CO2分離回収材に及ぼす湿度の影響に関する量子化学的検討

抄録

Ion hydration is well known as a fundamental process in many natural phenomena. To capture CO2 efficiently, this study explores a novel “moisture-driven CO2 sorbent” based on diffusion of ions and the structure of ion hydration complexes forming inside water-laden resin structures. We present a quantitative analysis, with atomistic modeling, to investigate the behavior of ions and the impact of hydration in a moisture-driven CO2 sorbent. We also show that the stability of the carbonate (CO3 2- ) ion is reduced as the water content of the resin is lowered. As the hydration cloud of the carbonate ion shrinks, it becomes energetically favorable to split a remaining water molecule and form a bicarbonate (HCO3 - ) ion plus a hydroxide (OH- ) ion. These two ions bind less water than a single, doubly charged carbonate ion. As a result, under relatively dry conditions, more OHions are available to capture CO2 than in the presence of high humidity.