| In view of problems in greenhouse effect,energy crisis and separation of organic hydrocarbons,a series of microporous polyimides and poly(Schiff-base)s for CO2-capture,hydrogen storage and separation of light hydrocarbons were synthesized.The effects of chemical structures and porosity parameters on the adsorption/separation properties of gas and organic hydrocarbons of microporous polymers were investigated systematically.Subsequently,the carbonization,sulfonation and ionized modifications on polyimides were conducted to further improve gas adsorption capacity and selectivity.The main research content is summarized as below:A series of semi-cycloaliphatic microporous polyimides(sPIs)have been synthesized by one pot polycondensation from bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride(BCDA),1,2,4,5-cyclohexanetetracarboxylic dianhydride(CHDA)and 1,2,3,4-cyclobutane tetracarboxylic dianhydride(CBDA)with 1,3,5,7-tetrakis(4'-aminophenyl)adamantane(TAPA)and tetrakis(4-aminophenyl)methane(TAPM),respectively.sPIs show BET sepcific surface areas of 25-1108 m2/g.The semi-cycloaliphatic microporous polyimides containing a large amount of nitrogen and oxygen heteratoms and cycloaliphatic structures exhibit excellent gas adsorption and selectivity.At 273 K and 1 bar,the CO2 capacity of sPI-1 is up to 23.7 wt%,which is the highest among the porous polyimides.A series of microporous copolyimides(cPIs)with adjustable cycloaliphatic and aromatic content have been synthesized via copolymerization of 1,3,5,7-tetrakis(4'-amin-ophenyl)adamantane(TAPA)with different molar ratios of comonomers of cycloaliphatic bicyclo[2.2.2]oct-7-ene-2,3,-5,6-tetracarboxylic dianhydride(BCDA)and aromatic pyromellit-ic dianhydride(PMDA).These cPIs exhibit BET specific surface area of 814-1108 m2/g.At 273 K and 1 bar,the CO2 uptake and CO2/N2 selectivity of cPIs are 17.4-23.7 wt%and 28.0-39.8,respectively.Meanwhile,at 298 K and P/P0 = 0.9,benzene and cyclohexane vapor uptakes of cPIs are up to 160.3 wt%and 85.4 wt%,respectively,indicating that cPIs show excellent organic vapor adsorption properties.The microporous carbons(UMC-Ts)have been successfully prepared using nitrogen-and oxygen-rich semi-cycloaliphatic polyimide as a precursor in the presence of KOH.After carbonization treatment,the specific surface area of sPI-2 increased from 900 to 2406 m2 g-1.At 273 K and 1 bar,the adsorption capacity of CO2 increased significantly from 23.3 wt%to 34.0 wt%.At 77 K and 1 bar,the adsorption capacity of H2 increased from 2.2 wt%to 3.7 wt%.Moreover,it is interesting to observe that UMC-Ts possess extraordinarily large uptake for benzene(74.4 wt%,298 K)and cyclohexane(64.8 wt%,298 K)at the very low relative pressure(P/P0 = 0.1),which indicates that polyimide-based microporous carbons show excellent properties for capture of benzene and cyclohexane vapor.The porous polyimide(PI-M-S-Ag)with silver ions was successfully prepared by sulfonation and ionic modification of microporous polyimide(PI-M).The results show that the C3H6/C3H6 selectivity increase from 2.0 of PI-M to 16.3 of PI-M-S-Ag.At 273 K and 1 bar,the C3H6/CH4 selectivity of PI-M-S-Ag is up to 3785,which is the highest in the reported porous materials.Three ordered microporous poly(Schiff base)s(COF-Ms)have been prepared via solvothermal method using tetrakis(4-aminophenyl)methane(TAPM)with tetrakis(4-formylp-henyl)methane(TFPM),tetrakis(4-formylphenyl)silane(TFPS)and 1,3,5,7-tetrakis(4'-fo-rmylphenyl)adamantane(TFPA).The BET surface areas of COF-Ms are 650-1172 m2/g.The CO2 uptake of COF-MA is up to 14.4 wt%at 273 K and 1 bar. |
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