氨基功能型离子液体吸收CO2的性能

氨基功能型离子液体在常温常压下对CO₂具有较强的吸收选择性能,在分离固定CO₂方面具有较好的应用前景。合成了4种氨基功能型离子液体,对产物进行了IR和¹H NMR表征,探究了这些功能型离子液体的CO₂吸收性能及再生性能。结果表明,4种氨基功能型离子液体均具有强于常规型离子液体的CO₂吸收性能,再生性能良好,可循环使用;离子液体的CO₂溶解度受黏度影响显著,随吸收温度的升高而降低,随吸收压力的升高,吸收剂浓度的增加而增大;强化传质能提高再生效率,多次的再生对离子液体的吸收性能没有明显影响。     

超强碱离子液体-有机胺-水复配溶剂高效CO2捕集

CO₂捕集是实现碳减排的重要技术之一。其中，化学吸收法是一种有效的、适用于低CO₂分压的CO₂捕集技术。开发出一种高效、低能耗、环保的吸收剂是该领域的研究难点和热点。离子液体(ILs)作为一类绿色溶剂，在CO₂捕集中具有结构可调节、反应速率快、吸收量高等优势，但存在黏度大、价格昂贵等问题，本工作提出将超强碱离子液体1,8-二氮杂二环[5,4,0]十一碳-7-烯咪唑([HDBU][Im])与单乙醇胺(MEA)复配得到离子液体复配溶剂，来提高吸收剂的CO₂吸收量并降低吸收CO₂后溶剂的黏度。研究了离子液体浓度、吸收温度、CO₂分压等对离子液体复配溶剂捕集CO₂性能的影响，测定了离子液体复配溶剂在不同CO₂负荷下的密度和黏度等物性。结果表明，30wt%MEA+10wt%[HDBU][Im]具有较好的吸收能力，在40℃下，CO₂吸收量达到0.1453 g CO₂     

相变离子液体体系吸收分离CO2的研究现状及展望

全球工业化的迅速发展及人口增长使得化石燃料消耗不断增加，导致二氧化碳(CO₂)排放量逐年递增，引发全球化气候问题。醇胺吸收法目前在工业CO₂捕集应用最广泛，主要以单乙醇胺、甲基二乙醇胺等水溶液为吸收剂，存在溶剂损耗大、再生能耗高等问题，开发高效低能耗的新型吸收剂是实现CO₂大规模捕集的关键。离子液体具有气体亲和性好、蒸气压低、结构性质可调等特点，其中相变离子液体体系因节能潜力大被认为是新一代CO₂吸收剂，其吸收CO₂后由均相变为互不相溶的液-液或液-固两相，再生时仅需对CO₂富相加热处理，可有效减少吸收剂再生体积，降低再生能耗。重点总结近五年相变离子液体体系在CO₂分离的研究现状和进展，对不同相变行为的液-液和液-固相变离子液体体系分类阐述和讨论，并对其发展趋势进行展望。     

N,N-二乙基乙醇胺(DEEA)溶液CO2吸收解吸性能的实验研究

胺法捕集回收二氧化碳工艺存在的最大缺陷是高吸收速率与低再生能耗不能共存,高效溶剂的开发是解决这一问题的有效途径之一。为筛选出吸收解吸综合性能良好的吸收剂,本文利用溶剂快速筛选实验装置对几种不同醇胺吸收剂进行了实验研究,主要从溶液吸收负载、吸收速率、解吸负载、解吸速率、循环容量及相对再生能耗等方面进行了分析比较,实验结果显示N,N-二乙基乙醇胺(DEEA)溶液表现出较好的CO₂捕获性能。此外,通过溶解度装置、填料吸收塔及再生塔分别对DEEA溶液的平衡溶解度、传质系数及再生能耗进行了实验研究与验证。实验结果表明:增加溶液浓度会降低其CO₂平衡溶解度;增加CO₂分压能增加其CO₂平衡溶解度;增大进料温度能增加溶液在填料塔中的传质系数;提高富液负载及贫液负载会降低溶液的再生能耗。因此,基于其较好的吸收解吸性能,DEEA是一种可以工业化应用的潜在吸收剂。     

