铌酸催化剂在有机合成中的应用

【作者】 伍志鲲；

【导师】 李菊仁；

【作者基本信息】 湖南师范大学 ， 有机化学， 2001， 硕士

【摘要】 面对日益严格的环境保护要求和绿色化学的兴起，除继续发展“三废”治理技术外，最重要的是应发展治本技术，化学反应尽量少产“三废”，最好是“原子经济”反应，实现“零排放”。鉴于液体酸催化剂对设备的腐蚀严重，原料和产物与催化剂的分离困难，环境污染严重等，对于催化剂和催化新工艺的研究已提到重要议事日程上来。固体超强酸、离子交换树脂、沸石分子筛、高分子载体Lewis酸、金属氧化物及其复合物、无机酸盐及其水合物、固载杂多酸及其盐等是目前开发及应用较多的几类典型的固体酸催化剂。 1979年，F．Kurosawa发现铌酸（Nb₂O₅·nH₂O）具有独特的固体酸催化特性，在酯的水解，烯烃水化，气相酯化，醇脱水成稀等反应中有较高的催化活性、选择性和活性稳定性。到目前为止，国外（特别是日本），已对铌系催化剂进行了大量研究，有的还应用到工业上。我国对此研究起步较晚，因此加速研制开发铌系催化剂有着非常重要的理论意义和实用价值。 本文首次详细探索了铌酸催化液相酯化反应的一些规律。对合成邻苯二甲酸二辛酯、邻苯二甲酸二异辛酯、顺丁烯二酸二辛酯、顺丁烯二酸二异辛酯的优化合成条件（包括反应时间、反应温度、物料比、催化剂用量、催化剂的粒度、带水剂种类）做了较系统的研究。其次，本文对铌酸催化环己醇脱水成烯反应作了探索，并与γ-Al₂O₃进行了比较，发现其催化活性及活性稳定性均优于γ-Al₂O-3。当把铌酸负载在硅胶上（重量比为2.5％）时，其催化活性大大增强。为了进一步提高铌酸的催化活性，本文对铌酸进行了多种处理，如水洗处理、焙烧处理、酸处理、低温结晶法和熔融法处理以及加入助剂等，并利用现代分析测试手段对其结构进行了考察。最后，本文以邻苯二甲酸酐和异辛醇的酯化反应为探针反应，对铌酸液相催化酯化反应进行了动力学研究。更多还原

【Abstract】 Facing the more strict requirements of environmental protection and the arise of green chemistry, the most importance is laid in managing the fundamental sources besides developing the treatment technique of triwaste continually. The chemistry reactions in factories, mines etc. should produce less wastes as possibly as they can. The best things are to realize atomic economy reaction and nonemission. Due to the serious erosion, the arduous separation of catalyst with products and reactants and the severely environmental contamination of liquid acid catalysts, the research on new catalysts and catalytic technologies are emergent. Solid superacids, ion exchange resins, zeolite molecular sieves, polymer carriers-lewis acids, metal oxides and their compounds, inorganic acid salts and their hydrates, loaded heteropolyacids and their salts, are among typical solid acid catalysts which are widely and deeply studied and applied nowadays.Niobic acid(Nb₂0₃-5H2O)was a new kind of special solid-acid catalyst founded by F.Kurosawa in Japan in 1979, and maintained high catalytic activity and stability in aqeous systems such as gasphase esterification, hydration, dehydration, and so on. Lots of research was carried on in foreign countries, especially in Japan, but in our county, little work has been done about it by now, so exploring and exploiting the catalyst have theoretic significance and pragmatic value.Thesis studied some laws of liquid-solid esterification initially. The optimally synthetic conditions（including reaction temperature, reaction time, catalyst amount, catalyst particle sizes, ratio of reactants and water-removing reagents）of di-2-ethylhexyl phthalate, dhn-octyl phthalate,di-2-ethylhexyl maleate and di-n-octy maleate were explored elaborately. Secondly, the dehydration of cyclohexanol catalyzed by niobic acid in gas-phase was investigated. Compared with r-Al₂O₃, niobic acid is excellent in catalytic activity and stability. Experiments showed that niobic acid had prominent catalytic activity when loaded on silica gel（wt:2.5%）,maybe due to the great dispersion of niobic acid, even the formation of monolayer structure of niobic acid. In order to improve the activity of niobic acid furthermore, we treated the niobic acid by different methods, including water-washing treatment, heat treatment, acid-dipping treatment, hydrothermal treatment, fusing treatment and adding assistant catalysts, companied with modern analysis technologies and ways. At last, the synthesis of di-2-ethylhexyl phthalate, as a probing reaction, was researched on the dynamics initially.更多还原