本文選題：溫度場 + 密度泛函理論��； 參考：《西安科技大學(xué)》2014年博士論文

【摘要】：甲烷吸附與解吸是研究瓦斯擴散、滲流、累積和防治煤與瓦斯突出的重要理論基礎(chǔ)，是煤礦安全生產(chǎn)的重要研究課題之一。本文通過溫度場下甲烷氣體兩次解吸實驗、煤體紅外光譜實驗和密度泛函理論（DFT）分別從宏觀能量和微觀結(jié)構(gòu)兩方面對煤體中甲烷氣體的吸附與解吸機理進行了研究，發(fā)現(xiàn)宏觀規(guī)律和微觀量化計算結(jié)果之間具有相關(guān)性。通過實驗數(shù)據(jù)分析和理論計算完成的主要工作如下： （1）溫度是甲烷氣體解吸的最重要影響因素。通過宏觀溫度場下甲烷氣體的兩次解吸實驗分析，結(jié)果表明甲烷氣體的吸附為物理吸附，沒有能級結(jié)構(gòu)。甲烷氣體在煤體中的賦存是一個同時包含吸附、解吸、擴散、滲流和累積的動態(tài)過程，溫度升高會導(dǎo)致煤體中的甲烷氣體吸附速度和解吸速度同時增大，解吸氣體含量增多，對此動態(tài)過程，提出了綜合速度概念，綜合速度由吸附速度和解吸速度合成，該速度與溫度之間是非線性關(guān)系。 （2）煤對甲烷氣體的吸附力為誘導(dǎo)力與色散力。在五種煤樣紅外光譜數(shù)據(jù)分析的基礎(chǔ)上，采用密度泛函理論（DFT）對瓦斯吸附和解吸進行動力學(xué)分析，發(fā)現(xiàn)在吸附和解吸過程中，甲烷氣體和煤體大分子結(jié)構(gòu)鍵長、鍵角、二面角以及密立根電荷的變化，發(fā)現(xiàn)吸附過程主要是由于煤分子和甲烷分子之間存在電場相互作用，甲烷分子在吸附過程中被極化，煤大分子自身密立根電荷量也重新分布，煤分子和甲烷分子最終達到電場力相互平衡，吸附力為誘導(dǎo)力各色散力。 （3）提出了采用密立根電荷量定量分析吸附空位的方法，對煤體甲烷氣體多分子層吸附理論進行了驗證。通過對吸附過程的動力學(xué)分析，結(jié)果顯示在吸附過程中起主要作用的是電場力，，整個煤體結(jié)構(gòu)中的密立根電荷量分布發(fā)生了明顯變化，即分子結(jié)構(gòu)中的電荷分布對煤的吸附性有重要影響，故以密立根電荷量作為煤對甲烷氣體的吸附空位的判定依據(jù)。計算了甲烷氣體的吸附能和吸附勢阱深度，發(fā)現(xiàn)在同一吸附空位附近有多個吸附平衡位置，對應(yīng)的吸附距離和吸附能都不同，說明甲烷氣體存在多層吸附的可能性。 （4）甲烷氣體的吸附與解吸動力學(xué)過程是宏觀能量和微觀結(jié)構(gòu)之間相互作用的共同結(jié)果。通過宏觀實驗結(jié)論和微觀理論分析相互驗證，研究宏觀規(guī)律和微觀機理之間的對應(yīng)關(guān)系，溫度變化引起甲烷氣體宏觀能量變化，同時會對甲烷氣體的微觀吸附結(jié)構(gòu)產(chǎn)生影響，而微觀吸附結(jié)構(gòu)的變化又反過來影響宏觀壓強和煤體結(jié)構(gòu)，即解吸和吸附是宏觀因素和微觀因素共同作用的結(jié)果。
[Abstract]:Methane adsorption and desorption is an important theoretical basis for the study of gas diffusion, seepage, accumulation and prevention of coal and gas outburst, and is one of the important research topics of coal mine safety production. In this paper, the adsorption and desorption mechanism of methane gas in coal is studied from macroscopic energy and microcosmic structure by means of twice desorption experiment of methane gas under temperature field, infrared spectrum experiment of coal and density functional theory (DFT). It is found that there is a correlation between macroscopic law and microscopic quantitative calculation results. The main works are as follows: (1) temperature is the most important factor of methane desorption. Through two desorption experiments of methane gas under macroscopic temperature field, the results show that the adsorption of methane gas is physical adsorption, and there is no energy level structure. The occurrence of methane gas in coal body is a dynamic process including adsorption, desorption, diffusion, seepage and accumulation. The increase of temperature will lead to the increase of adsorption rate and desorption rate of methane gas in coal body and the increase of desorption gas content. For this dynamic process, the concept of synthetic velocity is put forward, which is composed of adsorption speed and desorption velocity, which is nonlinear with temperature. (2) the adsorption force of coal to methane gas is induced force and dispersion force. Based on the analysis of infrared spectrum data of five kinds of coal samples, the density functional theory (DFT) was used to analyze the kinetics of gas adsorption and desorption. It was found that in the process of adsorption and desorption, the bond length and bond angle of methane gas and coal macromolecular structure were long. With the change of dihedral angle and Millikan charge, it is found that the adsorption process is mainly due to the electric field interaction between the coal molecule and methane molecule, the methane molecule is polarized during the adsorption process, and the charge amount of the coal macromolecule itself is also redistributed. Finally, coal and methane molecules reach the equilibrium of electric field force, and the adsorption force is inductive force. (3) the method of quantitative analysis of adsorption vacancy by Milliken charge quantity is proposed. The multilayer adsorption theory of methane gas from coal is verified. Through the kinetic analysis of the adsorption process, the results show that the electric field force plays a major role in the adsorption process, and the distribution of the Milliken charge in the whole coal structure has changed obviously. That is, the charge distribution in the molecular structure has an important effect on the adsorption of coal, so Millikan charge is used as the basis for judging the adsorption vacancy of methane gas by coal. The adsorption energy and potential trap depth of methane gas are calculated. It is found that there are many adsorption equilibrium sites near the same adsorption vacancy, and the corresponding adsorption distance and adsorption energy are different. (4) the adsorption and desorption kinetics of methane gas is the result of the interaction between macroscopic energy and microstructure. The corresponding relationship between macroscopic law and microscopic mechanism is studied through the mutual verification of macroscopic experimental conclusion and microscopic theoretical analysis. The change of temperature leads to the change of macroscopic energy of methane gas, and at the same time, it has an effect on the microstructure of methane gas adsorption. The change of microcosmic adsorption structure in turn affects the macroscopic pressure and the coal structure, that is, desorption and adsorption are the result of both macro and micro factors.
【學(xué)位授予單位】：西安科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：TD712;TD713

