Development of pure Mg open-cell foams as structured CO2 captor

The CO2 capture capacity of the superficial oxide layer formed in pure open-cell Mg foams was studied at low temperatures (40-60 °C) varying the relative humidity from 40 to 80%. Mg foam samples with pore size of 350 μm and surface area of 5.4 m2/g were used for these analyses. Optical microscopy and X-ray diffraction techniques were used to characterize the cell structure and the superficial oxide formed in the cell-foams, respectively. The final products formed after the CO2-H2O capture experiments were identified by scanning electron microscopy and attenuated total reflexion-Fourier transform infrared spectroscopy (ATR-FTIR). The MgCO3 and other products, formed after CO2 + H2O capture process, were thermally decomposed, to quantify the amount of CO2 captured by the superficial MgO layer using standard thermogravimetric analysis. The results showed that the highest amount of CO2 captured was obtained at 60 °C and 80% of relative humidity, with a CO2 capture capacity of 0.87 mmol/g, which is comparable with others CO2 MgO-based captors. The considerable CO2 capture capacity at low temperatures supports the potential of the pure open-cell Mg foams to be used as structured CO2 captors.