本文選題：柴油類替代燃料 + 多支鏈芳烴��； 參考：《中國科學技術(shù)大學》2016年博士論文

【摘要】：當前經(jīng)濟、社會發(fā)展所需的一次能源仍依托于化石燃料,它提供了全球能源總量約85%的比重�；剂系母咝鍧嵢紵约按萌剂系陌l(fā)展始終是困擾人們的兩大難題。這就要求研究者一方面深入理解化石燃料燃燒中的難點問題,另一方面完善對于生物燃料等代用燃料燃燒機理的認識。柴油中含有長鏈烷烴、環(huán)烷烴、單環(huán)芳烴和多環(huán)芳烴等多種有機成分。多支鏈單環(huán)芳烴是柴油中的重要組分類型,也通常被用作柴油替代燃料的代表性組分,其燃燒研究中不同支鏈位置和數(shù)量的動力學效應(yīng)是需要重點解決的問題。而作為柴油代用燃料的生物柴油主要由酯類燃料構(gòu)成,對于其特征基團酯基在燃燒中的轉(zhuǎn)化機理也需要得到充分的認識。因此,本論文分別針對這兩個問題,選取最簡單的雙支鏈芳烴一一二甲苯的三種同分異構(gòu)體,以及最簡單的三支鏈芳烴之一1,2,4-三甲苯,對不同支鏈位置和數(shù)量的多支鏈單環(huán)芳烴開展燃燒反應(yīng)動力學實驗和模型研究；并選取最簡單的包含C2以上烷基基團的甲酯類燃料丙酸甲酯,研究酯基在甲酯類燃料分解中的作用。本論文的工作主要從兩個方面展開。在實驗方面,開展了流動反應(yīng)器熱解和低壓層流預混火焰研究,利用同步輻射真空紫外光電離質(zhì)譜技術(shù)對熱解和火焰物種進行診斷,包括主要物種、穩(wěn)定中間產(chǎn)物、自由基和多環(huán)芳烴。在熱解中測得熱解物種摩爾分數(shù)隨溫度變化的曲線,在火焰中測得火焰物種摩爾分數(shù)隨火焰高度變化的曲線。在模型方面,構(gòu)建了三種二甲苯燃料和1,2,4-三甲苯的燃燒反應(yīng)動力學模型以及丙酸甲酯的熱解反應(yīng)動力學模型,并利用實驗測量結(jié)果對模型進行了深入的驗證�；谏伤俾史治龊挽`敏性分析對關(guān)鍵物種和反應(yīng)進行動力學分析,明確燃料的燃燒反應(yīng)動力學特性。對于二甲苯體系,熱解過程中燃料的單分子解離反應(yīng)和自由基進攻反應(yīng)是引發(fā)燃料初始分解的重要反應(yīng),其中以自由基進攻反應(yīng)貢獻最大。自由基進攻反應(yīng)主要包括氫提取反應(yīng)和本位加成反應(yīng)。熱解過程中自由基進攻以H進攻為主導。通過氫提取反應(yīng)燃料會生成相應(yīng)的二甲苯基,本位加成反應(yīng)則會生成甲苯。鄰二甲苯基和對二甲苯基可以通過單分子脫氫生成相應(yīng)的二亞甲基苯,而間二甲苯基由于無法大量生成間二亞甲苯,只能通過環(huán)異構(gòu)過程生成對二亞甲基苯�；鹧嬷袣涮崛》磻�(yīng)是二甲苯的主要初始消耗路徑,由H和OH自由基進攻引發(fā),可以發(fā)生在甲基位和苯環(huán)位,分別生成對應(yīng)的二甲苯基和二甲基苯基。貧燃火焰中二甲苯基主要通過氧化反應(yīng)消耗,進而生成苯和甲苯。富燃火焰中二甲苯基與熱解過程中類似,主要是通過單分子解離反應(yīng)消耗的。而對于間二甲苯基,氧化反應(yīng)在富燃條件下仍具有一定貢獻。芳烴生長路徑在鄰二甲苯和對二甲苯/間二甲苯的燃燒過程中有明顯區(qū)別。鄰二甲苯具有鄰位結(jié)構(gòu),在茚和萘的生成過程中,鄰位成環(huán)作用起到了極其重要的作用。在對二甲苯和間二甲苯體系中,fulvenallenyl((?))自由基是重要的芳烴生長前驅(qū)體之一,而該自由基主要是由二甲苯基的單分子解離反應(yīng)引導生成fulvenallene((?)),并進一步通過脫氫或氫提取反應(yīng)生成。在間二甲苯體系中,間二甲苯基無法大量生成二亞甲苯,造成間二甲苯基富集并向著其他反應(yīng)通道進行分解。在此過程中造成芳烴生長前驅(qū)體之一的fulvenallenyl自由基大量生成,進而使得芳烴生長的反應(yīng)流量增大,最終造成間二甲苯體系中芳烴生成趨勢比對二甲苯體系更強。在1,2,4-三甲苯的熱解和火焰中,燃料的主要消耗路徑為自由基進攻反應(yīng),特別是H提取反應(yīng)和本位加成反應(yīng)。在低壓熱解中,燃料的單分子解離反應(yīng)也占有一定比例。1,2,4-三甲苯涉及到鄰-、間-、對-三個甲基位點的結(jié)構(gòu),其燃燒動力學也因此涉及到三個二甲苯的反應(yīng)動力學。燃料初級分解過程產(chǎn)生了大量的二甲基芐基,在貧燃與富燃條件下的消耗路徑不同,但都對后續(xù)小分子產(chǎn)物的生成具有重要意義。fulvenallenyl自由基是萘、菲等重要的PAH生成前驅(qū)體,主要由燃料相關(guān)路徑生成,該路徑已被實驗證實。根據(jù)富燃火焰中m/z=105(對應(yīng)于二甲苯基)的光電離效率曲線,可以發(fā)現(xiàn)二甲苯基主要由80%間二甲苯基和20%對二甲苯基組成,非常接近于模型的預測值(間二甲苯基：對二甲苯基=5：1)。Fulvenallenyl是間二甲苯基的后續(xù)產(chǎn)物之一,1,2,4-三甲苯中產(chǎn)生大量間二甲苯基驗證了芳烴生長的路徑。此外,茚主要來自于另一條與燃料直接相關(guān)的路徑。對于多支鏈芳烴燃料的初始熱解分解過程,單分子解離反應(yīng)以脫氫反應(yīng)為主,脫甲基反應(yīng)貢獻幾乎可以忽略。雙分子反應(yīng)主要包括氫提取反應(yīng)和本位加成反應(yīng),其中以氫提取反應(yīng)為主導。并且隨著甲級數(shù)量的增加,甲基位氫提取反應(yīng)貢獻也隨之增加。此外,在三甲苯火焰中苯環(huán)位氫提取反應(yīng)貢獻可忽略。甲基位發(fā)生脫氫反應(yīng)后生成的自由基是二甲苯和三甲苯分解過程中的最主要的中間物種,其中二甲苯生成二甲苯基,三甲苯分解生成二甲基芐基。對于1,2,4-三甲苯,三個甲基并不等價,不同甲基位的脫氫反應(yīng)會生成不同二甲基芐基異構(gòu)體。三甲苯比二甲苯多一個甲基,隨著甲基數(shù)量的增多,相應(yīng)的燃料初始脫氫自由基的單分子解離反應(yīng)數(shù)量也隨之增加。在丙酸甲酯的熱解過程中,單分子解離反應(yīng)、氫提取反應(yīng)以及初始中間產(chǎn)物的后續(xù)分解反應(yīng)對于燃料丙酸甲酯的分解意義重大。因此本工作中對這些反應(yīng)路徑進行了理論計算,并計算了其反應(yīng)速率常數(shù),用以建立更加準確的熱解反應(yīng)動力學模型�；诶碚撚嬎�,發(fā)現(xiàn)了CH3CHCO和CH3OH兩條新的生成通道,一條是直接通過四元環(huán)過渡態(tài)生成。另一條包括三個步驟,分別為H轉(zhuǎn)移、H旋轉(zhuǎn)和CH3OH消去�；趯嶒灪屠碚撚嬎�,我們建立了一個包含98個物種和493個反應(yīng)的丙酸甲酯熱解反應(yīng)動力學模型。該模型可以很好地模擬出大多數(shù)熱解物種的摩爾分數(shù)曲線。丙酸甲酯的分解和其他熱解產(chǎn)物的生成對初始反應(yīng)的速率常數(shù)十分敏感。ROP分析顯示三個單分子解離反應(yīng)是丙酸甲酯的主要消耗反應(yīng),即MP=CH3+CH2COOCH3、MP=CH3+CH3CH2COO和MP=CH3CHCO+CH3OH。燃料中的酯基對于氧化產(chǎn)物的生成具有重要意義。
