【作者】 颜学敏；

【导师】 雷家珩；

【作者基本信息】 武汉理工大学 ， 材料物理与化学， 2007， 博士

【摘要】 介孔材料自1992年被报道以来，由于其广泛的应用前景和科学内涵，目前已成为化学和材料学科的前沿和热点。近两年来其研究论文每年接近2200篇，研究内容主要集中在：（1）不同元素组成、骨架结构和介孔形貌的有序介孔材料的合成及其特性研究；（2）合成方法和技术的优化；（3）有序介孔材料的表面功能化及其应用等。本论文的工作主要是将介孔材料的研究与世界范围内的环境恶化问题相结合，通过设计并合成具有高催化活性的杂多酸／介孔氧化硅纳米复合材料，结合介孔材料在大分子催化反应方面的独特性能将其与杂多酸进行复合，并用于柴油中大分子有机硫化物的氧化脱除研究，考察了不同介孔复合材料及其制备方法对催化活性的影响，并探讨了其催化作用机理。从而得到了3种新的柴油深度脱硫催化剂，并解决了杂多酸的固载问题。本论文的主要创新点包括：1、用γ-氨丙基三乙氧基硅烷（APTES）表面改性介孔氧化硅SBA-15，通过氨基的固定作用，将具有Keggin结构的磷钨酸（HPW）和磷钼酸（HPMo）通过传统的浸渍法固载在改性SBA-15表面，制备出具有以氨基为过渡层（Amino）的三元有序夹心复合材料HPW／Amino／SBA-15和HPMo／Amino／SBA-15。通过比较这两种负载型杂多酸催化剂对二苯并噻吩（DBT）的催化氧化作用，发现负载的HPW催化剂具有更高的催化活性。在杂多酸的固载过程中，虽然较低的酸性环境和回流时的高温导致了磷钨酸部分降解，并影响到其催化性能，但负载后的催化剂容易分离和重复使用，经5次循环后，其催化活性没有发生明显的变化。2、以十六烷基三甲基溴化铵（CTAB）为模板剂，正硅酸乙酯（TEOS）和HPW为无机源，一步合成出具有介孔结构的HPW／SiO₂（记为HPW／SiO₂（Ame））纳米复合材料。同时通过sol-gel法制备出微孔结构的HPW／SiO₂（记为HPW／SiO₂（Ami））复合材料。通过比较上述两种具有不同孔径的负载型杂多酸催化剂对DBT溶液的催化氧化活性，发现介孔HPW／SiO₂（Ame）纳米复合催化剂对大分子的DBT的氧化脱硫具有更高效的催化活性。从而说明介孔结构在大分子DBT的催化氧化中起到了重要的作用。该催化剂保持了杂多酸的Keggin结构，DBT的转化率在2小时内可以达到99.4％，循环使用7次后，DBT的转化率在2小时内为80.6％。3、以TEOS和HPW为无机源，以三嵌段共聚物聚环氧乙烷-聚环氧丙烷-聚环氧乙烷（PEO-PPO-PEO，P123）为模板剂，通过挥发诱导自组装方法一步合成出具有介孔结构的HPW／SiO₂（记为HPW／SiO₂（E-x％））纳米复合材料。该方法的主要策略是利用HPW的酸性来催化正硅酸乙酯的水解，并与正硅酸乙酯水解后形成带正电荷的硅物种通过静电作用形成Si-HPW聚集体，随着溶剂的挥发与模板剂胶束组装形成有序的介观结构。该催化剂保持了杂多酸的Keggin结构，在DBT类有机硫化物的催化氧化中具有优异的催化活性，DBT的转化率在2小时内可以达到99.6％，经7次循环使用后无明显的催化活性损失。4、研究了柴油中各种典型有机硫化物单组分模拟体系的催化氧化反应动力学，发现有机硫化物的表观活化能顺序为二苯并噻吩＞4，6二甲基二苯并噻吩＞苯并噻吩。探讨了HPW／SiO₂（E-x％）纳米复合材料催化氧化柴油中典型有机硫化物的反应机理，发现其催化作用机理与典型的Ishii-Venturello催化机理相一致，即固载在介孔氧化硅上的Keggin阴离子[PW₁₂O₄₀]^3-首先被H₂O₂氧化为过氧多酸阴离子，DBT类有机硫化物在介孔孔道中扩散并与催化活性中心过氧多酸阴离子接触，使得富电子的硫原子被氧化形成相应的砜。通过乙腈溶剂的萃取作用将砜从石油醚溶液中分离出来以达到脱硫的目的。5、研究了HPW／SiO₂（E-x％）纳米复合催化剂对真实油品中的催化氧化脱硫性能。对硫含量为1800μg／g的直馏柴油的氧化脱硫研究发现，经过4h的反应，直馏柴油中的硫含量从1800μg／g降低到312μg／g，脱除率达到82.7％。催化剂经3次循环使用后无明显活性损失。研究了柴油中烃类物质对HPW／SiO₂（E-x％）对油品催化氧化脱硫的影响，发现烷烃对DBT的选择氧化影响基本没有影响，而烯烃和芳烃对DBT的氧化有明显影响。6、利用Ag⁺离子改性HPW／SiO₂（E-x％）催化剂，通过Ag⁺离子对多环噻吩的Л-络合作用，将吸附过程与氧化过程相结合，对柴油中的苯并噻吩（BT）和DBT类有机硫化物进行选择性氧化，取得良好的脱硫效果。经过4h的反应，直馏柴油中的硫含量从1800μg／g降低到228μg／g，脱除率达到87.3％。催化剂经3次循环使用后无明显活性损失。更多还原

【Abstract】 Since its report in 1992, the mesoporous material has become the leading edgeand hot issue in the field of chemistry and materials as a result of its broad applicationprospect and scientific connotation. In past two years, the amount of research papersrelated to mesoporous material has run to approximately 2200 each year and theresearch contents mainly focus on the following aspects: （1） research on the synthesisand features of ordered mesoporous material with different elements, skeletonstructure and mesoporous morphography; （2） synthetic method and techniqueoptimization; （3） Functionalization and application of ordered mesoporous material.This paper is to combine the research of mesoporous material with the globalenvironmental deterioration. By designing and synthesizing heteropoly acid with highcatalytic activity/mesoporous silicates composition, the author tries to recombinemesoporous material