Efficient carbon dioxide capture from flue gas and natural gas by a robust metal–organic framework with record selectivity and excellent granulation performance

The design of porous materials for CO2 capture from flue gas and natural gas is highly demanded. However, it is challenging to target materials that combine high CO2 capacity and CO2 selectivity. In this work, we report a robust metal–organic framework (MOF) Zn-ox-mtz with one dimensional channels and narrow windows for excellent CO2 capture from CO2/N2 (simulated flue gas) and CO2/CH4 (simulated natural gas) with high selectivity. Zn-ox-mtz exhibits a high CO2 capacity (58.0 STP cm3 g−1 at 15 kPa), excellent CO2/N2 (15/85, S > 106) and CO2/CH4 (50/50, S > 105) selectivity and good chemical stability. In addition, the practical separation performance is demonstrated by breakthrough experiments under various process conditions. A efficient separation is achieved with the impressive CO2 capacity of 2.60 ± 0.12 mmol g−1 at 298 K. Importantly, the outstanding performance is sustained under high humidity. The molecular sieving mechanism investigated by theoretical calculations indicated that CO2 with small molecular size is tightly trapped by multiple C = O···H-C hydrogen bonding and O = C···O forces in the cavity while CH4 and N2 with larger molecular size display overlarge energy barrier to cross the contract pore windows. Moreover, the granulation of Zn-ox-mtz by hydroxypropyl cellulose is realized with high MOF loading (93.8 %) and the granulated Zn-ox-mtz beads retained the excellent CO2/N2 and CO2/CH4 separation performance.