携带流燃烧时SCR催化剂碱金属失活机理研究

采用携带流燃烧法研究了不同的碱金属种类、碱金属浓度、K和Na混合对催化剂脱硝活性的影响,并通过多种物理化学表征方法对催化剂碱金属失活机理进行了分析。结果表明,碱金属K、Na使得催化剂失活机理类似,且K盐对催化剂的失活效果要强于Na盐,Cl~-、SO_4~(2-)、CO_3~(2-)三种阴离子使得催化剂脱硝活性降低的能力顺序为:Cl-SO_4~(2-)CO_3~(2-);掺烧碱金属使催化剂失活后,催化剂表面有所掺烧的碱金属盐沉积,并堵塞表面孔道,造成比表面积下降。催化剂碱金属失活后其表面活性成分V的含量大幅下降。     

紫外-可见吸收光谱法研究阴离子对刚果红/β-葡聚糖络合物的影响

利用紫外-可见吸收光谱法探究了阴离子的浓度及种类对刚果红在溶液中形成聚集体的影响,在此基础之上,进一步研究了阴离子浓度和种类对刚果红与燕麦β-葡聚糖所形成络合物的影响规律。结果表明：随着阴离子浓度的增大,刚果红溶液的峰值吸光度呈逐渐下降趋势,且最大吸收波长发生蓝移。刚果红最大吸收波长、峰值吸光度和499 nm处吸光度与阴离子浓度的对数值之间具有明显的线性相关性。阴离子对刚果红聚集的影响符合Hofmeister序列的顺序,说明疏水相互作用是刚果红分子聚集成胶束的重要驱动力。对于刚果红/β-葡聚糖络合物体系来说,当阴离子浓度超过第一临界浓度时,刚果红胶束开始形成并结合在β-葡聚糖上形成络合物,差谱图在556 nm处产生了络合物的吸收峰;当阴离子浓度超过第二临界浓度时,刚果红/β-葡聚糖络合物进一步通过刚果红胶束之间的聚集形成超分子结构,导致差谱图吸收峰红移至583 nm处,并因为更大尺寸超分子结构的形成而在光谱图长波方向出现明显的米氏散射效应。阴离子对上述超分子结构的影响也符合Hofmeister序列的顺序,说明刚果红/β-葡聚糖络合物主要通过刚果红胶束之间的疏水相互作用聚集成超分子结构。本研究提示,离子对刚果红分子本身在溶液中的聚集状态及其与生物大分子的相互作用具有重要的影响。     

一种含蒽醌基偶氮染料的合成及其对硼酸的选择性识别

设计合成一种含蒽醌基偶氮染料,在pH 8.3 EDTA-NaOH缓冲介质中,利用紫外-可见吸收光谱法研究了其与硼酸、阴离子及阳离子的相互作用。结果表明,以邻位酚羟基为识别位点,蒽醌基和偶氮基为信号报告基团,受体分子可选择性识别硼酸,吸收光谱蓝移50nm,溶液颜色由玫瑰红色变为黄色,常见阴离子及阳离子均不影响其对硼酸的识别。同时对识别机理进行了初步探讨,得出硼酸与受体分子形成1∶1稳定络合物,结合常数为760L.mol-1。     

氯盐溶液近红外光谱分析研究

氯盐近红外光谱分析在生物医学上有着十分重要的意义。在室温下对氯化钠,氯化钾,氯化钙水溶液的近红外光谱采集分析表明,氯盐溶液浓度的变化会影响水分子的氢键而使得水溶液的近红外光谱发生变化。通过选择合理波长区间以及温度变化影响为零的波长点(等吸光点),减小温度的干扰对溶液近红外光谱影响,采用偏最小二乘法建立了氯盐溶液的浓度模型用于预测氯盐的离子浓度。分析氯盐溶液中氯盐阳离子的离子半径大小、离子电荷数和离子在水中络合效应等因素对水的近红外光谱所造成的影响以及产生影响因素的原因。实验结果表明,温度和浓度都会影响溶液的近红外光谱,氯盐溶液浓度较低时,温度的影响占主导地位;氯盐浓度高时,浓度的影响占主导地位。氯盐在水溶液中形成络合物,并与氯盐阳离子共同作用对水的氢键产生影响,对于浓度相同种类不同的氯盐溶液, 形成的络合物和阳离子破坏效应对水的氢键的破坏作用为: CaCl₂>NaCl>KCl。最终建立的样品浓度模型校正集的决定系数(R2)=99.97%,交叉验证均方误差(RMSECV)=4.51,剩余预测偏差(RPD)=62.7,满足日常生化检测精度要求。     

