The Preparation Of The Ordered Mesoporous Materials And Their Applications

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.