Extra Unsaturated Metal Centers of Zirconium‐Based MOFs: a Facile Approach towards Increasing CO2 Uptake Capacity at Low Pressure

Abstract

Developing adsorption materials to capture CO2 at low pressure has attracted great attention due to the low CO2 partial pressure in fuel gases. Herein, zirconium‐based metal–organic frameworks (PCN‐X) are successfully synthesized and open metal sites (Fe3+ and Al3+) are incorporated into the PCN‐X MOFs. The results indicate that the CO2 adsorption capability is enhanced through the strong interaction between extra open metal centers and CO2 molecules at low pressure. Meanwhile, the CO2 adsorption capacity of PCN‐X with incorporated Al3+ is higher than with incorporated Fe3+, which can be attributed to the higher isosteric heat of CO2 adsorption. The adsorption kinetics further indicate the faster CO2 transmission on PCN‐X with extra Al3+ than with extra Fe3+. Besides, modified PCN‐X, treated by some inorganic acids, exhibits favorable chemical stability, which is suitable for CO2 capture from acidic fuel gases.