Characterization of C80 Naphthenic Acid and Its Calcium Naphthenate

A C80 naphthenic acid (tetraacid) and its calcium naphthenate have been characterized with respect to their interfacial properties at both the oil/water and the air/water interfaces as well as their thermal properties. Naphthenic acids in crude oils may give rise to different problems in oil production including naphthenate deposition and formation of stable emulsions. This may lead to severe disturbances of regularity and shut‐in in the oil production. The interfacial activity and film properties of the compounds were examined by the oscillating drop method. The calcium naphthenate film was primarily elastic and solid‐like. Measurements on the acid gave similar results, an elastic, solid‐like film was formed, but the effect was less pronounced than for the calcium naphthenate. Langmuir‐Blodgett films of the acid and its naphthenate were deposited on conducting substrates and subsequently analyzed by scanning electron microscopy, SEM. It was found that the pure acid formed crystalline structures in the interfacial film on compression. The calcium naphthenate, on the other hand, form a continuous amorphous film on the substrate.     

Interfacial dilational rheology properties of films formed at the oil/water interface by reaction between tetrameric acid and calcium ion

This article aims to determine the applicability of interfacial dilational rheology to study the formation of viscoelastic film at the oil/water interface by reaction between tetrameric acids ARN and calcium ions, and to determine the influence of asphaltenes and naphthenic acids (NA) on this film. It was first found that the formation of viscoelastic film by reaction between ARN and calcium ions is easily observed by dilational rheology: Significantly high values of E′ (130?mN/m) were measured for this system at low ARN concentration (10?µM). These values are at least 5 to 10 times higher than values obtained for ARN without Ca²⁺ or other crude oil components such as asphaltenes and naphthenic acids.

The influence of asphaltenes and NA on the viscoelastic film formation has been studied. When asphaltenes or NA are present, the interfacial viscoelastic film is weakened: There is a gradual decrease of E′ and E″ when the asphaltenes or NA concentration increases. These two components can therefore inhibit the ARN/Ca²⁺ film formation. This decrease is similar to the one previously observed by shear rheology. Several explanations are proposed.     

C80 Calorimeter Studies of the Thermal Behavior of LiPF 6 Solutions

The thermal behavior of several LiPF₆ solutions was studied using a C80 calorimeter. It was found that oxygen might react with the solvents and decrease their thermal stability. The dissolution of LiPF₆ influences the thermal behavior remarkably with more heat generation and a lower onset temperature. Furthermore, the exothermic peak of LiPF₆ based on an electrolyte containing diethyl carbonate (DEC) was found around 185 ^∘C, which is 9.5–13.6 ^∘C lower than that containing dimethyl carbonate (DMC), which may be due to the relative activity of C₂H₅— and CH₃— in DEC and DMC, respectively.     

Algebraic expressions of irreducible bases for molecules C20H20, C80, and C240

Using the symmetrized boson representation technique, concise algebraic expressions of the irreducible bases symmetry adapted to the group chain I_h⊃C₅ for the fullerene molecules C₂₀H₂₀, C₈₀, and C₂₄₀ are derived for the most general cases and those for any specific case can be derived from them easily without a projection procedure. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 73: 283–297, 1999     

Rheological Measurements and Thermal Characterization of Lamellar Gel Phase Emulsions Developed with Cetearyl Alcohol/Nonionic Ethoxylated Surfactants

The aim of this research was to characterize emulsion systems (ES) containing nonionic ethoxylated surfactants by using rheological, microscopic, and thermogravimetric assays. Three formulations were developed: ES-1: 8.0% (w/w) oleth-20; ES-2: 4.0% (w/w) oleth-20 / 4.0% (w/w) steareth-21; and ES-3: 8.0% (w/w) steareth-21. The systems showed typical non-Newtonian pseudo-plastic behavior. The presence of a lamellar gel phase was observed for all systems, with ES-2 being more pronounced. Through thermogravimetry, the profiles of the three systems were found to be similar, consisting of two main events, the first one being characterized by loss of water and, beyond 110°C, by loss of the oil phase.     

