Preparation,Adsorption And Catalytic Properties Of Functional Organic Porous Materials

This paper aims to develop and utilize the marine resources of the South China Sea.Through reasonable design and construction of monomers and selection of appropriate polymerization and post-functionalization methods,a series of new organic porous materials have been developed in a targeted manner,and their corresponding performance,such as direct methane conversion,seawater uranium extraction and gas adsorption capacity,have been explored.From the perspective of basic experiments,each job mainly includes the following parts:1)the rational design and synthesis of building monomers;2)the preparation（polymerization）of organic porous materials;3)further functionalization（post-function）according to the needs of the function 4)structural characterization of building monomers and organic porous materials;5)and performance testing of organic porous materials.The structure and performance are mainly characterized by mass spectrometry,nuclear magnetic carbon spectrum,hydrogen spectroscopy,gas chromatography,gas adsorption and desorption isotherm,FT-IR,XPS,SEM,TEM,TGA and other means.（1）Considering that the main component of combustible ice is methane gas,and for better development and utilization of methane gas,we have for the first time developed a catalytic system based on a composite of iridium complex and organic porous material for methane conversion.We have prepared a series of porous polycarbazole-based composite catalytic materials containing iridium complexe with high specific surface area(467-1210 m²g^-1)and good thermodynamic and chemical stability.We have optimized the catalytic activity of the selective boronation reaction of methane through the selection and design of monomers and the precise control strategy of pore size.Catalyst CAL-3-Ir can produce CH₃Bpin in 29%yield in 9 hours,and its catalytic conversion frequency（TOF）is about 14 h^-1.The catalyst CAL-3-Ir has the suitable pore size distribution,it is conducive to the selective generation of monoboration product CH₃Bpin,thus it has the highest chemical selectivity in the monoboration reaction of methane（CH₃Bpin:CH₂-（Bpin）₂=16:1）.（2）We have prepared two porous polycarbazole materials PHN-1 and PHN-2 with different spatial configurations through oxidative coupling reaction catalyzed by FeCl₃ at room temperature and pressure.We use two different post-functionalization methods to modify PHN-1 and PHN-2.One is to convert the cyano groups on PHN-1 and PHN-2 into tetrazole group with higher nitrogen content through Na N₃ and NH₄Cl.The second one is to convert the cyano group on PHN-1 and PHN-2 into amidoxime group with good chelating properties for uranium via hydroxylamine aqueous solution to obtain PHN-1-AO and PHN-2-AO.The resulting polymers all have large specific surface areas.For example,the specific surface areas of PHN-1 and PHN-2 are 340 m² g^-1 and 293 m² g^-1,respectively.After post-functionalization,although the specific surface area of PHN-1-TZ and PHN-2-TZ containing tetrazole groups has decreased,their CO₂ adsorption capacity is better than that of the parent materials PHN-1 and PHN-2.For example,PHN-2-TZ can achieve 4.93 wt%carbon dioxide adsorption performance at 298 K and 1.0 bar with the aid of Lewis acid-Lewis base and local dipole-quadrupole interaction and the affinity between N atom and CO₂.Compared with its parent material PHN-2,this performance has a 55.0%improvement in CO₂ adsorption performance.Besides,PHN-1-AO and PHN-2-AO containing amidoxime group have a greater improvement in uranium extraction performance than the parent materials PHN-1 and PHN-2.For example,the uranium extraction ability of PHN-1-AO can reach 119.4 mg g^-1 in real seawater containing 8.02 ppm uranium.By contrast,the ability of its parent material PHN-1 is less than 10 mg g^-1,showing that the amidoxime group of PHN-1-AO has greatly promoted and improved its uranium extraction performance.（3）We have prepared PIM-1,a precursor material with the selective solubility and microporous structure.It also has the cyano group that can be further chemically modified and a large specific surface area of 724 m² g^-1.Moreover,its linear structure polymer structure can give it a selective solubility.As a result,it can be further processed into some shapes.Therefore,we have not only prepared the powder materials with amidoxime group（PIM-1-AO）but also made it into membrane material（PIM-1-AO film）and composite block material combined with sponges（foam-supporting PIM-1-AO）.By comparing the uranium extraction performance of these three substances,we found that the PIM-1AO film has the highest uranium extraction capacity in real seawater containing 7.98 ppm uranium,approximately180.3 mg g^-1.The performance of foam-supporting PIM-1-AO is not as good as the PIM-1-AO film,but with the sponge’s ability to enrich the water,it can reduce the uranium extraction saturation time to 4 hours.Besides,we found that PIM-1-AO and foam-supporting PIM-1-AO are more advantageous in recycling,they can be collected and reused more easily without losing their quality.After 5 cycles,they could also maintain good uranium extraction performance.Thus,compared with powdery materials,they have certain advantages in practical industrial applications.Moreover,based on the conversion of the cyano group of PIM-1 to obtain a tetrazole group,we have further modified iodide on this group to prepare PIM-1-AI.It can be used as a non-metallic substance to catalyze the chemical reaction between CO₂ and epoxy substances.Under the catalytic conditions of CO₂ pressure of 2.5MPa and 90 ^oC,when it is used as a catalyst,the yield of the corresponding cyclic carbonate produced can reach up to 99%.