Experimental Study on the Influence of Magnesium on the Separation of Carbon Dioxide from Gas Mixtures with Nitrogen by Combustion Processes

The goal of this paper consists in the experimental evaluation of the possibility to separate industrial gases using magnesium combustion in carbon dioxide–nitrogen mixtures of various concentrations. The choice was made primarily due to the chemical inertness of these two gases. The study investigates how the Mg combustion changes the concentration of the initial gas mixture and the possibility to apply this process to separate this gas mixture. On the other hand, due to its greenhouse effect, CO2 separation is a process of high interest in itself. Mg reacts exothermically with CO2, so a potential use for this purpose will also benefit from a significant amount of recovered thermal energy. N2 has a particular importance due to its potential to be purified using Mg combustion, and this application might be an economical alternative to air distillation, which is widely used for N2 production at industrial scale. In practice, the CO2-N2 mixtures are commonly used as flue gases resulting from various combustion systems. Mg combustion residue is analyzed by means of energy-dispersive X-ray spectroscopy. It is found that Mg can substantially reduce the concentration of CO2, even more than the stoichiometric reaction for the formation of MgO would suggest. The percentage decrease in CO2 concentration reaches values over 10 vol.%. A secondary yet notable effect is the heat generated by the Mg and CO2 reaction, which is currently being studied as an energy source alternative.