S. Nousir, K. Ghomari, R. Roy, A. Azzouz
University of Quebec at Montreal, CA
polyalcohols, montmorillonite, CO2, hydrophilic character, reversible capture
Polyol-clay matrices were prepared by incorporating various polyalcohols ranging from ethylene-glycol to bulky polyol dendrimers. Through thermal programmed desorption (TPD) revealed a significant enhancement of both the hydrophilic character and affinity towards CO2. The amounts of water and CO2 retained were found to increase almost proportionally with the number of OH groups grafted on the incorporated organic moiety. The improvement of the CO2 retention capacity (CRC) appears to be also due to the enhancement of the hydrophilic character of the polyol-clay matrices. The CRC value was found to be strongly influenced by the operating conditions. Much higher CRC values were obtained without purge in nitrogen stream. At low nitrogen flowrates, the major part of the adsorbed CO2 can be released at 20-50oC from dry adsorbents, but at ca. 60-70oC from hydrated matrices. However, CO2 can be easily and completely released even at room temperature through forced convection in a gas stream, or under static conditions in dry and CO2-free media. The CO2 retention was found to involve purely physical interactions, and the adsorbent regeneration does not necessarily require heating. This opens new prospects for obtaining low-cost hybrid adsorbents for the reversible capture of other gases.