High CO2/CH4 Selectivity of a Flexible Copper(II) Porous Coordination Polymer under Humid Conditions

The development of highly efficient CO2 separation materials is very important for environmental preservation and energy conservation. Crystalline porous coordination polymers (PCPs)/metal-organic frameworks are one of a number of promising types of porous materials for CO2 separation because of their controllable pore size, shape and surface function. Simultaneously, the unique structural flexibility of PCPs affords both high CO2 selectivity and inexpensive regeneration. However, this family of materials suffers from the coexistence of water that destroys the framework of PCPs and its adsorption in the pores is greater than that of CO2, which results in a deterioration in CO2-separation performance. Herein, a flexible and hydrophobic CuII PCP that is stable towards water has been designed and synthesised. This PCP has extremely high adsorption selectivity for CO2 over CH4, derived from its structural flexibility. Furthermore, the obtained water-tolerant flexible PCP, under CO2/CH4 mixed-gas conditions, exhibits highly selective CO2 adsorption over CH4, even in the presence of water.