【作者】 陶莉；

【导师】 晁自胜；

【作者基本信息】 湖南大学 ， 化学工程与技术， 2009， 博士

【摘要】 绿色化学的核心是“原子经济性”,而提高“原子经济性”的关键手段非催化莫属。就目前来说,关于工业催化剂的设计、制备及其应用已能满足大多数化学反应的需求,但仍难满足人们对理想“绿色化学”的期望,有关新型的高性能结构催化剂设计和制备仍然任重道远,是当前和今后化学工业与材料科学等相关学科的研究重点。目前高性能结构催化剂大多为纳米结构材料,主要采用自组装方法进行合成。本论文致力于以五种结构规整和完善（well-defined）的分子为自组装前体,来进行高性能结构催化剂的定向设计合成,并以所合成的材料为催化剂应用于几种具有工业价值的绿色反应中。希望能通过这些研究工作对以后高性能结构催化剂的开发及在绿色化学中的应用提供科学指导和有益的借鉴。本论文的主要研究工作及研究成果如下:1、金属掺杂的SBA-15超分子组装合成通过表面活性剂超分子组装原位合成了掺杂一系列金属掺杂的SBA-15,考察了酸介质的种类、表面活性剂的种类及其组合、合成体系组成等各种因素对于材料合成的影响,并通过XRD、TEM、DRS UV-Vis等技术对所合成材料的结构和性能进行了详细的表征。在以钨酸钠为钨源、P123为模板、盐酸或磷酸为合成介质的条件下,采用原位合成了W-SBA-15。与盐酸介质中的合成相比较,磷酸介质中合成的W-SBA-15具有更高的孔道有序度、W的掺杂量以及材料的酸量;在混合表面活性剂为模板的合成体系中,离子表面活性剂的加入,使合成体系中的组装驱动力由单一的氢键驱动变为氢键和静电作用,混合胶束与无机物种间的自组装行为加强,从而增加了材料的有序度。其中,W-SBA-15的合成中,CTAB的加入,提高了W在介孔材料中的掺杂量,且在磷酸介质中,合成的材料的形貌比较均一;SDBS的加入,改善了Cr-SBA-15的结晶性能,有效提高了材料的孔道有序性。首次将磷酸介质中合成的W-SBA-15应用于H₂O₂/O₂氧化的油酸一步法制备壬二酸反应。当介孔材料中掺杂的W只以四配位形式存在,且W /Si摩尔比为0.025时,壬二酸的收率为43.6%,纯度96.7%。2、非离子表面活性剂导向下锰氧化合物纳米管的合成分别以非离子表面活性剂脂肪醇聚氧乙烯醚（AEO₉）、壬基酚聚氧乙烯醚（TX-10）为模板,辅以氧化还原,一步法合成了管壁为介孔结构的水锰矿（γ-MnOOH）纳米管,并详细研究了反应原料配比、合成温度以及助还原剂对材料合成的影响,对合成的样品的结构和性能进行了TEM等表征。以KMnO₄为氧化剂、MnCl₂·4H₂O为还原剂以及CH₃CHO为助还原剂,凝胶于100℃下晶化24小时,以TX-10或AEO₉为模板均合成出了水锰矿（γ-MnOOH）纳米管,其中后者表现为竹节状。3、PAMAM导向下有机-无机复合材料的合成通过发散法分别合成了乙二胺为核心的1.0³.0代的PAMAM,己二胺为核心的1.0².0代PAMAM,对苯二胺为核心的0.5代PAMAM,并采用ESI-MS, ¹H NMR, DTG-TG, FT-IR等技术对其结构进行表征。以硝酸镧为无机物种,通过调控PAMAM的核心,并以其为模板,水热调控合成了不同形貌的有机无机复合材料,其中脂肪烃二胺为核的为棒状形貌,芳香烃二胺为核的则为串珠状形貌。以硝酸镧、硝酸铜、硝酸钴、硝酸银为无机前驱体,以EPAMAM-1.0为模板,分别水热合成了La-Co-EPAMAM,La-Cu-EPAMAM,La-Ag-EPAMAM有机-无机复合材料。在EPAMAM-1.0与非离子表面活性剂AEO₉混合模板的存在下,以硝酸镧为无机物种,水热合成了含稀土镧的纳米管。并采用TEM、FT-IR等技术对合成的有机无机复合材料进行了表征。将合成的有机-无机复合材料应用于以O₂为氧化剂,环己烷的温和氧化制备KA油的反应中,均具有一定的催化活性,且Co、Cu、Ag的加入使得催化活性进一步提高。不同代数的EPAMAM为模板合成的La³⁺-PAMAM为催化剂时,催化活性接近,环己烷的转化率为7%左右,KA油的选择性为94%左右;以EPAMAM-1.0为模板合成的La-Co-EPAMAM,La-Cu-EPAMAM,La-Ag-EPAMAM有机无机复合材料的催化活性较单一的La³⁺-EPAMAM有所提高,环己烷的转化率分别为7.83、7.46、6.33%,KA油的选择性分别为98.4、96.4、94.5%。4、TS-1晶核溶液下,离子液体导向TS-1分子筛的合成详细地考察了离子液体的种类、碱源、晶化温度、矿化剂等因素对TS-1分子筛合成的影响。结果发现:在以1-乙基-3甲基四氟硼酸咪唑盐（EmimBF4）为模板、正丁胺为碱源、F-为矿化剂、晶化温度为140℃及晶化时间为70小时的条件下,合成出的TS-1具有较高的结晶度。其中,在以HF为矿化剂和酸调节剂、EmimBF4为模板、TS-1晶核溶液存在条件下,合成的TS-1分子筛具有棒状形貌,且分子筛中的Ti全部以四配位形式存在,同时免除了传统TS-1合成工艺中蒸馏去除乙醇以及焙烧脱除模板的过程。将含有离子液体EmimBF₄的TS-1应用苯/H₂O₂羟基化制备苯酚的反应中,苯酚的选择性高达100%;应用于苯乙烯/H₂O₂制备苯甲醛和苯乙醛的反应中,仅生成苯甲醛和苯乙醛两个产物。5、以冰晶为模板多孔材料的合成以冰晶为模板进行了介孔Si-Al氧化物材料和ZSM-5微孔分子筛的绿色合成的探索研究。其中介孔Si-Al氧化物材料分别以硅酸钠、硝酸铝为硅源、铝源,其BET比表面积为46.86 m²/g,孔体积为0.18 cm³/g;ZSM-5分子筛以硅溶胶、硫酸铝为硅源和铝源,其骨架中硅铝比小于25,BET比表面积为168.9 m²/g。冰晶所形成的五元环,与ZSM-5的五元环具有相似的结构,结合本研究中的实验现象和结果,推测了冰晶模板合成ZSM-5的可能机理。将合成的ZSM-5经过NH₄NO₃离子交换制备成H-ZSM-5,并将其用作乙醇脱水制备乙烯的催化剂。发现该催化剂与Si/Al=25的商品化HZSM-5相比,具有与相近的催化活性。更多还原

【Abstract】 “Atom economy”is the core of“green chemistry”and can be achieved by employing high-performanced structuring catalysts. While the design, synthesis and application of catalysts have met the general requirements of most chemical reactions currently in chemical industry, it is still a far way to improve further the reactivities and properties of catalysts under the requirement of“green chemistry”. The construction of high-performanced structuring catalysts is thus constitutes one of the most important hot-points and has been paid much attention from both academic and industrial domains all over the world. A high-performanced structural catalyst, as an advanced functionalized material, is characteristic of its unique architecture constructed with building blocks in certain regularity and specific properties regulated by its structure. As far as to the current technique, the high-performanced structural catalysts are mainly prepared via the molecular self-assembly route, which can generated ordered structures with an ordering in molecular or atomic levels, under weak interactions, such as, hydrogen bond, van der Waals