氨基酸离子液体-MDEA混合水溶液对CO2的降膜吸收

氨基酸离子液体对CO₂吸收速度快,而N-甲基二乙醇胺（MDEA）有较高的CO₂吸收负荷,因此选用四甲基铵甘氨酸（［N₁₁₁₁］［Gly］）与MDEA水溶液复配成混合吸收剂用于CO₂的降膜吸收。用恒定容积法研究了混合吸收剂吸收CO₂的性能,实验结果显示,提高CO₂分压和增大［N₁₁₁₁］［Gly］浓度均能提高混合吸收剂对相似文献   

质子化哌嗪化学吸收CO2过程研究与分析

为研究有机胺吸收/解吸CO₂变化过程,以哌嗪(PZ)为吸收剂,利用浓硫酸调节PZ的质子化程度,通过核磁共振技术研究不同pH下的PZ溶液吸收CO₂情况,进一步揭示PZ和质子化PZ化学吸收/解吸CO₂的过程机理。结果表明,吸收过程中PZ与CO₂反应生成哌嗪单氨基甲酸盐和双氨基甲酸盐;当溶液pH为7.95时,溶液中哌嗪双氨基甲酸盐和部分单氨基甲酸盐发生水解,生成碳酸氢根;当溶液pH低于7.95时,溶液中CO₂以哌嗪单氨基甲酸盐和碳酸氢根形式共存。与PZ吸收剂相比,质子化PZ吸收CO₂过程中的双氨基甲酸盐相对含量降低,解吸性能提高,有利于PZ吸收剂的再生。     

离子液体-醇胺水溶液捕集CO_2研究进展

以离子液体(ILs)-醇胺复配水溶液捕集CO_2研究为依据,探究了ILs-醇胺复配溶液捕集CO_2的研究进展,总结了ILs-醇胺复配溶液的解吸能耗,为进一步提高富液中CO_2解吸性能的研究提供借鉴。     

金属离子促进乙醇胺捕集二氧化碳研究

为了解决醇胺法燃烧后捕集二氧化碳再生能耗过高的问题,研究了一种向胺溶液中添加金属离子以降低其CO₂解吸能耗的方法,称之为金属离子络合物热缓冲自热利用技术。以广泛商业化应用的单乙醇胺（MEA）溶液为研究载体,并在MEA溶液中分别添加金属离子铜或镍, 通过建立含有金属离子的MEA捕集CO₂体系的化学反应模型,解释金属离子热缓冲剂效应的内在机理。机理显示在MEA-金属离子-CO₂-H₂O体系中,金属-MEA络合物作为一种有效的反应热缓冲剂,将有机胺吸收CO₂过程中释放的反应热（放热反应）存储于金属络合物的解离键能中（吸热反应）,在CO₂高温解吸中通过其络合放热反应将储存的能量释放出来用于CO₂解吸,形成自热再生低能耗CO₂捕集技术,从而降低了MEA再生的能耗。本文进行了综合的实验测定来评价金属离子对MEA溶液捕集CO₂过程的性能提升影响,包括CO₂反应热、解吸速率、吸收-解吸循环负载、汽液平衡溶解度等。实验结果表明铜离子或镍离子作为添加剂,能增加MEA的CO₂平衡循环负载14%~20%或7%~10%,同时能够降低MEA的CO₂反应热值6.6%~24%或6.0%~20%。     

功能型离子液体的合成表征及CO2吸收性能

合成了两种传统型离子液体［bmim］BF₄和［emim］BF₄及含有胺基和羟基的功能型离子液体［NH₂P-mim］Br、［NH₂-e-mim］BF₄、［OH-e-mim］Br,并对合成的离子液体进行IR和¹H NMR表征。常温常压条件下,对所合成的离子液体开展CO₂吸收性能实验,发现胺基改性离子液体［NH₂P-mim］Br、［NH₂-e-mim］BF₄和羟基改性离子液体［OH-e-mim］Br的CO₂饱和吸收量分别是常规离子液体的3～9倍和1～2倍,且含有乙基官能团的离子液体吸收平衡时间普遍较短。最终探讨了温度、CO₂分压等对功能型离子液体吸收CO₂过程的影响。     

