Study On Synthesis And Catalytic Performance Of Polymetalloporphyrin Nanosheets

Porous organic polymers(POPs)is a large class of materials that have been developing in the last decade.They have very stable pore structure,low density,high specific surface area,excellent catalytic performance and adsorption performance.At present,POPs have shown potential applications in gas adsorption,luminescence,heterogeneous catalysis,proton conduction,sensing,energy and many other fields.With the deepening of research,twodimensional organic porous polymer nanosheets have been emerged.Two-dimensional nanosheets have unique physical,chemical,electrical and mechanical properties.A variety of inorganic,inorganic-organic hybrid and organic two-dimensional nanosheets have been successfully prepared,but organic two-dimensional nanosheets with complete conjugation and good stability are still lacking.In this thesis,we have designed and successfully synthesized two polymetalloporphyrin nanosheets,and the nanosheets were characterized in detail.Finally,we explored their application in heterogeneous catalysis.In the third chapter of this thesis,the synthesis method of two polymetalloporphyrin nanosheets are elaborated.First,we synthesized the monomers Ni(II)5,10,15,20-Tetraethynylporphyrin and Zn(II)5,10,15,20-Tetraethynyl-porphyrin,and then Cu(II)catalyzed monomer Glaser–Hay coupling to form the COFs,named PNi P-COF and PZn P-COF.A thin layer of nanosheet was obtained by ultrasonic exfoliation in ethanol,named PNi PNs and PZn PNs,respectively.After that,the structure and morphology of the two nanosheets were analyzed by infrared spectroscopy(IR),thermogravime tric analysis(TGA),transmission electron microscopy(TEM),atomic force microscopy(AFM),dynamic light scattering(DLS),Tyndall effect,Raman spectroscopy,X-ray energy spectroscopy(XPS),13 C CP/MAS NMR and so on.The fourth chapter of this thesis elaborates on the application of the prepared nanosheets in the catalytic reduction of nitrobenzenes.The optimal catalyst and experimental conditions were screened out.The selectivity of the catalytic product was studied by GC-MS.Comparing the performance of the catalyst,it was found that the nanosheets has higher reactivity than the bulk COFs.Next,the reaction substrate was expanded,and the universality of the nanosheets was examined.The PNi PNs catalyst also maintained high activity after five consecutive cycles of reductions,with conversion of 4-NP into 4-AP close to 100% within 4.0 minutes.The large scale experiment proves that the catalytic substrate can be expanded to the gram level and the complete conversion of 4-NP into 4-AP was also achieved in the scaled-up reaction in 50 minutes.Finally,the mechanism of the reaction is studied in detail by gas chromatography.