超细层状钛酸盐和复合纳米TiO₂的制备及性质研究

【作者】 杨娟；

【导师】 汪信； 陆路德； 李丹；

【作者基本信息】 南京理工大学 ， 材料学， 2002， 博士

【摘要】 制备新型纳米及亚微米材料并研究材料结构尺寸对材料性能的影响规律是当今材料科学的研究前沿之一。本论文主要研究超细层状钛酸盐（Na₂Ti₃O₇、K₂Ti₄O₉）的制备及颗粒尺寸对其离子交换性质、嵌入性质、柱撑特性及剥离性质的影响，主要内容如下： 利用硬脂酸法方便快速、反应物前驱体均匀混合的特点，成功制备了超细层状K₂Ti₄O₉，将硬脂酸法特点与固相反应特点相结合，通过选择不同粒径的TiO₂为原料，首次制备了一系列不同尺寸的层状钛酸盐，研究表明：原料TiO₂粒径直接影响到固相反应速率和产物颗粒尺寸，利用纳米TiO₂为原料，可显著提高固相反应速率并获得超细层状钛酸盐。 通过X-射线粉末衍射（XRD）、透射电子显微镜（TEM）、热重分析（TG）、傅立叶红外光谱（FT-IR）、BET比表面积测试等手段，重点考察了钛酸盐颗粒尺寸对其酸交换反应、烷基胺嵌入反应、SiO₂、Al₂O₃柱撑反应及其产物结构的影响。结果表明：颗粒尺寸不仅影响了层状钛酸盐酸交换反应速率，对交换产物结构也产生影响，超细K₂Ti₄O₉有利于得到层间含水量高、层间距大的酸交换产物；Na₂Ti₃O₇、K₂Ti₄O₉颗粒尺寸对其烷基胺嵌入性质产生不同影响，Na₂Ti₃O₇体系烷基胺嵌入反应较难进行完全，而K₂Ti₄O₉颗粒尺寸对其正丙胺嵌入产物的层间距、烷基胺嵌入量产生明显影响，超细K₂Ti₄O₉有利于得到高正丙胺嵌入量、大层间距的嵌入产物；而超细K₂Ti₄O₉的正丁胺嵌入产物由于嵌入过程出现剥离使得产物层间距小于相应大尺寸K₂Ti₄O₉的正丁胺嵌入产物；K₂Ti₄O₉颗粒尺寸对不同的柱撑体系有着不同的影响规律：SiO₂复合体系中，超细K₂Ti₄O₉有利于得到大层间距和高APS（SiO₂前驱体）含量的柱撑产物，而Al₂O₃复合体系中，由于Al₂O₃前驱体Al₁₃⁷⁺与K₂Ti₄O₉片层骨架独特的相互作用，超细K₂Ti₄O₉得到的柱撑产物层间距反而较小，但采用超细K₂Ti₄O₉能得到高比表面积、具有单分散微孔结构的Al₂O₃复合纳米TiO₂。 实验中首次发现了超细层状K₂Ti₄O₉在正丙胺溶液中的剥离现象，并以剥离产物为前驱物，通过静电吸附的方法制备了自组装纳米TiO₂多层膜；首次发现了超细层状Na₂Ti₃O₇、K₂Ti₄O₉在AgNO₃溶液中可以剥离，通过X-光电子能谱（XPS）、FT-IR和TEM对剥离前后产物进行了表征。 采用硬脂酸法快速、方便地制备了微结构可控的Al₂O₃、SnO₂复合纳米TiO₂，并与Sol-Gel法产物相比较，XRD、FT-IR、TEM结果表明：硬脂酸法制备的复合纳米TiO₂表面贫羟基，具有良好的分散性、更高的比表面积，且可通过改变复合量对摘要博士论文产物晶型和粒径进行控制。发现sno:在硬脂酸法和501一Gel法中对TIO:微结构有着完全相反的影响规律，硬脂酸法可以制得锐钦矿型纳米Ti02一snoZ复合氧化物;以光催化降解甲基橙为模拟实验考察了所制备的复合纳米TIOZ的光催化活性，结果表明，硬脂酸法制备的TIOZ一sno:光催化活性优异，其中样品Ti仇一snoZ（间.15）的光催化活性优于DegussaP一25.更多还原

【Abstract】 The preparation of new nanometer and micrometer-sized material and the influence of particle sizes on the properties of the material are extensively studied in recent years in material science. In this Ph. D. dissertation, A series of layered titanates Na2Ti3O7,K2Ti4O9 with different particle sizes, especially the ultrafine layered Na2Ti3O7, K2Ti4O9 samples were fabricated. The influence of the sizes on the ion-exchange, alkylamine-intercalation, pillaring and exfoliation properties of the layered titanates was studied. The dissertation was mainly discussed as follows:Ultrafine layered K2Ti4O9 was successfully fabricated by stearic acid method, which were usually used for the preparation of nanoparticles. A series of layered titanates with differenet particle sizes were obtained by solid-state reaction using TiO2 with different average particle sizes as the raw material. It was shown that the solid state reaction was accelerated by decreasing the particle size of TiO2 and ultrafine layered titanates could be prepared by using nanometer-sized TiO2 as the starting material.The influence of the particle sizes of the titanates on the structure of products exchanged by H+, intercalated by alkylarm’ne and pillared by SiO2, Al2O3 was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravity analysis (TG), Fourier transform infrared spectroscopy (FT-IR) experiments. It was found that the ion-exchanging reaction was enhanced by the small-sized layered titanate and more water molecules were intercalated in the interlayer space of the small-sized layered K2Ti4O9. Compared with the large sized layered titantaes, the n-propylamine intercalated product with larger interlayer distance and much more propylamine content was obtained by using small sized K2Ti4O9. But in the n-butylamine intercalated system, due to the exfoliation, products of ultrafine K2Ti4O9 exhibited the small interlayer distance. Particle sizes of the titanates have different influencing regulation in SiO2 and Al2O3 pillared system, it was found that SiO2 pillared products with large interlayer distance and higher APS content was obtained using ultrafine layered titanate as the host material. In the Al2O3 pillaring system, the intercalation of the precursor of Al2O3 in the interlayer caused the decreasing of the charge density of the lattice, and the layer structure was partially exfoliated. And the thermally stabled TiO2 composite with high specific surface area and uniform pore size distribution could be obtained using ultrafine K2Ti4O9 as the hostThe exfoliation of ultrafine layered titanate was firstly found in our experiment. The exfoliated nanolayer was used as the building blocks for the fabrication of self-assembly nanoTiO2 multilayer. The exfoliation of ultrafine layered titanates in the AgNO3 solution was firstly found by the XRD experiment. The delaminated product was characterized by the X-ray photoelectron spectroscopy (XPS) and FT-IR.A rapid and simple method, stearic acid method was also developed to prepare nanostructured TiO2 composites. Microstructure of the samples was investigated by XRD, FT-IR, TEM and BET specific surface area measurement and the results were compared with those obtained by conventional sol-gel method. It was found that nanocrystalline powders with good dispersity, high crystallinity and large specific surface area were successfully prepared by stearic acid method. The anatase structured TiO2-SnO2 binary oxides could only be prepared by stearic acid method. The photocatalytic decomposition of methyl orange was used as a model system to determine the relative influences of the preparation method and the concentration of coupled oxides on the photocatalytic activities. It was found that TiO2-SnO2 (r=0.15) prepared by stearic acid method showed higher photocatalytic activity than Degussa P-25.更多还原