Amino acid modified montmorillonite clays as sustainable materials for carbon dioxide adsorption and separation

For carbon dioxide sequestration purposes or for fuel production from biogas, CO2 needs to be separated from other gases in large scale processes and "green" and sustainable methodologies for this are not currently in use. Adsorption can be a viable alternative and one way of promoting the CO2 adsorption, and hence the selectivity of the adsorbent, is surface modification with amine groups. In the present work, we used a sustainable methodology to prepare amine modified clays by the insertion of amino acids in a raw clay. The adsorbed amounts of carbon dioxide in these low-cost materials reached 0.8 mmol/g (at a temperature of 25 degrees C and a pressure of 8 bar), and selectivity values of 170 for the CO2/CH4 separation (at 9 bar) were achieved.