A microporous Cd(II)-MOF for efficient separation of trace SO2 from SO2/CO2/N2 mixture

Trace SO2 removal of flue gas is very important to prevent environmental pollution. Porous Metal-Organic Frameworks (MOFs) possess natural advantages for the mixed gas separation. In the present work, a new microporous Cd(II)-MOF (named HBU-23) has been conveniently synthesized, it possesses a three dimensional (3D) coordination network with trinuclear cluster units. The BET surface area of HBU-23 reaches 384.20 m2/g and the pore size distribution is 6.79 Å. HBU-23 exhibits excellent adsorption ability for SO2, and the saturated adsorption capacity can reach 91.38 cm3/g under ambient condition. More importantly, the compound exhibits higher IAST selectivities for the mixture gases of SO2/CO2 (10 %, 58.9), SO2/N2 (10 %, 2333.5) and SO2/CH4 (10 %, 484.8), which indicate its' possible applications in the field of flue gas and natural gas desulfurization. Breakthrough experiments further prove that it can be efficiently removal trace SO2 from flue gas, and it can be reused at least three cycles without obvious degradation in separating ability. Furthermore, HBU-23 also shows better separation selectivity of C2H2/CO2 (50 %, 3.0) and CO2/N2 (15 %, 28.4). GCMC simulations and DFT calculations reveal its effective separation property can attribute to the strong interaction and binding energy between HBU-23 and SO2 molecules. The work will contribute to the rational design new MOFs used as gas adsorbents.