本文選題：二惡英 + 密度泛函理論�。� 參考：《山東大學(xué)》2015年碩士論文

【摘要】：二惡英是一類(lèi)典型的持久性有機(jī)污染物(POPs),由于其劇毒性對(duì)環(huán)境和人類(lèi)產(chǎn)生嚴(yán)重危害,已被列入《斯德哥爾摩公約》中的POPs名單。二惡英是伴隨人類(lèi)生產(chǎn)活動(dòng)形成的一種副產(chǎn)物,通過(guò)研究二惡英的生成機(jī)理及其影響因素,找到減少和避免二惡英的生成和排放的方法,從而減少其對(duì)人類(lèi)健康的危害。垃圾焚燒過(guò)程中二惡英的生成機(jī)理是十分復(fù)雜的,也是最受人們關(guān)注并且研究最多的,雖然目前對(duì)此過(guò)程二惡英的生成機(jī)理還存在一些爭(zhēng)議,但是通常認(rèn)為二惡英是通過(guò)從頭合成和前驅(qū)物合成兩種途徑生成的。本文主要圍繞垃圾焚燒過(guò)程中二惡英前驅(qū)物生成機(jī)理,通過(guò)量子化學(xué)計(jì)算開(kāi)展了一系列的研究工作,在深入研究二惡英的前驅(qū)物生成機(jī)理過(guò)程中,提出了酚氧自由基、苯自由基和苯氧雙自由基形成二惡英的理論模型,并設(shè)計(jì)了一系列自由基的自耦合與交叉耦合反應(yīng),運(yùn)用變分過(guò)渡態(tài)理論計(jì)算了它們的熱力學(xué)和動(dòng)力學(xué)性質(zhì)；我們還對(duì)氯酚前驅(qū)物的表面催化機(jī)理進(jìn)行了詳細(xì)的研究,設(shè)計(jì)了氯酚在氧化銅和二氧化硅表面的反應(yīng)路徑,并和分子耦合反應(yīng)作比較來(lái)分析氧化銅和二氧化硅在二惡英生成過(guò)程的催化機(jī)理和催化效果。論文的主要研究?jī)?nèi)容和成果如下：一、氯酚氣相生成二惡英新機(jī)理。氯酚是公認(rèn)的形成二惡英的最重要的前驅(qū)物,但人們對(duì)其轉(zhuǎn)化成二惡英分子機(jī)理的認(rèn)識(shí)仍不十分清晰。我們選擇2-氯酚為模型化合物,通過(guò)密度泛函理論計(jì)算,研究了一系列二惡英的形成機(jī)制,發(fā)現(xiàn)酚氧自由基、苯自由基和苯氧雙自由基均是形成二惡英的重要中間體,對(duì)二惡英的形成有重要貢獻(xiàn)。本文設(shè)計(jì)了一系列自由基的自耦合與交叉耦合反應(yīng),運(yùn)用變分過(guò)渡態(tài)理論計(jì)算了它們的熱力學(xué)和動(dòng)力學(xué)性質(zhì),研究結(jié)果改進(jìn)了人們對(duì)二惡英形成機(jī)理的認(rèn)識(shí),也為相關(guān)的實(shí)驗(yàn)研究提供了一定的理論指導(dǎo)。二、氯酚在氧化銅,二氧化硅表面反應(yīng)生成二惡英的機(jī)理。前驅(qū)物分子主要通過(guò)高溫氣相反應(yīng)和低溫表面催化反應(yīng)形成二惡英,其中70%以上的二惡英是通過(guò)表面催化機(jī)理生成的。研究表明,垃圾焚燒過(guò)程的飛灰中含有過(guò)渡金屬氧化物、金屬氯化物和大量二氧化硅,這些被認(rèn)為是生成二惡英的重要催化劑,但具體作用機(jī)制還不清楚。本論文分別研究了2,4,5-TCP在氧化銅和二氧化硅表面的吸附及反應(yīng)機(jī)理,并和分子耦合反應(yīng)作比較。研究結(jié)果表明,氯酚分子極易吸附在二氧化硅表面形成穩(wěn)定的氯酚鹽,但后續(xù)反應(yīng)過(guò)程中由于硅氧鍵難以斷裂而對(duì)形成二惡英沒(méi)有明顯催化效果,而氧化銅對(duì)氯酚反應(yīng)形成二惡英有催化作用,研究結(jié)果為理解二惡英表面形成機(jī)理提供了一定的理論依據(jù)。
[Abstract]:Dioxin, a typical persistent organic pollutant, has been listed in the POPs list of Stockholm Convention because of its high toxicity to the environment and human beings. Dioxin is a by-product formed with human production. By studying the formation mechanism of dioxin and its influencing factors, we can find a way to reduce and avoid the formation and emission of dioxin, so as to reduce its harm to human health. The formation mechanism of dioxin in MSW incineration process is very complex, and it is the most concerned and studied, although there are still some controversies on the formation mechanism of dioxin in MSW incineration process. However, it is generally believed that dioxins are produced by both ab initio synthesis and precursor synthesis. Based on the mechanism of dioxin precursor formation during MSW incineration, a series of research work was carried out by quantum chemical calculation. In the process of studying the formation mechanism of dioxin precursor, phenolic oxygen free radical was proposed. A theoretical model for the formation of dioxins from benzene radical and benzoxy double radical is proposed. A series of self-coupling and cross-coupling reactions are designed and their thermodynamic