Solubility of CO2 in imidazolium-based tetrafluoroborate ionic liquids

The solubility of CO₂ in imidazolium ionic liquids (ILs), 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF₄]), 1-hexyl-3-methyl imidazolium tetrafluoroborate ([hmim][BF₄]) and 1-octyl-3-methyl imidazolium tetrtafluoroborate ([omim][BF₄]) was determined at 305-25 K and pressures from 1 to 9 MPa. The influence of chain length of alkyl substituents on the imidazolium cation on the solubility of CO₂ was investigated. The differences in solubility with chain length are in the sequence [omim][BF₄] > [hmim][BF₄] > [bmim][BF₄]. The solubility data were correlated by the extended Henry's law, and enthalpy, Gibbs free energy and entropy changes were obtained.     

Osmium catalyzed asymmetric dihydroxylation of methyl trans-cinnamate in ionic liquids, followed by supercritical CO2 product recovery

In this work, osmium-catalyzed asymmetric dihydroxylation (AD) of methyl trans-cinnamate was studied. Osmium and chiral ligand catalysts were immobilized in ionic liquid only, without any other reaction solvents, while the recovery of the product was performed by extraction with supercritical CO₂, and compared with results obtained by extractions with organic solvents such as hexane and diethyl ether. In supercritical CO₂ extraction experiments, optimal extraction pressure was found and ionic liquid chosen, so that the highest reaction yields coupled with lowest osmium content in the crude product can be achieved. Finally, recycle experiments of the same (ionic liquid + catalytic system) mixture were successfully conducted. Application of ionic liquids and supercritical CO₂ in osmium catalyzed AD allows for the isolation of the diol basically without contamination with osmium, in high yield and enantiomeric excess, and it makes possible the efficient reuse of ionic liquid solvent and the catalytic system.     

Thermodynamic modeling of CO2 solubility in ionic liquid with heterosegmented statistical associating fluid theory

Heterosegmented statistical associating fluid theory is used to represent the CO₂ solubility in ionic liquids. As in our previous work, ionic liquid molecule is divided into several groups representing the alkyls, cation head, and anion. The cation of ionic liquid is modeled as a chain molecule that consists of one spherical segment representing the cation head and groups of segments of different types representing different substituents (alkyls). The anion of ionic liquid is modeled as a spherical segment of different type. To account for the electrostatic/polar interaction between the cation and anion, the spherical segments representing cation head and anion each have one association site, which can only cross associate. Carbon dioxide is modeled as a molecule with three association sites, two sites of type O and one site of type C, where sites of the same type do not associate with each other. The parameters of CO₂ are obtained from the fitting of the density and the saturation vapor pressure of CO₂. For the CO₂-ionic liquid systems, cross association between site of type C in CO₂ and another association site in anion is allowed to occur to account for the Lewis acid–base interaction. The parameters for cross association interactions and the binary interaction parameters used to adjust the dispersive interactions between unlike segments are obtained from the fitting of the available CO₂ solubility in ionic liquids. The model is found to well represent the CO₂ solubility in the imidazolium ionic liquids from 283 to 415 K and up to 200 bar.     

Viscosity of n-alkyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)amide ionic liquids saturated with compressed CO2

The viscosity of imidazolium-based ionic liquids (ILs) saturated with gaseous, liquid and supercritical carbon dioxide (CO₂) was measured by a high-pressure viscometer at three different temperatures (25, 50, and 70 °C). The high-pressure viscosity of 1-ethyl-3-methylimidazolium ([EMIm]), 1-n-hexyl-3-methylimidazolium ([HMIm]), and 1-n-decyl-3-methylimidazolium ([DMIm]) cations with a common anion, bis(trifluoromethylsulfonyl)amide ([Tf₂N]), saturated with CO₂ was measured up to a maximum of 287 bar. As CO₂ pressure is increased the viscosity of the IL mixture dramatically decreases. While, the ambient pressure viscosity of 1-alkyl-3-methyl-imidazolium [Tf₂N] ILs increases significantly with increasing chain length, the viscosity of all the CO₂-saturated ILs becomes very similar at high CO₂ pressures. From previous vapor–liquid equilibrium data, the viscosity with concentration was determined and found to be the primary factor to describe the fractional viscosity reduction. Several predictive and correlative methods were investigated for the mixture viscosity given pure component properties and include arithmetic mixing rules, the Irving (Predictive Arrhenius) model, Grunberg equation, etc. The modified Grunberg model with one adjustable parameter provided an adequate fit to the data.     

