本文選題：煤自燃　切入點(diǎn)：模型化合物　出處：《中國(guó)礦業(yè)大學(xué)》2014年博士論文　論文類型：學(xué)位論文

【摘要】：煤自燃是煤炭工業(yè)中普遍存在的一種嚴(yán)重災(zāi)害，研究煤自燃的特性和機(jī)理對(duì)防治災(zāi)害降低損失具有重要的意義。煤的低溫氧化是煤自燃發(fā)展過(guò)程中的一個(gè)重要階段，是影響煤炭自燃發(fā)生和發(fā)展的關(guān)鍵階段。而煤是一種由相似但不相同分子結(jié)構(gòu)構(gòu)成的復(fù)雜有機(jī)礦物燃料，其結(jié)構(gòu)異常復(fù)雜，并含有多種易氧化的活性基團(tuán)。直接研究其中某種活性基團(tuán)氧化過(guò)程中的結(jié)構(gòu)變化往往達(dá)不到預(yù)期的效果。因此，可采用模型化合物，將復(fù)雜大分子體系分解為簡(jiǎn)單小分子結(jié)構(gòu)，從而研究復(fù)雜煤分子中表面活性基團(tuán)的低溫氧化特性。 根據(jù)煤化學(xué)和煤的大分子模型理論，煤氧復(fù)合過(guò)程中，煤分子中的含氧官能團(tuán)、側(cè)鏈和橋鍵等活性基團(tuán)易被氧化，即煤氧化自熱效應(yīng)的導(dǎo)因，而煤中芳香環(huán)的化學(xué)性質(zhì)相對(duì)穩(wěn)定，較難參與氧化反應(yīng)，且苯環(huán)數(shù)目對(duì)活性基團(tuán)的特性影響不大。因此，本文選擇用芳環(huán)與某些煤中代表性的活性基團(tuán)組成煤自燃模型化合物：苯乙醚、苯乙醛、苯丙醇、苯甲酸、二苯基甲烷、二苯基硫醚進(jìn)行模擬實(shí)驗(yàn)研究。 對(duì)6種模型化合物進(jìn)行“氣-液”和“氣-固”反應(yīng)條件下的程序升溫氧化實(shí)驗(yàn)。通過(guò)對(duì)不同溫度下的各類氧化產(chǎn)物進(jìn)行氣相色譜、紅外光譜以及色譜-質(zhì)譜聯(lián)用分析。發(fā)現(xiàn)模型化合物的低溫氧化與煤的低溫氧化類似，其氧化過(guò)程中存在臨界溫度，即溫度超過(guò)一定值時(shí)，模型化合物的氧化活性會(huì)迅速增強(qiáng)；模型化合物的低溫氧化是一個(gè)多步的復(fù)雜反應(yīng)，包含對(duì)氧氣的化學(xué)吸附和中間產(chǎn)物生成這一過(guò)程。通過(guò)對(duì)模型化合物氧化產(chǎn)物的定性分析發(fā)現(xiàn)其主要成分包含CO、CO2、苯、苯酚及其它各類氧化的中間產(chǎn)物或副產(chǎn)物，也與煤自燃產(chǎn)物相一致。在此基礎(chǔ)上，對(duì)各模型化合物氧化反應(yīng)歷程進(jìn)行了分析。 通過(guò)模型化合物的耗氧特性，分析了模型化合物氧化過(guò)程中的活化能及指前因子等氧化動(dòng)力學(xué)參數(shù)；結(jié)果表明，6種模型化合物中苯乙醛（—CHO）和二苯基甲烷（—CH2—）的活化能較小，，氧化活性較強(qiáng)。但因醛基—CHO在煤中的含量較低，故煤中的亞甲基橋鍵—CH2—對(duì)煤的自燃特性具有重要影響。通過(guò)TG/DTA技術(shù)研究了模型化合物在低溫氧化過(guò)程中的放熱特性，發(fā)現(xiàn)煤自燃模型化合物在低溫氧化最初階段有微幅的增重，隨著溫度的進(jìn)一步升高進(jìn)而迅速失重，并最終維持穩(wěn)定。相比之下，模型化合物的DTA曲線在整個(gè)低溫氧化過(guò)程中存在不止一個(gè)吸/放熱峰，表明模型化合物的中活性結(jié)構(gòu)的在不同溫度階段有復(fù)雜的熱變化。 通過(guò)對(duì)煤中活性官能團(tuán)氧化特性的分析，選取植酸、2,6-二叔丁基對(duì)甲酚、沒(méi)食子酸正丙酯等五種抗氧化劑進(jìn)行模型化合物的低溫氧化抑制實(shí)驗(yàn)，并應(yīng)用于煤樣自燃抑制實(shí)驗(yàn)。結(jié)果表明，2,6-二叔丁基對(duì)甲酚和植酸在160℃之后對(duì)煤的氧化有良好的抑制效果。同時(shí)，通過(guò)各抗氧化劑對(duì)煤自燃阻化實(shí)驗(yàn)結(jié)果分析其氧化抑制機(jī)理。
[Abstract]:Coal spontaneous combustion is a common serious disaster in coal industry. It is very important to study the characteristics and mechanism of coal spontaneous combustion to prevent disaster and reduce loss. The low temperature oxidation of coal is an important stage in the development of coal spontaneous combustion. Coal is a kind of complex organic mineral fuel, which is composed of similar but different molecular structure, and its structure is extremely complex. And it contains many kinds of easily oxidized active groups. The structural changes in the oxidation process of some active groups are often not as good as expected. Therefore, model compounds can be used. The complex macromolecular system was decomposed into simple small molecular structures, and the oxidation characteristics of surface active groups in complex coal molecules were studied at low temperature. According to the theory of macromolecular model of coal chemistry and coal, the oxygen-containing functional groups, side chains and bridge bonds in coal molecules are easily oxidized in the process of coal-oxygen compounding, that is, the conduction of coal