forces and coulomb forces.. This dissertation was concentrated on the directional design of the high-performanced structural catalysts via molecular self-assembly, involving a few templates like nonionic surfactant, block copolymer, PAMAM dendrimers, ionic liquid and ice crystal as the templates. The performances of the prepared catalysts were evaluated by several selected reactions with industrial value.The dissertation focuses on the following five parts:1. The synthesis of transition metal-modified SBA-15 via supramolecular self-assembly.Transition metal-modified SBA-15 has been synthesized via supramolecular self-assembly of surfactants. Influencing factors, such as, the acidity of medium, the nature of surfactant and the batch composition, are investigated systematically. The specimens are characterized by means of XRD, TEM, DRS UV-Vis, BET, SEM, and NH₃-TPD. W-doped SBA-15 has been synthesized by in situ method, using aqueous H₃PO₄ or aqueous hydrochloric acid as acid medium, P123 as template, sodium tungstate and TEOS as tungsten and silicon resources, respectively. Comparing with those by using aqueous hydrochloric acid, the specimens synthesized in presence of H₃PO₄, have got some advantage such as ordered mesoporous channel, the content of W-doped and the acidity. In the synthesis system of M-SAB-15, using P123 and ionic surfactant as mixed template, the assembly forces between the inorganic and organic compounds are hydrogen bone and electrostatic interaction, which caused the stronger assembly between micelles and inorganic species and the as-synthesized specimens have owned more ordered structure. With CTAB adding, the tungsten in gel solution can be effectively incorporated into bone of SBA-15 and especially, the uniform morphologies of samples are obtained in presence of H3PO4. The additions of SDBS efficiently improve the crystallinity of Cr-SBA-15 and order pore channel.The catalytic properties of W-SBA-15 using H₃PO₄ as acid medium are first applied in the one-step selective oxidation reaction of oleic acid to azelaic acid, using aqueous hydrogen peroxide and O2 as oxidants. The yield and purity of azelaic acid is 43.6%, 96.7% while the molar ratio of W/Si in the gel is 0.025 and tungsten species in the mesoporous materials only with isolated [WO₄] tetrahedral.2. Synthesis of MnO_x nanotube template by nonionic surfactantMnOx nanotube with the wall being composed of monoclinic manganite, is first synthesized via a redox-assisted supramolecular assembly, using KMnO₄ and MnCl₂ as inorganic precusors, acetaldehyde an additive and polyoxyethylene （10） nonyl phenyl ether （TX-10） or polyoxyethylene fatty alcohol （AEO₉） as template. The samples are characterized by XRD, TEM, BET, XPS and Raman. The results of BET discuss that the walls of nanotube possess mesoporous pore. The parameters such as the molar ratio of reactants, temperature, and acetaldehyde are studied in details.3. Synthesis of Organic/inorganic composites template by PAMAM dendrimersA series of PAMAM, including different generations of PAMAM with ethylenediamine-core, generation 0.5².0 of PAMAM with hexanediamine-core and generation 0.5 of PAMAM with p-phenylenediamine-core, are successfully prepared by divergent synthesis and characterized by ESI-MS, 1H NMR, DTG-TG, FT-IR. Then, the PAMAM dendrimers are used as template to prepare the organic/inorganic composites.The morphologies of the lanthanum-contained organic/inorganic composites, using La（NO₃）₃ as inorganic precursor, can easy controlled by simply change the core of PAMAM. The nanorods are obtained template by the PAMAM with aliphatic diamine as core, while the catenular particles using aromatic diamine core. Bimetallic