R&D activities in Japan on methanol synthesis from CO2 and H2

Methanol synthesis from CO₂ and H₂ can be a useful process for conversion and transportation of hydrogen energy derived from non-fossil energies. More than ten research groups in Japan have extensively investigated the methanol synthesis from both academic and practical points of view. Recent R&D activities in Japan for developing high performance catalysts, for elucidating the reaction mechanism and also for operating a bench scale plant have been reviewed in this paper.     

CO2响应型Pickering乳液的构筑及应用

互不相溶的油/水两相在固体颗粒的作用下,其中一相以小液滴形式溶于另一相中形成的乳液称为Pickering乳液。由于其制备成本低、稳定性强且环境友好,目前已应用于医药、食品及化妆品等多个领域。在实际的应用中,具有长期稳定性质和可快速乳化/破乳的乳液在石油开采、催化等领域需求广泛,因而制备具有环境刺激响应性质的Pickering乳液迫在眉睫。与pH、磁场、温度、光等刺激手段相比,CO₂响应型乳液具有廉价易得、无污染、响应迅速、生物相容性好等优势,是解决产品循环回收问题的有效策略。目前CO₂刺激响应型Pickering乳液体系仍处于研究的初级阶段,且该乳液的响应机制、构筑策略仍有待明确和拓展。本文总结了Pickering乳液的稳定/响应机制,综述了CO₂响应型Pickering乳化剂的种类及构筑策略,列举了其在乳液聚合、界面催化、生物医药领域的应用进展,并展望了其未来的发展前景。     

Fluorolactonization of unsaturated carboxylic acids with F-TEDA-BF4 in ionic liquids

Fluorolactonization of unsaturated carboxylic acids under action of the electrophilic reagent F-TEDA-BF₄ in ionic liquids (ILs) has been studied. This reaction proceeds in ILs faster and provides a better stereoselectivity in comparison to acetonitrile as reaction media. Gem-difluorinated γ-lactones have been synthesized by interaction of unsaturated carboxylic acids with F-TEDA-BF₄ in ILs.     

Pd(OAc)2 catalyzed synthesis of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles in imidazolium ionic liquids (ILs) without additives and with recycling/reuse of the IL

A facile, high yielding, method for the synthesis of a library of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles from readily available Schiff bases is reported employing catalytic amounts of Pd(OAc)₂ in imidazolium ionic liquids (bmim)BF₄ and (bmim)PF₆ without ligands and/or additives. Simple product isolation and recycling/re-use of the IL are additional advantages of this method.     

Predictions of cation and anion effects on solubilities,selectivities and permeabilities for CO2 in ionic liquid using COSMO based activity coefficient model

The solubilities and selectivities for CO₂, N₂ and CH₄ in ionic liquid were predicted using a COSMO based activity coefficient model, COSMO-SAC method. The 1-alkyl-3-methylimidazolium cations were focused in this work. The anion species include tetrafluoroborate [BF₄], hexafluorophosphate [PF₆], triflate [OTf], dicyanamide [dca] and bis(trifluoromethane)-sulfonimide [Tf₂N]. The predicted results of the solubilities of CO₂ in the ionic liquids by COSMO-SAC method are in agreement with the experimental data within the averaged deviation of 0.0017 in mole fraction. The predicted results of selectivities for CO₂/N₂ and CO₂/CH₄ represent the effects of anion species qualitatively. Permeability through supported liquid membrane can be presented by solubility and diffusion coefficients in the liquid. The permeabilities of CO₂ through the ionic liquid membranes were also predicted by a solution-diffusion model with COSMO-SAC method. The predicted results of the CO₂ permeabilities through the ionic liquids represent the experimental data within the order of the permeabilities.     

ZIF-67/CeO2催化CO2和甲醇直接合成碳酸二甲酯

采用沉淀法将ZIF-67负载到CeO₂上,制备了具有多重活性位点的非均相催化剂ZIF-67/CeO₂,并研究其催化CO₂和甲醇直接反应生成碳酸二甲酯(DMC)的性能。采用 X 射线衍射、N2吸附-脱附、傅里叶变换红外光谱和 X 射线光电子能谱研究了ZIF-67/CeO₂的各种理化性质。结果表明,ZIF-67的引入使ZIF-67/CeO₂催化剂产生更多的氧空位。在考察的ZIF-67/CeO₂系列催化剂中,0.3-ZIF-67/CeO₂(0.3为Co、Ce物质的量之比)在具有高的比表面积的同时还能保持介孔结构,具有丰富的酸碱位点,并且具有较高的CO₂吸附容量,表现出最好的催化性能。在反应温度为140℃、压力为4.5 MPa的条件下反应4 h,DMC收率可达到3.79 mmol_DMC·gcat^-1。     

