Facile synthesis of dptz-CuGeF6 at room temperature and its adsorption performance for separation of CO2, CH4 and N2

Abstract

Efficient capture of CO2 from flue gas and removal of CO2 from biomethane by physical adsorption are in great need. Herein, we report the facile synthesis of a new pillared-layer metal-organic frameworks, dptz-CuGeF6 for CO2 separation from the flue gas or the biomethane. The resulting samples were characterized. Structurally, the dptz-CuGeF6 possess double-interpenetrated frameworks formed by two staggered, independent sql sheets, in which the cations Cu2+ are coordinated by four dptz ligands, making the dptz-CuGeF6 exhibit narrow and uniform ultra-micropores of 5.25 Å. Its CO2 capacity reached 2.17 mmol/g at 15 kPa and 3.23 mmol/g at 100 kPa separately, and its selectivity of CO2/CH4 (50:50) and CO2/N2 (15:85) reached as high as 80 and 175.5, respectively. The stability experiments demonstrated the intact structure of dptz-CuGeF6 was retained after exposure in moisture air (RH = 50% or RH = 80%) as well as in several polar solvents. Breakthrough experiments confirmed that CO2/CH4 or CO2/N2 binary mixture were efficiently separated. Molecule simulation revealed that both F···CCO2 and multiple C-H···OCO2 interactions in the pores of dptz-CuGeF6 played an important role in enhancing its selectivity of CO2 adsorption. The dptz-CuGeF6 would be promising for CO2 capture and separation from flue gas or biomethane.