CO₂ sorption on mesoporous solids: Effect of temperature and water content

CO₂ captured by solid adsorbents is considered one of the promising technologies for carbon capture and sequestration. The sorption equilibria of CO₂ on commercial CO₂ adsorbents (silica gel and Norit SX2) and synthesized CaO were measured experimentally by using a volumetric method in a temperature range of 0-8 °C, at which CO₂ hydrate is stable to form. The CO₂ uptake increases with decreasing temperature in silica gel and Norit SX2 on a dry basis; differs in CaO as the adsorption rate of CO₂ in calciumbased sorbent is high at higher temperatures. The effect of water content on the samples studied was measured at a temperature of 2 °C on a wet basis. The highest CO₂ amount adsorbed was obtained at the lowest value of water ratio studied (R_w = 0.03), which is close to CO₂ sorption in a dry basis. However, the adsorption capacities on wet synthesized CaO were water-content dependent, of which the highest sorption capacity was obtained at a particular isotherm with a water ratio of 0.67. It can be concluded that CaO has the ability to be further utilized for CO₂ separation in the presence of a minute quantity of water.