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     

离子液体在生物催化中的应用

近年来,离子液体(ILs)以其独特的优势成为生物催化反应研究的热点,尤其是作为生物催化反应的溶剂或共溶剂的研究更是备受关注.许多酶能在ILs或其形成的两相体系或单相体系中保持催化活性.如目前研究最多的脂肪酶,有多种能在ILs中表现出活性稳定、反应选择性提高、产率提高等优良特性;某些蛋白酶在ILs中稳定性提高,具有酯酶的活性;β-半乳糖苷酶在ILs中的催化产率提高;全细胞在ILs中的催化反应效果也较好;但是也有某些酶,如纤维素酶、某些过氧化物酶等在ILs中活性会降低或丧失.因此有关这一方面的研究还有待进一步深入.     

Modelling carbon dioxide solubility in ionic liquids

Solubility information for CO₂ in different ionic liquids, ILs, in part can potentially be used to select a specific IL for the separation of CO₂ from hydrocarbon fluids. Unfortunately, not all CO₂–IL systems have been experimentally described at similar temperatures and pressures; therefore, a direct comparison of performance by process simulation is not always possible. In the extreme cases, the design of a CO₂ separation process may require predicting the CO₂–IL equilibria for which there are no available solubility data. To address the need for this information, a semi‐empirical correlation was developed to estimate the dissolution of CO₂ in CO₂–IL solvent systems. The theoretical COSMO–RS calculation method was used to calculate the chemical potential of CO₂ in a wide variety of ILs and the Soave–Redlich–Kwong equation was used to calculate the fugacity coefficient of the CO₂ vapour phase. The model was correlated with available literature data, yielding an average error of AAR = 23% and small bias. © 2012 Canadian Society for Chemical Engineering     

碱液吸收法治理含NOx工艺尾气实验研究

为了提高碱液吸收氮氧化物废气的吸收效率,控制氮氧化物废气的排放,在直径为25 mm,高度1 000 mm的填料吸收塔内,对碱液吸收法治理含NOx工艺尾气的过程进行了研究,主要探讨了填料塔中的填料、吸收液、喷淋密度和氧化度对氮氧化物脱除效果的影响。结果表明:相对于同样的吸收条件,填料的表面积越大,空隙率越高,则吸收效果越好;NaOH溶液和Na2CO3溶液对氮氧化物都能达到较好的脱除效果,但是相对于最佳的脱除效果,NaOH溶液的质量浓度却比Na2CO3溶液的质量浓度低;碱液吸收含NOx工艺尾气的适宜喷淋密度为12 m3/(m2.h);当氧化度为50%左右时,吸收效果可以达到更好。     

离子液体吸收分离一氧化碳的研究进展

离子液体(ILs)作为一种新型的绿色溶剂在吸收和分离一氧化碳(CO)方面显示出了独特的优异性和潜在的应用价值。对近年来ILs参与CO吸收分离的研究工作进展进行了综述,主要包括常规ILs、阴离子功能化ILs、ILs/Cu (Ⅰ)盐和ILs支撑液膜。重点论述了CO在ILs中的溶解度及对其他气体的选择性,并与ILs吸收分离二氧化碳(CO₂)性能进行了比较;着重讨论了阴阳离子种类、取代基类型、温度、压力等因素对ILs吸收分离CO性能的影响,并介绍了ILs吸收CO的机理。最后,对设计合成新型功能化ILs应用于高效吸收分离CO提出了一些建议。     

Air-drying with ionic liquids

Ionic liquids (ILs) are employed for air-drying for the first time. The experimental gas–liquid equilibrium (EQ) of N₂/O₂ + [EMIM][BF₄] and N₂/O₂ + [EMIM][BF₄] + H₂O systems under a broad temperature range are measured. The new modified UNIFAC-Lei model is successfully extended to predict the N₂/O₂-IL-H₂O system based on extensive phase EQ data. The air-drying experiment using [EMIM][BF₄] as an absorbent is conducted, confirming that this new technology is effective and efficient. © 2018 American Institute of Chemical Engineers AIChE J, 65: 479–482, 2019     

功能化离子液体在二氧化碳吸收分离中的应用

吸收及分离二氧化碳是降低碳排放和应对全球气候变化的主要策略之一,这就必然要求全球科技工作者注重开发具有选择性高效吸收分离二氧化碳的新材料和新路线。作为近20多年来发展的一类代表性的新材料,离子液体（尤其是功能化离子液体）具有独特的物理化学性质,例如几乎没有蒸气压、液态温度范围大、热稳定性和化学稳定性好、电化学窗口宽、不可燃、结构-性质可调控等。这些性质使离子液体在二氧化碳吸收及分离领域受到广泛关注。重点综述了近5年（2015~2019）来功能化离子液体吸收分离二氧化碳的研究进展, 主要内容包括单位点离子液体、多位点离子液体、基于功能化离子液体的混合物、功能化离子液体杂化材料对二氧化碳的吸收分离。同时, 对目前该领域的发展所面临的主要问题和进一步的研究工作进行了分析讨论。     