ZIF-67/CeO2催化CO2和甲醇直接合成碳酸二甲酯

采用沉淀法将ZIF-67负载到CeO₂上,制备了具有多重活性位点的非均相催化剂ZIF-67/CeO₂,并研究其催化CO₂和甲醇直接反应生成碳酸二甲酯(DMC)的性能。采用X射线衍射、N₂吸附-脱附、傅里叶变换红外光谱和X射线光电子能谱研究了ZIF-67/CeO₂的各种理化性质。结果表明,ZIF-67的引入使ZIF-67/CeO₂催化剂产生更多的氧空位。在考察的ZIF-67/CeO₂系列催化剂中,0.3-ZIF-67/CeO₂(0.3为Co、Ce物质的量之比)在具有高的比表面积的同时还能保持介孔结构,具有丰富的酸碱位点,并且具有较高的CO₂吸附容量,表现出最好的催化性能。在反应温度为140℃、压力为4.5 MPa的条件下反应4 h,DMC收率可达到3.79 mmol_DMC·g_cat^-1。     

Non-catalytic pyrolysis of ethane to ethylene in the presence of CO2 with or without limited O2

Influence of the presence of CO₂, which is a mild oxidant, on the performance of the thermal cracking of ethane to ethylene in the absence or presence of limited O₂ at different temperatures (750–900‡C), space velocities (1500–9000 h^-1) and CO₂/C₂H₆ and O₂/C₂H₆ mole ratios (0–2.0 and 0–0.3 respectively) has been investigated. In both the presence and absence of limited O₂, ethane conversion increases markedly because of the presence of CO₂, indicating its beneficial effect on the ethane to ethylene cracking. The increased ethane conversion is, however, not due to the oxidation of ethane to ethylene by CO₂; the formation of carbon monoxide in the presence of CO₂ is found to be very small. It is most probably due to the activation of ethane in the presence of CO₂.     

片状纳米结构CeO2晶体的制备及其吸附CO2性能

在室温下,将CeCl₃溶液与CO₂储存材料（CO₂SM）混合、搅拌0.5 h制备了片状碳酸铈前驱体（CCPs）,并在500℃下煅烧CCPs 4 h,制得平均尺寸为4.94 μm×0.92 μm,厚度为0.04~0.08 μm纳米结构片状CeO₂晶体。在此过程中,CO₂SM不但可以提供CO₃^2-,还能起到分散剂和结构导向剂的作用。反应过程中,系统地研究了CO₂SM用量、Ce³⁺浓度和搅拌时间3个因素对CCPs形态和大小的影响,得到最优制备条件：0.1 g CO₂SM和50 mL 0.03 mol·L^-1 Ce³⁺水溶液以1 000 r·min^-1转速在室温下搅拌0.5 h。煅烧CCPs后,所制备的片状CeO₂晶体在室温下CO₂吸附量可达0.554 mmol·g^-1。     

Ultrasound-promoted synthesis of 2-amino-6-(arylthio)-4-arylpyridine-3,5-dicarbonitriles using ZrOCl2·8H2O/NaNH2 as the catalyst in the ionic liquid [bmim]BF4 at room temperature

We herein present an efficient and environmentally benign protocol for the synthesis of 2-amino-6-(arylthio)-4-arylpyridine-3,5-dicarbonitrile derivatives via the three-component condensation of a variety of aldehydes, arylthiols, and malononitrile catalyzed by ZrOCl₂·8H₂O/NaNH₂ (20 mol %) in the ionic liquid [bmim]BF₄ under ultrasound irradiation at room temperature.     

Novel carbonyl iron-bismuth clusters - synthesis, structure, CO2 insertion and potential as molecular precursors for BiFeO3

