Facile Synthesis of Highly Efficient MgO for Catalytically Accelerating CO ₂ Absorption in Tertiary Amine Solutions

The industrial application of traditional tertiary amine solutions for CO2 absorption is limited by their slow absorption rates. Therefore, this study aims to synthesize mesoporous MgO nanoparticles through a simple method and utilize them to catalytically speed up the absorption of CO2 in representative tertiary amine MDEA solutions. This study primarily employed five magnesium sources as precursors to produce MgO nanoparticles through calcination. Among these, the MgO derived from the Mg(OH)2 precursor exhibited the most effective catalytic performance for CO2 absorption in MDEA solutions. Compared to the noncatalytic test, MgO-MgH achieved a 302.2% increase in the CO2 absorption rate and an 82.6% increase in absorption capacity. The superior CO2 absorption efficiency of the MgO-MgH catalyst is mainly attributed to its abundant surface alkaline sites and oxygen vacancies. Online FT-IR characterization results evidenced the catalytic role of MgO-MgH in facilitating the CO2 absorption process. A possible catalytic absorption mechanism over MgO-MgH is proposed. Moreover, the MgO-MgH’s stability was confirmed through a ten-cycle CO2 absorption–desorption study. This study proposes a method to enhance CO2 absorption by incorporating an easily synthesized alkaline nanomaterial, MgO-MgH, effectively overcoming its drawback and advancing the practical application of tertiary amine absorbents for CO2 capture.