| Metal-Organic Frameworks(MOFs)recently have shown potential application prospect in natural gas adsorption,photocatalysis and other fields.The characteristic that MOFs exhibits highly designability,enable us to moderate porous,topological structures and surface properties easily.To further enhance photocatalytic performance and CH4 adsorption ability of MOFs,Modified preparation of MOFs is of great significance.In this dissertion,we aimed to research the influence of modified preparation method on porous,topological structures and surface properties of MOFs.Meanwhile,we investigated the relationship between the structure and property of MOFs in the field of photocatalysis and natural gas adsorption.1.By in-situ doping,carbon nanotubes were introduced into the synthesis system of MIL-53(Fe),then MIL-53(Fe)/MWCNT composites were successfully prepared.It was found that the doping of carbon nanotubes improved the light absorption capability of the composites and promoted the separation of photogenerated electrons and holes.MIL-53(Fe)/MWCNT showed the higher photocatalytic activity in the photocatalytic degradation of Rhodamine B.2.MIL-53(Fe)was prepared by surfactant-assisted synthesis method.The surfactant included tetraethylammonium hydroxide(TEAOH),polyoxyethylene polyoxypropylene polyoxyethylene(P123)and polyvinyl alcohol(PVA).It was found that the pore structure of MIL-53(Fe)prepared by PVA or P123 displayed"large pore" and MIL-53(Fe)/PVA or MIL-53(Fe)/PVA showed better light-absorption property and indicated a lower photoelectron-hole recombination rate.However,the framework structure of MIL-53(Fe)prepared by TEAOH exhibited“narrow pore”.MIL-53(Fe)/TEAOH promoted the photoelectron-hole recombination and decreased optical absorption.The photocatalytic degradation of Rhodamine B showed that the photocatalytic activity of MIL-53(Fe)/PVA or MIL-53(Fe)/PVA was superior to MIL-53(Fe),while the photocatalytic activity of MIL-53(Fe)/TEAOH was inferior to MIL-53(Fe).3.MIL-53(Fe)-X(X=NH2,NO2,Br)were successfully synthesized with organic ligand 2-amino-1,4-terephthalic acid(BDC-NH2),2-nitro-1,4terephthalic acid(BDC-NO2),2-bromine-1,4-terephthalic acid(BDC-Br)and metal ion Fe3+.MIL-53(Fe)exhibited flexible skeleton structure,which can change between "large pore" and "narrow pore".The introduction of functional group(-NH2,-NO2,-Br)led to the transformation of the skeleton structure from"large pore" to "narrow pore" that decreased adsorption capacity of the materials.As a result,MIL-53(Fe)-X showed inferior photocatalytic performance.4.The influence of the solvents on the structure and CH4 adsorption capacity of HKUST-1 was investigated.The solubility of 1,3,5-benzene tricarboxylic acid in different solvents at the temperature range from 298K to 360K was determined as follows:N,N-dimethyl formamide>ethanol>methanol>isobutyl alcohol>isopropyl alcohol.The results showed that methane adsorption capacity order of HKUST-1 prepared by different solvent was same to the solubility order of 1,3,5-benzene tricarboxylic acid in different solvents.The higher solubility of the organic ligands in the solvent led the higher crystallinity,which finally caused the increase methane adsorption capacity of the product HKUST-1.Therefore,the solvent effect can provide a new idea for the design of energy gas adsorption materials. |
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