The reaction of Fe₂(CO)₉ with Bi(OSiMe₂^tBu)₃ gave soluble [(CO)₄FeBi(OSiMe₂^tBu)]₂ (1) in moderate yield whereas in case of Bi(O^tBu)₃ used as starting material both [(CO)₄FeBi(O^tBu)]_n (2) and the bismuth-iron cluster [(CO)₃FeBi₃(O^tBu)₄{OCO(O^tBu)}]₂ (3) were isolated. The latter forms upon insertion of CO₂, released during reaction of diiron nonacarbonyl with bismuth tert-butoxide, into a Bi-O^tBu bond. The compounds were characterized by IR and ¹H NMR spectroscopy as well as thermogravimetric analyses. Additionally, the molecular structures of compounds 1 and 3 were elucidated by single crystal X-ray diffraction. The core structure of [(CO)₄FeBi(OSiMe₂^tBu)]₂ (1) is build up by a four-membered Bi₂Fe₂ ring whereas [(CO)₃FeBi₃(O^tBu)₄{OCO(O^tBu)}]₂ (3) is composed of two tetrahedral FeBi₃ cluster cores that dimerise via bridging -OCO(O^tBu) ligands. Analysis of the TGA residues by PXRD revealed that compound 2 is the best precursor for multiferroic BiFeO₃ among the compounds studied here, although Bi₂₅FeO₃₉ was detected as minor impurity.     

关于限域离子液体吸附CO_2的密度泛函理论(DFT)的研究

近年来,温室效应日趋严重,因此吸收CO_2的材料受到了广泛的关注.采用了密度泛函理论(DFT)研究以SiO_2为载体的限域离子液体对CO_2的吸附.对比纯净离子液体(ILs)以及限域离子液体与CO_2的相互作用情况,在这两种状态下两种体系的吸附情况大不相同.从几何结构、相互作用以及电荷分析等方面对ILs、 SiO_2以及ILs/SiO_2复合结构进行研究.计算结果表明,载体、离子液体和CO_2之间都存在较强的相互作用.离子液体的负载不仅改变了SiO_2载体的结构,而且受载体的影响阴阳离子之间的相互作用力也发生了改变.计算结果为进一步深入限域离子液体对CO_2的吸附打下了理论基础.     

Li2ZrO3材料吸收CO2性能的进一步研究

用不同结构的ZrO₂合成了一系列在高温下吸收CO₂的Li₂ZrO₃材料，并详细的研究了反应物质的物理和化学性质对生成物吸收CO₂性能的影响。采用SEM、XRD以及TG分析法分别进行了材料结构及其吸收CO₂性能的表征，并使用XPS法测定了材料表面的元素组成。实验结果表明，使用不同结构的ZrO₂合成的Li₂ZrO₃，其吸收CO₂的性能明显的不同。用ZrO₂(t)(四方)合成的Li₂ZrO₃吸收CO₂的速度快，在500 ℃下，20% CO₂（80%空气）的气氛中保持3h，其吸收量可达25（±0.6）%（wt），而以ZrO₂(m)(单斜)为原料制备的Li₂ZrO₃在上述吸收条件下重量仅增加9（±0.6）%（wt）。此外，实验结果还表明化学元素的掺杂对用ZrO₂(m)合成的Li₂ZrO₃的CO₂吸收速度及吸收容量影响较大。     

TiO_2纳米带光催化二氧化碳甲烷化

研究了在常温常压下TiO2纳米带光催化CO2催化加氢气反应。在紫外光照射下,二氧化碳的加氢还原产物为甲烷。利用高分辨TEM,XRD,UV-Vis DRS,低温氮吸附-脱附,TG等考察了催化剂与甲烷产率的构效关系。结果表明,在600℃焙烧时得到的双晶材料具有最佳的光催化活性。优异的光催化活性主要得益于TiO2双晶脱水纳米带(DNR Bicrystalline dehydratednanoribbon)。上面形成的纳米晶界能够提高催化剂在紫外区的光吸收能力,TiO2(B)和锐钛矿独特的双晶间隔结构也提高了界面电荷分离的效率。担载贵金属Pt显著地提高了反应速率。     

Interfacial tension between water and high pressure CO2 in the presence of hydrocarbon surfactants

Interfacial tension of water–CO₂ interface was measured by pendant drop method in the presence of a surfactant of various concentrations. The surfactants used were three surfynols which are non-ionic blanched hydrocarbon with different length of the alkyl side chain. Prior to the interfacial tension measurements, the solubility of the surfynols in CO₂ were determined from cloud point method. The measured interfacial tensions indicated that an addition of small amount surfactant did reduce the interfacial tension. The interfacial activities of surfactants were evaluated from the slope of the interfacial tension reduction curve against the surfactant concentration and rationalized in terms of the molecular natures such as hydrophobic alkyl chain length.     

CO2 anion-radical in organic carboxylations

This letter shows a first approximation to the use of CO₂ anion-radical in the obtention of α-methyl and α-ethylcyanoacetic acids from propionitrile and butyronitrile, respectively, through a paired electrochemical reaction with CO₂. The electrosynthesis of α-chloro-phenylacetic acid from benzyl chloride and phenylacetic acid from toluene by another proposed pathway is also discussed.