层状铌基纳米复合功能材料的构建与催化应用研究

发布时间：2018-05-15 13:25

本文选题：层状铌酸盐 + 聚合-络合法　；参考：《安徽理工大学》2015年硕士论文

【摘要】：本文采用聚合-络合法合成层状铌酸盐KNb3O8,经过离子交换、剥离组装、复合等方法对其进行改性处理,制备了TiO2/Nb3O8和ZrO2/Nb3O8纳米复合功能材料。ZrO2/Nb3O8经硫酸浸渍后,得到超强酸SO42--ZrO2/Nb3O8材料。选用高分辨透射电子显微镜(HRTEM)、X-射线衍射(XRD)、激光拉曼光谱(LRS)、傅里叶变换红外光谱(FT-IR)、氨气吸附程序升温热脱附(NH3-TPD)等技术对催化剂的物理化学性质进行表征。使用液相紫外技术和气相色谱技术分别考察了样品降解亚甲基蓝的光催化性能和对甲苯硝化反应的酸催化性能。结果显示,采用聚合-络合法制备的铌酸盐KNb3O8拥有较规整的层状结构。由于受层间水合质子的影响,酸化后的样品的XRD主晶面峰向小角移动。剥离重组后的样品保留了部分层板结构,但样品的结晶度明显下降。TiO2/Nb3O8和ZrO2/Nb3O8复合材料在保留层状主体的基础上,表面也存在锐钛矿型的Ti02晶体和四方相的Zr02晶体。光催化降解亚甲基蓝结果表明,前驱体层状铌酸盐KNb3O8及其改性后的样品对亚甲基蓝均有较好的光降解效果。随着层间离子(H+或K+)的变化,样品的光催化性能变化不大。由于TiO2表面几乎没有酸性,而被降解物亚甲基蓝是碱性的,Ti02对于降解物的吸附性能较差,故其光催化性能也较差。而纳米片改性和纳米微晶的复合改性提高了样品的比表面积,提高了它们对亚甲基蓝的吸附量,光催化效果也明显增强。甲苯定域选择性硝化反应结果表明,前驱体层状铌酸盐和其改性后的样品对于甲苯定域选择性硝化反应都有很好的酸催化效果。H+离子交换层间K+离子后,样品的酸催化性能不好。这是由于HNb3O8的层间距太小,反应物分子难以进入层间与活性位点的质子接触。而纳米片改性以及纳米微晶的复合改性提高了样品的比表面积、酸量和酸强度,故它们的酸催化效果较好。
[Abstract]:In this paper, layered niobate KNB _ 3O _ 8 was synthesized by polymerization-complexation method. It was modified by ion exchange, peeling and assembling, and ZrO2/Nb3O8 nano-composite functional material .ZrO _ 2 / NB _ 3O _ 8 was impregnated with sulfuric acid to obtain superacid SO42--ZrO2/Nb3O8 material. The physical and chemical properties of the catalysts were characterized by high resolution transmission electron microscopy (HRTEM), laser Raman spectroscopy (LRS), Fourier transform infrared spectroscopy (FTIR), and ammonia adsorption temperature programmed thermal desorption (NH3-TPD). The photocatalytic properties of methylene blue degradation and acid catalytic activity for nitration of toluene were investigated by liquid phase UV and gas chromatography, respectively. The results show that niobate KNb3O8 prepared by polymerization-complexation method has a regular layered structure. Due to the influence of interlaminar hydration proton, the peak of XRD main crystal plane of the acidified sample moves to small angle. After peeling and recombination, some laminar structures were retained, but the crystallinity of the samples decreased obviously. TIO _ 2 / NB _ 3O _ 8 and ZrO2/Nb3O8 composites had anatase Ti02 crystals and tetragonal Zr02 crystals on the surface. The photocatalytic degradation of methylene blue showed that the precursor layered niobate KNb3O8 and its modified samples had better photodegradation effect on methylene blue. With the change of interlayer ion H or K), the photocatalytic performance of the sample changed little. Because there is almost no acid on the surface of TiO2, and the degradation of methylene blue is alkaline, the adsorption performance of the degradation compound is poor, so its photocatalytic performance is also poor. The surface area of the samples was improved and the adsorption amount of methylene blue was increased, and the photocatalytic effect was also obviously enhanced by the nano-chip modification and the composite modification of nanocrystalline. The results of selective nitration of toluene show that both the layered niobate and the modified sample have good acid catalytic effect on the selective nitration of toluene. The acid catalytic performance of the sample is not good. This is due to the fact that the interlayer spacing of HNb3O8 is so small that it is difficult for reactant molecules to enter the interlaminar proton contact with active sites. However, the surface area, acid content and acid strength of the samples were improved by the nano-chip modification and the composite modification of nanocrystalline, so their acid catalytic effect was better.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TB383.1

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