oxidation autoheating effect. However, the chemical properties of aromatic rings in coal are relatively stable, and it is difficult to take part in oxidation reactions, and the number of benzene rings has little effect on the properties of active groups. In this paper, aromatic rings and some representative active groups in coal are selected to form coal spontaneous combustion model compounds: phenylether, phenylacetaldehyde, phenylpropanol, benzoic acid, diphenyl methane and diphenyl sulfide. The temperature programmed oxidation experiments of six model compounds were carried out under the conditions of "gas-liquid" and "gas-solid" reactions. The oxidation products at different temperatures were analyzed by gas chromatography. Infrared spectrum and chromatography-mass spectrometry analysis showed that the oxidation of the model compound at low temperature is similar to that of coal at low temperature. The oxidation activity of the model compound increases rapidly when the temperature exceeds a certain value. The oxidation of model compounds at low temperature is a multistep complex reaction involving the chemical adsorption of oxygen and the formation of intermediate products. Phenol and other kinds of oxidation intermediates or by-products are also consistent with coal spontaneous combustion products. On this basis, the oxidation reaction mechanism of each model compound is analyzed. The oxidation kinetic parameters such as activation energy and preexponential factor during oxidation of the model compounds were analyzed through the oxygen consumption characteristics of the model compounds. The results showed that the activation energies of phenylacetaldehyde and diphenyl methane (Ch _ 2) in the six model compounds were small. The oxidation activity is strong. However, because of the low content of aldehyde Cho in coal, the methylene bridge bond (Ch 2-) in coal has an important effect on the spontaneous combustion characteristics of coal. The exothermic properties of the model compounds in the process of low temperature oxidation have been studied by TG/DTA technique. It was found that the model compound of coal spontaneous combustion increased slightly in the initial stage of oxidation at low temperature, and then lost weight rapidly with the further increase of temperature, and finally maintained stability. There is more than one heat absorption / exothermic peak in the DTA curve of the model compound during the whole process of low temperature oxidation, which indicates that the active structure of the model compound has complex thermal changes at different temperatures. By analyzing the oxidation characteristics of active functional groups in coal, five kinds of antioxidants, such as phytate 2, 6 and 2 tert-#china_person0#, were selected to carry out the low temperature oxidation inhibition experiments of the model compounds, such as cresol, n-propyl gallate, and so on. The results showed that the oxidation of cresol and phytic acid to coal was inhibited after 160 鈩

本文編號(hào)：1614003