【摘要】：多孔碳球(NCS)因其具有的較高的化學(xué)穩(wěn)定性、較好的導(dǎo)電性、較低的價格,同時孔結(jié)構(gòu)的引入使得其具有較大的比表面積,可控的孔道結(jié)構(gòu),可調(diào)變的徑等特點,因而被廣泛應(yīng)用在能量高效存儲和轉(zhuǎn)換、催化、生物醫(yī)學(xué)等方面。不同結(jié)構(gòu)的多孔碳球在不同的方面有著特殊的應(yīng)用。因此,許多科學(xué)家致力于多孔碳球的合成,并取得了很大的進(jìn)展。在文獻(xiàn)和課題組之前取得的一些研究成果的基礎(chǔ)之上,在其他條件均不改變,僅通過改變表面活性劑的鏈長,成功制備了不同結(jié)構(gòu)的介孔碳球(MCN),實現(xiàn)了 MCN結(jié)構(gòu)由中空到發(fā)散狀結(jié)構(gòu)轉(zhuǎn)變,并且該發(fā)散狀的MCN顆粒尺寸均控制在120 nm以下。本文主要圍繞如何實現(xiàn)不同結(jié)構(gòu)的MCN的合成、機(jī)理及其功能化展開了一些研究性的工作。主要得到如下結(jié)果:1.在使用TEAH_3為堿源,其他條件相同,僅僅只簡單地調(diào)變表面活性劑的鏈長,實現(xiàn)了 MCN從中空到發(fā)散狀結(jié)構(gòu)的合成和轉(zhuǎn)變,同時結(jié)合原位跟蹤體系過程中pH值的手段,發(fā)現(xiàn)主要是因為不同鏈長的表面活性劑形成膠束的CMC濃度不同,導(dǎo)致形成膠束的數(shù)量不同,在堿源的量相同的情況下導(dǎo)致膠束表面吸附的堿量不一樣,這種情況下,致使膠束表面硅物種的包覆程度不一樣,是實現(xiàn)不同結(jié)構(gòu)的MCN的關(guān)鍵原因。2.將制備的MCN為載體,通過不同的磺酸功能化技術(shù),探究出氣相磺化法是最佳的磺酸化條件。將制備的不同結(jié)構(gòu)的MCN磺酸功能化,以間甲酚與叔丁醇的烷基化反應(yīng)作為探針反應(yīng),詳細(xì)探究了不同碳化溫度和不同結(jié)構(gòu)的磺酸功能化的多孔碳納米球(MCN-SO_3H)的催化性能,發(fā)現(xiàn)了最佳碳化溫度的催化性能是由不同結(jié)構(gòu)的MCN所決定的。3.詳細(xì)探究了 MCN-SO_3H在探針反應(yīng)中的循環(huán)使用效果不佳的原因:(1)反應(yīng)物的吸附致使孔道被堵住,即堵孔現(xiàn)象。(2)MCN的載體本身是由間苯二酚-甲醛的碳前驅(qū)體合成的,探針反應(yīng)使用的溶劑是間甲酚和叔丁醇。載體本身的間苯二酚的羥基會與間甲酚和叔丁醇中的羥基在酸性條件下發(fā)生反應(yīng),導(dǎo)致孔道可能被堵,同時底物本身參與反應(yīng)的量的減少,導(dǎo)致得到的催化產(chǎn)物很少。(3)由于反應(yīng)溶劑中不可避免有水的引入與生成,導(dǎo)致催化劑在較高的溫度下-SO_3H可能會脫落。此外,通過在MCN中引入不同鏈長的醇,將其磺酸功能化后,實現(xiàn)催化劑的不同親疏水性的調(diào)變,并探究了不同的親疏水性的催化劑在該烷基化反應(yīng)中的催化效果,同時有望在低溫的壬醛與乙二醇的縮醛反應(yīng)中較好的催化性能。
[Abstract]:Due to its high chemical stability, good electrical conductivity, low price, and the introduction of pore structure, (NCS) has the characteristics of large specific surface area, controllable pore structure, adjustable diameter and so on. Therefore, it is widely used in energy efficient storage and conversion, catalysis, biomedicine and so on. Porous carbon spheres with different structures have special applications in different aspects. Therefore, many scientists have made great progress in the synthesis of porous carbon spheres. On the basis of some of the research results obtained before the literature and the research group, and without change in other conditions, only by changing the chain length of the surfactant, The mesoporous carbon sphere (MCN), with different structures was successfully prepared to realize the transition of MCN structure from hollow to divergent structure, and the size of the dispersed MCN particles was controlled below 120 nm. This paper focuses on the synthesis, mechanism and functionalization of MCN with different structures. The main results are as follows: 1. When TEAH_3 was used as base source and other conditions were the same, the chain length of surfactant was simply adjusted, which realized the synthesis and transformation of MCN from hollow to divergent structure, and combined with the method of in situ tracking the pH value in the system. It was found that the amount of micelle formed was different due to the different CMC concentration of micelle formed by surfactant with different chain length, and the amount of alkali adsorbed on micelle surface was different when the amount of alkali source was the same. The different coating degree of silicon species on micelles is the key reason to realize MCN with different structure. 2. By using the MCN as carrier and different sulfonic acid functionalization techniques, it was found that the gas phase sulfonation method was the best sulfonic acid condition. The catalytic properties of sulfonic acid functionalized MCN nanospheres (MCN-SO_3H) with different carbonation temperatures and structures were investigated by using the alkylation of m-cresol with tert-butanol as a probe. It is found that the catalytic performance of the optimum carbonization temperature is determined by the different structure of MCN. The reasons for the poor recycle of MCN-SO_3H in the probe reaction were discussed in detail: (1) the adsorption of reactants resulted in the blocking of the pore channel, that is, the phenomenon of blocking the pore. (2) the carrier of MCN itself was synthesized from the carbon precursor of resorcinol-formaldehyde. The solvent used in the probe reaction is m-cresol and tert-butanol. The hydroxyl group of resorcinol in the carrier itself reacts with the hydroxyl group in m-cresol and tert-butanol in acidic conditions, which may result in the blocking of the pore channel and the reduction of the amount of the substrate itself participating in the reaction. (3) owing to the inevitable introduction and formation of water in the reaction solvent, the catalyst may fall off at a higher temperature-SO_3H. In addition, by introducing alcohol with different chain length into MCN and functionalizing its sulfonic acid, the different hydrophobicity of the catalyst was adjusted, and the catalytic effect of different hydrophilic catalyst in the alkylation reaction was investigated. At the same time, it is expected to have good catalytic performance in the acetal reaction between nonaldehyde and ethylene glycol at low temperature.
【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O643.36

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本文編號：2269084