Specializing liquid electrolytes and carbon-based materials in EDLCs for low-temperature applications

Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifetime, fast charging speed and environmentally-friendly nature, which play a critical part in satisfying the demand of electronic devices and systems. Although it is generally accepted that EDLCs are suitable for working at low temperatures down to-40℃, there is a lack of comprehensive review to summarize the quantified performance of EDLCs when they are subjected to low-temperature environments. The rapid and growing demand for high-performance EDLCs for auxiliary power systems in the aeronautic and aerospace industries has triggered the urge to extend their operating temperature range,especially at temperatures below-40℃. This article presents an overview of EDLC’s performance and their challenges at extremely low temperatures including the capability of storing a considerable amount of electrical energy and maintaining long-term stability. The selection of electrolytes and electrode materials is crucial to the performance of EDLCs operating at a desired low-temperature range. Strategies to improve EDLC’s performance at extremely low temperatures are discussed, followed by the future perspectives to motivate more future studies to be conducted in this area.

An Efficient and Stable Ionic Liquid System for Synthesis of Ethylene Glycol via Hydrolysis of Ethylene Carbonate

An ionic liquid system of [Bmim]X/[Bmim]OH(X Cl,BF4,and PF6,) was developed for the hydroly-sis of ethylene carbonate to ethylene glycol. The important parameters,such as the variety of ionic liquids,molar ratio of [Bmim]X to [Bmim]OH,amount of ionic liquid,molar ratio of water to ethylene carbonate,reaction tem-perature,pressure and reaction time,were investigated systematically. Excellent yield(>93%) and high selectivity(99.5%) of ethylene glycol were achieved. Under the optimum reaction conditions,the ionic liquid system could be reused at least five times and the selectivity of ethylene glycol remained higher than 99.5%.

Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids

A series of acetate ionic liquids were synthesized using a typical two‐step method.The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions.The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions,obtained using ultraviolet‐visible spectroscopy,and the relationship between their catalytic activities and basicities was established.The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH.This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used.A possible electrophilic‐nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time‐of‐flight mass spectrometry.In addition,the effects of significant reaction parameters such as concentration of catalyst,molar ratio of alcohol to propylene oxide,reaction temperature,and steric hindrance of the alcohol were investigated in detail.

Improved Cellulose by Ionic Liquid Mixture with Solid Acid Catalysis and Its Application in Polyethylene Glycol Liquefaction

Ionic liquid (IL), [BMIM]Cl-water was applied in cellulose pretreatment process and the pretreated cellulose was used in subsequent polyethylene glycol liquefaction process as a new application method. Cellulose recovery rate and molecular weight value of pretreated cellulose were investigated to understand the influence of IL-water mixtures by adding the different amount of catalysis on cellulose crystalline structure. Gel permeation chromatograph, X-ray diffraction, Fourier transform infrared spectrometer and thermo gravimetric/differential thermal analysis were used to clarify the changes of pretreated cellulose. The results showed that the pretreated cellulose was improved in crystalline structure, molecular weight distribution and thermal stability. The liquefied residues from untreated cellulose and pretreated cellulose were considered as a significant index to determine the effect of IL-water mixture on cellulose. It suggested that the lower molecular weight of cellulose was obtained, the crystalline structure was disrupted and less order was formed. The liquefied residues result suggested that the lower residues at the latter stages of the reaction from the pretreated cellulose were observed.

Polyethylene Glycol as Support and Phase Transfer Catalyst in Aqueous Palladium-catalyzed Liquid-phase Synthesis

Excellent yields and purity were obtained in the aqueous medium Suzuki, Sonogashira, Stille and Heck reactions using palladium (II) as catalyst in liquid phase synthesis. Polyethylene glycol (PEG) acted as soluble polymeric support and phase transfer catalyst as well.