[Abstract]:In the current economy, the energy needed for social development is still dependent on fossil fuels, which provides a total of about 85% of the total energy in the world. The high efficiency and clean combustion of fossil fuels and the development of alternative fuels have always been the two difficult problems that perplex people. This requires researchers to understand the difficult problems in fossil fuel combustion, and the other one, the other one. There are many kinds of organic components such as long chain alkanes, naphthenic hydrocarbons, mono cyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons. Polybranched mono arene is an important component of diesel fuel and is usually used as a representative component of diesel fuel alternative fuels. The dynamic effect of placing and quantity is a key problem to be solved. And the biodiesel as a substitute fuel for diesel is mainly made up of ester fuel, and the transformation mechanism of its characteristic group ester in combustion must be fully understood. Therefore, this paper selects the simplest double branched aromatics one by one for these two problems. Three isomers of xylene and one of the simplest three branched aromatics, 1,2,4- three toluene, were used to conduct combustion kinetics experiments and model studies on multi branched chain mono cyclic aromatic hydrocarbons with different branched chain positions and numbers, and the most simple methyl methyl propionate, which contained the alkyl group above C2, was selected, and the ester group was studied in methyl ester combustion. The work of this paper is mainly carried out in two aspects. In the experiment, the pyrolysis of the flow reactor and the low-pressure laminar premixed flame are studied, and the pyrogenation and flame species are diagnosed by synchrotron vacuum ultraviolet photoionization mass spectrometry, including the main species, the stable intermediate products, the free radicals and polycyclic aromatic hydrocarbons. The curves of the molar fraction of the pyrolytic species with the temperature are measured in the pyrolysis, and the curves of the flame species mole fraction change with the flame height are measured in the flame. In the model, the kinetic model of the combustion reaction of three kinds of xylene fuel and 1,2,4- three toluene and the kinetic model of the pyrogenation of propionate are constructed, and the experiment is used for the experiment. Based on the generation rate analysis and sensitivity analysis, the kinetic characteristics of the key species and reactions are analyzed, and the kinetic characteristics of the fuel combustion reaction are determined. For the xylene system, the single molecular dissociation reaction and the self based attack reaction of the fuel during the pyrolysis process are the initial decomposition of the fuel. The free radical attack reaction mainly consists of the free radical attack reaction. The free radical attack reaction mainly includes the hydrogen extraction reaction and the standard addition reaction. The free radical attack is