Inverse and highly selective separation of CO2/C2H2on a thulium-organic framework

The selective removal of CO(2)impurities from C(2)H(2)is important but extremely difficult due to their very similar physical properties and almost identical kinetic diameters. In this work, a hydro-stable 3D porous thulium(iii)-organic framework, {[Tm-2(OH-bdc)(2)(mu(3)-OH)(2)(H2O)(2)]center dot 11H(2)O}(n)(1) (OH-H(2)bdc = 2,5-dihydroxyterephthalic), functionalized with hydroxyl groups and aqua ligands with anecutopology is constructed. The activation of1at different temperatures realizes two novel porous MOFs (1aand1a ') with channels of 6.2 x 9.3 and 6.3 x 9.3 angstrom(2)and 6.3 x 10.6 and 9.3 x 12.2 angstrom(2), respectively.1aand1a ' show distinctly different ability to separate a CO2/C(2)H(2)mixture. As compared with the poor CO2/C(2)H(2)separation performance of1a ',1ashows an excellent capability to selectively capture CO(2)from CO2/C(2)H(2)based on the results of single-component adsorption isotherm and breakthrough experiments. The CO(2)and C(2)H(2)uptakes on1aare 5.83 mmol g(-1)and 2.01 mmol g(-1)at 298 K and 1 bar, respectively. More importantly,1aachieves a high selectivity for CO(2)over C(2)H(2)with an IAST selectivity of 17.5 at 298 K and 1 bar. Furthermore,1aexhibits good reusability in CO2/C(2)H(2)separation. To the best of our knowledge,1arepresents the first example of lanthanide-based MOFs for CO2/C(2)H(2)separation.