Emulsions of Heavy Crude Oils. II. Viscous Responses and Their Influence on Emulsion Stability Measurements

The stability of 30 heavy crude oil emulsions was studied in a parallel-plate laboratory coalescer (DC field). Particularly, viscous responses and their influence on the emulsion stability measurements were investigated. In addition to highlighting previous results from the same experimental setup and discussing these based on recent experience, new results at different temperatures and volume fractions of water were presented. A new semi-empirical model for the characteristic time of the destabilization process was presented. The electrical forces were modelled with a point-dipole approximation and the hydrodynamic resistance to droplet transport was modelled with an empirical term including the logarithmic viscosity of the oil phase. The new model clearly performed much better than the previous model, particularly for very viscous crude oils. Studies of the performance of industrial electrocoalescers have showed that simple electrostatic theory can potentially explain complex separation phenomena when the resistance to the coalescence step is reduced by an efficient demulsifier. The ultimate goal is to build a model for both the laboratory setup and the industrial coalescer so that laboratory experiments can be used to predict the behavior of the industrial process.     

Synthesis and Electrochemical Behavior of Mixed Organoboron/Organomercury Compounds

As part of our ongoing interest in the synthesis and reduction chemistry of organoboron species, we have investigated the synthesis of mixed organoboron/organomercury complexes by reaction of the Li(THF)₄ salt of dimesityl‐1, 8‐naphthalenediylborate with 1, 2‐(HgCl)₂C₆F₄ and 1, 3‐(HgCl)₂C₆F₄, respectively. The resulting tetranuclear B₂Hg₂ complexes ( 2 and 3 , respectively) were characterized by multinuclear NMR spectroscopy and single‐crystal X‐ray analysis. The cyclic voltammogram of complex 2 , which features a B–Hg–Hg‐B core connected by an ortho‐phenylene (Hg–Hg connection) and two peri‐naphthalenediyl linkers (B–Hg connection), shows significant coupling of the two electroactive boryl units, presumably via a direct σ interaction of the vacant p orbitals of the four neighboring Lewis acids. This conclusion is supported by DFT calculations, which show that the LUMO of 2 spans the four Lewis acids, with a major in phase contribution from the boron 2p orbitals and the mercury 6p orbitals.     

Investigation on stabilities and spectroscopy of C80O2 based on C80 (D5d) using density functional theory

The relative stabilities of the 17 possible isomers for C₈₀O₂ based on C₈₀ (D_5d) were studied using Becke three parameters plus Lee, Yang, and Parr's (B3LYP) method and 6‐31G (d) basis set in density functional theory. The most stable geometry of C₈₀O₂ was predicted to be 23,24,27,28‐C₈₀O₂ (A) with annulene‐like structures, where the additive bonds are those between two hexagons (6/6 bonds) near the equatorial belt of C₈₀ (D_5d). Electronic spectra of C₈₀O₂ isomers were calculated based on the optimized geometries using intermediate neglect of differential overlap (INDO) calculation. Compared with those of C₈₀ (D_5d), the first absorptions in the electronic spectra of C₈₀O₂ are blue‐shifted owing to the wide energy gaps. ¹³C nuclear magnetic resonance spectra and nucleus independent chemical shifts of the C₈₀O₂ isomers were computed at B3LYP/6‐31G level. The chemical shifts of the bridged carbon atoms in the epoxy structures of C₈₀O₂ compared with those of the bridged carbon atoms in the annulene‐like structures are changed upfield. Generally, the isomers with the annulene‐like structures of C₈₀O₂ are more aromatic than those with the epoxy structures. The addition of the oxygen atoms near the pole of C₈₀ (D_5d) is favorable to improving the aromaticities of C₈₀O₂. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

Thermal properties and kinetics study of charged LiCoO2 by TG and C80 methods

The thermal stability of lithium-ion battery cathode could substantially affect the safety of lithium-ion battery. In order to disclose the decomposition kinetics of charged LiCoO₂ used in lithium ion batteries, thermogravimetric analyzer (TG) and C80 microcalorimeter were employed in this study. Four stages of mass losses were detected by TG and one main exothermic process was detected by C80 microcalorimeter for the charged LiCoO₂. The chemical reaction kinetics is supposed to fit by an Arrhenius law, and then the activation energy is calculated as E _a=148.87 and 88.87 kJ mol⁻¹ based on TG and C80 data, respectively.     

