Synthesis and doping of alkali metals on MOF-74 for CO2 and CH4 pure and binary mixtures adsorption

Abstract

The emergence of the industrial revolution, marked by a global supply-demand network mostly dependent on fossil fuels, has resulted in the generation of carbon emissions. Metal-organic frameworks (MOFs) have materialized as a innovative category of adsorbents extensively studied by researchers on CO2 adsorption over recent years because of their significant adsorption capability. Amongst the different types of MOFs, Mg-MOF-74 is known for its open metal sides and its applicability of CO2 adsorption on flue gas. This work modifies Mg-MOF-74 by doping alkali metal cations (Na, Li, and K) to improve the efficacy of CO2 adsorption. The crystal structures of pure Mg-MOF-74 and Mg-MOF-74 doped with Na, Li, and K were compared by characterization using field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), and Brunauer-Emmet Teller (BET) surface area. A CO2 adsorption test determined the CO2 adsorption capacity of the modified Mg-MOF-74 at 70 °C temperature and up to 50 bar pressure. It was found that the BET specific surface area and the pore sizes of Mg-MOF-74 increased gradually by doping with Na, Li, and K by 7.07%, 11.75 %, and 14.91%. The CO2 and CH4 adsorption breakthrough experiment shows that the CO2 adsorption capacity has been increased from 8.9 wt% to 11.68 wt% under dynamic conditions.