本文選題：碳捕集 + 多元胺��； 參考：《北京化工大學》2015年博士論文

【摘要】：胺水溶液法是目前最有效、可行的大規(guī)模CO2捕集方法之一。為實現(xiàn)對煙道氣中CO2的吸收分離,需要探求吸收能力高、能耗低的胺類吸收劑。本文從實驗和理論兩方面研究了吸收劑分子結(jié)構(gòu)與吸收性能之間的構(gòu)效關(guān)系。實驗測定了吸收劑的CO2溶解度、酸堿度、混合熱等熱力學性質(zhì),并進行了相關(guān)的熱力學模擬。理論研究方面,結(jié)合統(tǒng)計力學積分方程理論與密度泛函理論,對胺-水、胺-CO2及胺-N2O相互作用開展研究。主要工作包括：(1)測量了不同結(jié)構(gòu)多元胺中CO2的溶解度及胺與水的混合熱,確定了分子結(jié)構(gòu)與CO2溶解度及混合熱之間的對應(yīng)關(guān)系；利用溶解度數(shù)據(jù)估算出胺與CO2的反應(yīng)熱,分析了吸收劑分子內(nèi)不同官能團對反應(yīng)熱的影響；綜合考慮CO2溶解度、混合熱與反應(yīng)熱等熱力學性質(zhì)、吸收劑的物性及價格,篩選出了兩種具有潛力的碳捕集吸收劑：二乙烯三胺與3,3'-二氨基二丙基胺,并采用酸堿滴定法測定了其酸解離常數(shù)(pKa)。(2)為得到高吸收量、低腐蝕與低能耗的吸收劑,在篩選出胺中添加了N-甲基二乙醇胺與二甘醇使其形成混合吸收劑,得到{二乙烯三胺+N-甲基二乙醇胺+水}及{二乙烯三胺+N-甲基二乙醇胺+二甘醇+水}兩類混合吸收劑,測定了兩種混合吸收劑在不同濃度時的CO2溶解度。結(jié)果表明：二乙烯三胺混合吸收劑不但提高了溶解度,降低了反應(yīng)熱,而且減小了由揮發(fā)導致的溶劑損失,降低了對設(shè)備的腐蝕性。二乙烯三胺與N-甲基二乙醇胺為3：7(摩爾比)時,綜合性能最佳。(3)基于密度泛函理論構(gòu)建了采用自由能泛函表述的橋函數(shù),并將其應(yīng)用到積分方程的三維參考作用點(3D-RISM)模型中進行能量校正,提高3D-RISM的自洽性,定量表征了H2O、CO2及N20在不同胺分子周圍的三維密度分布,確定了胺分子中不同官能團對溶劑化效應(yīng)及對C02密度分布的影響,從分子層面解釋了溶劑化效應(yīng)及構(gòu)效關(guān)系。根據(jù)胺分子周圍H2O、CO2及N20的密度分布,計算得到了胺分子的溶劑化自由能及Henry系數(shù),計算結(jié)果與實驗值基本吻合,表明該模型對胺吸收劑-C02相互作用而形成的空間結(jié)構(gòu)描述是可靠的,為設(shè)計新型高效的吸收劑、改善吸收過程中的熱力學與動力學性能提供了理論依據(jù)。(4)以非隨機雙流體電解質(zhì)(e-NRTL)模型為基礎(chǔ),構(gòu)建胺與C02反應(yīng)體系的熱力學模型,利用熱容、混合熱、汽液平衡、飽和蒸汽壓以及CO2溶解度,通過e-NRTL模型獲得了DETA、DETA-H2O、DETA-H2O-CO2及DETA-MDEA-H2O-CO2等體系的相關(guān)熱力學參數(shù),并計算了混合胺體系的CO2溶解度,模型計算值與實驗值基本吻合,表明該模型可用于計算工業(yè)碳捕集過程中相關(guān)體系的汽液平衡、混合熱、溶解度,為工藝流程設(shè)計提供重要的基礎(chǔ)參數(shù)。
[Abstract]:Amine aqueous solution method is one of the most effective and feasible methods for CO 2 capture. In order to achieve the absorption and separation of CO2 in flue gas, the amine absorbent with high absorbability and low energy consumption is needed. In this paper, the structure-activity relationship between the molecular structure of absorbent and its absorption properties is studied from both experimental and theoretical aspects. The thermodynamic properties of CO _ 2 solubility, pH and mixing heat of absorbent were measured and the thermodynamic simulation was carried out. In terms of theoretical study, the interaction of amine-water, amine-CO2 and amine-N2O is studied in combination with the theory of statistical mechanical integral equation and density functional theory. The main works are as follows: (1) the solubility of CO _ 2 in polyamines with different structures and the heat of mixing between amine and water are measured, the corresponding relationship between molecular structure and solubility of CO _ 2 and heat of mixing is determined, and the heat of reaction between amine and CO _ 2 is estimated by solubility data. The influence of different functional groups in absorber on the reaction heat was analyzed, the thermodynamic properties of CO2 solubility, mixing heat and reaction heat, the physical properties and the price of absorbent were considered synthetically. Two potential carbon-trapping absorbents, diethylenetriamine and 3Aminodipropylamine, were screened out, and their acid dissociation constants (PKA). (2) were determined by acid-base titration to obtain high absorbency, low corrosion and low energy consumption. N- methyl diethanolamine and diethylene glycol were added to the screened amine to form a mixed absorbent. Two kinds of mixed absorbers {diethylenetriamine N-methyldiethanolamine water} and {diethyltriamine N-methyldiethanolamine diethylene glycol water} were obtained. The results show that the mixture of diethylenetriamine absorbent not only improves the solubility, reduces the reaction heat, but also reduces the solvent loss caused by volatilization and the corrosion to the equipment. When the molar ratio of diethylenetriamine and N-methyldiethanolamine is 3:7 (molar ratio), the comprehensive performance is the best. (3) based on density functional theory, a bridge function expressed by free energy functional is constructed. It is applied to the three-dimensional reference point model of the integral equation (3D-RISM) for energy correction, which improves the self-consistency of 3D-RISM, and quantitatively characterizes the three-dimensional density distribution of H _ 2O _ 2 and N _ (20) around different amine molecules. The effects of different functional groups on the solvation effect and the density distribution of CO2 were determined. The solvation effect and structure-activity relationship were explained at the molecular level. According to the density distribution of H _ 2O _ 2 and N _ (20) around amine molecule, the solvation free energy and Henry's coefficient of amine molecule are calculated. The calculated results are in good agreement with the experimental values. It is shown that the model is reliable for describing the spatial structure of the interaction of amine absorbent C02, and is used to design new and efficient absorbent. The thermodynamic and kinetic properties of the absorption process are improved. (4) based on the non-random two-fluid electrolyte (e-NRTL) model, the thermodynamic model of the reaction system of amine and CO2 is constructed, using heat capacity, mixing heat, vapor-liquid equilibrium. The thermodynamic parameters of DETA-DETA-H2O-DETA-H2O-CO _ 2 and DETA-MDEA-H2O-CO _ 2 were obtained by e-NRTL model, and the solubility of CO _ 2 in mixed amine system was calculated. The calculated values of the model were in good agreement with the experimental values. It is shown that the model can be used to calculate the vapor-liquid equilibrium, mixing heat and solubility of the relevant systems in the process of industrial carbon capture, which provides important basic parameters for the process design.
【學位授予單位】：北京化工大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：X701;TQ028.17

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