【作者】 张丽；

【导师】 马学兵；

【作者基本信息】 西南大学 ， 应用化学， 2020， 硕士

【摘要】 固体碱是工业上应用广泛的碱性催化剂,如双氢异构化、酯化、烷基化、氧化还原、Aldol缩合及Michael加成等C-C键形成的反应中均需要固体碱催化剂。目前有机骨架固体碱在催化反应和吸附化学中有广泛的应用。但存在活性位点包埋、孔结构难以构筑和骨架缺乏刚性等缺点,严重影响了固体碱的催化和吸附活性。为了提高有机聚合物固体碱的催化活性,论文设计了中空、多孔有机聚合物固体碱纳米球/碗,具有如下结构特点:（1）有机聚合物固体碱具有有机溶剂溶胀性,可暴露更多催化位点;（2）空心结构使反应底物产生浓度差,可驱动传质;（3）介孔壳层为物质的传输提供顺畅的传质通道;（4）碱位点周围具有自由空间,有利于反应物种达到催化活性位点。本文以聚苯乙烯（PS）为内核模板,通过乳液聚合,在PS表面涂覆一层功能化聚合物;四氢呋喃去除PS内核,制得空心有机聚合物纳米球PS-NH₃/OR HOPNs;通过氢化钠溶液洗涤,去除离子对中有机酸模板剂,构建碱位点周围的自由空间;以N,N-二甲基甲酰胺DMF为退火剂,对多孔空心聚合物进行高温溶胀-低温冷冻-去除固态DMF的方法,构建苯乙烯骨架中可相互连接的介孔通道,从而制备了拥有介孔通道和位点自由空间的空心有机聚合物固体碱#PS-NH₂ HMOPBs。同时,制备了实心聚合物微球PS-NH₂ OPNs、空心聚合物微球PS-NH₂ HOPNs和固体碱#PS-NH₂ HMOPNs（80）、#PS-NH₂ HMOPNs（115）、#PS-NH₂ HMOPNs（145）,并且对比研究了它们在催化Knoevenagel反应的活性差异。SEM图片表明固体碱PS-NH₂ HMOPBs（a）的形貌呈规则的纳米微碗,分散性良好。TEM证明其具有内部空腔结构。红外光谱分析表明,1453 cm^-1处特征峰是-NH₂的弯曲振动,在3500～3350 cm^-1也存在N-H键的伸缩振动峰,同时在1070～1170 cm^-1出也都出现了C-N伸缩振动峰,证明氨基（-NH₂）位点已负载苯乙烯聚合物骨架上。结合聚合物的元素分析表明,去除酸性离子后,硫含量明显降低,最后通过氮含量计算出PS-NH₂ HMOPBs（a）的碱性-NH₂含量为0.82 mmol·g^-1。氮吸附-脱附分析说明,PS-NH₂ HMOPBs（a）的比表面积为41.2 m²·g^-1,孔容0.21 cc·g^-1,孔径均匀分布在4 nm左右。退火法处理后的固体碱#PS-NH₂ HMOPBs（80）既保持了4 nm左右的介孔结构,同时在10-40 nm处产生新孔通道,比表面积和孔容分别增加至56 m²·g^-1和0.41cc·g^-1。总之,本文通过构建空心、多孔壳层、相互连接的孔通道和自由空间的碱位点,为有效改善底物传质过程提供了有效的策略。本文将实心聚合物微球PS-NH₂ OPNs、空心聚合物微球PS-NH₂ HOPNs、介孔空心固体碱微碗PS-NH₂ HMOPNs（a）和80℃、115℃和145℃不同温度退火的样品#PS-NH₂ HMOPBs（80）、#PS-NH₂ HMOPBs（115）、#PS-NH₂ HMOPBs（145）用于催化Knoevenagel缩合反应,并对比研究其催化反应动力学。以PS-NH₂ HMOPBs（a）为Knoevenagel缩合反应的固体碱催化剂,得出最佳催化反应条件为:20℃下,以乙醇作反应溶剂,催化剂用量为5 mol%。对比几组样品的催化反应动力学,固体碱#PS-NH₂ HMOPBs（80）的催化效果最佳,反应2 h,催化反应收率为99%,循环使用十次后收率为92%,催化剂经HCl溶液修复处理后收率可达97%。更多还原