and kinetic properties are calculated by the variational transition state theory. We also studied the surface catalytic mechanism of chlorophenol precursor in detail and designed the reaction path of chlorophenol on the surface of copper oxide and silica. The catalytic mechanism and catalytic effect of copper oxide and silicon dioxide in the formation of dioxin were analyzed by comparison with the molecular coupling reaction. The main research contents and achievements are as follows: 1. New mechanism of gas phase formation of dioxins from chlorophenols. Chlorophenol is recognized as the most important precursor for dioxin formation, but the mechanism of its conversion to dioxin is still unclear. We selected 2-chlorophenol as model compound and studied the formation mechanism of a series of dioxins by density functional theory (DFT). It was found that phenolic radical, benzene radical and benzoxy bisradical are important intermediates for dioxin formation. It has an important contribution to the formation of dioxins. In this paper, a series of self-coupling and cross-coupling reactions of free radicals are designed, and their thermodynamic and kinetic properties are calculated by using variational transition state theory. The results improve the understanding of the formation mechanism of dioxins. It also provides some theoretical guidance for related experimental research. Second, the reaction mechanism of chlorophenol on the surface of copper oxide and silica. The precursor molecules form dioxins mainly through high temperature gas phase reaction and low temperature surface catalytic reaction, in which more than 70% of the dioxins are generated by surface catalytic mechanism. The results show that the fly ash of MSW incineration process contains transition metal oxide, metal chloride and a large amount of silica, which are considered as important catalysts for the formation of dioxins, but the mechanism of action is not clear. In this paper, the adsorption and reaction mechanism of 2H4 + 5-TCP on the surface of copper oxide and silica were studied, and the results were compared with those of molecular coupling reaction. The results show that chlorophenol molecules are easy to adsorb on the surface of silica to form stable chlorophenol salts. However, in the subsequent reaction process, due to the difficulty of breaking the bond between silicon and oxygen, there is no obvious catalytic effect on the formation of dioxins. Copper oxide can catalyze the formation of dioxins in chlorophenol reaction. The results provide a theoretical basis for understanding the surface formation mechanism of dioxins.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：X705;X50

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 章驊,何品晶,李國(guó)建,武田信生;生活垃圾焚燒飛灰中的二惡英檢測(cè)[J];同濟(jì)大學(xué)學(xué)報(bào)(自然科學(xué)版);2004年12期

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本文編號(hào)：1844246