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

Abstract

In the present work, carbon dioxide (CO2) capture capacity was evaluated after a humid impregnation process performed on the surface of open-cell magnesium (Mg) foams, with an alkaline solution of lithium hydroxide (LiOH). The Mg foams were fabricated by the infiltration casting method, using irregular particles of sodium chloride (NaCl) as space holders. Optical microscopy, helium (He) pycnometry and nitrogen (N2) adsorption-desorption techniques were used to measure the pore size, density (ρfoam) and specific surface area (As), 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 (H2O) 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 (Li) impregnation. The later as consequence of the lithium oxide (Li2O) 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.