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离子液体型二氧化碳捕集吸收剂的研究
曹领帝
学位类型博士
导师张香平
2015-10
学位授予单位中国科学院研究生院
学位授予地点北京
学位专业化学工程
关键词Co2捕集 离子液体 复配溶剂 低共熔溶剂 吸收性能
其他摘要

CO2排放被认为是引起全球气候变暖最主要的因素之一。化学吸收法是目前最有效、最实用的碳捕集技术,而高效、节能、环保的吸收剂一直是科学家们孜孜不倦的追求。离子液体具有可忽略的蒸汽压、低比热及结构可设计性等优点,为开发CO2捕集的新型吸收剂带来契机。然而,常规离子液体的CO2吸收量低,功能化离子液体具有合成复杂、成本高、粘度大等缺点,是制约离子液体用于CO2捕集工业化应用的瓶颈。因此,开发高CO2吸收量、高吸收速率、低吸收热和低成本的离子液体型吸收剂是当前CO2捕集领域的研究热点。基于此,本论文从工业应用的角度出发,开展了多位点有机胺、离子液体-有机胺复配溶剂以及低共熔溶剂吸收CO2的应用基础研究,为开发新型高效CO2吸收剂提供理论支持。本论文的主要研究内容及创新性成果如下:(1)新型多位点有机胺N-甲基-N-(2-羟乙基)-1,3-丙二胺(HMPDA)的CO2吸收性能研究。根据伯胺的CO2的吸收速率快,叔胺的CO2吸收量大的优势,开发了一种CO2吸收量高、吸收速率快且吸收热低的多位点新型有机胺溶剂。用研制的釜式气体吸收评价实验装置和气液相平衡实验装置分别研究了HMPDA水溶液的CO2吸收速率和吸收量,发现30 wt % HMPDA水溶液的CO2吸收速率高于30 wt % MEA及30 wt % MDEA水溶液。在250 kPa、313 K时,30 wt % HMPDA水溶液的CO2吸收量可达1.5 mol CO2/mol HMPDA,高于30 wt % MEA(0.6 mol CO2/mol MEA)和30 wt % MDEA(0.9 mol CO2/mol MDEA)水溶液的CO2吸收量。研究了温度、浓度对吸收性能的影响,并考察了CO2吸收前后吸收剂的粘度和密度变化。BT2.15微量热测试系统研究了313 K时30 wt % HMPDA水溶液的CO2吸收热。结果表明,CO2负载量低于0.45 mol时,30 wt % HMPDA水溶液的CO2吸收热低于30 wt % MEA和30 wt % MDEA水溶液的CO2吸收热。(2)[Bmim][NO3]-MEA复配体系的CO2吸收性能研究。针对现有MEA碳捕集工艺再生能耗高的不足,选择稳定的离子液体[Bmim][NO3]与MEA形成复配溶剂,替代一部分水,以降低再生能耗。研究了复配溶剂的密度、粘度、比热、折光率等物化性质。与MEA水溶液相比,离子液体的加入增加了溶剂的密度、粘度和折光率,降低了比热。气液平衡实验表明离子液体的加入略微降低CO2的饱和吸收量和吸收速率,提高了CO2的物理溶解度,降低了CO2的扩散系数。用微量热技术研究了复配溶剂的CO2吸收热,并分析了温度,压力以及CO2负载量和吸收热之间的关系。结果表明,在有化学反应参与的吸收阶段(CO2负载量为0.5 mol CO2/mol MEA),吸收热主要是化学反应放出的热;此后,吸收热明显下降,主要来自离子液体的物理吸收作用。提高离子液体浓度,可明显降低复配溶剂的CO2吸收热。(3)离子液体-MDEA复配体系的CO2吸收性能研究。考察了不同离子液体复配溶剂的循环CO2吸收量,测量了313-353 K下的CO2饱和溶解度,计算了物理吸收热和亨利系数。结果表明,不同复配溶剂的循环吸收量大小顺序为:MDEA-PZ-[Bmim][BF4] > MDEA-PZ-[Bmim][Cl] > MDEA-PZ-[Bmim][NO3]。气液平衡实验表明,CO2的溶解度随着温度的升高而下降,随着压力的升高而增加,离子液体的加入略微降低了CO2的平衡溶解度。用Gibbs-Helmholtz方程计算的吸收热表明,复配体系的CO2吸收热与加入离子液体的种类有关,离子液体的加入减小了CO2的亨利系数,降低了CO2吸收热,尤其在较高的CO2负载量以及较高温度时,吸收热降低更加明显。(4)新型低共熔溶剂的合成、表征及其CO2吸收性能研究。针对现有低共熔溶剂CO2吸收量低的缺点,新合成一种基于离子液体[Bmim][Cl]的低共熔溶剂,用红外、核磁和拉曼光谱对新低共熔溶剂的结构进行表征,证实低共熔溶剂中氢键的存在是形成共熔物的原因。研究了低共熔溶剂的物化性质诸如密度、粘度和比热等物化性质和稳定性,低共熔溶剂的熔点最大降低约70 K。考察了低共熔溶剂的CO2吸收量和吸收热,最大吸收量可达21.4%,低共熔溶剂的CO2吸收热随着CO2吸收量的增加而减小。研究了低共熔溶剂的CO2吸收机理,发现共熔物与CO2之间以化学反应为主,生成的氨基甲酸盐和[Bmim][Cl]形成新的氢键,进而提高了CO2的吸收量。 

