Transition metal cation-exchanged SSZ-13 zeolites for CO2 capture and separation from N2

Abstract

CO2 capture from post-combustion flue gas mixture (CO2/N2:15/85) is challenging and requires adsorbents with high capacity and high selectivity toward CO2. Our work validated the potential of transition metal cation-exchanged SSZ-13 zeolites for efficient CO2 capture, as evaluated by unary static isothermal adsorption and binary dynamic column breakthrough experiments as well as predicted performance in pressure/vacuum swing adsorption (P/VSA) process. Among the investigated transition metals (Co(II), Ni(II), Zn(II), Fe(III), Cu(II), Ag(I), La(III), and Ce(III)) exchanged SSZ-13, Co(II)/SSZ-13 and Ni(II)/SSZ-13 showed the highest CO2 uptake (4.49 and 4.45 mmol/g, respectively) and superior selectivity of CO2 over N2 (52.55 and 42.61, respectively) at 273 K and 1 atm. We attribute such outstanding separation performance to the Pi backdonation exclusively formed between CO2 and transition metal cation sites. This demonstrates a new approach of developing adsorbents for CO2 capture in the real-world industrial processes.