Sensitivity Analysis of Computations of the Vapor-Liquid Equilibria of Methane + Methanol or Glycols at Gas Hydrate Formation Conditions

The Soave-Redlich-Kwong (SRK-EOS) and Peng-Robinson (PR-EOS) equations of state are used often to describe the behavior of pure substances and mixtures despite difficulties in handling substances, like water, with high polarity and hydrogen bonding. They were employed in studying the binary vapor-liquid equilibria (VLE) of methane + methanol, monoethylene glycol (MEG), and triethylene glycol (TEG). These liquids are used to inhibit the formation of gas hydrates. The investigation focused on the conditions at which methane-water clathrates can form 283.89?K to 323.56?K and 5.01?MPa to 18.48?MPa. The pressure of methane in methanol is overestimated by a factor of two by either the SRK-EOS or the PR-EOS. In the methane + MEG system, the predicted pressures for both equations of state are generally less than experimental pressure except for the highest concentration of methane in MEG calculated by the SRK-EOS. In the methane + TEG system, the predictions of both models are close and trend similarly. Because of the comparative lack of extensive experimental methane + TEG data, the similarity of the methane + TEG computed results can be used as a basis for further study of this system experimentally.

合成气乙二醇产品质量提升技术综述

总结合成气制乙二醇产品质量提升的4种技术手段:液相加氢,精馏加碱,产品塔釜加药剂和离子交换树脂吸附,分析4种方法的作用原理和效果,提出产品质量提升的根本在于加氢催化剂性能的提高,液相加氢需进一步提高催化剂活性,从而简化生产工艺。综述对乙二醇生产具有一定的借鉴作用。

三种温和还原法制备Pt/SDB

Pt/SDB是液相催化交换(LPCE)反应处理核电产生含氚废水的一种很有前途的催化剂。采用悬浮聚合法制备得到介孔聚苯乙烯-二乙烯基苯(SDB),以硼氢化钠(SBH)、水合肼(HH)或乙二醇(EG)为还原剂,温和还原法制备SDB载体负载铂活性颗粒,产物分别记为Pt/SDB-SBH、Pt/SDB-HH或Pt/SDB-EG。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、氮气吸附脱附和氢-水催化交换实验等对其结构形貌及催化活性表征。结果表明:Pt/SDB-SBH疏水催化剂具有突出的性能和优异的催化活性,Pt纳米颗粒平均粒径约为3.3 nm,Pt^(0)组分比例为72.0%,催化交换柱效率达65.0%,并在120 min保持稳定。为低温还原制备Pt/SDB疏水催化剂提供了一种新的策略。

全馏分催化汽油抽提降苯工艺研究

针对国Ⅵ汽油标准下催化汽油存在的苯含量超标问题,通过液液抽提的方式,对全馏分催化汽油进行了降苯工艺研究。通过对12种溶剂进行筛选,确定了最优的抽提溶剂乙二醇(EG);考察了以EG为抽提溶剂条件下,萃取时间、温度、溶剂比对抽提效果的影响;并进行了炼厂全馏分催化汽油的九级离心萃取实验。实验结果表明,EG具有优异的动力学性能,在5 min内即可与原料达到液液相平衡;提高溶剂比对萃取选择性影响不大,但会显著提高苯的脱除率;提高温度同样会提高苯的脱除率,但会降低萃取选择性;在优选实验条件下,苯含量最高可由原料的1.37%(w)降低至0.64%(w),脱除率达64%(φ),同时可保证其余芳烃收率在78%以上。

乙二醇在电沉积中的应用

纯乙二醇(EG)和乙二醇-离子液体(EG-ILs)作为电解液在电沉积中进行了大量的应用。对EG体系中电沉积半导体材料、热电材料和金属单质进行总结,发现EG作为有机溶剂,具有较高的沸点而适合较大范围温度下的电沉积,电沉积温度从高温往室温发展,能通过添加剂和工艺参数对镀层进行调控。对EG-ILs体系中电沉积磁性材料、耐蚀材料和催化材料进行总结,发现在EG-ILs中电沉积得到镀层材料的耐腐蚀和催化性能优异。综述了金属在EG镀液中的电沉积机理。

GC法测定对乙酰氨基酚口服液体制剂辅料中乙二醇及二甘醇残留量

目的:建立对乙酰氨基酚口服液体制剂辅料中乙二醇、二甘醇残留量的检测方法。方法:采用气相色谱法,检测器为氢火焰离子化检测器(FID),以Agilent VF-17ms(30 m×?0.53 mm,1.0μm)为色谱柱,程序升温,进样口温度为270℃,检测器温度290℃。结果:在确定的色谱条件下各主峰分离度良好;乙二醇和二甘醇分别在5.94~118.80μg/mL、5.34~106.8μg/mL的质量浓度范围内线性关系良好(r≥0.999);2者检测限分别为0.894μg/mL和0.846μg/mL,定量限分别为2.683μg/mL和2.538μg/mL;重复性的RSD均<2.0%;乙二醇回收率在95.6%~99.5%,二甘醇回收率在95.3%~97.3%。结论:方法灵敏度高,专属性和重复性良好,线性和回收率均符合2020年版《中国药典》要求,适用于检测对乙酰氨基酚口服液体制剂中的的乙二醇、二甘醇残留量检查。