碱金属钨酸盐晶体与熔体微结构与特征拉曼振动波数的相关性

本文选取了5种锂钨酸盐晶体结构,搭建了8种含Na+阳离子的团簇模型,并分别基于MS(materials studio)软件的CASTEP(cambrigde serial total energy package)模块和Gaussian09软件对其拉曼振动波数和散射活性进行了DFT(密度泛函理论)计算。通过分析,发现晶体中W-Onb(non-bridging oxygen,即非桥氧)键对称伸缩振动波数随其键长的减小而增大,在熔体中也存在类似关系。为反映局部应力对W-Onb键对称伸缩振动波数的影响,在本工作中分别对晶体和熔体中的微结构进行了指认。结果表明,在Li_2O-WO_3二元系中,构成晶体的主要阴离子基团为[WO_6]~(6-),且该基团W-Onb键的对称伸缩振动波数随着桥氧数的增大而增大;在熔体中W-Onb键的对称伸缩振动波数一般为[WO_4]~(2-)[WO_5]~(4-)[WO_6]~(6-),且当W-O基团确定后,该振动波数会随着桥氧数的增大而增大。该相关性有助于碱金属钨酸盐晶体及熔体结构中阴离子基团的诊断与鉴别。本文测定了A2WnO3n+1(A=Li,Na,K;n=1,2,3)共9种成分熔体的原位拉曼光谱,以验证该相关性。     

冠醚过渡金属络合物的振动光谱

碱金属、碱土金属、稀土元素的阳离子冠醚络合物和它们的振动光谱研究已有文献报导。但关于过渡金属阳离子冠醚络合物的文章却不多。我们的目的是制备一系列典型的冠醚过渡金属络合物,并测定它们的红外,拉曼光谱,寻找络合物形成前后的光谱变化规律,希望通过光谱研究得到一些结构信息。     

一类阴离子自由基液态电极材料研究

将碱金属溶于含有芳香化合物的醚类溶剂,碱金属的一个电子转移给芳香化合物形成一个碱金属离子和一个阴离子自由基,同时溶于醚类溶剂得到一类具有高电子电导率和离子电导率的蓝黑色液体.当碱金属为钠、芳香化合物为联苯、醚类溶剂为乙二醇二甲醚时,其电子电导率和离子电导率分别为8.4×10~(-3)S.cm~(-1)和3.6×10~(-3)S.cm~(-1),电极电位为0.09 V vs.Na/Na~+,适合作为负极材料,具有原材料低廉、易于制备等优点.我们将该液体作为负极,分别以苯醌和蒽醌(AQ)溶液作为正极构建了一种新型二次电池,结果表明以AQ溶液作为正极的电池具有长循环寿命、低成本的优势.该阴离子自由基液态负极材料的提出为开发新型的储能电池提供了新思路.     

盐离子对蛋白质带电特性的影响

本文应用分子理论,研究盐离子对蛋白质带电特性的影响,理论模型考虑蛋白质与阴离子的结合作用。研究发现,由于蛋白质与阴离子的结合,距离蛋白质表面附近处的阴离子被吸附在了蛋白质表面,在距离蛋白质表面附近区域,阴离子分布较少。通过计算体系中的静电势,我们发现,在距离蛋白质表面附近,静电势呈现了较大的负值,带正电荷的阳离子感受到静电吸引,会出现在距离蛋白质表面附近的区域,这会使得在距离蛋白质表面附近的区域,阳离子数目增多。这样,在不同阴离子浓度、以及阴离子与蛋白质不同结合能条件下,阴离子会在不同程度上影响蛋白质的带电特性、影响体系中的静电特性。通过考察不同结合能条件下,蛋白质表面电荷面密度随阴离子浓度的变化关系还发现,较大的结合能会使得阴离子与蛋白质结合增快,蛋白质表面会呈现从正电荷态向负电荷态的转变。理论结果符合实验观测,由此表明,盐离子与蛋白质的结合导致蛋白质表面带电特性的改变,是盐离子影响蛋白质带电特性的本质。     