新型相变有机胺吸收捕集CO2技术研究进展

CO₂捕集、利用与封存(CCUS)技术是实现碳减排的关键技术之一,有机胺吸收技术是目前研究最广泛、最成熟的CO₂捕集技术,已有少数工业应用案例。吸收剂是吸收技术的核心,吸收剂的研发创新是该领域的热点方向。相比于单一相的有机胺吸收剂,相变吸收剂在吸收CO₂后产生相变行为,仅需对富相进行再生,可大幅减少再生体积,降低再生能耗。本文介绍了传统混合胺相变吸收体系的典型工艺、吸收机理和吸收剂研究进展,分析了吸收剂吸收CO₂后富相黏度高、富相体积占比大及其导致的再生能耗增加的问题。本文系统梳理了为解决上述问题而研发的四种新型的相变吸收体系,分别为空间位阻胺混合型相变吸收剂、物理溶剂混合型相变吸收剂、醇胺混合型相变吸收剂、催化剂-有机胺复合型相变吸收剂,对各类新型相变吸收体系的设计构建原理及性能强化机制进行了分析。最后,基于对研究进展的深入分析,提出了相变吸收剂的未来研究方向。     

Efficient capture of carbon dioxide with novel mass‐transfer intensification device using ionic liquids

A novel mass‐transfer intensified approach for CO₂ capture with ionic liquids (ILs) using rotating packed bed (RPB) reactor was presented. This new approach combined the advantages of RPB as a high mass‐transfer intensification device for viscous system and IL as a novel, environmentally benign CO₂ capture media with high thermal stability and extremely low volatility. Amino‐functionalized IL (2‐hydroxyethyl)‐trimethyl‐ammonium (S)?2‐pyrrolidinecarboxylic acid salt ([Choline][Pro]) was synthesized to perform experimental examination of CO₂ capture by chemical absorption. In RPB, it took only 0.2 s to reach 0.2 mol CO₂/mol IL at 293 K, indicating that RPB was kinetically favorable to absorption of CO₂ in IL because of its efficient mass‐transfer intensification. The effects of operation parameters on CO₂ removal efficiency and IL absorbent capacity were studied. In addition, a model based on penetration theory was proposed to explore the mechanism of gas–liquid mass transfer of ILs system in RPB. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2957–2965, 2013     

Efficient capture of CO2 from flue gas at high temperature by tunable polyamine-based hybrid ionic liquids

For an ideal absorbent for CO₂ capture from flue gas, there are some key features including easy preparation, high stability, low absorption enthalpy, high capacity at high temperature and excellent reversibility. Herein, several polyamine-functionalized ionic liquids (ILs) were easily prepared from cheap polyamines and lithium salts, which exhibited significantly improved stability due to the presence of multisite coordinating interactions. The viscosity was reduced by introducing polyalcohol-based ILs, leading to polyamine-based hybrid ILs. Interestingly, these polyamine-based hybrid ILs exhibited high CO₂ capacity (4.09 mmol/g, 0.1 bar) at high temperature (80°C) and excellent reversibility in the presence of H₂O and O₂, which is superior to many other good absorbents. Moreover, these ILs also showed good performance for CO₂ capture from stimulated air (2.10 mmol/g, 380 ppm). We believe that this method with easy preparation, low cost, high efficiency and excellent reversibility has a great potential in the industrial capture of CO₂ from flue gas.     

Prediction of CO2/O2 absorption selectivity using supported ionic liquid membranes (SILMs) for gas–liquid membrane contactor

Given their unique and tunable properties as solvents, ionic liquids (ILs) have become a favorable solvent option in separation processes, particularly for capturing carbon dioxide (CO₂). In this work, a simple method that can be used to screen the suitable IL candidates was implemented in our modified gas–liquid membrane contactor system. Solubilities, selectivities of CO₂, nitrogen (N₂), and oxygen (O₂) gases in imidazolium-based ILs and its activity coefficients in water and monoethanolamine (MEA) were predicted using conductor-like screening model for real solvent (COSMO-RS) method over a wide range of temperature (298.15–348.15?K). Results from the analysis revealed that [emim] [NTf₂] IL is a good candidate for further absorption process attributed to its good hydrophobicity and CO₂/O₂ selectivity characteristics. While their miscibility with pure MEA was somehow higher, utilizing the aqueous phase of MEA would be beneficial in this stage. Data on absorption performances and selectivity of CO₂/O₂ are scarce especially in gas–liquid membrane contactor system. Therefore, considering [emim] [NTf₂] IL as a supporting material in supported ionic liquid membranes (SILMs), using aqueous phase of MEA as an absorbent would result in a great membrane-solvent combination system in furthering our gas–liquid membrane contactor process. In conclusion, COSMO-RS is a potentially great predictive utility to screen ILs for specified separation applications. In addition, this work provides useful results for the [emim] [NTf₂]-SILMs to be extensively applied in the field of CO₂ capture and selective O₂ removal.     

