Enhancement of CO 2 Adsorption and CO 2 /N 2 Selectivity on ZIF ‐8 via Postsynthetic Modification

Imidazolate framework ZIF‐8 is modified via postsynthetic method using etheylenediamine to improve its adsorption performance toward CO 2 . Results show that the BET surface area of the modified ZIF‐8 (ED‐ZIF‐8) increases by 39%, and its adsorption capacity of CO 2 per surface area is almost two times of that on ZIF‐8 at 298 K and 25 bar. H 2 O uptake on the ED‐ZIF‐8 become obviously lower compared to the ZIF‐8. The ED‐ZIF‐8 selectivity for CO 2 /N 2 adsorption gets significantly improved, and is up to 23 and 13.9 separately at 0.1 and 0.5 bar, being almost twice of those of the ZIF‐8. The isosteric heat of CO 2 adsorption (Q st ) on the ED‐ZIF‐8 becomes higher, while Q st of N 2 gets slightly lower compared to those on the ZIF‐8 Furthermore, it suggests that the postsynthetic modification of the ZIF‐8 not only improves its adsorption capacity of CO 2 greatly, but also enhances its adsorption selectivity for CO 2 /N 2 /H 2 O significantly. ©2013 American Institute of Chemical Engineers AIChE J, 59: 2195–2206, 2013