Synthesis And Adsorption Properties Of Nanoporous Triazine-based Frameworks (NPTFs) Modified By N,O,S Atoms

Recently, nano-porous organic polymer material, a new class of porous materials, becomes research hotspot due to its high specific surface area, lightweight skeleton construction, abundant construction and modification methods and excellent gas sorption properties. In this work, two kinds of aromatic monomers containing a couple of cyan and strong polar atoms (such as O, S and N) were designed, and then Nanoporous Triazine-based Frameworks (NPTFs) were synthesized by utilizing the dynamic trimerization reaction in ZnCl2ionothermal conditions. Series characterization methods were used to study structures and gas adsorption properties of the polymers.Firstly, three aromatic acid anhydride (1,2,4,5-Benzenetetracarboxylic dianhydride,1,4,5,8-Naphthalenetetracarboxylic dianhydride,3,4,9,10-Perylenetetracarboxylic dianhydride) were reacted with4-Aminobenzonitrile, a kind of monomers containing double cyan and imides (m1, m2and m3) were obtained respectively. And then three nanoporous triazine-based frameworks (NPTFs) containing imides (NPTF-1, NPTF-2, NPTF-3) were synthesized by utilizing the dynamic trimerization reaction in ZnCl2ionothermal conditions. The chemical structures were confirmed by FTIR, XRD, SEM, TEM, et al. The low pressure nitrogen adsorption-desorption isotherms shows that the material BET specific surface area up to1053m2/g. NPTF-1possesses the highest carbon dioxide loading (144mg/g,273K,1bar) and enthalpy of adsorption (CO2,39.3kJ/mol). Adsorption selectivity of carbon dioxide over nitrogen is19.5(NPTF-1). The hydrogen adsorption test indicates a medium H2capacity of1.23wt%(77K,1bar).Secondly, two novel porous polymer (NPTF-4NPTF-5) were constructed by1,3,5-triazine and dibenzofuran or dibenzothiophene under the same conditions of NPTF-1. The chemical structures were confirmed by FTIR, XRD, SEM, TEM, et al. BET specific surface area (1551m2/g and1045m2/g), the amount of carbon dioxide uptake (142mg/g and91mg/g)(273K,1bar) and the enthalpy of adsorption (38.7kJ/mol and33.5kJ/mol) were calculated from gas adsorption-desorption method.(1)The introduction of imide could improve CO2adsorption enthalpy and uptake but will reduce carbon dioxide adsorption selectivity. (2) The introduction of oxygen atom to NPTFs materials is beneficial to CO2adsorption enthalpy and the selectivities for CO2over N2, but there is no significant contribution for sulphur atom.