【作者】 徐斌；

【导师】 许宪祝；

【作者基本信息】 哈尔滨工业大学 ， 无机化学， 2012， 硕士

【摘要】 多级孔材料由于其具有较高的水热稳定性和较大的比表面积，因此被广泛应用于催化、吸附、离子交换等领域。目前的多孔材料主要以纳米材料为主，纳米多孔材料在催化剂的重复利用时必须经过繁杂的离心分离过程，以实现催化剂的分离。而具有宏观尺寸的多级孔材料则可以实现催化剂的自动分离，从而省去复杂的离心过程，对于催化剂的工业应用具有重要意义。本论文利用水热合成法，成功合成了具有宏观尺寸的含铁硅基微球FeSil-HPB，并利用SEM、XRD、FT-IR、UV-vis、N2吸附-脱附等手段对样品进行了表征，并系统的研究了合成条件中碱源的种类、碱源的含量、树脂含量、铁源的种类以及陈化温度等对合成产物的影响，并利用XPS对样品Fe的存在价态进行了分析。为了研究FeSil-HPB的催化活性，将其用于苯酚及大分子萘酚的羟基化反应，以及苯的苄基化反应，并对实验过程中的实验现象进行了理论分析。实验结果表明，当碱源为具有一定碳链的TPAOH或TEAOH，且碱含量高于一定值时（TEOS:TPAOH的摩尔比小于1:0.21）才能获得FeSil-HPB，当树脂含量越低时所得产物中铁的存在状态越单一，当为5%时，铁基本以骨架内四配位铁的形式存在。FeSil-HPB的孔径分布较大，除存在微孔外，在20-50nm范围内均有孔存在。对与样品中铁的价态分析发现，样品中的铁以Fe3+和Fe2+两种形式存在，分析认为这主要是由于碱性条件下酒石酸钾钠的还原性和焙烧过程中产生还原性气体CO共同作用的结果。在催化应用方面，催化剂可以保持完整微球结构，可以实现催化剂与反应液的自动分离。此外，催化剂对苯酚及1-萘酚的羟基化反应都表现出了较强的催化活性，这与样品的孔径尺寸较大，便于反应物的运输有关。对于苯酚的羟基化反应，催化剂可实现四次重复利用，但仍然存现在活性中心流失的问题。对于苯的苄基化反应，我们发现，不同的产物表现出了差别较大的性质，经分析发现这与产物中纳米氧化铁团簇的量有关，纳米氧化铁团簇的可以起到活化苯的作用，从而可以加快反应的进行。更多还原

【Abstract】 Hierarchically porous materials are widely used in catalysis, adsorption, ionexchange and other fields, because of their high hydrothermal stability and largespecific surface area. Most of porous materials are in form of nanosized particlesand they must go through the complex centrifugal separation process in order toachieve the reuse of the catalyst. The beads with macroscopic morphology canachieve straightforward separation from liquid medium, in which the complexity ofthe centrifugation process would be eliminated. From view of catalysis, this is ofgreat significance for the industrial applications of the catalyst.In our work, hydrothermal method was successfully used to synthesizehierarchically porous ferrosilicate beads (FeSil-HPB), which were characterized bySEM, XRD, FT-IR, UV-vis, XPS and N2adsorption-desorption measurement.Synthetic conditions have been widely studied, such as type and contention ofbase, resin content, iron source, the aging temperature and so on. Furthermore,FeSil-HPB was used to catalyze the hydroxylation of phenol and naphthol andbenzylation of benzene reaction. The characterization results showed that the beadswith hierarchical porosity could be successfully prepared in the media of TPAOH orTEAOH. The contention of the bases and content of resin have a big influence onthe shape and structure of the beads. Based on the characterization results of UV-visand XPS, it is concluded that the iron presence in the forms Fe3+and Fe2+and mostof them are tetrahedrally coordinated in the framework. The porous ferrosilicatebeads showed highly catalytic activity in both small and bulky substrates, forexamples in the hydroxylation of phenol and1-naphthol. The high activities aremainly due to the presence of hierarchically porosity with large mesopores, whichfavors mass transport of reactants. The beads could be recycled to an acceptedcontent after easy regeneration through room temperature washing in thehydroxylation of phenol, but loss of the active center still occurred. The ferrosilicatebeads also proved to be active in the benzylation of benzene. We found that thenature of iron coordinated environment and nano-iron oxide clusters might play animportant role in determining the reaction rate. More importantly, in the procedureof heterogeneous catalysis, the beads can remain the integrity of the structure and morphology during stirring. Therefore, the beads can achieve straightforwardseparation from the reaction mixture.更多还原