紫外光谱研究PDDA/PSS多层膜组装盐效应

以阳离子聚电解质聚二甲基二烯丙基氯化铵(PDDA)与阴离子聚苯乙烯磺酸钠(PSS)通过逐层组装,在石英表面构建了多层膜,并用紫外-可见光谱仪(UV-Vis)跟踪监测,考察聚电解质中添加NaCl的浓度变化对组装过程的影响.结果显示:PDDA/PSS组装膜在前7层均呈现较好的指数关系,由所得回归方程可知,自组装膜的增长量主要与回归参数q=exp(1/t1)有关,而q与盐的浓度呈正比,说明随着盐度的增加,所得多层膜的组装量也相应增加；PDDA/PSS组装多层膜在8-13层呈现较好的线性增长模式.随着盐度的增加,回归直线的斜率越大.但当盐度足够大时,所得回归直线斜率增速减慢,表明此时盐度对组装膜的影响减弱.     

平面型络合物阳离子和平面型络合物阴离子所成盐的三阶光学非线性研究

采用简并四波混频方法对平面型络合物阳离子和平面型络合物阴离子所成盐的溶液的三阶光学非线性在１．０６μｍ波长处进行了研究，发现该化合物在纳秒尺度具较大的非线性响应，而且具有相同的阳离子，而阴离子中金属离子的原子序数较大的样品具有相对较大的三阶非线性极化率。     

Physicochemical characterization of paramagnetic ionic liquids 1‐vinyl‐3‐alkylimidazolium tetrahalogenidoferrate(III) [VRIM][FeClmBr4 − m]

Using microwave‐assisted synthesis method, a series of paramagnetic ionic liquids comprising 1‐vinyl‐3‐alkylimidazolium VRIM⁺ cation and tetrahalogenidoferrate (III) FeCl_mBr_{4 ? m}^? anion were designed and synthesized. The structure was analyzed using ¹H NMR and Raman spectroscopy. Ultraviolet–visible absorption spectra, thermal stability, magnetic susceptibility, viscosity, ionic conductivity, and solubility were characterized. Results show that elongation of the alkyl chain leads to replacement of bromides with a small amount of chlorides in the anion, shifting of UV maximum absorption peaks to shorter wavelengths, reduction of ionic conductivity, and solubility in polar solvents, as well as increase in fluidity, magnetic susceptibility, and solubility in nonpolar solvents. Copyright © 2014 John Wiley & Sons, Ltd.     

Study of ion transport and materials properties of K+-ion conducting solid polymer electrolyte (SPE): [(1-x) PEO: xCH3COOK]

Study of ion transport behavior in K⁺-ion conducting solid polymer electrolyte (SPE) films: [(1-x) PEO: xCH₃COOK] has been reported. Poly (ethylene oxide) PEO has been used as polymeric host and potassium acetate: CH₃COOK as complexing salt. SPE films in varying salt concentrations have been prepared by hot-press cast method. SPE film: [95PEO: 5CH₃COOK] has been identified as Optimum Conducting Composition (OCC) with room temperature conductivity (σ _rt) ~ 2.74 × 10⁻⁷ S/cm. As a consequence of salt complexation in polymeric host, σ _rt-enhancement of approximately two orders of magnitude was achieved in SPE OCC film. Ion transport property has been characterized in terms of ionic conductivity (σ), total ionic (t _ion)/cation (t ₊) transference numbers using different ac/dc techniques. Temperature-dependent conductivity measurement was done to explain mechanism of ion transport and to evaluate activation energy (E _a). XRD, FTIR, and DSC techniques were used to study materials property in SPE OCC film which also confirmed the complexation of salt in the polymeric host as well as increase in degree of amorphousity.

     

Role of salt concentration on conductivity optimization and structural phase separation in a solid polymer electrolyte based on PMMA-LiClO4

Although a large number of ionic conductors based on poly(methyl-methacrylate) (PMMA) are reported in literature, an optimization of salt concentration with respect to conductivity and stability properties remains by and large neglected. We report, perhaps for the first time, such an optimization of salt (LiClO₄) concentration on structural, morphological, electrical, and ion–polymer interaction in PMMA-based solid polymer films. The active coordination site for the cation (Li⁺), out of the two possible electron donating functional groups (i.e. C=Ö and Ö–CH₃) in PMMA, has been ascertained on the basis of evidences recorded in Fourier transform infrared spectrum. The results suggested C=Ö as the only possible site in PMMA matrix for coordination with Li⁺ cation. The X-ray diffraction results have clearly indicated an optimum limit of salt dissolution in PMMA matrix corresponding to O/Li = 4 (i.e., ~21wt.%) above which “phase-separation” occurs distinctly. The effect of salt concentration on amorphous → crystalline phase changes in PMMA and its correlation to morphology have been clearly observed in terms of their impact on electrical properties. An optimum electrical conductivity of ~7.2 × 10^?5S cm^?1 has been recorded at 100°C (~PMMA glass transition). The temperature dependence of conductivity follows typical Vogel–Tamman–Fulcher behavior.     

