Efficient and selective CO2 capture at low concentration from CH4 or N2 using Zn-MOF@AFP composite

The synthesis of structured CO 2 adsorbents with high separation selectivity, strong stability, and low cost to meet industrial needs is very challenging. Here, we synthesized an ultra-stable Zn-MOF (Zn 2 (3-amion-1,2,4-triazolate) 2 (oxalate), Zn 2 (Atz) 2 Ox), and adopted an efficient in-situ growth strategy to produce millimeter-sized spherical Zn 2 (Atz) 2 Ox@AFP (Amino-Functionalization Poly(acrylates), AFP) composite. Due to the heterogeneous crystallization induced by the nanoscale crystal seeds and the confined space of AFP, the three-dimensional (3D) Zn 2 (Atz) 2 Ox bulk crystals transformed into 2D nanosheets with higher CO 2 adsorption efficiency and faster kinetics. Zn 2 (Atz) 2 Ox@AFP has a high affinity for CO 2 (2.05 mmol g −1  at 0.05 bar and 313 K) while exhibiting an inhibitory effect for N 2 (only 0.051 mmol g −1  at 1.0 bar and 313 K), leading to an excellent ideal adsorbed solution theory (IAST) selectivity (2990 for CO 2 /N 2 (5/95, v/v)). Interestingly, Zn 2 (Atz) 2 Ox@AFP exhibits a unique gating effect on CH 4 adsorption, which further extends its application range to natural gas purification. Dynamic breakthrough experiments confirmed that Zn 2 (Atz) 2 Ox@AFP can selectively capture CO 2 in the simulated CO 2 /N 2 (5/95) and CO 2 /CH 4 (5/95) mixed gases.