dominated by the H attack during the pyrolysis process. The corresponding dimethylbenzene can be generated by the hydrogen extraction reaction fuel, and the standard addition reaction will produce toluene. The adjacent two methylene and the two a will be formed. The phenyl group can dehydrogenate the corresponding two methylene benzene through a single molecule, while the two methylene can not produce a large number of two methylbenzene, and can only produce to two methylene benzene through the cyclic isomerization process. The hydrogen extraction reaction in the flame is the main initial consumption path of the xylene, which is induced by the H and OH radical attack, and can occur in methyl and benzene. The ring position produces corresponding dimethylbenzene and two methyl phenyl respectively. The two methylene in the lean combustion flame is mainly consumed by the oxidation reaction, and then produces benzene and toluene. The two methyl in the rich flame is similar to the pyrolysis process, mainly by the single molecule dissociation reaction. And for the two methylene, the oxidation reaction is still under the condition of rich combustion. There is a significant difference in the aromatics growth path in the combustion process of xylene and p-xylene / m xylene. The ortho dimethylbenzene has a neighborhood structure. In the formation of the nylene and naphthalene, the neighbouring ring formation plays an extremely important role. The fulvenallenyl ((?)) radical is heavy in the system of p-xylene and two toluene. One of the precursors of aromatics growth is required, and the free radical is guided by the two methylene single molecule dissociation reaction leading to fulvenallene ((?)) and further generated by dehydrogenation or hydrogen extraction. In the m xylene system, the two methylene can not produce a large amount of toluene, resulting in the enrichment of two methylene and the other reactions. In this process, the fulvenallenyl free radical of one of the precursors of aromatics growth is produced, and the flow rate of the aromatics growth is increased, and the aromatics generation trend in the xylene system is stronger than that of the p-xylene system. In the thermal solution and flame of 1,2,4- three toluene, the main consumption path of the fuel is The free radical attack reaction, especially the H extraction reaction and the standard addition reaction. In the low pressure pyrolysis, the single molecular dissociation reaction of the fuel also occupies a certain proportion of the.1,2,4- trimethyl benzene involving the adjacent, inter, and the structure of the three methyl sites, and its combustion kinetics also involves the reaction kinetics of the three xylene. The primary decomposition process of fuel is also involved. A large number of two methyl benzyl groups have been produced, which are different in the poor combustion and burning conditions, but are important for the generation of subsequent small molecular products..fulvenallenyl free radicals are important PAH precursors, such as naphthalene and phenanthrene, which are mainly generated by fuel related paths. The path has been