【作者】 卢云；

【导师】 蒋平平；

【作者基本信息】 江南大学 ， 化学工艺， 2011， 硕士

【摘要】 本文采用共沉淀法,选择氢氧化钠为共沉淀剂,合成硝酸根型类水滑石[M_1-xAl_x（OH）₂]^x+（NO₃^-）x/n·mH₂O。通过离子交换合成磷钨酸根阴离子插层类水滑石[Mg²⁺_1-xAl³⁺x（OH）₂]^x+[PW₁₂O₄₀]^3-x/3·mH₂O。通过紫外-可见分光光度法、红外光谱法、多晶X射线衍射法、等离子电感耦合元素分析、比表面积、热重分析对催化剂进行表征。结果显示磷钨酸根阴离子成功插层进入了镁铝硝酸根型类水滑石层间且插层后水滑石的层状结构仍保持的很完整。合成出的类水滑石及其焙烧产物作为固体催化剂,用长碳链不饱和酯类化合物作为原料进行催化环氧化探针反应。发现插层类水滑石较插层前选择性和转化率都有了明显的提高。考察了催化剂的焙烧条件、层间阴离子对催化性能的影响,同时在插层类水滑石为催化剂体系下考察了反应温度、反应时间、溶剂、氧源、催化剂用量、催化剂重复使用等因素对环氧化脂肪酸甲酯的影响。结果显示自制不同系列类水滑石材料作为环氧化脂肪酸甲酯的催化剂均有一定的催化活性。实验得到最佳选择性和转化率分别为59.36 %和56.14 %。催化剂在重复使用4次后催化活性仍很稳定,重复使用率高于90 %。最后还对插层类水滑石作为催化剂催化环氧化脂肪酸酯反应的催化机理进行了初步的探讨。长碳链不饱和酯类化合物环氧化是选择性催化氧化反应的难点之一,已成为研究热点。杂多酸根阴离子插层类水滑石作为此类反应的催化剂,既克服了杂多酸盐类催化剂分离困难无法重复使用的缺点,又改善了传统类水滑石转化率和选择性低的问题,在催化环氧化长碳链不饱和酯类方面具有较大的应用前景。更多还原

【Abstract】 In this paper, the hydrotalcites was synthesized by using coprecipitation method performed with a solution of NaOH as precipitator. The pillared-hydrotalcites can be obtained through ion exchang method. Hydrotalcites and the intercalated material have been studied by characterization techniques such as XRD, FT-IR, UV–Visa spectroscopy, TG, BET and ICP. The results showed that the anion have intercalated within the LDHs interlayer without modifying its original structure.The catalysts were tested by epoxy reaction of fatty acid ester of this thesis. The results showed that the pillared-hydrotalcites had better selectivity and conversion. The effects of roast conditionswas, different ion in the layer, reaction time, temperature and catalyst reuse ect. performance on the epoxidation of fatty acid methyl ester were discussed in details. The results indicated that the series of catalysts showed certain catalytic activity in epoxidation of fatty acid methyl ester. The highest selectivity and conversion of reaction were 59.36% and 56.14%,respectively. After recycling four times, the activity was also very steadily and the recycle utility rate greater than 90%. The mechanism of the epoxidation for the fatty acid ester under the pillared-hydrotalcites as catalyst was finally investigated.The epoxidation of long carbon chain unsaturated compounds has become one of the hot research topics of the world-class scientists. It showed that the catalysts which were modified by the heteropoly acid anion had better catalytic properties than before modification. Otherwise, the catalyst was easily moved from the reaction system. Hydrotalcite-like compounds, as a new kind of functional material and application in catalysis of epoxidation, have broad prospects.更多还原