【Abstract】 Solid base is one of the most widely used solid base catalysis in the industry,they are required for C-C bond formation reactions such as isomerization,esterification,alkylation,redox,aldol condensation,and Michael addition.At present,organic framework solid bases have been universally applied in catalytic reactions and adsorption chemistry.However,there are some shortcomings such as active sites embedding,difficult pore structure construction and lack of rigidity of the skeleton,which seriously affect the catalytic and adsorption activity of solid base.In order to improve the catalytic activity of organic polymer solid bases,hollow and porous organic polymer solid base nanospheres/nanobowls are designed in this paper,which have the following structural characteristics:（1）Organic polymer solid bases are swellable with organic solvents and can be exposed more catalytic sites;（2）Hollow structure make a difference in concentration of the reaction substrate,which can drive mass transfer;（3）Mesoporous shell provides a smooth mass transfer channels;（4）Free space around basic sites is beneficial for the reactive species to reach the catalytic active site.In this paper,polystyrene nanosphere（PS）is used as core template,and a layer of functionalized polymer is coated on the PS surface by emulsion polymerization.The PS core is removed by tetrahydrofuran（THF）to obtain hollow organic polymer nanospheres PS-NH₃/OR HOPNs;Through the sodium hydride solution,organic acid templates were washed to build free space around base sites;By a method for high-temperature swelling-low-temperature freezing-removing solid DMF,using N,N-dimethyl formamide（DMF）as an annealing agent,inter-connected mesoporous channels in the styrene backbone were constructed,and the hollow organic polymer solid bases#PS-NH₂ HMOPBs with mesoporous channels and free space around base site were prepared.At the same time,solid polymer microspheres PS-NH₂ OPNs,hollow polymer microspheres PS-NH₂ HOPNs,and samples annealed at different temperatures of 85℃,115℃and 145℃were prepared,respectively corresponding to#PS-NH₂ HMOPBs（80）,#PS-NH₂HMOPBs（115）and#PS-NH₂ HMOPBs（145）.Finally,their catalytic differences in Knoevenagel reactions were studied.In SEM images,solid base PS-NH₂ HMOPBs（a）have regular nano-bowl morphology and good dispersibility,and TEM images also show they have an internal cavity structure.Infrared spectrum（IR）analysis shows that the characteristic peak at1453 cm^-1is bending vibration of NH₂,the stretching vibration peak of N-H bond also exists at 3500～3350 cm^-1,and the stretching vibration peak of C-N bond also appears at1070～1170 cm^-1.These prove that the amino groups were loaded on polymer styrene backbone.Combined with elemental analysis,it shows that sulfur content was significantly reduced after acid ions were removed,and-NH₂ content of PS-NH₂HMOPBs（a）is 0.82 mmol·g^-1 according to nitrogen element content.In Nitrogen adsorption-desorption analysis,the surface area of PS-NH₂ HMOPBs（a）was 41.2m²·g^-1,the pore size was uniformly distributed 4 nm.The solid base#PS-NH₂HMOPNs（80）annealed at 80℃maintained the original mesoporous structure,while new pore channels were generated at 10-40 nm,and the specific surface area,pore volume increased to 56 m²·g^-1 and 0.41 cc·g^-1.In summary,we provide an effective strategy for effectively improving the mass transfer process of substrates by forming hollow porous shells,inter-connected pore channels,and free space around base sites.In this paper,solid base polymer spheres PS-NH₂ OPNs,hollow polymer spheres PS-NH₂ HOPNs,mesoporous hollow solid base nano-bowls PS-NH₂ HMOPBs（a）,and#PS-NH₂ HMOPBs（80）,#PS-NH₂ HMOPBs（115）and#PS-NH₂ HMOPBs（145）were used to catalyze the Knoevenagel condensation reaction,and their catalytic reaction kinetics were explored.Then using PS-NH₂ HMOPBs（a）as the solid base catalyst,the optimal Knoevenagel condensation reaction conditions are researched as follows:ethanol is used as the reaction solvent at 20℃,and the amount of catalyst is 5 mmol%.Comparing the catalytic reaction kinetics of different samples,it was concluded that#PS-NH₂ HMOPBs（80）have the best catalytic activity,and the yield was 99%at 2 h.After ten cycles,the yield was 92%,and the catalytic activity was restored to 97%when they were repaired with HCl solution.更多还原