Characterization of ion transport property in hot-press cast solid polymer electrolyte (SPE) films: [PEO: Zn(CF3SO3)2]

Characterization of ion transport property in dry solid polymer electrolyte (SPE) films: [PEO: Zn(CF₃SO₃)₂] in different salt wt% ratio has been reported. SPE films have been prepared by a hot-press casting procedure. Salt concentration dependent conductivity study at room temperature identified SPE film: [90PEO: 10 Zn(CF₃SO₃)₂] as optimum conducting composition (OCC) with σ _rt ~ 1.09 × 10⁻⁶ S/cm which is approximately three orders of magnitude higher than that of pure PEO host (σ _rt ~ 3.20 × 10⁻⁹ S/cm). The reason attributed for σ _rt enhancement has been the increase in degree of amorphous phase in polymeric host after salt complexation. This has been confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and polarized optical microscopy (POM) analysis. To evaluate the usefulness of SPE OCC film in all-solid-state-battery applications, ion transport property has been characterized in terms of basic ionic parameters viz. ionic conductivity (σ) and total ionic (t _ion)/cation (t ₊) transport numbers. Mechanism of ion transport has been explained by temperature dependent conductivity measurements and the activation energy (E _a) has been computed by least square linear fitting of “log σ − 1/T” Arrhenius plot.

     

Raman and ab initio study of the conformational isomerism in the 1‐ethyl‐3‐methyl‐imidazolium bis(trifluoromethanesulfonyl)imide ionic liquid

The calculated and experimental Raman spectra of the (EMI⁺)TFSI⁻ ionic liquid, where EMI⁺ is the 1‐ethyl‐3‐methylimidazolium cation and TFSI⁻ the bis(trifluoromethanesulfonyl)imide anion, have been investigated for a better understanding of the EMI⁺ and TFSI⁻ conformational isomerism as a function of temperature. Characteristic Raman lines of the planar (p) and non‐planar (np) EMI⁺ conformers are identified using the reference (EMI⁺)Br⁻ salt. The anion conformer of C₂ symmetry is confirmed to be more stable than the cis (C₁) one by 4.5 ± 0.2 kJ mol⁻¹. At room temperature, the population of trans (C₂) anions and np cations is 75 ± 2% and 87 ± 4%, respectively. Fast cooling quenches a metastable glassy phase composed of mainly C₂ anion conformers and p cation conformers, whereas slow cooling gives a crystalline phase composed of C₁ anion conformers and of np cation conformers. Copyright © 2006 John Wiley & Sons, Ltd.     

Modeling and simulation of Li-ion conduction in poly(ethylene oxide)

Polyethylene oxide (PEO) containing a lithium salt (e.g., LiI) serves as a solid polymer electrolyte (SPE) in thin-film batteries and its ionic conductivity is a key parameter of their performance. We model and simulate Li⁺ ion conduction in a single PEO molecule. Our simplified stochastic model of ionic motion is based on an analogy between protein channels of biological membranes that conduct Na⁺, K⁺, and other ions, and the PEO helical chain that conducts Li⁺ ions. In contrast with protein channels and salt solutions, the PEO is both the channel and the solvent for the lithium salt (e.g., LiI). The mobile ions are treated as charged spherical Brownian particles. We simulate Smoluchowski dynamics in channels with a radius of ca. 0.1 nm and study the effect of stretching and temperature on ion conductivity. We assume that each helix (molecule) forms a random angle with the axis between these electrodes and the polymeric film is composed of many uniformly distributed oriented boxes that include molecules with the same direction. We further assume that mechanical stretching aligns the molecular structures in each box along the axis of stretching (intra-box alignment). Our model thus predicts the PEO conductivity as a function of the stretching, the salt concentration and the temperature. The computed enhancement of the ionic conductivity in the stretch direction is in good agreement with experimental results. The simulation results are also in qualitative agreement with recent theoretical and experimental results.     

