【作者】 郑崇辉；

【导师】 张密林；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2007， 博士

【摘要】 水滑石作为固体碱催化剂替代NaOH等均相碱性催化剂广泛应用于加氢、聚合、缩合反应、烷基化反应和重整反应。近年来，人们借助迅速发展的纳米技术，制备了纳米水滑石。纳米水滑石具有大的比表面积和高的比表面能，大大提高了水滑石作为固体超强碱的催化活性。但纳米水滑石存在分离回收困难和在液相催化体系中易团聚等弊端。因此，研究和开发一种易于分离和回收，同时又具有较高催化活性的新型纳米固体碱催化剂，具有重要的理论和实际意义。本文结合国内外本领域的研究现状，以层状水滑石为前体，开展了将磁性基质与二维层状水滑石前体组装制备磁性纳米类水滑石催化剂的制备研究，旨在制备出具有潜在应用价值的环境友好新型纳米水滑石材料。采用化学共沉淀法，将磁性基质与二维层状水滑石组装制备了镍基、镁基二元磁性水滑石。在二元水滑石的基础上，制备了三元磁性铜镍铝、锌镁铝水滑石。研究了在一定合成条件和磁性基质浓度下，铜、镍锌、镁、铝摩尔比和焙烧温度对水滑石结构、纯度、结晶度和磁学性能的影响。发现一定量磁性基质的引入没有改变水滑石典型层状结构，XRD图谱显示磁性水滑石仍具有水滑石特征衍射峰。保持一定量的磁性基质，控制二价离子的配比，可以制备出晶体结构规整，结晶度好的磁性水滑石。Cu²⁺离子的引入导致了明显的Jahn-Teller效应，随CU²⁺离子量的增加，这种效应更加显著。磁性水滑石的比饱和磁化强度由磁性基质的添加量决定。采用水热法制备了一系列高结晶度的镍铝水滑石。实验结果表明水热法可以实现磁性基质与水滑石的组装。同时对磁性镍铝水滑石的磁强度进行了研究。通过离子交换法成功将具有Keggin结构的杂多酸引入到镍铝水滑石层间，将磁性基质与杂多酸柱撑水滑石进行组装，制备出了层间通道高度为1.04nm的大孔道磁性柱撑水滑石材料。且杂多酸柱撑水滑石赋予磁性后其典型的结构没有改变。柱撑水滑石的热稳定性高于其相应的水滑石前驱体。更多还原

【Abstract】 Hydrotalcite-like compounds have been widely used in hydrogenation, polymerization, condensation, alkylation and reforming reaction which can substitute for traditional homogeneous base catalysts such as NaOH. In recent years, nano-scale hydrotalcite has been synthesized by rapid developing nanotechnology. Nano-scale particles with high specific surface area and free energy can greatly improve the catalytic activity of solid base. But the disadvantages of these catalysts such as difficulties of separating and reclaiming in the liquid phase greatly limited their applications. Therefore, it is essential to design and prepare a novel nano-scale solid base catalyst with high catalytic activity, which makes it possible to be easily separated and recovered.In this dissertation, magnetic nano-scale hydrotalcite-like compounds have been prepared by assembling of magnetic substrates and layered hydrotalcite-like compounds which was used as precursor, aiming to achieve one kind of novel environmental friendly catalytic material.In the paper, magnetic Ni-based and Zn-based hydrotalcite-like compounds have been prepared by chemical co-precipitation method. On the basis of binary magnetic hydrotalcite-like compounds, magnetic ternary CuNiAl and ZnMgAl hydrotalcite-like compounds have also been prepared. The influence of the molar ratio of the composition components, the calcination temperatures on the structure, purity, crystallinity, and magnetic properties of the materials has been systematically investigated. The results revealed that the crystallinity of the samples decreases after the incorporation magnetic substrate into the hydrotalcite material. While the typical layered structure of hydrotalcite has been not affected by introducing a certain range of magnetic substrates during the preparation process. Characteristic diffractions of magnetic CuNiAl hydrotalcite-like compound are observed in the XRD patterns. HTLc with integrated crystal structure and good crystallinity can be obtained by controlling the binary ion molar ratio in the certain amount of magnetic substrates. Furthermore, introducing of Cu²⁺ leaded to obvious Jahn-Teller effect, and the effect was remarkable with the increasing amount of Cu²⁺. The magnetic hydrotalcite saturation magnetization was determined by the amount of magnetic substrates.High crystalline magnetic Ni-Al hydrotalcite-like compounds were prepared through hydrothermal method. The results indicated the successful assembling of magnetic substrates and the mother hydrotalcites.The POM-HTLc （polyoxometalate pillared layered hydroxides） were synthesized through introducing the intercalation of POM with Keggin-type into the layers of Ni-Al HTLc using ion exchange reaction method. The results demonstrated that the introduction of magnetic substrates into the POM-HTLc did not affect the typical layered structure of hydrotalcites. Macroporous magnetic HTLc material with 1.04 nm of inter space was obtained. The structure and thermal properties of as-mde samples were characterized by FT-IR, XRD, TG-DSC techniques. Thermal stability of HTLc was higher than precursor accordingly. Thermal decomposition and layer destruction of POM anion in HTLc occurred at the same time and the temperature was lower than decomposition temperature of POM.更多还原