离子液体在乙酸乙酯-乙醇-水体系分离中应用

乙酸乙酯、乙醇和水是化工行业中常见的共沸体系。分别以乙二醇、氯化1-己基-3-甲基咪唑离子液体为萃取剂,用Aspen Plus模拟乙酸乙酯、乙醇和水形成的共沸体系的分离。使用Sensitivity分析对上述流程分别进行参数优化。结果表明:乙二醇和离子液体做萃取剂时,乙酸乙酯、乙醇和水的纯度都可以达到99.0%以上;与乙二醇萃取精馏工艺相比,离子液体使用量降低91%,极大降低了成本;使用离子液体能有效降低能耗和费用,能耗降低31.2%,年度费用降低26.9%。

南海某气田三甘醇接触塔液位控制波动处理

南海某气田天然气脱水采用三甘醇脱水工艺,其主要设备三甘醇接触塔液位存在波动,与其相关的设备及参数也随之波动,影响了脱水系统的平稳运行。为提升三甘醇脱水效果,在排除常规原因后,深入分析三甘醇接触塔、闪蒸罐结构以及烃类对液位控制的影响,充分运用PID的调节规律,制定有效的控制策略。通过定期有效排烃、PID整定等措施,三甘醇接触塔液位实现了稳定控制。三甘醇脱水系统设备的有效排烃,以及存在烃类影响时采取合理的PID调节策略,有效提升了液位控制效果,可在采取同类天然气脱水工艺的气田推广。

液相加氢技术在煤制乙二醇中的实践分析

煤制乙二醇工艺作为我国石油资源相对匮乏情况下的重要替代方案,其产品质量的提高和工艺改进至关重要。本文通过对液相加氢技术和煤制乙二醇工艺的概述,详细分析了液相加氢技术的工艺原理、操作流程、催化剂装卸等关键环节,并对煤制乙二醇的背景和技术路线进行了介绍。最后针对乙二醇质量提升中的常见问题,提出了改造方案并进行了效果分析。实验结果表明,液相加氢技术能有效提高乙二醇产品的紫外透光率,提升产品质量。

液体循环式热回收在严寒和寒冷地区铅蓄电池生产厂房中的应用分析

分析了铅蓄电池生产厂房通风设计的特点,阐述了常规热回收装置的优、缺点,得出了液体循环式热回收是最适合应用在蓄电池厂房的结论。针对严寒和寒冷地区,以气温居中的银川地区为例,通过工程实践,计算分析了应用液体循环式热回收系统的经济性。并且,指出了系统设计时应注意的问题。

A Comparative Trial: The Safety and Clinical Efficacy of PEG 3350 and Liquid Paraffin in Management of Chronic Functional Constipation in Children

Background: Constipation is one of the most common problems in the pediatric age group. In the vast majority, chronic constipation is idiopathic or functional. In addition to education and behavioral changes, disimpaction and maintenance treatment with medications are the main pillars of successful outcome. The medications are variably effective and have potential side effects. Objectives: The current clinical trial was designed to evaluate clinical efficacy of polyethylene glycol (PEG) 3350 and liquid paraffin in chronic functional constipation. Besides, subjects were followed carefully for the side effects. Material and Methods: This study was involved 110 children suffering from chronic functional constipation. They were placed into two different groups, randomly. Each group was treated with PEG 3350 or liquid paraffin. The clinical efficacy and side effects were monitored. Results: After disimpaction with bisacodyl suppositories or combined with Mineral oil enemas in hard fecal impaction, maintenance therapy with PEG 3350 or liquid paraffin was started. The treatment duration and efficacies were not different between the two groups. Furthermore, serious adverse drug reaction was not observed. The family history of constipation and presence of incontinence were two worse prognostic factors. Conclusion: No difference was observed between PEG 3350 and liquid paraffin in chronic functional constipation in children in terms of their efficacies. They are safe and effective medications in this age group.

