【作者】 罗劭娟；

【导师】 奚红霞；

【作者基本信息】 华南理工大学 ， 化学工程， 2010， 硕士

【摘要】 随着现代工业的发展,环境问题的日益突显,传统的微孔材料由于较小的孔径及孔容,使其在涉及大分子的环境污染治理中受到了限制。近年来出现的介孔材料不仅具有孔道大小均一、结构排列整齐有序、孔径可以在2~50nm范围内连续调节等重要特征,并且以其高的比表面积、较大的孔容使得这类材料在吸附、催化、药物缓释等涉及大分子的分离、反应领域具有广阔的应用前景而备受人们关注。目前在介孔材料研究领域,面临的主要挑战是来自生产实际的需要,现有的介孔材料还不能完全满足多数应用的要求,并且高质量的介孔材料的制备过程大多比较繁琐、能耗较大,同时由于其结构的复杂性,使其微细结构及形成机理尚不明确,进而影响其结构调控和构效关系预测。因此,开发介孔材料的简单绿色合成方法、揭示其微细结构及形成机理、预测其构效关系、拓展其应用领域等成为介孔材料研究领域的人们课题。鉴于此,本文选取几种典型的介孔材料,就其合成工艺、合成机理、改性及其在吸附、催化方面的应用进行深入研究,为这些介孔材料的实用化提供理论和技术基础。第一,本文采用P123(PEO20PPO70PEO20)为模板剂,TEOS为硅源试剂,在强酸性条件下制备合成出中微双孔分子筛SBA-15,考察模板剂与硅源的摩尔比、离子导向剂、水浴老化温度以及共溶剂N,N-二甲基酰胺(DMF)对中微双孔分子筛SBA-15的孔结构参数,介孔有序性以及形貌等方面的影响。通过优化合成条件,得到制备高质量的中微双孔分子筛SBA-15的最佳合成条件。随后,以Gaussian链的形式对三嵌段共聚物P123(PEO20PPO70PEO20)及正硅酸四乙酯(TEOS)进行粗粒化描述,采用介观动力学(MesoDyn)方法模拟了介孔分子筛SBA-15形成过程中模板剂P123与硅源试剂TEOS的协同自组装过程,探讨了P123/TEOS超分子聚集结构对于SBA-15独特的二维六方结构形成过程的影响;同时还通过向体系引入稳恒剪切力来代替实际搅拌外力,模拟再现了SBA-15分子筛的六角介观相的形成过程。借鉴微孔分子筛的研究经验,利用介观模拟方法揭示介孔分子筛的形成过程和机理是本文的创新之处。第二,本文采用微波辐射晶化法,利用沸石纳米粒子的自组装分两步合成出Beta-MCM-41型中微双孔分子筛,成功地将微孔沸石的初级和次级结构单元引入到介孔分子筛MCM-41的孔壁中,从而在MCM-41有限的孔壁空间中形成了部分微孔结构,且合成的Beta-MCM-41型分子筛具有较大的比表面积和孔容,且孔径均一。用微波法取代传统能耗大、时间长的水热法快速合成新型Beta-MCM-41中微双孔分子筛,也是本文的新意之处。随后,本文分别用Beta、MCM-41、SBA-15、Beta-MCM-41四种分子筛及γ-Al2O3作为载体,通过等体积浸渍法制备了含15%Mo、3%Co和3%Ni的催化剂,在间歇高压加热反应釜内初步考察了六种催化剂对含二苯并噻吩(DBT)的模拟油品的催化加氢脱硫的活性。通过绘制六种催化剂的反应动力学曲线,得出六种催化剂的催化活性大小为:Co-Mo-Ni-Beta-MCM-41> Co-Mo-Ni-MCM-41> Co-Mo-Ni-γ-Al2O3> Co-Mo-Ni-SBA-15>商业Co-Mo-Al2O3> Co-Mo-Ni-Beta。新型Beta-MCM-41中微双孔分子筛显示出较好的燃油加氢脱硫性能,且其加氢脱硫反应为一级动力学反应。第三,本文利用呋喃甲醇和蔗糖为碳源前驱体、以SBA-15为硬模板成功合成出了两种介孔碳CMK-5和CMK-3,并用过硫酸铵和硫酸的混合液对介孔碳CMK-5进行改性,得到具有与CMK-5相同的介孔六方相结构、但具有更强表面酸性的的介孔碳CMK-5-COOH;用三嵌段聚合物F127、正硅酸四乙酯TEOS和蔗糖在浓硫酸的催化作用下通过一步EISA自组装得到大孔径、大孔容和高比表面积的介孔碳FMC。测定三种染料分子在商业活性炭和上述四种介孔碳上的吸附等温线表明,三种染料分子在五种吸附剂上的吸附都属于优惠型吸附,且在介孔碳上的吸附均优于商业活性炭。羧基化的CMK-5-COOH对碱性染料的吸附能力得到进一步的提高,而用简单一步法自组装法合成的FMC对Acidic/azo类染料甲基橙有很好的吸附能力,约为商业活性炭的3.5倍。用蔗糖取代制作工艺繁杂的酚醛树脂醇溶液作为碳源前驱体,一步自组装合成介孔碳是亦是本文的新意之处。更多还原

