【作者】 张丹；

【导师】 许茜；

【作者基本信息】 东北大学 ， 冶金物理化学， 2019， 博士

【摘要】 近年来,金属有机骨架材料(Metal-Organic Frameworks,简称MOFs)在光催化和天然气吸附等领域展现了潜在的应用前景。MOFs具有超强的可设计性的特点,能够轻易调节材料的孔结构、拓扑结构及表面性质。为了提高MOFs的光催化及能源气体吸附性能,改性制备金属有机骨架材料,调控其结构,提高材料的应用性能具有重要意义。本论文研究改性制备方法对MOFs材料的骨架结构、孔结构及孔道表面性质的影响,探究MOFs材料的结构特征和光催化性能及甲烷吸附能力的关系。1.通过原位掺杂的方法,将碳纳米管(MWCNT)引入金属有机骨架材料MIL-53(Fe)的合成体系中,制备出复合材料MIL-53(Fe)/MWCNT。研究发现碳纳米管的掺杂提高了复合材料的吸光性能,并且促进了复合材料的光生电子和空穴的分离。复合材料在光催化降解罗丹明B的实验中表现出更强的光催化性能。2.利用表面活性剂四乙基氢氧化铵(TEAOH)、聚氧乙烯-聚氧丙烯-聚氧乙烯(P123)、聚乙烯醇(PVA),改性制备MIL-53(Fe)。研究发现由表面活性剂PVA或P123改性制备MIL-53(Fe)的开孔方式为开放孔结构,吸光能力增强,光生电子和空穴的复位受到抑制。而由表面活性剂TEAOH改性制备MIL-53(Fe)的开孔方式为窄孔结构,吸光能力降低,并促进了光生电子和空穴的复位。光催化降解罗丹明B的实验表明由表面活性剂PVA或P123改性制备的MIL-53(Fe)光催化性能优于未使用表面活性剂改性制备的MIL-53(Fe),而由表面活性剂TEAOH改性制备的MIL-53(Fe)光催化性能弱于未使用表面活性剂改性制备的MIL-53(Fe)。3.利用含有不同官能团的有机配体2-氨基-1,4-对苯二甲酸(BDC-NH2)、2-硝基-1,4-对苯二甲酸(BDC-NO2)、2-溴-1,4-对苯二甲酸(BDC-Br),以金属离子Fe3+为中心离子制备了 MIL-53(Fe)-X(X=NH2、NO2、Br)。MIL-53(Fe)的骨架为柔性骨架结构,能够在开放孔和窄孔之间转变。官能团-NH2、-NO2、-Br的引入,导致材料的骨架结构由开放孔结构转变为窄孔结构,材料的吸附能力减弱,引起材料光催化性能的降低。4.考察了不同溶剂对所制备的金属有机骨架材料HKUST-1的结构及甲烷吸附能力的影响。在298～360K范围内,实验测出有机配体1,3,5-均苯三甲酸在不同溶剂中的溶解度大小顺序为N,N-二甲基甲酰胺>乙醇>甲醇>异丁醇>异丙醇。研究发现由不同溶剂制备的HKUST-1的甲烷吸附量大小顺序与配体均苯三甲酸在溶剂中的溶解度大小顺序相同。有机配体在溶剂中的溶解度越大,生成的产物结晶度越高,引起产物HKUST-1的甲烷吸附量增大。因此,溶剂效应为能源气体吸附材料的设计提供了一种新的思路。更多还原

【Abstract】 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.更多还原