proved by experiments. According to the m/z=105 in the burning flame, According to the photoionization efficiency curve of dimethylbenzene, it is found that the dimethylbenzene group is composed mainly of 80% two methylene groups and 20% dimethylbenzene groups, very close to the predicted value of the model (two methylene: p-xylene =5:1).Fulvenallenyl is one of the follow-up products of the two methylene benzyl, and a large number of dimethylbenzene is produced in 1,2,4- triphenyl. In addition to the path of aromatics growth, in addition, it mainly comes from another path that is directly related to fuel. For the initial decomposition process of multi branched aromatic hydrocarbon fuels, the single molecular dissociation reaction is mainly dehydrogenation reaction, and the contribution of demethylation reaction can almost be ignored. The main factors for the double molecular reaction include the hydrogen extraction reaction and the standard addition reaction, In addition, the contribution of the hydrogen extraction reaction of the benzene ring position in the trimethylamine flame is negligible. The free radical formed after the methyl dehydrogenation reaction is the most important intermediate species in the decomposition process of xylene and three toluene, The dimethylbenzene generates dimethylbenzene and three toluene is decomposed to produce two methyl benzyl. For 1,2,4- three toluene, three methyl groups are not equivalent, and the dehydrogenation reaction of different methyl sites will produce different two methyl benzyl isomers. Trimethylamine is more methyl than dimethylbenzene. With the increase of methyl number, the corresponding fuel dehydrogenated free radicals. The number of dissociation reactions also increased. During the pyrolysis of methyl propionate, the single molecule dissociation reaction, the hydrogen extraction reaction and the subsequent decomposition reaction of the initial intermediate products were of great significance for the decomposition of methyl propionate. Based on the theoretical calculation, two new generation channels of CH3CHCO and CH3OH are found. One is generated directly through the transition state of the four membered ring. The other includes three steps, namely, H transfer, H rotation and CH3OH elimination. Based on the experimental and theoretical calculations, we have established a total of 98 species and one of them. 493 reaction kinetic models of the pyrolysis of methyl propionate. This model can well simulate the mole fraction curve of most pyrolytic species. The decomposition of methyl propionate and the generation of other pyrolysis products are sensitive to the rate constant of the initial reaction..ROP analysis shows that the main consumption of three single molecule dissociation reactions is the main consumption of methyl propionate. Reaction, that is, the ester groups in MP=CH3+CH2COOCH3, MP=CH3+CH3CH2COO and MP=CH3CHCO+CH3OH. fuels are of great importance for the formation of oxidation products.

【學位授予單位】：中國科學技術(shù)大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TK16
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本文編號：1823938