with heteropoly acid on the basis of the uniqueness ofmesoporous material in macromolecule catalytic reaction and to apply it to theresearch on oxidative desulfurization of macromolecule organic sulfide in diesel fuel.This paper has investigated different mesoporous composite materials as well as theinfluence of their preparation method on catalytic activity and probed into its catalysismechanism. The fruits of this paper are that we have obtained three kinds of newcatalysts with drastic desulfurization of diesel fuel and solved the immobilization ofheteropoly acid. The innovative points of this paper are listed as follows:1. Usingγ-ammonia propyl-triethoxysilicane alkane （APTES） surfacemodification mesoporous silicate SBA-15 and by the fixation of amino, the author hasimmobilized phosphotungstic acid （HPW） and phosphomolybdic acid （HPMo）with Keggin structure on the surface of modification SBA-15 by means of traditionalimmersion method. As result, the triconstitutent nanocomposites with amino moietiesas the transition layer, i.e. HPW/Amino/SBA-15 and HPMo/Amino/SBA-15 wereobtained. By comparing the catalytic oxidation of two kinds of loading heteropolyacid catalyst to dibenzothiophene （DBT） in solution, the author has discovered thatloading HPW catalyst possesses much higher catalytic activity. In theimmobilization process of heteropoly acid, low acidic environment and high refluxingtemperature can result in partial retrogradation of phosphotungstic acid, but itscatalytic activity has no evident change after five circles, due to easy separation andresuage for the loading heteropoly acid. 2. With hexadecyl trimethyl ammonium bromide （CTAB） as template and withethyl orthosilicate （TEOS） and HPW as inorganic source, the author has synthesizedHPW/SiO₂ nanocomposite material with mesostructure in one pot. In comparasion,HPW/SiO₂ composite material with microporous structure was also prepared （referredto HPW/SiO₂（Ami））. By comparing the catalytic oxidation activity of the above twoloading heteropoly acid catalysts with different pore structure and charactarization toDBT solution, the author has also discovered that mesoporous HPW/SiO₂（Ame）nanocomposite catalyst has higher oxidative desulfurization catalytic activity onmacromolecular DBT oxidation, which illustrates that mesostructure plays a key roleon catalytic oxidation of macromolecular DBT. This catalyst has preserved the Kegginstructure of heteropoly acid. The frist percent conversion of DBT was 99.4% withintwo hours, and after seven usages, that could be 80.6%.3. With TEOS and HPW as inorganic source and with triblock copolymerpolyethylene oxide- polypropylene oxide- polyethylene oxide （PEO-PPO-PEO, P123）as template, the author has synthesized mesoporous HPW/SiO₂ nanocompositematerials （referred to HPW/SiO₂（E-x%）） by evaporation-induced self-assemblymethod. The main strategy of this method is to utilize the self-generated acidity ofphosphotungstic acid （HPW） to drive tetraethoxysilane （TEOS） hydrolysis. TheTEOS hydrolysis leads to forming the positive charge silicate species that cancombine with HPW anion to form colloidal Si-HPW entities resulting from the staticinteraction. These Si-HPW entities can be assembled to form mesostructure withsolvent evaporation. This catalyst has preserved the Keggin structure of heteropolyacid and possesses excellent catalytic activity in the catalytic oxidation process ofDBT organic sulfide. The percent conversion of DBT can reach 99.6% within twohours while that has no evident catalytic activity loss after seven periodic duties.4. Based on the research of the catalytic oxidation reaction kinetics of varioustypical organic sulfide single component imitation systems, the author discovers thatthe order of the apparent activation energy of organic sulfide is that dibenzothiophene＞4,6 Dimethyl-dibenzothiophene＞benzothiophene. Probing into the catalyticoxidation reaction mechanism of HPW/SiO₂（E-x%） nanocomposites for typicalorganic sulfide in diesel oil, the author brings to light that its catalytic mechanism ofaction is in consistent with typical Ishii-Venturello catalytic mechanism, i.e., Kegginnegative ion [PW₁₂O₄₀]^3- immobilizing on mesoporous silicate is firstly oxidized asperoxoicpolyacid negative ion by H₂O₂, and then DBT organic sulfide diffuse into mesopores and contacts with catalytic activity center, as a result, electron-rich sulfuratom are oxidized into correspondent sulphone. The final desulfurization wereachieved after the sulphones were extracted out from oil solution using acctonitiles asextracting agents.5. The effect of HPW/SiO₂（E-x%） nanocomposite catalyst on catalytic oxidationin actual petroleum product have also been investigated. By researching on theoxidative desulfurization of straight-run diesel oil with sulfur content of 1800μg/g, itis discovered that the sulfur content of straight-run diesel oil decreases from 1800μg/gto 312μg/g and thedesulfurization rate reaches 82.7% after 4 hours’ reaction. Thecatalyst has no evident activity lose after three usages. The influence of hydrocarbonmaterial in diesel fuel on catalytic oxidative desulfurization of petroleum productwere investigated, the author discovers that hydrocarbon of methane series almost hasno effect on oxidation of DBT, while olefin hydrocarbon and aromatic hydrocarbonhave evident effect on DBT oxidation.6. Ag⁺ ion was used to modify the HPW/SiO₂（E-x%） catalyst. Using theЛ-complexing action of ion Ag⁺ to multiring thiofuran, the desulfurization process cancombine adsorption with oxidation. The catalyst can selective oxidize BT and DBTorganic sulfide in diesel fuel, it has achieved excellent desulfurization effect. Afterfour hours of reaction, the sulfur content of straight-run diesel oil decreases from1800μg/g to 228μg/g and the rate of desulfurization rate reach 87.3%. The catalyst hasno evident activity loss after three usages.更多还原