organic/inorganic composites, such as La-Co-EPAMAM, La-Cu-EPAMAM and La-Ag-PAMAM are synthesized by hydrothermal method using generation 1.0 PAMAM with ethylenediamine-core as template, La（NO₃）₃ , Co（NO₃）₂ , AgNO₃ and Cu（NO3）2 as inorganic precursor, respectively. The La-contained nanotubes are synthesized via hydrothermal method, using La（NO₃）₃ as La resource, EPAMAM-1.0 and AEO9 as mixed-templates. The textures of above specimens are tested by some technical measures, such as TEM, FT-IR and so on.The catalytic performances of the above organic/inorganic composites are tested in the oxidation reaction of cyclohexane with molecular oxygen. Compared with La2O3 powders, La-EPAMAM composites template by generation 1.0, 2.0 or 3.0 of PAMAM with ethylenediamine-core have better catalytic activities. The catalytic performances of La-EPAMAM are independent of generation of PAMAM and the conversions of cyclohexane, the selectivity of KA are about 7%, 94%.It is noteworthy that addition of Cu, Co, Ag can promote the activities of the catalysts. Using La-Co-EPAMAM, La-Cu-EPAMAM or La-Ag-PAMAM as catalysts, the conversion of cyclohexane are7.83%, 7.46%, 6.33% and the selectivity of KA are 98.4%, 96.4%, 94.5%。4. Synthesis of TS-1 zeolite using ionic liquid and TS-1 nuclei solution as co-templateThe influencing factors of synthesis of TS-1, such as kinds of ionic liquid, alkali source, temperature and mineralizer type, are studied in details. The specimens are characterized by XRD, FT-IR, SEM, TEM and BET. The results show that TS-1 zeolite synthesized under 140℃for 70h, using 1-ethyl-3-methylimidazolium tetrafluoroborate （EmimBF4） and TS-1 nucleic solution as co-template, n-butyl amine as alkali source, F- as mineralizer, has higher crystallinity. Notably, TS-1 zeolites using EmimBF4 and TS-1 nucleic solution as co-template, HF as mineralizer and acid regulator, is first successfully prepared under weak acidic condition with the rod morphology. The results of XRD and DRS UV-Vis show that Titanium species in the TS-1 zeolites only with isolated [TiO₄] tetrahedral. Comparing with the traditional technology of TS-1, the new process is simplified for without distillation for removing ethanol and calcine for removing the organic template.As similar as commercial TS-1, TS-1 zeolites contained EmimBF4 have special activities in the reaction using dilute H2O2 as oxidant. The catalytic properties of the synthesized specimens are tested in the reaction of benzene with 30 wt% H2O2 to phenol, styrene with 30 wt% H₂O₂ to phenylacetaldehyde and benzaldehyde, respectively. The selectivity of phenol is 100% in the former reaction and the products only including phenylacetaldehyde and benzaldehyde in the latter.5. Green synthesis of porous materials using ice crystal as templateThe green synthesis of Si-Al oxide mesoporous materials and ZSM-5 zeolites are demonstrated. The Si-Al oxide mesoporous materials synthesized by using sodium silicate as Si resource, aluminum nitrate as Al resource, has BET 46.86 m2/g, pore volume 0.18cm3/g. ZSM-5 zeolites using Colloid silica and aluminum sulfate as inorganic precursor, has BET 168.9 m²/g, lower than ZSM-5 synthesized by organic template. The result of FT-IR indicates the molar Si/Al is lower than 25. The five-membered ring formed by ice crystal is similar to that of ZSM-5. Based on experimental results and phenomena, the mechanism of synthesis of ZSM-5 template by ice crystal is postulated.ZSM-5 synthesized by ice template is pretreated by the ionic exchanged method with NH₄NO₃ and then applied in the dehydration of ethanol to ethylene. The results show that the specimen （ice template） has the similar catalyst activity to the commercial HZSM-5.更多还原