【Abstract】 With the development of modern industry, the environmental problems become more and more serious. The practical applications of the traditional microporous materials on macromolecular pollutants treatment are becoming more restricted because of their small pore size and small pore volume. Recently, Mesoporous materials have attracted much more attention due to some advantages, such as their uniform pore structure, their ordered pore arrangement, as well as their controllable pore size in the range of 2 to 50 nm, their high surface area and pore volume, which are expected to be widely used in the fields involving macromolecules, such as adsorption, separation, catalysis, drug control-release and et al. At present, the main challenge mesoporous materials must face is from the practical applications. The existing mesoporous materials still could not satisfy the all requirements from the practical applications, while the time-consuming preparation process of high quality meosporous materials leads to high energy consumption. Simultaneously, the fine structure and the formation mechanism of mesoporous materials are still ambiguous as a result of their complicated structure, which have a serious impediment to the structure regulation of mesoporous materials and the structure-properties relationship forecast. Therefore, developing simple, green synthetic methods used for the preparation of mesoporous materials, revealing their fine structure and the formation mechanism of mesoporous materials, forecasting the structure-properties relationship of mesoporous materials and broadening the application areas have become the hot topics among the mesoporous materials area. In view of all mentioned above, in this paper, the synthesis process, the formation mechanism, the modification technology and the adsorption/catalysis properties of several kinds of typically mesoporous materials are investigated in order to provide theory and technology support for the practical application of these mesoporous materials.First of all, the micro-mesoporous molecular sieve SBA-15 is prepared under the strong acidic condition by using P123 (PEO20PPO70PEO20) and TEOS as the template and silicon source reagent respectively. The effect of the molar ratio of P123 to TEOS, the types of the ion induced agent, ageing temperature and the types of co-solvent (DMF) on the structure properties, the degree of order of mesopores and morphology of the micro-mesoporous sieve SBA-15 have been investigated. Finally, the optimal synthesis condition of high quality micro-mesoporous molecular sieve SBA-15 is obtained through the experiments.Afterward, the Gaussian chain is employed to roughly describe the triblock copolymer P123 and TEOS. Mesoscale Dynamics simulation method (MesoDyn) is performed to investigate the super-molecular self-assembly process between the template (triblock copolymer P123) and the silica source (TEOS) during the formation of micro-mesoporous silica SBA-15, and the 2D hexagonal mesophase formation process of SBA-15 is also studied by introducing the steady shear instead of the stirring in the actual experiments. Moreover, the effects of super-molecular aggregates (P123/TEOS) on the formation of SBA-15 are analyzed too. In this paper, Mesoscale Dynamic simulation method is employed to investigate the formation process and the formation mechanism of the mesoporous molecular sieve SBA-15 by reference to the experience in studying the microporous molecular sieves, which is the innovation of this paper.Secondly, the micro-mesoporous molecular sieve Beta-MCM-41 is synthesized in two steps via the self-assembly of zeolite nanoparticles under the microwave radiation The primary and secondary building units of zeolite nanoparticles are successfully introduced into the pore walls of the mesoporous molecular sieve MCM-41, and the micro-mesoporous molecular sieve Beta-MCM-41 with large surface area and large pore volume, coupled with the uniform pore diameter is obtained. In this paper, the energy-consuming and time-consuming hydrothermal synthesis method is taken place by the energy-saving and time-saving microwave radiation method to quickly prepare the novel micro-mesoporous molecular sieve Beta-MCM-41, which is also a new point of this paper.Then, the catalysts for fuels hydrodesulfurization (HDS) are prepared by loading 15%Mo, 3%Co and 3%Ni on the lab-prepared Beta, MCM-41, SBA-15, Beta-MCM-41 andγ-Al2O3 respectively via impregnation, and then their HDS activity is investigated by using the dibenzothiophene (DBT) as a substitute for real fuels in the high pressure heating reaction still. The reaction kinetics study shows that the catalytic activity of the six catalysts followed in the following order: Co-Mo-Ni-Beta-MCM-41> Co-Mo-Ni-MCM-41> Co-Mo-Ni-γ-Al2O3> Co-Mo-Ni-SBA-15> commercial Co-Mo-Al2O3> Co-Mo-Ni-Beta. The novel micro-meso- -porous molecular sieve Beta-MCM-41 demonstrates a good performance in HDS of fuels. The HDS reactions catalyzed by the six catalysts are all first-level dynamic reactions.Finally, the mesoporous carbon CMK-5 and CMK-3 are synthesized by taking furfuryl alcohol and sucrose as carbon source, and SBA-15 as hard template. And then the mesoporous carbon CMK-5 is modified by using the mixture of (NH4)2S2O8 and H2SO4 to get a new carboxylated mesoporous carbon CMK-5-COOH with the same hexagonal structure as CMK-5 and much stronger surface acidity. Subsequently, the mesoporous carbon FMC with large pore diameter, large pore volume and surface area is prepared employing triblock copolymer F127, TEOS and sucrose via one-step EISA catalysted by H2SO4. The adsorption isotherms of three kinds of dyes on commercial activated carbon and above four kinds of mesoporous carbons show that the adsorption of dyes on five kinds of adsorbents belong to benefit one, and the dye adsorbability of four mesoporous carbons is better than that of the commercial activated carbon. The basic dye adsorbability of the carboxylated CMK-5-COOH is much better than that of the CMK-5 due to the increasing surface acidity. The acidic/azo dye (methyl orange) of the mesoporous carbon FMC is proved to be excellent, approximately 2.5 times more than that of the commercial activated carbon. In this paper, the mesoporous carbon FMC is quickly and easily synthesized by taking sucrose as a carbon source instead of phenol aldehyde resinol, which is another new point of this paper.更多还原