- 學位論文
反應速率促進劑PZ加速醇胺TEA水溶液吸收二氧化碳之反應動力學研究
Effect of Piperazine on the Kinetics of Carbon Dioxide with Aqueous Triethanolamine Solutions
摘要
本研究主要利用濕壁柱探討CO2 與PZ 水溶液、混合醇胺TEA + PZ 水溶液的反應動力學，濃度範圍為PZ (0.05-0.3 kmol·m-3) + H2O 及 TEA (1.0-2.0 kmol·m-3) + PZ (0.05-0.3 kmol·m-3) + H2O。溫度範圍30、 35 及40°C，操作壓力為常壓下。對於CO2，本研究以pseudo-first-order 的模式來描述CO2 與醇胺之反應動力行為，而對於PZ、TEA 則皆使 用一級反應的反應動力學模式來探討。相關的物理數據如黏度、密 度、亨利常數以及擴散係數也ㄧ併量測。CO2 亨利常數以及擴散係數 是採用N2O 類比法來推算。 而在三級醇胺TEA 中加入PZ 來吸收CO2 的反應動力學數據在 文獻上尚未有探討則是我們以TEA + PZ + H2O 這個系統來研究的另 一主題。 由實驗結果可發現，本研究的實驗範圍符合擬一級反應之條件的 假設，而且以一級反應可以用來合理解釋CO2 與PZ、TEA 的反應。 CO2 與 PZ + H2O 的反應速率常數經實驗結果和文獻上Bishnol and Rochell, 2000 的結果相近，代表本實驗得到結果是正確的。另外由實 驗結果我們可以得知，在TEA 醇胺水溶液中，加入少量的PZ，確實 能使系統的反應吸收速率大大提升。
並列摘要
The objectives of this research are to study both experimentally and theoretically the absorption of carbon dioxide into aqueous blends of triethanolamine (TEA) and piperazine (PZ). The solution systems studied are CO2/PZ/H2O, and CO2/PZ/TEA/H2O. The concentration range are : 0.1, 0.2, 0.3, and 0.4 kmol m-3 PZ for CO2/PZ/H2O; and 0.1, 0.2, 0.3, and 0.4 kmol m-3 PZ was blended into 1.0 and 1.5 kmol m-3 TEA for CO2/PZ/TEA/H2O. The temperatures were from 30 to 40 °C. The experimental reaction kinetics data were represented by a combined mass transfer-reaction kinetics-equilibrium model which contains a set of differential-algebraic equations. A numerical method was applied to obtain the concentration of each species as functions of time and position. When integrating to the contact time, the average specific absorption rate was obtained and the reaction rate constants of carbon dioxide with TEA and PZ were determined. The period of the project is three years. For the second year, the program to perform the calculation of the combined mass transfer-reaction kinetics-equilibrium model was carried out and tested, the thermophysical properties such as density, viscosity, Henry’s constant, and diffusivity of PZ and water system were completed as planned. The specific CO2 absorption rate will be measured using a wetted-wall column apparatus. The physicochemical properties such as density, viscosity, Henry’s law constant and diffusivity of nitrous oxide in amines were also be measured. The N2O analogy was used to estimate the Henry’s law constant and diffusivity of CO2 in amines solutions. The mutual diffusivity of TEA and PZ in water were measured using the apparatus based on the Taylor dispersion method. A rigorous mathematical model applied to interpret the rate data is based on the principle of diffusional mass transfer accompanied with liquid-phase chemical reactions over the wetted-wall column. The kinetics data of CO2/PZ/TEA/H2O were used to determine the reaction rate constants for CO2/TEA, CO2/PZ. The determined reaction rate constants were consistent for both single amine and blend amine systems. the results of the proposed research can provide the fundamental kinetics data for the process design for the CO2 absorption using aqueous PZ/TEA solutions as absorbents.