Starch-based gel electrolyte thin films derived from native sago (Metroxylon sagu) starch

Starch-based gel electrolyte (SbGE) thin films were prepared by mixing native sago starch with different amounts of glycerol, and subsequently doped with various types of ionic salts. SbGE thin films showed substantially enhanced mechanical properties and ionic conductivity through incorporating optimal composition of native sago starch, glycerol, and ionic salts. A maximum room temperature ionic conductivity of the order of 10^?3 S cm^?1 was achieved for optimized SbGE thin film consisting of 80 wt% of native sago starch and 20 wt% of glycerol, and doped with 8 wt% of LiCl. SbGE thin films were characterized by Fourier transformed infrared spectrometry, scanning electron microscopy, and electrochemical impedance spectroscopy. Due to their favorable mechanical properties, high ionic conductivity at room temperature, ease of preparation, environmentally benign, and cheap, SbGE thin films show high potential utility as gel electrolyte materials for the fabrication of solid-state electrochemical devices.     

Modeling and simulation of Li-ion conduction in poly(ethylene oxide)

Polyethylene oxide (PEO) containing a lithium salt (e.g., LiI) serves as a solid polymer electrolyte (SPE) in thin-film batteries and its ionic conductivity is a key parameter of their performance. We model and simulate Li⁺ ion conduction in a single PEO molecule. Our simplified stochastic model of ionic motion is based on an analogy between protein channels of biological membranes that conduct Na⁺, K⁺, and other ions, and the PEO helical chain that conducts Li⁺ ions. In contrast with protein channels and salt solutions, the PEO is both the channel and the solvent for the lithium salt (e.g., LiI). The mobile ions are treated as charged spherical Brownian particles. We simulate Smoluchowski dynamics in channels with a radius of ca. 0.1 nm and study the effect of stretching and temperature on ion conductivity. We assume that each helix (molecule) forms a random angle with the axis between these electrodes and the polymeric film is composed of many uniformly distributed oriented boxes that include molecules with the same direction. We further assume that mechanical stretching aligns the molecular structures in each box along the axis of stretching (intra-box alignment). Our model thus predicts the PEO conductivity as a function of the stretching, the salt concentration and the temperature. The computed enhancement of the ionic conductivity in the stretch direction is in good agreement with experimental results. The simulation results are also in qualitative agreement with recent theoretical and experimental results.     

Electrical properties of ZrO2-CeO2 at intermediate temperatures

Both ZrO₂-CeO₂ powder materials and thin film ceramic membranes have been prepared by sol-gel processes. Sol and suspensoid were used as dips for preparing the thin film membranes in this work. The membranes, with a thickness in the range of 200 nm to a few mm, were coated on porous alumina ceramic substrates by a slip-coating or spin-coating process for different purposes. The ZrO₂-CeO₂ thin film membranes are highly conductive and transparent with an ionic conductivity as high as 10⁻² S/cm at 600 °C, which is two orders of magnitude higher than that of the bulk materials. This is perhaps caused by a different microstructure for the thin film membranes compared to the bulk materials. The thin films, but not the bulk samples, are stable in reduced atmosphere. By controlling the composition and atmosphere, the ZrO₂-CeO₂ materials can be ionic, electronic or mixed conductors. For the bulk samples a transition has been observed where the conductivity increases by about two orders of magnitude. Paper presented at the 4th Euroconference on Solid State Ionics, Renvyle, Galway, Ireland, Sept. 13–19, 1997     

A study of iso- and alio-valent cation doped Ag2SO4 solid electrolyte

2 SO₄. The solid solubility limits up to x≤3 mole% for monovalent, x≤5.27 mole% for divalent and x≤3.63 mole% for trivalent cation doped Ag₂SO₄ are set with XRD, SEM, IR and DSC techniques. A predominant dependence of conductivity on the ionic size of iso- and alio-valent cations is observed. In particular, the conductivity enhances in both α and β phases, despite having a lower ionic-size dopant cation (relative to that of Ag⁺) in the transition element cation doped Ag₂SO₄. Ca²⁺, Ba²⁺, Y³⁺ and Dy³⁺ doped samples show depature from the regular behaviour in the β-phase. The conductivity behaviour is discussed considering ionic size, valence and electronic structure of the guest cations. Received: 3 February 1997/Accepted: 27 May 1997