【參考文獻】

相關(guān)期刊論文 前10條

1 H.F.雅納斯,于策;煤樣的瓦斯解吸過程[J];煤炭工程師;1992年02期

2 王恩元，何學(xué)秋，林海燕;瓦斯氣體在煤中的賦存形態(tài)[J];煤炭工程師;1996年05期

3 陳昌國,魏錫文,鮮學(xué)福;用從頭計算研究煤表面與甲烷分子相互作用[J];重慶大學(xué)學(xué)報(自然科學(xué)版);2000年03期

4 陳昌國,鮮曉紅,張代鈞,鮮學(xué)福;微孔填充理論研究無煙煤和炭對甲烷的吸附特性[J];重慶大學(xué)學(xué)報(自然科學(xué)版);1998年02期

5 王剛;程衛(wèi)民;潘剛;;溫度對煤體吸附瓦斯性能影響的研究[J];安全與環(huán)境學(xué)報;2012年05期

6 楊向平,李陽初,沈復(fù);能量不均勻固體表面上多元非理想溶液的吸附等溫線模型[J];化工學(xué)報;1998年02期

7 趙旭,王毅力,郭瑾瓏,韓海榮,解明曙;顆粒物微界面吸附模型的分形修正——朗格繆爾(Langmuir)、弗倫德利希(Freundlich)和表面絡(luò)合模型[J];環(huán)境科學(xué)學(xué)報;2005年01期

8 易俊;姜永東;鮮學(xué)福;張渝;;超聲熱效應(yīng)促進煤層瓦斯解吸擴散數(shù)值模擬[J];重慶建筑大學(xué)學(xué)報;2008年04期

9 張力,邢平偉;煤體瓦斯吸附和解吸特性的研究[J];江蘇煤炭;2000年04期

10 王恩元,何學(xué)秋;瓦斯氣體在煤體中的吸附過程及其動力學(xué)機理[J];江蘇煤炭;1996年03期

相關(guān)博士學(xué)位論文 前1條

1 劉紀(jì)坤;煤體瓦斯吸附解吸過程熱效應(yīng)實驗研究[D];中國礦業(yè)大學(xué)(北京);2012年

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