Low viscous aminoalkyl-phenyl-silane with π–π interaction and its optimal SO2 capture condition

The high viscosity of ionic liquids (ILs) limits their practical application in SO₂ capture. In this work, the low viscous aminoalkyl-phenyl-silanes were synthesized to capture SO₂. The π–π interaction between phenyl groups reduced the volatility of aminoalkyl-phenyl-silanes greatly, but it did not increase their viscosity significantly. Among them, N-[(dimethylphenylsilyl)methyl]-N-methylbenzenemethanamine (DPSA) containing two phenyl groups exhibited the strongest π–π interaction. Therefore, the thermal decomposition temperature reached 150°C, while its viscosity was only 8.45 mPa·s at 25°C, which is much lower than that of ILs. The absorption enthalpy and entropy change of DPSA absorption reaction were −79.284 kJ/mol and −224 J/mol/K, respectively. These values are more negative than those of SO₂ capture reaction with ILs. An objective function was proposed to obtain the optimal absorption and desorption temperature. Furthermore, five cycles of regeneration experiments indicated that DPSA possessed good regeneration ability.     

Enhancement of CO2 capture in the MDEA solution by introducing TETA or TETA-AEP mixtures as an activator

TETA or TETA-AEP mixtures were used as an activator to enhance CO₂ capture in the MDEA solution. The effect of amount and type of activators, and the viscosity of absorbents on CO₂ capture were discussed. The results showed that the positive effect of TETA-AEP mixtures on CO₂ capture in the MDEA solution was greater than that of TETA. The optimal absorbent was No. V, whose CO₂ absorption capacity/desorption efficiency was 3.08 times/1.18 times of No. ?. The viscosity had a little influence on CO₂ absorption and an obvious effect on CO₂ desorption.     

Cover Chem. Eng. Technol. 2/2015

CO₂ Capture in a Bubble‐Column Scrubber Bubble columns are widely used in industry, such as on operations of reaction, fermentation, crystallization, desorption, and absorption. They can be operated in batch, continuously, or in semi‐batch, as well as in two or three phases. With the advantages of easy operation, simple structure, high mass transfer efficiency, high absorption factor, and low energy consumption, bubble columns have attracted wide attention in the industry. In recent years, as the carbon dioxide capture, storage, and regeneration are urgent issues, CCS and CCU have been used as the key point to solve greenhouse effect. This plays a great role in CO₂ capture and storage in thermal power plants, in which the CCS capture and regeneration account for 70 % of the power generation cost. How to achieve effective capture and regeneration has become a topical subject in the energy saving and carbon reduction. Among various technologies of CO₂ capture, absorption is the most mature, and MEA is used most widely. Although the capture of acid gases is still dominated by filling towers, many recent studies have confirmed the advantages of bubble towers that prevail over filling towers or other appliances. Thus, bubble columns have been adopted as the absorber and MEA as the absorbent for the new attempt of CO₂ capture. The operation variables include CO₂ concentration, pH, temperature, air flow rate, available gas‐liquid flow rate ratio, absorption efficiency, absorption velocity, overall mass transfer coefficient, and absorption factor, which are the important parameters for the design and operation of absorber. This study adopts the Taguchi experiment design to obtain the priority of parameter type and the optimal parameters of bubble towers for CO₂ capture, so as to achieve energy saving and carbon reduction. DOI: 10.1002/ceat.201400240 CO₂ Capture Using Monoethanolamine in a Bubble‐Column Scrubber Pao‐Chi Chen*, Yi Xin Luo, Pao Wein Cai Chem. Eng. Technol. 2015 , 38 (2), 274–282.     

