Synthesis And Properties Study Of Fluorenyl Cardo Microporous Poly ?Schiff Base?for H₂ Separation

Hydrogen has already been recognized as one of the most promising clean energy in the 21 st century.The development and application of hydrogen energy is an effective way to solve the energy crisis and environment pollution.In the process of hydrogen production and application,the separation and purification technology of H2 have become the key in hydrogen energy development.Comparing with the conventional separation methods,such as pressure swing adsorption and distillation,membrane-based separation is considered to be a more promising new technology,which has the advantages of low energy consumption,mechanical simplicity,continuous operation,easy to scale up and smaller footprint.In recent years,Microporous organic polymers(MOPs)are a novel class of polymers.They have attracted significant attention owing to their ease of synthesis,low weigh and high specific surface areas that allow for potential applications in gas separation.However,there are few reports that MOP-based membrane can be used for H2 separation.In this article,we designed a microporous poly(schiff base)materals with cage-type channels porosity via incorporation of cardo moiety into polymer chains.Futhermore,TR-PBO/TC-cPSB mixed matrix membranes and TC-x-cPSB membranes have also been prepared by different processes.The effect of monomer configuration and the synthetic route on the material microporous structure and membrane separation properties are systematically studied.The structure-function relationship of the materials was drawn by analysing their separation performance and microstructure characterization.The related research contents and results are as follows:(1)Firstly,BAFL and terephthalaldehyde were selected as monomer to prepare the cPSB microsphere.Then,a series of TC-cPSB-X microsphere were prepared by annealing of the cPSB microsphere at different temperatures.These microporous materials were synthesized and characterized by FT-IR,XPS,TG,XRD and BET.Experimental results indicated that cPSB possess a specific cage-type microporous morphological structure with huge cavities interconnected by small windows.However,the cage-type microporous morphological structure disappeared when the annealing temperature is above 400 ?.(2)Secondly,Solvent-evaporation method and thermally rearranged reaction were used to prepare blend membranes(TR-PBO/TC-cPSB-X)with different composition.TR-PBO was chosen as polymer matrix and TC-cPSB as blend additives.The impact of different TC-cPSB contents on mechanical properties,thermal performances and permeabilities and selectivities for H2/CO2 separation of TR-PBO/TC-cPSB-X blend membranes were researched.The results showed that the additives and the polymer matrix had good compatibility.Compared with the pristine TR-PBO membrane,the blend membranes exhibited a better H2/CO2 selectivity.When the mass fraction of TC-cPSB increased from 0 wt% to 15 wt%,H2 permeability coefficient was improved from 98.4 Barrer to 312.5 Barrer and the selectivity of H2/CO2 from 1.4 to 5.4.When TC-cPSB content is more than 10 wt% the separation performance exceeded the Robeson “upper-bound” among polymeric membranes.(3)Finally,we designed amendable poly(schiff base)cage-type microporous materials with enhanced H2/CO2 selectivity via incorporation of cardo moiety into polymer chains.Three kinds of TC-x-cPSB membranes have been synthesized by polycondensation of BAFL and various aromatic diamines.The effects of specific cage-type microporous morphological structure and gas transport properties of the TC-x-cPSB membranes have been systematically investigated.It was found that all the TC-x-cPSB membranes exhibit an outstanding H2/CO2 selectivity and exceed the Robeson “upper-bound”.Among the three kinds of membranes,the TC-m-cPSB membrane exhibits the best performance with H2 permeability of 1056.5 Barrers and the H2/CO2 selectivity of 17.4.