Design,synthesis And Gas Adsorption/separation Properties Of Triazine-based Porous Organic Materials

Porous organic polymer(POPs)materials are mainly composed of light elements such as C,H,B,N,O,etc.,which are connected by strong covalent bonds(C-C,C-N,C-O,B-O,B-N bonds,etc.).POPs materials possess high physical/chemical stability,and can be used under harsh conditions such as high temperature,high pressure,humidity,high acidity and alkalinity.Currently,POPs materials have been widely used in the fields of catalysis,adsorption,separation,biomedical and optoelectronic materials,etc.Triazine-based porous organic materials are a class of POPs materials with great promising applications.Its main structural characteristic is the inclusion of aromatic 1,3,5-triazine rings with planar ?-conjugate properties in the frameworks.Due to their rich nitrogen content,high stability,high BET specific surface area and porosity,triazine-based porous organic materials are widely used in gas adsorption and separation,such as carbon dioxide capture,natural gas purification,and hydrogen storage.In this thesis,a series of triazine-based porous organic materials were successfully synthesized by ionic thermal polymerization and click polymerization through rational design of organic building blocks.We introduced benzodiimidazole units into triazinebased porous organic materials to prepare a series of benzodiimidazole functionalized triazine-based porous organic materials;We explored in detail the effects of reaction conditions on pore properties,and their applications in carbon dioxide adsorption and separation;We have used bisbenzimidazole monomers to construct highly porous triazine-based porous organic materials,and studied their applications in natural gas purification and carbon dioxide capture;We have also established triazole-functionalized triazine-based porous organic materials by copper-catalyzed click polymerization,and studied their applications in carbon dioxide capture,natural gas purification and hydrogen storage.These explorations provide new ideas for the design of new porous organic polymers.The main research results of this thesis are as follows:1.We obtained highly porous covalent triazine frameworks(CTF-DIs)materials containing benzodiimidazole by ionic thermal polymerization of benzodiimidazolyl dicyano monomer BCBDI.Their porous properties could be adjusted from the main micropores to the micro/medium/macropores,by varying the reaction conditions,including the polymerization temperature and the ratios of catalyst/BCBDI.The N2 adsorption isotherm at 77 K indicates that CTF-DIs have good porous properties and their BET specific surface areas are up to 1877 m2 g-1.At the same time,their CO2 adsorption capacities at 273/298 K and 1 bar are up to 89.2 and 54.2 cm3 g-1,respectively,and the CO2 adsorption enthalpy is up to 52 k J mol-1.The CO2/N2 adsorption selectivity of CTF-DI-6 is up to 53(273 K,1 bar)and the CO2/CH4 adsorption selectivity is up to 15(273 K,1 bar),which were calculated by ideal adsorption solution theory(IAST).2.We successfully synthesized a series of highly porous covalent triazine frameworks(CTF-BIBs)materials by using 1,4-bis(5-cyano-1H-benzimidazol-2-yl)benzene(BCBIB)as building block.We investigated the effect of reaction temperature on the porous and gas adsorption properties of CTF-BIBs.The BET specific surface areas of CTF-BIBs are up to 2088 m2 g-1.At the same time,these CTFBIBs exhibit excellent CO2 and light alkane(C1-C3)adsorption capacity,as well as excellent selective separation abilities for CO2/N2,CO2/CH4,C2H6/CH4 and C3H8/CH4 mixed gases.Among them,the CO2 absorption capacity of CTF-BIB-1 is up to 97.6 cm3 g-1(4.35 mmol g-1)at 1 bar and 273 K.And at 1 bar and 298 K,the adsorption selectivity for C3H8/CH4 mixed gas is 386.6.Breakthrough simulations show that CTFBIB-1 exhibites excellent separation performance for the equimolar CO2/C3H8/C2H6/CH4 mixed gas.3.Using copper-catalyzed click polymerization,we used 1,3,5-tris(4-azidophenyl)-triazine(TEPT)with 1,3,5-triethynylbenzene(TEB)and 1,4-diethynylbenzene(DEB),respectively,to synthesis 1,2,3-triazole functionalized triazine-based porous organic polymers(TT-POPs)in DMF solution.The structure of TT-POPs contains two N-rich heteroaromatic rings(triazole rings and triazine rings),which provide a plurality of affinity sites for gas adsorption.We studied the hydrogen storage capacity of TT-POPs and then evaluated the adsorption capacities of TT-POPs for CO2,C2H2 and C2H4,and the selective separation abilities for CO2/N2,CO2/CH4,C2H2/CH4 and C2H4/CH4 mixed gas.At 273 K and 1 bar,TT-POP-1 has the higher CO2 adsorption capacity(67.5 cm3 g-1).The adsorption selectivities of TT-POPs were calculated by the IAST method,and the C2H2/CH4 mixed gas adsorption selectivity of TT-POP-2 was up to 3704.2(298 K,1 bar).In this thesis,we have constructed a series of triazine-based porous organic polymer materials with specific functional groups by rational design of organic building blocks.The nitrogen-rich porous organic materials have excellent carbon dioxide adsorption capacity,selective adsorption and separation properties of light hydrocarbons,and outstanding hydrogen storage capacity.The work of this thesis provide a fast and effective way for the design and synthesis of functionalized triazinebased porous organic materials.These also indicate that triazine-based porous organic materials have broad applications in gas adsorption and separation.