Breakthrough Study of CO2 Adsorption and Regeneration Performance of Mn‐ and Ce‐Doped Ni–Al Layered Double Hydroxides Derived Mixed Oxides in Packed‐Bed Column

Carbon dioxide (CO2) capture is an important strategy to mitigate greenhouse gas emissions and reduce global warming effects. This study synthesizes two nanomaterials, Ce-doped Ni-Al mixed metal oxide (CNAO) and Mn-doped Ni-Al mixed metal oxide (MNAO), from Mn- and Ce-doped Ni-Al-layered double hydroxides using a co-precipitation method followed by a calcination process. The materials are characterized using various techniques, such as High-resolution transmission electron microscopy-energy dispersive x-ray spectroscopy/selected area electron dispersion (HRTEM-EDS/SAED), X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and attenuated total reflection Fourier transform infrared (ATR FT-IR). The CO2 adsorption performance of the materials is evaluated using packed-bed column experiments at the testing conditions of 13 vol% +/- 1 vol% CO2 in N-2 simulated flue gas, flow rate of 20 mL min-1, inlet pressure of 14.15 +/- 0.1 psi, and temperature of 31 C-degrees +/- 2 C-degrees. The results show that both CNAO and MNAO are promising nanomaterials for CO2 capture applications due to their high CO2 adsorption capacity and efficiency. CNAO has a higher saturation capacity of 11.4 mmol g(-1) and a longer breakthrough time than MNAO, which has a saturation capacity of 10.0 mmol g(-1). The doping of Ce and Mn enhances the CO2 adsorption capacity of the materials compared to the un-doped Ni-Al mixed oxide. The mechanisms of CO2 adsorption are mainly linearly adsorbed CO2, bidentate, and monodentate or bulk carbonate formation, as revealed by ATR FT-IR analysis. The regeneration performance results suggest that CNAO is more stable than MNAO under multiple regeneration cycles and more promising material for large-scale CO2 capture applications.