Clay honeycomb monoliths as low cost CO2 adsorbents

Clay honeycomb monoliths were manufactured from a natural montmorillonite and used for CO2 adsorption, their performance being compared with that of the same clay but in the form of powder. Volumetric adsorption isotherms, thermogravimetric studies, temperature-programmed desorption experiments and transient kinetic analysis, the two latter followed by mass spectrometry, were employed to investigate the interaction of the samples with CO2, both under static and dynamic conditions, and at different temperatures. This research demonstrated that the honeycomb monoliths kept the adsorptive properties of the starting material in terms of capture capacity (around 15 mg/g), Henry constant, heat of adsorption and activation energy. Most of retained CO2 was weakly adsorbed, the temperature needed for its release being 130 degrees C, an appropriate value which is sufficiently high to avoid undesirable desorption while being low enough to minimize the costs derived from controlled regeneration for further CO2 reuse. The kinetics of the CO2 uptake over the monolith (though of second order like over the powder) was slightly different, allowing a wider operative window for a highly efficient CO2 removal. These results suggest the potential of the honeycomb monolithic design for an even more competitive use of clays as low cost CO2 filters. (C) 2017 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.