Enhanced CO2 capture capacity on open-cell Mg foams via humid impregnation with lithium at low temperatures

Highlights: • Open-cell Mg foams were successfully manufactured by the infiltration casting method. • A solution of LiOH was used as Li-ion precursor to perform the impregnation process. • Impregnation with Li had a noteworthy effect on the specific surface area. • The CO₂ chemisorption capacity considerably increased after Li impregnation. - Abstract: In the present work, carbon dioxide $\left({\text{CO}}_2\right)$ capture capacity was evaluated after a humid impregnation process performed on the surface of open-cell magnesium $\left(\text{Mg}\right)$ foams, with an alkaline solution of lithium hydroxide $\left(\text{LiOH}\right)$. The Mg foams were fabricated by the infiltration casting method, using irregular particles of sodium chloride $\left(\text{NaCl}\right)$ as space holders. Optical microscopy, helium $\left(\text{He}\right)$ pycnometry and nitrogen $\left({\text{N}}_2\right)$ adsorption-desorption techniques were used to measure the pore size, density $\left({\rho }_{\text{foam}}\right)$ and specific surface area $\left({\text{A}}_{\text{s}}\right)$, respectively. The microstructural modifications after the impregnation process were analysed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). Afterwards, a thermogravimetric analysis was performed to evaluate the CO₂ capture capacity under different water steam $\left({\text{H}}_2\text{O}\right)$ conditions. After the H₂O–CO₂ chemisorption process, the carbonated products were identified by the attenuated total reflexion – Fourier transform infrared spectroscopy (ATR-FTIR) technique and then, quantified through a thermal decomposition process. Thermal analysis outcomes showed that H₂O–CO₂ chemisorption capacity of the Mg foams considerably increased after lithium $\left(\text{Li}\right)$ impregnation. The later as consequence of the lithium oxide $\left({\text{Li}}_2\text{O}\right)$ high reactivity with CO₂, and its effect on the thickening of the oxide film layer formed on the surface of the open-cell Mg foams. These results promote the possible use of this kind of cellular material as structured CO₂ captor, proposing a new functional application for metallic foams and giving an alternative solution to the current environmental issues.