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CO2 emission has been considered as one of the primary contributors to climate change and global warming. Chemical absorption of CO2 is widely established and proved to be the most promising strategy in CO2 capture. Accordingly, efficient, energy-saving and environmentally-friendly solvent is the desired theme of academic and industrial researchers. Ionic liquids (ILs) have aroused considerable interests as solvent for CO2 capture due to their unique properties, such as negligible vapor pressure, low heat capacity and tunable designability. However, the CO2 uptake of conventional ILs is low. The synthesis of functionalized ILs is tedious and the subsequent purification is challenging. Also, functionalized IL usually shows high viscosity which is detrimental to CO2 diffusivity. Therefore, it is crucial to develop novel ILs based solvent with high CO2 uptake, fast absorption rate and low heat of CO2 absorption. This dissertation serves to extend the knowledge of CO2 absorption using multiple reaction site amine, ILs-amine hybrids and novel deep eutectic solvents (DESs) from the point of industrial view, which provides insights on the industrial application of ILs in CO2 capture. The main research work and creative results of this dissertation are as follows:(1) Performance of CO2 absorption with novel multiple reaction site amine solution were studied. Absorption rate and absorption capacity of CO2 with amine solutions were determined using the home-made on-line stirred cell and vapor liquid equilibrium (VLE). The results show that the absorption rate of CO2 with HMPDA solution is faster than those of MEA and MDEA solutions. CO2 capacity in 30 wt % HMPDA solution is up to 1.5 mol CO2/mol HMPDA, which is higher than those of 30 wt % MEA (0.6 mol CO2/mol MEA) and 30 wt % MDEA (0.9 mol CO2/mol MDEA) solutions. Effects of temperature and concentration on the CO2 absorption, and the density and viscosity of amine solutions before and after CO2 absorption were investigated. Finally, heat of CO2 absorption in HMPDA solution at 313 K was investigated using BT 2.15 calorimeter. Heat of CO2 absorption in HMPDA solution is lower than that of MEA solution when CO2 loading<0.45 mol CO2/mol amine.(2) Performance of CO2 absorption with [Bmim][NO3]-MEA hybrids were studied. Physicochemical properties, such as density, viscosity, heat capacity and refractive index of hybrids were determined and found that the addition of ILs in MEA solutions increases the density, viscosity and refractive index, while decreases the heat capacity. VLE of CO2 shows that addition of ILs slightly decreases the CO2 solubility and absorption rate while increases the physical absorption of CO2 in hybrids. Also, the addition of ILs decreases the diffusivity of CO2 in hybrids, which is related to the increased viscosity due to the addition of ILs. Effects of temperature, pressure and CO2 loading on heat of CO absorption in hybrids were analyzed. It is found that heat of CO2 absorption decreases as the pressure and CO2 loading increases. Importantly, higher concentration of ILs in hybrids can lower the heat of CO2 absorption to a large extent.(3) CO2 absorption in aqueous MDEA-ILs solutions were studied. Cycle CO2 loading, heat of physical absorption were calculated and found that the cycle CO2 loading ranks as: MDEA-PZ-[Bmim][BF4] > MDEA-PZ-[Bmim][Cl] > MDEA-PZ-[Bmim][NO3]. VLE results show that CO2 solubility in MDEA-ILs solutions increases with the partial pressure of CO2 and decreases with addition of ILs. Calculated heat of CO2 absorption shows that kind of ILs has a significant role on heat of CO2 absorption. Experimental heat of CO2 absorption shows that addition of ILs lowers the heat of CO2 absorption and this phenomenon is significant when CO2 loading is and temperature is high.(4) Performance of CO2 absorption in newly synthesized deep eutectic solvents was carried out. In order to improve the CO2 uptake of existing DESs, we synthesized imidazolium based DESs and characterized the structural information of DESs using IR, Raman and NMR. Newly formed hydrogen bond in DESs is found to be responsible for the formation of eutectics and the depression of melting point up to 70 K, which broadens the application range of DESs. The thermal stability and physicochemical properties, such as density, viscosity and heat capacity of DESs were also measure over wide temperature range. Maximum CO2 uptake of DESs is up to 21.4%, which is found to be the largest CO2 uptake of DESs. Heat of CO2 absorption with DESs was experimentally determined using BT2.15 calorimeter and found that heat decreases as CO2 loading increases. Absorption mechanism between CO2 and DESs shows that CO2 is primarily bonded chemically with DESs and the hydrogen bond improved CO2 uptake of DESs. 

语种中文
文献类型学位论文
条目标识符http://ir.ipe.ac.cn/handle/122111/21344
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曹领帝. 离子液体型二氧化碳捕集吸收剂的研究[D]. 北京. 中国科学院研究生院,2015.
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