CO2 Capture by Liquid Solvents and their Regeneration by Thermal Decomposition of the Solid Carbonated Derivatives

The chemical capture of CO₂ by either aqueous Na₂CO₃ and K₂CO₃ or nonaqueous solutions of the amines 2‐amino‐2‐methyl‐1‐propanol (AMP) or piperazine (PZ) is described. The captured CO₂ is stored as solid NaHCO₃, KHCO₃, and AMP or PZ carbamates. Solid NaHCO₃ and KHCO₃ are decomposed at 200 °C and 250 °C, respectively, to regenerate the carbonates for their reuse. In the experiments with AMP or PZ, the solid carbamates are decomposed at 80 °C–110 °C to regenerate the free amines. The absence of water in the desorption‐regeneration step is intriguing and could have the potential of reducing one of the major disadvantages of aqueous absorbents, namely the energy cost of the regeneration step and amine degradation, yet preserving the efficiency of the absorption in the liquid phase.     

Ionic liquids for CO2 capture—Development and progress

Innovative off-the-shelf CO₂ capture approaches are burgeoning in the literature, among which, ionic liquids seem to have been omitted in the recent Intergovernmental Panel on Climate Change (IPCC) survey. Ionic liquids (ILs), because of their tunable properties, wide liquid range, reasonable thermal stability, and negligible vapor pressure, are emerging as promising candidates rivaling with conventional amine scrubbing. Due to substantial solubility, room-temperature ionic liquids (RTILs) are quite useful for CO₂ separation from flue gases. Their absorption capacity can be greatly enhanced by functionalization with an amine moiety but with concurrent increase in viscosity making process handling difficult. However this downside can be overcome by making use of supported ionic-liquid membranes (SILMs), especially where high pressures and temperatures are involved. Moreover, due to negligible loss of ionic liquids during recycling, these technologies will also decrease the CO₂ capture cost to a reasonable extent when employed on industrial scale. There is also need to look deeply into the noxious behavior of these unique species. Nevertheless, the flexibility in synthetic structure of ionic liquids may make them opportunistic in CO₂ capture scenarios.     

State of the art of ionic liquid-modified adsorbents for CO2 capture and separation

The enormous emission of carbon dioxide (CO₂) from industries has triggered a series of environmental issues. In recent years, ionic liquids (ILs) as novel absorbents are widely used for CO₂ capture owing to their low vapor pressure and tunable structures. IL-modified adsorbents have the advantages of both ILs and porous supports, such as high CO₂ selectivity and high specific surface area, which are novel agents to capture CO₂ with broad application prospects. In this review, more than 140 IL-modified adsorbents for CO₂ capture in recent years were systematically summarized. The types of ILs including conventional ILs and functionalized ILs on CO₂ separation performance of different IL hybrid adsorbents, and their adsorption mechanisms were also discussed. Finally, future perspectives on IL-modified adsorbents for CO₂ separation were further posed.     

Theoretical and experimental investigation of CO2 solubility in nanofluids containing NaP zeolite nanocrystals and [C12mim][Cl] ionic liquid

Today, CO₂ separation is very important, both as an environmental issue and also in various industries. In this study, the water-based nanofluid of NaP zeolite nanocrystals and 1-dodecyl-3-methylimidazolium chloride ([C₁₂mim][Cl]) ionic liquid were mixed and tested experimentally for CO₂ absorption in an isothermal high pressure cell equipped with magnetic stirring. Zeolite nanocrystals were synthesized via the hydrothermal approach and characterized. A series of experiments were performed at different conditions to investigate the impact of various parameters, including nanoparticle type, nanoparticle concentration, stabilizer concentration, and the vessel's initial pressure, on CO₂ solubility. It was found that 0.02 wt.% of zeolite nanoparticles, 0.4 wt.% of [C₁₂mim][Cl] ionic liquid, and 0.05 wt.% of sodium dodecyl benzene sulphonate (SDBS) in nanofluids result in higher absorption of CO₂ compared to other concentrations. Furthermore, CO₂ absorption was increased by increasing ionic liquid and surfactant concentration up to a certain value near critical micelle concentration, but after that the CO₂ absorption was decreased. The overall CO₂ absorption enhancement at 20 bar for 0.02 wt.% zeolite and ZnO water-based nanofluids with 0.4% [C₁₂mim][Cl] ionic liquid and 0.02 wt.% SDBS were 26.9%, 21.5%, 21.2%, and 17% in comparison to pure water, respectively. In an absorption process using nanofluids, besides the influence of the mentioned parameters, the micro-convection caused by Brownian motion and the grazing effect of nanoparticles should be noted. Considering the micro-convection and grazing effects, a theoretical model should take into account the Brownian motion and grazing effects on the mass transfer rate in nanofluids to investigate the absorption enhancement by nano-particles.