Low-Temperature Fast Production of Carbon and Acetic Acid Dual-Promoted Pd/C Catalysts

The Pd/C catalysts are widely used in synthesis of fine chemicals in industry, but their production suffers from a complicated two-step process involving impregnation and reduction, and requires large amounts of solvents and reductant, which would lead to a series of issues such as time consumption, resource waste and environmental pollution. Herein, ultra-small Pd nanoparticles uniformly anchored on carbon nanotubes (Pd/CNTs) were synthesized by using a one-pot and low-temperature reduction strategy. The present process/technology is very sensitive to and controlled by the supports and solvents, and the carbon support and acetic acid synergistically play crucial and decisive roles in the fast production of Pd/C catalysts. Also, the used solvents can be recycled and reutilized, which meets the requirements of sustainable chemistry and green economy. When the as-obtained Pd/CNTs catalyst was used to catalyze the oxidation of benzyl alcohol to benzaldehyde, it achieved a conversion efficiency as high as 99.3 % and a high selectivity up to >99.9 %. The simple, scalable and environmentally friendly strategy can be extended to anchor Pd nanoparticles on various carbon substrates, which sheds a new light on the synthesis of Pd/C catalysts.     

硅氧烷乳液聚合过程中大颗粒形成机理的研究：Ⅱ.聚硅氧烷乳液的耐酸碱…

研究了阴离子型与阳离子型聚硅氧烷乳液的耐酸碱稳定性，发现阴离子型乳液对酸碱都相当稳定，在乳液制备过程中，酸性催化剂不会引起乳液颗粒的凝聚；而阳离子型乳液的耐酸三稳定性性差，尤其是引起乳液颗粒慢速凝聚的碱浓度下限值很低，碱是制备阳离子型乳液的化剂，碱引起乳液颗粒的慢速凝聚是阳离子型乳液中大颗粒形成的主要原因，在乳液聚合过程中所发生的相当部分的乳化剂从水相向有机硅相的转移也是影响阳离子型乳液稳定性的一     

Gemini表面活性剂/C12En混合体系的界面吸附、扩张粘弹与泡沫稳定性

用表面张力法研究了阳离子gemini表面活性剂乙基-1, 2-双(十二烷基二甲基溴化铵)(简写为12-2-12)和非离子表面活性剂十二烷基聚氧乙烯醚(C₁₂E_n,其中n = 4, 10, 23)混合体系在气液界面上的吸附行为;用扩张流变技术研究了吸附膜的扩张粘弹行为,实验数据用Lucassen-van den Tempel (LVT)模型进行拟合并根据模型得到了极限弹性值.最后研究了混合体系的泡沫行为,用泡沫塌陷到初始高度一半所对应的时间(t_1/2)来表征泡沫的稳定性.结果表明,所有的非离子表面活性剂C₁₂E_n均与12-2-12产生了吸引作用.在12-2-12浓度相同的情况下,混合吸附层中吸附分子的最小分子占据面积的顺序为12-2-12/C₁₂E₂₃ > 12-2-12/C₁₂E₁₀ > 12-2-12/C₁₂E₄,而极限弹性的顺序为ε_{0, fit}(12-2-12/C₁₂E₄) > ε_{0, fit}(12-2-12/C₁₂E₁₀) > ε_{0, fit}(12-2-12/C₁₂E₂₃).与单组分12-2-12形成的吸附膜相比,只有12-2-12/C₁₂E₄形成更加紧密的结构.具有较小亲水头基的非离子表面活性剂C₁₂E₄的加入,可增强12-2-12吸附膜的弹性,进而增强了对应体系泡沫的稳定性.     

Preparation of Ultrafine and High Dispersion Pd/C Catalyst and Its Electrocatalytic Performance for Formic Acid Oxidation

A carbon supported Pd(Pd/C) catalyst used as the anodic catalyst in the direct formic acid fuel cells(DFAFC) was prepared via the improved complex reduction method with sodium ethylenediamine tetracetate(EDTA) as stabilizer and complexing agent.This method is very simple.The average size of the Pd particles in the Pd/C catalyst prepared with the improved complex reduction method is as small as about 2.1 nm and the Pd particles in the Pd/C catalyst possess an excellent uniformity.The Pd/C catalyst shows a high electrocatalytic activity and stability for the formic acid oxidation.