The solubility of gases in ionic liquids

In this Perspective, we provide a detailed discussion of the techniques and methods used for determining the solubility of gases in ionic liquids (ILs). This includes various experimental measurement techniques, equation of state (EOS) modeling, and predictive molecular‐based modeling. Many of the key papers from the past 15 years are discussed and put into the context of the latest advances in the field. Limitations of these methods plus future developments and new research opportunities are discussed. © 2017 American Institute of Chemical Engineers AIChE J, 2017     

Recovery of carbon monoxide from flue gases by reactive absorption in ionic liquid imidazolium chlorocuprate(I):Mass transfer coefficients

Recovery of carbon monoxide from flue gases by selective absorption of carbon monoxide in an imidazolium chlorocuprate(I) ionic liquid is considered in this work as an alternative to the use of molecular volatile solvents such as aromatic hydrocarbons. The present work evaluates the CO mass transfer rates from the gas phase to the ionic liquid solutions in the absence of chemical reaction. To that end, carbon dioxide was employed as an inert model gas and absorption experiments were performed to assess the influence of different process variables in a batch reactor with flat gas–liquid interface. The experimental mass transfer coefficients showed significant var-iation with temperature, (3.4–10.9) × 10-7 m·s-1 between 293 and 313 K; stirring speed, (10.2–33.1) × 10-7 m·s-1 between 100 and 300 r·min-1;and concentration of copper(I), (6.6–10.2) × 10-7 m·s-1 between 0.25 and 2 mol·L-1. In addition, the mass transfer coefficients were eventually found to follow a poten-tial proportionality of the type kL∝μ-0.5 and the dimensionless correlation that makes the estimation of the mass transfer coefficients possible in the studied range of process variables was obtained:Sh=10-2.64·Re1.07·Sc0.75. These results constitute the first step in the kinetic analysis of the reaction between CO and imidazolium chlorocuprate(I) ionic liquid that determines the design of the separation units.     

离子液体和低共熔溶剂催化二氧化碳合成有机碳酸酯的研究进展

离子液体和低共熔溶剂因其良好的溶解与催化能力,可催化CO₂转化为高附加值化学品。本文综述了离子液体和低共熔溶剂催化CO₂转化为有机碳酸酯的研究进展,分析了CO₂与醇生成直链碳酸酯以及与环氧化物生成环状碳酸酯的反应机理;介绍了传统型、质子型、功能化离子液体以及由氯化胆碱、季铵盐与季膦盐、有机碱等作为氢键受体组成的低共熔溶剂,及其在CO₂转化为直链和环状碳酸酯反应中的催化性能;总结了此两类反应中离子液体和低共熔溶剂设计的基本规律;指出了CO₂转化反应中离子液体与低共熔溶剂存在的催化效率低、稳定性不高、后续分离困难等问题,后续研究可结合计算机辅助设计方法,探索更合适的阴阳离子/氢键供受体组合,获得更高效的催化体系。     

Carbon dioxide absorption in a cross-flow rotating packed bed

This work investigates the feasibility of applying the cross-flow rotating packed bed (RPB) to the removal of carbon dioxide (CO₂) by absorption from gaseous streams. Monoethanolamine (MEA) aqueous solution was used as the model absorbent. Also, other absorbents such as the NaOH and 2-amino-2-methyl-1-propanol (AMP) aqueous solutions were compared with the MEA aqueous solution. The CO₂ removal efficiency was observed as functions of rotor speed, gas flow rate, liquid flow rate, MEA concentration, and CO₂ concentration. Experimental results indicated that the rotor speed positively affects the CO₂ removal efficiency. Our results further demonstrated that the CO₂ removal efficiency increased with the liquid flow rate and the MEA concentration; however, decreased with the gas flow rate and the CO₂ concentration. Additionally, the CO₂ removal efficiency for the MEA aqueous solution was superior to that for the NaOH and AMP aqueous solutions. Based on the performance comparison with the conventional packed bed and the countercurrent-flow RPB, the cross-flow RPB is an effective absorber for CO₂ absorption process.     

