【作者】 李娜；

【导师】 马荣华；

【作者基本信息】 齐齐哈尔大学 ， 无机化学， 2011， 硕士

【摘要】 多金属氧酸盐是一种优异的催化材料,它具有低温高活性、高选择性、对环境友好等优点,因此在许多领域都成为研究的热点。本文合成了过渡金属取代的Keggin结构的α-SiW₁₁M（M=Co,Mn,Cu）,并采用浸渍法合成了SiO₂负载的多金属氧酸盐,采用TG-DTG确定其结构为:α-K₂H₄SiW₁₁Co O₃₉·4H₂O/SiO₂,α-K₂H₄SiW₁₁MnO₃₉·5H₂O/SiO₂和α-K₂H₄SiW₁₁CuO₃₉·6H₂O/SiO₂,并用IR、XRD、UV等对其进行了表征。以柠檬酸和正丁醇为原料,催化合成柠檬酸三丁酯,考察三种盐的催化活性。研究了酸醇摩尔比、催化剂用量、回流温度和带水剂用量等对酯化率的影响。α-K₂H₄SiW₁₁CoO₃₉·4H₂O/SiO₂催化酯化的最佳条件为:催化剂浸渍时间为24 h,焙烧温度为200℃,酸醇摩尔比为1:6,催化剂用量为体系的0.63%,带水剂甲苯为3 mL,回流温度为145～150℃。在最佳条件下,酯化率为90.7%;α-K₂H₄SiW₁₁MnO₃₉·5H₂O /SiO₂催化酯化的最佳条件为:催化剂浸渍时间为24 h,焙烧温度为200℃,酸醇摩尔比为1:7,催化剂用量为体系的2.1%,带水剂为9 mL,回流温度为140℃。在最佳条件下,酯化率为86.7%;α-K₂H₄SiW₁₁CuO₃₉·6H₂O/SiO₂催化酯化的最佳条件为:催化剂浸渍时间为24 h,焙烧温度为200℃,酸醇摩尔比1:6,催化剂用量为体系的1.9%,甲苯为5 mL,回流温度130～135℃。在最佳条件下,酯化率为85.5%。催化剂的回收和重复使用表明负载型催化剂很容易从体系中分离出来,可以继续用于酯化反应中。该法不仅反应条件简单,操作简便,选择性高,副反应少,重复使用5次,且酯化率仍然不低,而且不腐蚀设备,不污染环境。更多还原

【Abstract】 HPA is one of excellent catalytic agent,it has high activity,high selectivity and non-pollution,The new materials become researched hotspot recently.The Keggin-structured polyoxometalates includingα-SiW₁₁O₃₉M（M=Co,Mn,Cu）,have been prepared, and supported by SiO₂,then characterized by IR spectroscopy,X-ray diffraction and UV spectroscopy.The structure of the catalysts, includingα-K₂H₄SiW₁₁CoO₃₉·4H₂O/SiO 2,α-K₂H₄SiW₁₁MnO₃₉·5H₂O/SiO₂,α-K₂H₄SiW₁₁CuO₃₉·6H₂O/SiO₂ ,are determined by TG-DT G.The catalysts were used in the esterification,to examination the catalytic activity.In the intermittent,the molar ratio of acetate to ethanol,the amount of the catalysts,the temperature of reaction and the amount of the carrier are studied,then the best reaction condition is determined.The best condition ofα-K₂H₄SiW₁₁CoO₃₉·4H₂O/SiO₂ are the dip time 24 h,temperature of roasting 200℃,the molar ratio of acetate to ethanol 1:6,the content of catalytic 0.63%,the carrier 3 mL,and the temperature 145～150℃.Then the esterification yield could reach 90.7%.The best condition ofα-K₂H₄SiW₁₁MnO₃₉·5H₂O/SiO₂ are the dip time 24 h,temperature of roasting 200℃,the molar ratio of acetate to ethanol 1:7,the content of catalytic 2.1%,the carrier 9 mL,and the temperature 140℃.Then the yield could reach 86.7%.The best condition ofα-K₂H₄SiW₁₁CuO₃₉·6H₂O/SiO₂ are the dip time 24 h,temperature of roasting 200℃,the molar ratio of acetate to ethanol 1:6,the content of catalytic 1.9%,the carrier 5 mL,and the temperature 130～135℃.Then the yield could reach 85.5%.The recycling and reuse are also examined in this paper,which shows that the catalysts are easily separated from the system,and continued for the next reation.The method is simple,easily operated,high selectivity,side effects less, esterification rate is still high after be reused 5 times,and don’t corrode equipment and pollute the environment.更多还原