interactions of Co-CO in the cavities of Co-ABHB, while Mg sites strongly capture only CO2, not CO. Breakthrough tests show that from a CO2/CO/N2 mixture, M-ABHBs demonstrated excellent separation performance. This work offers a design strategy for efficient carbon capture under complex industrial gas conditions.