【作者】 方诚刚；

【导师】 耿皎；

【作者基本信息】 南京大学 ， 应用化学， 2011， 硕士

【摘要】 二氧化碳的过量排放,给全球气候环境造成了严重的负面影响。二氧化碳的排放控制直接关系着工业生产、气候、人类健康和能源利用等方面,因此对脱碳技术的研究显得尤为重要和迫切。目前工业上使用较多的有机胺吸收法存在诸多的缺点,如MEA虽然吸收CO2速率快,但腐蚀性强且再生能耗高,MDEA有较高的CO2吸收负荷,但吸收速率较慢。离子液体的特殊优良性能使其可作为一种环境友好的脱碳吸收剂,其中氨基酸离子液体对CO2有较高的吸收速率。为了改进有机胺类C02吸收剂的应用性能,研究新型的脱碳吸收剂,本文合成了四甲基铵甘氨酸([N1111][Gly])离子液体,并与MDEA水溶液配制成三种不同浓度的吸收剂,分别为5%[N1111][Gly]+15%MDEA,10%[N1111][Gly]+15%MDEA和15%[N1111][Gly]+15MDEA,分别研究不同分压下CO2在其中的溶解性能,以及降膜过程中的吸收传质性能。首先在双釜吸收装置中用恒定容积法研究了混合吸收剂吸收CO2的性能,通过分析和比较证实提高CO2分压和增大离子液体[N1111][Gly]浓度都能使混合吸收剂对CO2的单位体积吸收容量得到提高,平衡摩尔吸收率也随着CO2分压的提高而增大,但其与[N1111][Gly]的浓度无关。本文设计并搭建了一套逆流降膜吸收装置,并利用该装置测定了混合吸收剂对纯CO2以及CO2-N2混合气体(20%CO2+80%N2)的降膜吸收性能,实验发现[N1111][Gly]浓度、气相和混合吸收剂的流动状况都对吸收传质系数造成影响。对于纯CO2气体的降膜吸收,气体或混合吸收剂的流量加大均提高了传质吸收效果,吸收剂中[N1111][Gly]离子液体的浓度增大也使吸收效果提高；对于CO2-N2混合气体的降膜吸收,气体流量加大能够提高传质吸收效果,但当气体流量大于一定流量后,气体流量继续增大反而会使吸收效果降低,混合吸收剂流量及吸收剂中[N1(?)][Gly]浓度的加大均对传质吸收效果带来正面的影响。综合各影响因素,通过量纲分析方法得到了吸收系数的准数关联式：纯CO2：Sh=5.637×10-11ReL1.225ReG0.695ScL2.085上式计算值与实验值之间的平均相对偏差为8.46%。C02-N2混合气体：Sh=0.0247ReL0.495ReG0.371ScL0.065上式计算值与实验值之间的平均相对偏差为10.03%。通过与30%MDEA水溶液的降膜吸收实验对比发现,加入[N1111][Gly]的吸收剂对CO2的降膜吸收效果明显提高,证实了季铵型氨基酸离子液体对改进传统MDEA吸收剂有潜在的应用价值。本文的还设计合成了一批新型的双季铵型的氨基酸离子液体,并对产物进行了1HNMR表征。选择了一种产物四甲基二丁基乙二铵二甘氨酸(C2(N114)2Gly2)配制成不同浓度的水溶液,用于CO2吸收实验中。实验结果显示,对于不同浓度的双季铵型的氨基酸离子液体溶液,浓度和吸收剂粘度均对吸收速率有影响,增大吸收剂中离子液体的浓度可以提高吸收速率,但离子液体浓度过大会使吸收剂黏度增大,反而降低吸收速率。本文的工作将氨基酸离子液体-MDEA混合水溶液用于了与工业实际相近的降膜吸收过程中,所取得的实验结果为氨基酸离子液体-MDEA混合水溶液吸收CO2的进一步探索和研究,为日后的工业应用模拟实验打下了一定基础。更多还原

【Abstract】 Excessive emissions of carbon dioxide has caused serious negative impact in many aspects of society. The removal of carbon dioxide is directly related to industrial production, climate, human health and utility of energy sources, thus the research about decarbonization technology is particularly important and urgent. At present, the main absorbents for removing carbon dioxide in industry are alkanolamines solutions which have many disadvantages, for instance, MEA absorbs CO2 rapidly, but the corrosion is strong and energy consumption of regeneration is high; MDEA has a higher load of CO2 absorption, but the slower absorption rate. Ionic liquids (ILs) have some special properties. It can be used as a good environmentally friendly decarburization absorbent and amino acid ionic liquids have a higher CO2 absorption rate. To improve the properties of alkanolamines absorbent and develop new decarbonization absorbent, tetramethylammonium glycinate ([N1111][Gly]) was synthesized and mixed with N-methyldiethanolamine (MDEA) aqueous solutions to bring complex absorbents at three different concentrations:5%[N1111][Gly]+ 15%MDEA,10%[N1111][Gly]+15%MDEA and 15%[N1111][Gly]+15MDEA.First, the CO2 absorption capabilities of the three complex absorbents were measured with the Constant Volume Method. The Analysis and comparison indicated that the absorption capacity per volume increased with a rise in CO2 pressure and concentration of [N1111][Gly], while the mole absorptivity at absorption equilibrium was unrelated with concentration of [N1111][Gly] under different CO2 pressures.This work designed and built a set of countercurrent falling film column to investigate falling film absorption of pure CO2 and CO2-N2 gas mixture (20%CO2+80%N2). The result showed that the concentration of [N1111][Gly], flow characteristics of gas and absorbents all influenced the mass transfer coefficient. Taking all factors, the effect of these influence factors on mass transfer coefficient could be described as: Pure CO2:Sh= 5.637×10-11ReL1.225ReG0.695ScL2.085 The correlation predicts the experimental data with a mean deviation of 8.46% CO2-N2 gas mixture:Sh= 0.0247ReL0.495ReG0.371ScL0.065 The correlation predicts the experimental data with a mean deviation of 10.03%By comparison with 30%MDEA in falling film absorption experiment, it was found that [N1111][Gly] could greatly enhance the absorption of MDEA aqueous solution, confirming that amino acid ionic liquid had potential to improve MDEA absorbent.This article has also designed and synthesized a new type of Dicationic Ionic Liquid (DIL), Di-tetraalkylammonium amino acid ionic liquids which were analyzed by 1HNMR. C2(N114)2Gly2 was mixed with water to bring aqueous solutions at different concentrations for CO2 absorption. The results indicated that the absorption rate was based on the concentration and the viscosity.In the present, the results lay a certain foundation for further exploration and research of CO2 absorption by aqueous solution of MDEA and amino acid ionic liquid for industrial applications in the future.更多还原