Study On The Synthesis Of Functionized MCM-41 By Manganese Chemical Modification And Manganese Oxide Mesophase

Since 1992 and initial publication by Kresge on the synthesis of varies types of mesoporous silica MCM-41 via the cooperation assembly periodic inorganic and surfactant-based structure. The researches were attracted to develop frameworks of mesoporous silica materials for the uniformly sized pores and the ordered arrangement of hexagonal structure. Since chemical modification has been applied in all of fields as a functionized method, considerable effort has been devoted to functionized MCM-41 by chemical modification so as to produce new functionized materials. In this thesis, the synthesis of the mesoporous silica molecular sieves MCM-41 was introduced, and the work of manganese chemical modification was done, at the same time, the study of manganese oxide mesophase was attempted.Major content of this work includes four aspects as follows:1. The pure mesoporous silica MCM-41 was prepared via the hydrothermal treatment in basic medium. The characteristics of samples were investigated using XRD, HRTEM, N2 adsorption technique and so on, and it was shown that mesoporous silica MCM-41 had been synthesized in this work with uniformly sized pores and long-distance ordered arrangement of hexagonal structure, and the pore size was about 2nm, and could be regulated by the second hydrothermal treatment or the addition of l,3,5-trimethylbenzene(TMB) as organic assistant expander.2. In the process of synthesis of mesoprous silica, manganese ion was doped to substitute partially for silica in the framework and hexagonal mesoporous manganese-containing silica Mn-MCM-41 was prepared. XRD, HRTEM, N2 adsorption isotherm showed the direct evidences for a well-ordered hexagonal nano pore structure. It was revealed that the hexagonal order was destroyed and the phase transition from hexagonal to amorphous structure with the increment of manganese ion, and with the appropriate neutral hexadecylamine (HDA) withcetyltrimethylammonium bromide(CTAB) as mixed template, Mn-MCM-41 wassynthesized with well uniformly pore size and hexagonal mesostructure for the additional function of N-metal covalent bond, and the ordered structure was mediated by the influence on the packing parameter.3. Manganese oxide nanoclusters were synthesized within ordered porous MCM-41 by using wet impregnation technique. The results showed that the nanoclusters of manganese oxide could be successfully confined and distributed into the pores of MCM-41, and pore channels could be destroyed with the introduction of manganese oxide nanoclusters. Simultaneously, the Einstein shift of spectra could be seen and the intensity of fluorescence at 350nm was reinforced with the increment of manganese oxide nanoclusters in the pores.4. The preparation of manganese oxide mesophase via hydrothermal treatment was studied here simply. It revealed that hexagonal structure was easily synthesized in the neutral medium, and lamellar structure was inclined to prepare under basic condition, and from the cooperative charge density matching mechanism and function of manganese iron and template molecular, the alkalescence influence on the structure was explained, and appropriate neutral hexadecylamine (HDA) availed to synthesis of mesophase with more ordered degree for the mediation of packing parameter.