| Metal-organic frameworks(MOFs)are a class of organic-inorganic hybrid materials with highly regular spatial network structure,large specific surface area and pore volume,good chemical stability and facile modification properties which have attracted much attention,giving these materials great application potential in industrial catalysis,selective adsorption and gas separation.The preparation of MOFs with new structure and introducing of functional groups or ligands could give them new properties,expanding their application in various fields.In this thesis,ferrocene derivatives and various metal ions were used as ligands and metal nodes,respectively,and a series of ferrocene-based MOFs with ultrathin two dimensional nanosheets,tremella-like and microspheres morphologies were prepared though simple solvothermal method.The effect of various preparation conditions on the crystal structure and morphology of ferrocene-based MOFs were studied,their formation mechanism was investigated,and applications in catalysis,pollutants treatment and selective adsorption of ion were also studied.(1)With the assistance of acetic acid modulator,a new type of two-dimensional ferrocene-based metal organic framework ultrathin nanosheet(FMOF)was prepared through a simple solvothermal method using 1,1’-ferrocene dicarboxylic acid(FDC)and zirconium chloride as raw materials,.The effect acid modulator on the crystal structure of FMOF was studied,and the results showed that FMOF with high crystallinity could be prepared only when acetic acid was used with proper adding amount.The morphology,physical and chemical properties of FMOF were characterized by PXRD,SEM,TEM,TG,AFM and XPS.And the adsorption/desorption isotherm indicated the BET surface area and average pore size of FMOF was 296.69 m2/g and 5.24 nm.Employing the "search-match" strategy,the PXRD pattern of the actual sample and Materials Studio software were used to construct the FMOF crystal structure model.The crystal system and space group assignment,crystal edge length,axis angle and interlayer distance of FMOF was demonstrated.Through the analysis of the morphology and crystal structure of the FMOF at different reaction stages,here came the conclusion that compared with tradition terephthalic acid with planar structure,the FDC ligand with non-planar structure featuring large steric hindrance would affect the coordination tendency of the Zr6O8 metal cluster node in different directions due to its steric effect,so the crystal would be more inclined to extend and grow in the same plane to decline the hindrance of ligands and finally forming a two-dimensional sheet(2)Using the reducing ligand in FMOF,the Pd/FMOF complex was prepared by in-situ reduction of potassium chloropalladite without the introduction of extra reducing agents.According to the different addition of potassium chloropalladite in the reaction,and Pd/FMOF with various loading amounts could be obtained.Subsequently,Pd/FMOF with a loading of 3.35 wt%was used as a catalyst in the oxidation of benzyl alcohol.After optimizing conditions such as solvent and reaction temperature,the conversion of benzyl alcohol was 89.3%within 12 hours.And gas chromatography analysis showed Pd/FMOF had a high selectivity of benzyl alcohol to converse into benzaldehyde.In addition,after 3 cycles of reaction,the conversion of 60%could still be achieved.Subsequently,using sodium borohydride as the reducing agent,a series of Au/FMOF were prepared by rapid reduction reaction.With tunable amount of chloroauric acid addition,Au/FMOF with different gold nanoparticles load amount could be obtained.In the reduction reaction of 4-nitrophenol(4-NP)to 4-aminophenol(4-AP)using of Au/FMOF as catalyst,and the effect of various reaction conditions such as reaction temperature,catalyst or reducing agent dosage and reactant concentration on the catalytic performance of Au/FMOF were studied.Reaction rate under different reaction conditions was also calculated through by pseudo-first-order kinetic model.The results showed that when Au/FMOF was used as catalyst,the reaction rate for 4NP could reach up to 1.71 min-1,and the conversion rate of more than 99%could still be achieved after being used for 10 cycles.Moreover,Au/FMOF also has excellent catalytic activity in the catalytic reduction of 2-nitrophenol(2-NP).