Separation of CO2/N2 in Ion-Exchange binder-free beads of zeolite NaY for Post-Combustion CO2 capture
Ezzeldin Aly, Lucas F.A.S. Zafanelli, Adriano Henrique, Kristin Gleichmann, Alírio E. Rodrigues, Francisco A. Da Silva Freitas, José A.C. Silva
Abstract
• Enhanced adsorption with bare commercial NaY through ion-exchange. • Improved dynamic adsorption of FAU zeolites with binder-free technology. • CO 2 loading at low pressure: Ca(71)Y < Ca(56)Y < NaY < K(23)Y < K(58)Y < K(95)Y. • Binder-free K(23)Y achieves 3.53 mol/kg CO 2 , selectivity 101 over N 2 . • Top performer under post-combustion CO 2 capture conditions: Binder-free K(23)Y. Ion-exchange on bare commercial zeolites can offer improved adsorption processes. In the context of CO 2 /N 2 separation for post-combustion CO 2 capture (PCC), here, we report, the effect of ion-exchange on commercial binder-free NaY zeolite with alkali (K + ) and alkaline earth (Ca 2+ ) metal cations, achieving exchange levels of 23 %, 58 %, and 95 % for K + and 56 % and 71 % for Ca 2+ . Adsorption isotherms of CO 2 and N 2 were measured over a temperature range of 306–344 K and pressures up to 350 kPa. At low pressures, the CO 2 adsorption capacity increases as Na + ions are exchanged to a higher level of K + , while a reverse trend is observed for Ca 2+ exchange. At 25 kPa and 306 K, the CO 2 loading (mol∙kg −1 ) follows the order 2.01-Ca(71)Y < 2.63-Ca(56)Y < 4.05-NaY < 4.29-K(23)Y < 4.59-K(58)Y < 4.72-K(95)Y. The selectivities of CO 2 (15 %)/N 2 (85 %) at 306 K and 101.3 kPa range from 52 for Ca(71)Y to 101 for K(23)Y, compared to 89 in the bare NaY zeolite. The working capacities for the most promising exchanged sample (K(23)Y) exhibit superior values of 4.51, 2.98, and 2.41 mol∙kg −1 considering regeneration pressures of 3, 10, and 15 kPa, relative to a feed pressure of 101.3 kPa, respectively. Dynamic simulations were conducted using the Aspen Adsorption package to accurately predict both single- and binary-component breakthrough curves.