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γ-(三乙氧基硅基)丙胺与MCM-41反应,得到氨丙基化的MCM-41,进而利用氨基与2-吡啶甲醛的缩合反应制得双氮螯合配体修饰的MCM-41;利用双氮螯合配体与甲基三氧化铼(MTO)的配位,实现MTO在MCM-41上的组装.X射线光电子能谱(XPS)分析表明,铼主要以+Ⅶ价态存在;傅里叶变换红外光谱(FT-IR)、紫外漫反射光谱(DRUV-vis)分析结果证明了配体与铼之间配位键的形成;X射线粉末衍射(XRD)、透射电子显微镜(TEM)以及氮气吸附结果表明,MCM-41引入官能团以及MTO组装后,其六方一维孔道结构得到保持,但孔体积、比表面积以及孔径发生明显变化.此外,还利用元素分析以及原子吸收等方法分析了组装材料中碳、氢、氮以及铼的含量.分别以30%双氧水、过氧化氢尿素复合物(UHP)为氧化剂,考察了其对不同烯烃环氧化反应的催化性能.当以UHP为氧化剂在25°C对环己烯环氧化时,反应的转化率约为50%,选择性大于99%;而在同样温度下,以30%双氧水对环己烯环氧化时,反应的转化率约为40%,选择性约为20%.较低的催化活性是由于底物在MCM-41中传质较慢,而组装的MTO又在环氧化条件下分解所致.
γ- (triethoxysilyl) propylamine is reacted with MCM-41 to obtain aminopropylated MCM-41, and then the amino-2-picolinaldehyde condensation reaction is used to prepare a bis-nitrogen chelating ligand-modified MCM- 41, the assembly of MTO on MCM-41 was achieved by the coordination of bis-nitrogen chelate ligand and MTO.The X-ray photoelectron spectroscopy (XPS) (FT-IR) and ultraviolet-visible diffuse reflectance spectroscopy (DRUV-vis) were used to confirm the formation of coordination bonds between the ligands and rhenium. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and nitrogen adsorption results show that the hexagonal one-dimensional pore structure of MCM-41 is maintained after the introduction of functional groups and MTO assembly, but the pore volume, specific surface area and pore size obviously change .In addition, elemental analysis and atomic absorption Methods The contents of carbon, hydrogen, nitrogen and rhenium in the assembly materials were analyzed, and their catalytic performances for epoxidation of different olefins were investigated with 30% hydrogen peroxide and urea hydrogen peroxide (UHP) respectively. UHP as oxidant at 25 ° C cyclohexene epoxidation, the reaction rate of about 50%, select Is greater than 99%, while at the same temperature epoxidation of cyclohexene with 30% hydrogen peroxide results in a conversion of about 40% and a selectivity of about 20%. The lower catalytic activity is due to the substrate being in the MCM -41 mass transfer slower, and the assembly of MTO again under epoxidation conditions caused by decomposition.