Synthesis And Adsorption/Separation Properties Of Nitrogen-Rich Microporous Polymers

The sharply rising level of atmospheric carbon dioxide is the major cause of climate change and global warming.The resulting greenhouse effect has also become one of the greatest environmental concerns nowadays.Owing to the high surface areas and nanometer pore channel,microporous organic polymers?MOPs?relying on physical adsorption are potential candidates for CO₂ capture.Studies have shown that increasing the nitrogen sites in MOPs can also be helpful for increasing CO₂ capacity and selectivity of the materials.In this thesis,a series of highly nitrogen-rich MOPs?PANs?are prepared from triazine-based tetraamines?p-BzDAT and m-BzDAT?and hexaamine?TMBDAT?.The triazin in PANs can enhance the interactions betwwen materials and CO₂ through specific dipole–quadrupole interactions.We investigate the effects of chemical and pore structures on the adsorption and separation of CO₂ by measuring the physical adsorptions for PANs.The main contents and results are described below:PANs were made by reacting triazine-based tetraamines and hexaamine with formamide?MF?and N,N-dimethylformamide?DMF?.The uniform micropore size were successfully obtained through precisely control of polymerization process,and their BET areas and pore sizes in the ranges of 842-1227 m²g^-11 and 0.53-3.82 nm,respectively.In addition,the S_BET,V_Total,V_microicro and S_microicro of PAN-N1 are also the highest among the four polymers.Moreover,PAN-N1 belongs to ultramicropore materials because its major pores locate at 0.54 nm.At273 K and 1 bar,the CO₂ capacity of PANs reached in the range of 11.8-20.3 wt%.Besides the high CO₂ uptake,dynamic breakthrough curves indicate that PANs could indeed separate gas mixtures of CO₂/N₂ and CO₂/CH₄ completely.In addition,PAN-N1 exhibits excellent selectivity for CO₂ over N₂,which are 127.6 and 11.3 at 273 K and 298 K,respectively.In general,the separation factors are ranked as PAN-N1>PAN-N2>PAN-N3>PAN-N4,being in line with the order of the adsorption capacity of CO₂.Thus,the improvement of CO₂uptake and selectivity over other gases can be achieved by finely modulating the microporous and ultramicroporous structure within polymer networks.