基于介孔氧化硅光控智能固体碱的制备和催化性能的研究毕业论文
2022-03-06 20:34:52
论文总字数:18057字
摘 要
目前固体碱催化剂已经广泛应用于双键异构化反应、氧化反应、还原反应、酯交换反应、Michael加成、Knoevenagel缩合等有机反应中。固体碱对设备的腐蚀性小,同时可以减少在生产过程中产生的废液,有望替代液体碱成为新一代环境友好型的催化剂。在众多的孔道材料中,介孔材料因具有开放的孔道结构、较大的比表面积和较低的传质阻力等优点而备受关注,和其他的介孔材料相比较,介孔氧化硅具有易于合成、孔结构可控、稳定性高等诸多优点。
门控催化系统可以将进入的刺激源转化为化学信号。在这些刺激源中,光可能对这些系统的控制表现出最显著的影响,因为光照是非破坏性的。光照也可以进行远程、空间和时间的控制,帮助抑制副作用。偶氮苯及其衍生物由于其独特的性质,例如良好的稳定性,良好的光机械性能,以及快速和可逆的光异构化而得到广泛研究。在这些报道的方法中,功能单元被拴在偶氮苯上,并且通过改变功能单元周围的空间或调节两个协作功能单元的相对位置来改变催化活性。
本文首先根据文献报道在碱性条件下合成介孔分子筛MCM-41再经过盐酸/乙醇混合液萃取去除模板剂,以对氨基偶氮苯与异氰酸丙基三乙氧基硅烷反应制得具有顺反异构体的硅烷偶联剂TSUA,通过原位合成法将胺源引入到介孔分子筛MCM-41孔道中,将偶氮苯嫁接在其孔口,最后制得催化剂样品。该方法不仅操作简单,而且制得的催化剂孔口的光响应分子分散均匀,催化剂结构有序性较好。对光响应催化剂进行了一系列的表征,对制备的材料进行催化性能的研究寻找负载最优量,对比光照前后的转化率。
关键词:光响应 偶氮苯 MCM-41分子筛 催化性能
Preparation and Catalytic Performance of Intelligent Light Control Solid Alkali Based on Mesoporous Silica
Abstract
The catalysts have been applied to many kinds of organic synthesis such as double bond isomerization of alkenes and alkynes, oxidation, reduction, transesterification, Aldol condensation, Michael addition, Knoevenagel condensation et al. Mesoporous solid bases can catalyze diverse reactions with a low cost and reduce the production of pollutants. They are promising to take the place of liquid bases and are significant for the development of environmentally benign catalytic processes. Among various mesoporous host used for the preparation of solid strong bases, mesoporous silicas are easier to synthesize and have better stability. An incredible degree of control has been achieved on silica with various pore symmetries. With strengthen of people's environment protection consciousness and the development of green chemistry, employment of eco-friendly solid bases catalysis in the fine chemical industry is of topical interest.
The gated catalytic system can convert incoming stimuli into chemical signals. In these stimuli, the light may have the most significant effect on the control of these systems, since the light is non-destructive. Light control can also be remote in space and time to help suppress side effects. Azobenzene and its derivatives have been extensively studied due to their unique properties, such as good stability, good optical mechanical properties, and fast and reversible photoisomerization. In these reported methods, the functional units are tethered to azobenzene and the catalytic activity is changed by changing the space around the functional unit or by adjusting the relative positions of the two cooperating functional units.
Firstly, according to reports in the literature in alkaline conditions for synthesis of mesoporous molecular sieve MCM-41 by HCl / ethanol mixed liquid extraction to remove a template agent, to the amino azobenzene and isocyanic acid propyl triethoxy silane reaction system was with Cis trans isomers of silane coupling agent TSUA. After grafting azobenzene derivatives and a source of ammonia is introduced into the mesoporous molecular sieve MCM-41, and finally preparing adsorbent samples. The method not only has simple operation, but also has the uniform light response molecules in the adsorbent, and the adsorbent has better structure. A series of characterization of the photoresponsive catalyst was carried out to find the optimal loading and the catalytic performance. At the same time, the number of cycles of the prepared materials were compared, and the conversion rate was compared before and after the illumination.
