Synthesis And Catalytic Properties Of Copper Manganese Silicate With Mesoporous Structure

Nano composite materials were consisted by two or multi-phase materials that owned special properties, which were better than that of single component. Mesoporous composite materials were usually formed by coating one material on the surface of other materials. In recent years, mesoporous structure composite materials had potential applications in catalysis, biological medicine, drug release and battery, etc. Transition metal silicates were environmental friendly catalyst materials, compared with general silicate catalyst, mesoporous structure of transition metal silicate catalysts exhibited better catalytic performance.The study and results of this dissertation mainly include the following aspects:（1） Preparation and characterization of copper silicate and manganese silicate with mesoporous structureMesoporous copper silicate and manganese silicate microspheres with uniform dispersion were synthesized by hydrothermal method in alkaline conditions of ammonia, using silica as template, copper acetate and manganese acetate as copper source. The factors of reaction time and ammonia on the morphology and structure of the products were investigated. The factors of reaction time and ammonia on the morphology and structure of the products were also studied. The BET surface areas of copper silicate hollow microspheres and manganese silicate hollow microspheres were 483.29 cm2/g and 229.72 cm2/g, respectively.（2） Synthesis and characterization of copper manganese silicate with mesoporous structureCopper manganese silicate composite materials were prepared by two-step template combined with hydrothermal method, using core-shell structure manganese silicate as template, copper acetate as raw material. The factors of molar ratio of core-shell manganese silicate/ copper and reaction time on morphology of composite products were studied. Furthermore, formation process of copper manganese silicate composite materials was also discussed. The BET surface areas of the composite microspheres corresponding to manganese silicate/copper molar ratio of 2:1, 1:1, 1:2 were 330.828 m2g-1, 450.071 m2g-1 and 466.244 m2g-1, respectively. While, the BET surface areas of the composite microspheres corresponding to reaction time of 6 h, 12 h, and 24 h were 241.958 m2g-1, 347.756 m2g-1 and 450.071 m2g-1, respectively.（3） Study on the catalytic performance of Cu-Mn/SiO₂ catalystCopper manganese silicate composite microspheres prepared by two-step template method were reduced in hydrogen atmosphere for 550 °C,3 h, then Cu-Mn/SiO₂ composite microspheres catalyst were obtained. The catalysts were used for catalytic hydrogenation of nitrobenzene, factors of reaction temperature（°C）, hydrogen pressure（MPa）, reaction time（h） and mass ratio of nitrobenzene to catalyst（s/c） were investigated and analyzed by orthogonal test.Combined with the effects of different experimental factors on the conversion of nitrobenzene and the selectivity of aniline, the optimum reaction condition was: reaction temperature of 120 °C,reaction pressure of 4 MPa, reaction time of 5 h and s/c of 25. Under this optimum condition, the conversion rate of nitrobenzene reached 87.32% and the selectivity rate of aniline attained 94.25%. The catalytic performance of all catalysts was investigated under the optiumum reaction condition, results showed that the catalytic activity of bimetallic catalysts was higher than that of single metal catalysts owing to the synergistic effect between two metals, the catalysts with the molar ratio of 1:1, reaction time of 24 h showed the best catalytic performance.