Addition of carbon dioxide to allyl glycidyl ether using ionic liquids catalysts

The addition of carbon dioxide to allyl glycidyl ether (AGE) was investigated without using any solvent in the presence of ionic liquid as catalyst. Ionic liquids based on 1-ethyl-3-methylimidazolium (EMIm), 1-butyl-3-methylimidazolium (BMIm), and 1-hexyl-3-methylimidazolium (HMIm) with different anions such as Cl⁻, BF₄⁻, PF₆⁻ were used as catalysts. The reaction was performed in a 50 mL stainless steel autoclave. The conversion of allyl glycidyl ether was affected by the structure of imidazolium salt ionic liquids; the one with the cation of bulkier alkyl chain length and with more nucleophilic anion showed better reactivity. Reaction temperature and carbon dioxide pressure enhanced the addition of carbon dioxide to AGE.     

离子液体中二氧化碳的溶解度研究进展

室温离子液体具有独特的气体选择溶解性,在二氧化碳(CO2)的捕集和分离中有很好的应用前景。综述了近年来CO2在不同离子液体中的溶解度研究进展,比较了CO2在常规离子液体和功能型离子液体中的不同溶解机制,分析、归纳了向离子液体中引入不同官能团对CO2溶解性能的影响规律,指出了离子液体捕集CO2的未来研究方向。     

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。     

Removal of carbon dioxide from flue gases with aqueous MEA solution containing ethanol

Adding ethanol to an aqueous amine solution offers several advantages for post-combustion CO₂ capture. The equilibrium isotherms at higher temperatures shift towards lower loadings, leading to an easier desorption. At constant temperature in the desorber bottom, the desorber pressure is increased, leading to energy savings in the CO₂ compression. Alternatively, at constant desorber pressure, the temperature in the desorber bottom is decreased, leading to a smaller efficiency drop of the power plant. Furthermore, the absorption rate of CO₂ is enhanced by adding ethanol. In the present work, the potential of using ethanol as a co-solvent for a 0.3 g/g aqueous monoethanolamine (MEA) solution is assessed based on simulations with an equilibrium stage model. A major drawback is the volatility of ethanol. The recovery of ethanol can be achieved using a water scrubber and subsequent stripping. The recovered ethanol vapor is sent directly to the desorber for heat integration. The process with ethanol recovery results in an increased complexity of the capture plant, difficulties in controlling the water balance and higher investment costs and offers, if any, only a moderate energetic advantage. The process concept could, however, be used for other co-solvents with similar properties as ethanol but lower vapor pressures.     

Rigorous correlations for predicting the solubility of H2S in methylimidazolium-based ionic liquids

Two general and simple models, a group contribution correlation (model I) and an empirical relation (model II), were proposed to predict the solubility of H₂S in methylimidazolium based ionic liquids (ILs) over wide range of temperatures (303.15-363.15 K) and pressures (60.8-2016.8 kPa). The constants of the suggested functionality relations were found via the Nelder-Mead simplex algorithm. Both correlations were trained with 407 data points of H₂S solubility in 9 methylimidazolium based ILs and tested through 121 H₂S solubility data points of 3 different methylimidazolium based ILs to ensure generality. A comprehensive statistical evaluation showed that both suggested correlations are vigorous and have satisfactory error trends. The dataset was subjected to a statistical outlier diagnostic test and the validity of the database was confirmed. In addition, the sensitivity analysis revealed that the experimental data and both models have the same responses toward pressure and temperature, which indicates the reliability of the proposed correlations.     

Regenerative low-cost ionic liquids: Synthesis,characterization, and application in desulphurization of flue gases

Three ionic liquids (ILs) containing the same cation but different anions were synthesized and used to separate SO₂ from its mixture with air in a semi-batch bubble column absorber. Desulphurization efficiency was determined using a state-of-the-art experimental set-up relevant to chemical process industries concerning the important process variables. The virgin and exhausted ILs were characterized using TGA, FTIR, and ¹H NMR analyses. The concentrations of SO₂ at the inlet to and exit from the absorber were measured using a ZRJFAY36, Fuji, Japan infrared SO₂ analyzer. A maximum of 92 percent removal efficiency (PRE) was achieved from a feed gas containing 250–1500 ppm SO₂ with the use of 2-hydroxyethyl ammonium lactate [MEA][L] or tri (2-hydroxyethyl) ammonium lactate ([TEA][L]), as the absorbents. This could be further enhanced by the interactive effect of the simultaneous increase in the superficial velocity of the gas and the volume of IL fed into the absorber. However, PRE was about 20% less with tri (2-hydroxyethyl) ammonium salicylate ([TEA][S]). It was observed that the ILs, [MEA][L] and [TEA][L], were fairly suitable for flue gas desulphurization in industrial situations. A design criterion for continuous operation using two semi-batch absorbers has been proposed.     

膜吸收法烟气脱碳研究进展

介绍了采用膜吸收法进行烟气脱碳过程中膜材料的种类、吸收液的选择以及膜吸收的耦合对脱碳的影响。综述了工艺流程、工艺参数及传质模型对膜吸收过程的影响,指出了膜吸收法烟气脱碳工程应用的经济性及发展方向。