Ionic liquid-assisted synthesis of silver nanorods by polyol reduction

Silver nanorods have been successfully synthesized in large scale by the ethylene glycol（EG） reduction in the presence of ionic liquid（IL） 1-butyl-3-methylimidazolium tetrafluoroborate（bmimBF_4） and polyvinyl-pyrrolidone（PVP）.The silver nanorods were characterized by scanning electron microscopy（SEM）,high-resolution transmission electron microscopy（HRTEM）,transmission electron microscopy（TEM）,electron energy disperse spectroscopy（EDS） and UV-vis spectroscopy.The results showed that the uniform silver nanorods have an average diameter of about 100 nm and the aspect ratio from 15 to 20.IL,bmimBF_4 may play a role of capping agent together with PVP in the formation of silver nanorods.On the other band,bmimBF_4 may accelerate nucleation and improve the stability of the resulting Ag nanorods due to the low interface tension of IL.

Design and optimization of an integrated process for the purification of propylene oxide and the separation of propylene glycol by-product

It is difficult to separate the methanol and hydrocarbons in the propylene oxide(PO)purification process due to their forming azeotrope.As for this,a novel PO separation process,in that the deionized water is employed as extractant and 1,2-propylene glycol(MPG)that is formed from the PO hydrolysis reaction is recovered,is presented in this work.The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol(DPG)are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column.In addition,the ionic liquid(IL)extractant is screened through the conductorlike screening model for segment activity coefficient(COSMO-SAC)and the comparisons of separation efficiency between the IL and normal octane(nC_(8))extractant for the separation of PO and 2-methylpentane are made.With the non-random two-liquid(NRTL)thermodynamic model,the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio,theoretical stages,feeding stage etc.on separation efficiency are detailedly discussed.The results show that the mass purity and the mass yield of PO can be up to 99.99%and 99.0%,and the condenser duty,reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%,30.21%and 78.86%compared to ones with nC_(8).The total annual cost(TAC)calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC_(8) for the investigated process.The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.

Study on Vapor Liquid Equilibrium for C_9 Separation by Azeotropic Distillation

In this work,ethylene glycol monomethylether(EE) was chosen as an entrainer for the azeotropic distillation of 1,3,5-trimethylbenzene+1-methyl-2-ethylbenzene system to investigate the influence of the entrainer on vapor liquid equilibrium(VLE) of this system.Three sets of binary VLE data in the system consisting of EE + 1,3,5-trimethylbenzene +1-methyl-2-ethylbenzene were measured using the Dvorak-Boublik still.The binary parameters of NRTL model were correlated by using the likelihood method.The ternary VLE data of the system were measured as well and were predicted by using the binary parameters of NRTL model.The test results indicated that the binary data passed the thermodynamic consistency tests,and the difference between the predicted values of ternary VLE and the experimental data reached the research standard for VLE data.Addition of EE had a great influence on the relative volatility between 1,3,5-trimethylbenzene and 1-methl-2-ethyl-benzene:when the ratio of solvent was 4,and the relative volatility between 1,3,5-trimethylbenzene and 1-methyl-2-ethylbenzene increased from 1.0125(without solvent addition) to 1.283.

乙二醇和1,2-丁二醇二元气液平衡体系的研究及模型预测

为了研究乙二醇-1,2-丁二醇在不同真空度下共沸组成的变化规律及差压精馏分离的可行性,使用改进的Othmer气液平衡釜测定了1~100 kPa下乙二醇-1,2-丁二醇二元体系的气液平衡数据,均通过了热力学一致性检验。分别采用Wilson、NRTL和UNIQUAC方程对不同压力下的气液平衡数据进行整体关联,结果表明,UNIQUAC方程计算精度更高,可适用于1~100kPa下的相平衡计算。采用UNIQUAC方程计算了不同压力下乙二醇-1,2-丁二醇的共沸组成,共沸组成中乙二醇的摩尔分数随压力的降低呈非线性增加。操作压力由100降低至1kPa时,共沸组成中乙二醇的摩尔分数的变化可达到12%,推断乙二醇-1,2-丁二醇具有差压精馏分离的可行性。