氧化铁功能化多孔材料的合成与应用

发布时间：2018-04-22 12:44

本文选题：多孔材料 + 氧化铁　；参考：《大连理工大学》2016年博士论文

【摘要】：多孔材料是材料科学中的重要研究内容。通过多孔材料和其它功能组分的结合,将纯多孔材料扩展到杂化多孔材料,可以极大地延伸此类材料的应用领域。氧化铁种类繁多性能各异,是较为常用的功能组分。α-Fe2O3纳米粒子与多孔材料结合后可以提高它的分散性,使其催化活性发挥更加充分。γ-Fe2O3和Fe304都具有强磁性,它们与多孔材料结合的复合物则可以利用外加磁场的作用快速的定位和收集。本论文将铁的氧化物作为功能组分,采用不同方法制备了一系列的铁基多孔材料。在不存在介孔模板剂的条件下,通过一步水热晶化法,制备出一种新颖的多级孔道含铁MFI型沸石分子筛微球,该微球由纳米片定向组装后形成。在合成体系中添加一定量的葡萄糖后,所得样品为4-5μm的均匀微球,具有多级孔道结构,比表面积达502m2/g,而且在其内部均匀分散了超细纳米α-Fe2O3颗粒。葡萄糖在分子筛的结晶和铁物种变化过程中发挥了重要作用。该分子筛微球在光催化氧化降解苯酚的反应中显示了良好的催化性能,反应1.5 h后苯酚溶液COD脱除率就可达到100%；经过多次循环反应后,仍然保持了良好的催化性能,表明其稳定性较好。此合成方法为原位合成其它功能化多孔材料开辟了新的路径。以十六烷基三甲基溴化铵为介孔模板剂,采用溶胶凝胶法合成出核壳型磁性介孔复合材料(γ-Fe203/nSi02/mSi02).该材料具有磁性强、比表面积高、孔容大和介孔孔道均匀等特点。γ-Fe2O3/nSiO2/mSiO2由γ-Fe2O3核以及核外的两层二氧化硅组成,内层无孔二氧化硅能够阻止磁性核与外部溶液接触,外层介孔二氧化硅则能被氨基功能化并在酸性条件下带正电荷。因此,带负电荷的重铬酸根离子能够通过静电吸附作用被此复合材料吸附。重铬酸根离子的吸附符合朗格缪尔吸附等温线,此复合材料最大重铬酸根吸附能力达到1.03 mmol Cr/g。更重要的是,吸附剂可以很容易的通过外加磁场从溶液中分离回收。将Fe304纳米粒子作为磁性核,以聚乙烯吡咯烷酮(PVP)为促进剂,采用混合溶剂晶化法制备出新型核壳结构磁性金属有机骨架复合材料Fe3O4/IRMOF-3。聚乙烯吡咯烷酮不仅作为稳定剂使Fe304纳米粒子均匀分散,而且促使IRMOF-3前驱体在Fe304表面生长。研究结果表明,该复合材料具有高结晶度、多孔特性、快磁响应速度以及稳定性。Fe3O4/IRMOF-3在苯甲醛与氰乙酸乙酯的Knoevenagel缩合反应中显示了良好的催化性能,经过4h的反应后氰乙酸乙酯转化率达到98.3%。反应后的催化剂可以快速磁性分离回收并重复使用多次。
[Abstract]:Porous materials are important research contents in material science. Through the combination of porous materials and other functional components, the pure porous materials can be extended to hybrid porous materials, which can greatly extend the application fields of these materials. Fe _ 2O _ 3 is a common functional component, which can improve the dispersion of 伪 -Fe _ 2O _ 3 nanoparticles combined with porous materials and make its catalytic activity play more fully. Both 纬 -Fe _ 2O _ 3 and Fe304 have strong magnetic properties. The composites combined with porous materials can be rapidly located and collected by the effect of external magnetic field. In this paper, a series of iron-based porous materials were prepared by using iron oxides as functional components. In the absence of mesoporous template, a novel MFI zeolite microsphere containing iron was prepared by one step hydrothermal crystallization method. After a certain amount of glucose was added into the synthesized system, the obtained sample was a uniform microsphere of 4-5 渭 m, with a multilevel pore structure with a specific surface area of 502m2 / g, and the ultrafine 伪 -Fe _ 2O _ 3 particles were uniformly dispersed inside the system. Glucose plays an important role in the crystallization of molecular sieve and the change of iron species. The molecular sieve microspheres showed good catalytic performance in the photocatalytic degradation of phenol, and the removal rate of COD in phenol solution reached 100% after 1.5 h reaction. It shows that its stability is good. This method opens up a new way for in situ synthesis of other functional porous materials. Using cetyltrimethylammonium bromide as mesoporous template, core-shell magnetic mesoporous composite (纬 -Fe203 / nSi02 / mSi02) was synthesized by sol-gel method. The material is characterized by strong magnetism, high specific surface area, large pore volume and uniform mesoporous channel. 纬 -Fe _ 2O _ 3 / nSiO _ 2 / mSiO _ 2 consists of 纬 -Fe _ 2O _ 3 core and two layers of silica outside the nucleus. Outer mesoporous silica can be functionalized by amino groups and positively charged under acidic conditions. Therefore, the negative charge dichromate ion can be adsorbed by the composite by electrostatic adsorption. The adsorption of dichromate ion accords with Langmuir adsorption isotherm. The maximum adsorption ability of dichromate ion is 1.03 mmol Cr / g. More importantly, the adsorbent can be easily separated and recovered from the solution by an applied magnetic field. Using Fe304 nanoparticles as magnetic nuclei and polyvinylpyrrolidone (PVP) as accelerator, a novel core-shell structure magnetic metal-organic matrix composite Fe _ 3O _ 4 / IRMOF-3 was prepared by mixed solvent crystallization method. Polyvinylpyrrolidone not only acts as stabilizer to evenly disperse Fe304 nanoparticles, but also promotes the growth of IRMOF-3 precursor on Fe304 surface. The results show that the composite has high crystallinity, porous properties, fast magnetic response speed and stability. Fe3O4 / IRMOF-3 shows good catalytic performance in the Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. After 4 h reaction, the conversion rate of ethyl cyanoacetate reached 98.3%. The catalyst can be recovered quickly by magnetic separation and reused many times.
【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TQ138.11;TB383.4

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