Key Words:Light response;Azobenzene;MCM-41 molecular sieve;Catalytic performance
目 录
摘要 I
Abstract II
第一章 绪论 1
1.1固体碱的定义 1
1.2固体碱的分类 1
1.2.1 有机固体碱 1
1.2.2 有机—无机复合型固体碱 1
1.2.3无机固体碱 1
1.3偶氮苯的分子结构及光致异构机理 2
1.3.1偶氮苯分子结构和光谱特征 2
1.3.2偶氮苯光致异构化机理 3
1.4 MCM-41分子筛 4
1.4.1分子筛发展历史 4
1.4.2 MCM-41的制备方法 4
1.5光响应 5
1.6本课题的主要研究内容 6
第二章 实验仪器和实验方法 7
2.1 实验仪器和材料 7
2.2 实验方法和实验步骤 7
2.2.1 MCM-41分子筛的制备 8
2.2.2氨基功能化MCM-41的制备 8
2.2.3 AB-TPI的制备 8
2.2.4偶氮苯功能化的AM的制备 8
2.2.5 碱量测定实验 8
2.2.6 Knoevenagel缩合反应 9
第三章 结果与讨论 10
3.1 TSUA的表征 10
3.2 MCM-41分子筛和负载TSUA和胺源后表征 10
3.2.1 小角XRD表征 10
3.2.2 红外表征 11
3.3 碱含量测定实验 12
3.4 Knoevenagel缩合反应 12
第四章 结论与展望 15
4.1 结论 15
4.2 展望 15
参考文献 17
致谢 19
第一章 绪论
1.1固体碱的定义
从广义上来说,固体碱应该是可以改变酸性指示剂的颜色或者能够吸附酸性化合物的固体。从Lewis的定义看,固体碱应是能给出电子对或者接受质子的固体。
1.2固体碱的分类
按照载体或活性位的性质不同,固体碱大体可分为有机固体碱、有机-无机复合型固体碱以及无机固体碱。
1.2.1 有机固体碱
有机固体碱主要主要是指端基为叔胺或叔磷基团的碱性树脂类固体碱。这种固体碱的强度较为均一,但是稳定性不好并且制备的过程较为复杂。
1.2.2 有机—无机复合型固体碱
目前所研制的有机无机复合固体碱主要是通过有机客体和无机主体(主要为分子筛)之间通过共价键的方式形成固体碱[1]。Lin等[2]把多种有机碱成功的嫁接到介孔氧化硅的孔道内,形成了一类新的固体碱。Li等[3]还成功地将金属有机碱(叔丁醇锂)嫁接到介孔氧化硅SBA-15孔道内的硅羟基上,每四分子的LTB会先脱除三分子叔丁醇,剩余的一分子LTB以化学键的形式与羟基上的氧相连,三分子锂独立与氧相连。由于每一个硅羟基在SBA-15表面都是孤立存在的,而碱性物种以共价键的形式与其相连,因而这些碱性位在载体上都是高度分散的活性位。
1.2.3无机固体碱
从组分和制备方法上看,无极固体碱可以分为金属氧化物固体碱、水滑石及沸石分子筛固体碱和负载型固体碱三类。
- 金属氧化物
金属氧化物固体碱催化剂主要包括碱金属、碱土金属氧化物和稀土元素氧化物。总体而言,碱金属和碱土金属氧化物的碱强度会随原子序数的增大而增加,其顺序为:MgOlt;CaOlt;CsOlt;BaO,Na2Olt;K2Olt;Rb2Olt;Cs2O[4]。研究还表明,不同的活化温度与金属氧化物的催水滑石及沸石分子筛化活性密切相关[5]。
(2)水滑石及沸石分子筛
请支付后下载全文,论文总字数:18057字