【作者】 刘玉章；

【导师】 蔡炳新；

【作者基本信息】 湖南大学 ， 物理化学， 2008， 硕士

【摘要】 本论文研究内容是采用喷雾燃烧法制备的Ag2O/SiO₂纳米复合催化剂在气态环己烷选择性催化氧化制备环己烯和环氧环己烷反应中催化性能的研究。从气固相催化反应研究的四个主要方面,即:催化剂的制备、催化剂的活化、催化剂的表征和催化剂的活性评价,对目标反应进行了系统的探讨。实验结果表明:制备条件、催化剂组分含量和反应条件对催化剂的催化性能均有较大影响。喷雾燃烧法是一种制备纳米复合催化剂的新方法。为研究该方法的应用价值,借助SEM、XRD、HRTEM和FT-IR等表征手段,研究了纳米复合催化剂在处理过程中的物理化学变化、表面结构、晶体结构、表面形貌和不同组分之间的相互作用。结果表明:采用高浓度反应母液制备的纳米复合催化剂其环氧化合能力明显强于采用正常浓度反应母液制备的纳米复合催化剂。由表征结果构建了纳米复合催化剂表面结构模型,根据表面结构模型,分析了纳米复合催化剂表面的供氧活性位,并推导出纳米复合催化剂的供氧能力随着组分含量的增加而增大的变化规律。催化剂的活性评价结果表明:由正常浓度反应母液制备的纳米复合催化剂其供氧脱氢能力较强,对影响催化剂催化性能的条件进行了探讨,并确定了催化剂组分大致范围以及反应条件大致范围,运用正交实验堆活性测试条件进行优化,以环己烷转化率和环己烯选择性为基准,得到了最佳反应方案:Ag2O质量分数为3 wt%、N2流速为40 mL·min?1、O₂流速为5 mL·min?1、环己烷流速为5.5 mL·h?1、温度为410℃。对采用高浓度反应母液制备的纳米复合催化剂进行催化性能测试,发现:含Ag2O质量分数为8 wt%的纳米复合催化剂其催化性能较好,在其催化作用下,环氧环己烷选择性最高可达95.2 wt%。更多还原

【Abstract】 The objective of this disquisition is to synthesize Ag2O/SiO₂ complex nanocatalysts by Atomizing-combustion method and investigate their use in transforming gaseous cyclohexane into cyclohexane or oxide cyclohexene by selective catalytic oxidation. The target reaction was systemtically researched in preparation catalyst, activation catalyst, characterization catalyst and tests for catalyst preparation methods, the component of catalysts and the conditions of catalysis reactions.Atomizing-combustion method is a new technology for synthesis complex nanocatalysts. For the value of the research of method, the nanocatalysts were characterized by Differential Scanning Calorimetry-Thermogravimetry （DSC-TG）, X-ray Diffraction （XRD）, Transmission Electron Microscope（TEM） and Fourier transform infrared （FT-IR）. The results showed that the nanocatalysts were prepared by super-high reaction base-liquid had stronger ability of oxide cyclohexene than the nanocatalysts were prepared by normal reaction base-liquid. The surface structure model of nanocatalysts was deduced from these characterization facts. Based on the surface structure model of nanocatalysts, the active sites suffering active oxygen of the complex nanocatalysts surface were analyzed. The variation rule was deduced that the offering active oxygen abilities of nanocatalysts increase in nonlincarity with the decrease of nanocatalyst content.The results of catalytic activity tests showed that the supplying oxygen and dehydrogenation of nanocatalysts prepared by normal consistency reaction liquid was very strong; and the epoxidation composite of nanocatalysts prepared by high consistency reaction liquid was very strong.更多还原