(3)By replacing the zirconium chloride used in the preparation of FMOF with zirconium acetate as the zirconium source,a tremella like ferrocene-based metal organic framework(TFMOF)morphology was synthesized through solvothermal method employing FDC and acetic acid as ligands and adjusting acid.PXRD analysis showed that TFMOF and FMOF have the same crystal structure,while different from FMOF featuring dispersed monolithic nanosheet,TFMOF was composed of a large number of thin films with size of about 1 μm and thickness of 20-30 nm,and obvious staggering and overlapping could also be found.The influence of modulator acetic acid and reaction temperature on the morphology of TFMOF was studied.Although TFMOF prepared at different temperatures exhibited various morphologies,they all featured good crystallinity.According to the SEM images of the early stage of TFMOF crystals,it could be seen that the tremella like morphology of TFMOF originates from the mutual bonding and agglomeration of crystal nuclei in the initial stage of the reaction,and then overlapping with each other during the growth,not by self-assembly after forming independent layers.Through the analysis of the morphology and crystal structure at different formation stages,we believed that the utilization of zirconium acetate was beneficial to accelerate the formation of Zr6O8 metal clusters at the initial stage of the reaction,thereby promoting the amount of crystal nuclei.Crystal nuclei with a higher concentration in the reaction solution tended to agglomerate,then the nuclei in the agglomerates would form films during the crystal growth stage,adjacent films were connected with each other by FDC molecules to form the TFMOF metal-organic framework with a white fungus-like morphology.Compared with FMOF,the reaction yield of TFMOF has a significant increase.(4)Taking the advantages of large number of saturated Zr6O8 metal nodes in TFMOF as potential adsorption sites,the adsorption performance toward organic dye congo red(CR)in water was investigated.After optimizing the adsorption conditions,the maximum adsorption capacity of TFMOF toward CR could reach 252.3 mg·g-1,and the adsorption equilibrium could be quickly reached within 10 minutes.Through the adsorption kinetics and adsorption isotherm studies,it was found that the adsorption behavior of TFMOF toward CR conformed to a quasi-two-stage adsorption kinetic model,and the adsorption behavior of TFMOF on CR could be described by the Sips adsorption isotherm model,indicating chemical adsorption of CR at a specific site of TFMOF.And it was found that the maximum adsorption capacity of CR in per unit TFMOF was close to the number of Zr6O8 clusters in TFMOF,and the chemical environment of Fe sites in TFMOF showed not changes before and after adsorption.Therefor we inferred that the combination was mainly between the Zr6O8 metal cluster combines and the sulfonic acid group in CR.After three cycles of adsorption,the maximum value of 120 mg·g-1 could still be reached,which was still better than the maximum adsorption capacity of most reported adsorbents.As ligand in TFMOF,FDC,which was distributed regularly at the molecular level,could be used as an efficient Fenton catalyst.With H2O2 as oxidant,the hydroxyl radicals generated by electron transfer could achieve high-efficiency in the degradation of various organic pollutants.After optimizing the conditions such as pH,H2O2 dosage in degradation of RhB as the target,follow-up studies showed that TFMOF has good catalytic degradation performance for three organic dyes RhB,MO and RBV,and more than 96%of these dyes could rapidly degraded within 30 min,80 min and 15 min,respectively.(5)Influenced by the competitive binding of the carbonyl group and steric hindrance of the hydrophobic molecular chain in polyvinylpyrrolidone(PVP),we prepared a new type of ferrocene-based metal organic framework microspheres FMOFCo with FDC and cobalt nitrate as ligand and metal node ion.PXRD analysis showed that FMOF-Co had the same crystal structure and elemental composition as the hollow microsphere particles reported in earlier research reports.Subsequently,the adsorption performance of FMOF-Co toward gold ions in aqueous solution was studied.The results showed that FMOF-Co could reach adsorption equilibrium in 20 minutes with a maximum adsorption capacity of 1888.9 mg·g-1.The adsorption behavior of FMOF-Co was then analyzed through adsorption kinetics,isotherms and thermodynamics,which showed that the adsorption process was chemical adsorption in accordance with pseudo-second-order kinetic model and the Langmuir adsorption isotherm model.Then,according to DFT calculation,it was concluded that the Fe site in the FDC ligand of FMOF-Co was the main adsorption site for gold ions.Using the unique affinity of FMOF-Co toward gold ions,the adsorption selectivity of FMOF-Co for gold ions in mixed ion solution containing copper ions and nickel ions was investigated.Under the condition that the concentration of gold ions and other ions were all 100 ppm,recovery efficiency of more than 95%of the gold ions in the solution could be attained,meanwhile only 0.6%and 2.0%of copper ions and nickel ions were recovered.Subsequently,in the study of the adsorption selectivity of the gold ions in the simulated waste solution with high concentration of other ions([Au3+]=100 ppm,[Cu2+]=18000 ppm,[Ni2+]=3300 ppm),the recovery of 85%of the gold ions could also be achieved,while still less than 3%of the copper ions and nickel ions were adsorbed. |
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