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1.
季铵盐相转移催化氧化噻吩脱硫的研究 总被引:3,自引:0,他引:3
在验证季铵盐相转移催化氧化噻吩脱硫符合Starks循环模型的基础上推导了噻吩氧化脱硫的反应历程. 反应历程主要包括氧化活性组分从水相向有机相的转移和有机相中的离子反应两个基本阶段, 通过理论计算得到了季铵盐阳离子的萃取平衡常数、阴离子的亲核性以及决定阴阳离子相互作用能的离子有效半径, 筛选出了与实验结果一致的具有良好的相转移催化效果的四丁基溴化铵, 脱硫率最高可达到86.36%; 动力学研究结果表明, 以四丁基溴化铵作为相转移催化剂(PTC), H2O2/HCOOH氧化噻吩脱硫为一级反应. 相似文献
2.
季铵盐相转移催化氧化噻吩的研究 总被引:7,自引:1,他引:6
以噻吩的正庚烷溶液模拟轻质油品,研究了H2O2—HCOOH氧化条件下,相转移催化氧化噻吩脱硫。实验结果表明,四丁基溴化铵用量0.10g,反应1.5h,反应温度45℃,脱硫率最高可达86.36%。动力学研究表明,以四丁基溴化铵作为相转移催化剂,过氧化氢 甲酸氧化噻吩脱硫为表观一级反应,反应速率常数 K30℃=0.6152h-1、K40℃=1.2672h-1、K50℃=0.8581h-1;相转移催化在H2O2—有机酸体系氧化噻吩脱硫反应中的作用为相转移催化剂阳离子Q+对氧化剂活性组分HCOOO-的转移作用。并建立了相转移催化氧化噻吩脱硫反应的循环模型。 相似文献
3.
Yuchen Fu Sai Zhao Yulong Fan Yannis Yan Lum Ho Yufeng Wang Dangyuan Lei Peiyang Gu Thomas P. Russell Yu Chai 《Angewandte Chemie (International ed. in English)》2023,62(38):e202308853
Nanoparticles (NPs) transfer is usually induced by adding ligands to modify NP surfaces, but aggregation of NPs oftentimes hampers the transfer. Here, we show that aggregation during NP phase transfer does not necessarily result in transfer failure. Using a model system comprising gold NPs and amphiphilic polymers, we demonstrate an unusual mechanism by which NPs can undergo phase transfer from the aqueous phase to the organic phase via a single-aggregation-single pathway. Our discovery challenges the conventional idea that aggregation inhibits NP transfer and provides an unexpected pathway for transferring larger-sized NPs (>20 nm). The charged amphiphilic polymers effectively act as chaperons for the NP transfer and offer a unique way to manipulate the dispersion and distribution of NPs in two immiscible liquids. Moreover, by intentionally jamming the NP-polymer assembly at the liquid/liquid interface, the transfer process can be inhibited. 相似文献
4.
Resins from diphenols with an aromatic ring as side group, phosgene, and a triphenol as crosslinking agent were synthesized under phase transfer conditions. The resins obtained with a phase transfer catalyst showed higher thermal stability than those obtained without catalyst. The function of the catalyst is to transport triphenol from the aqueous phase to the organic phase. The thermal stability of the resins was related to the structure and the content of triphenol. It was found that resins derived from diphenol I exhibited higher thermal stability as the content of triphenol increased. On the other hand, when diphenol II was used, the thermal stability decreased as the content of triphenol increased, due to steric hindrance of the methyl group on the side ring. Also, a resin from the triphenol alone was synthesized in the same conditions. The kinetic parameters of the decomposition process were determined for all resins. 相似文献
5.
The facilitated transport of penicillin G from aqueous solutions to the stripping phase through bulk liquid membrane (BLM)
containing TBP in 3% iso-octanol and n-butyl acetate was studied. Na2CO3 solution was used as the stripping phase. Experiments were performed as a function of stirring rate, TBP concentration and
type of diluent in the liquid membrane phase, pH, and initial penicillin G concentration in the feed phase, Na2CO3 concentration in the stripping phase, etc. The results showed that the BLM process could carry out the simultaneous separation
and concentration of penicillin G from dilute aqueous solutions, and arise “up-hill” effect due to the characteristic of non-equilibrium
mass transfer. The diffusion of penicillin G complex in the liquid membrane phase played an important role in BLM process.
The mass transfer mechanism of BLM for this system was also discussed. 相似文献
6.
The transfer process of multi‐walled carbon nanotubes (MWCNTs) from the high density polyethylene (HDPE) phase to the polyamide 6 (PA6) phase has been observed in the study. In this paper, the transfer is divided into six steps according to the level of mixing energy during the blending process. The MWCNTs could be extracted from HDPE phases and transfer into PA phases due to a stronger adhesion between MWCNTs and PA than HDPE. Additionally, the morphology change observed by optical microscope (OPM) is also thought to be crucial for the transfer. The PA phase version from disperse phase to continuous phase was obvious during the transfer process. Furthermore, the changes of electrical conductivity, yield strength and rheology have also been studied in this paper. The electrical conductivity changes with the transfer of MWCNTs and variation of phase morphology. Yield strength got the highest peak about 25.6 MPa and lowest peak about 22.3 MPa, respectively, at different mixing energies. The complex viscosity got the lowest value when the MWCNTs located in the interface. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
Zhou Y Lin W Wang H Li Q Huang J Du M Lin L Gao Y Lin L He N 《Langmuir : the ACS journal of surfaces and colloids》2011,27(1):166-169
Biosynthesized gold nanoparticles (GNPs) were transferred from water to a hydrophobic ionic liquid (IL), [Bmim]PF(6), with the assistance of alkyl trimethyl ammonium bromide. The phase transfer mechanism was illustrated through the exemplification of cetyltrimethyl ammonium bromide (CTAB). Interaction between GNPs and CTAB was demonstrated through zeta potential analysis. Moreover, an anion-exchange process was discovered between CTAB and IL. During the process, the hydrophobic CTAPF(6) formed in situ on the GNPs led to the hydrophobization and thus phase transfer of the GNPs. The phase transfer efficiency was found to be size-dependent. 相似文献
8.
Arenediazonium ions are dediazoniated through reduction by decamethylferrocene in the 1,2-dichloroethane (DCE) after the electrochemical
transfer of the arenediazonium ions from the aqueous side of the interface between the DCE and the aqueous phase (W). Cyclic
voltammetry of the ion transfer clearly shows that this process is described as an E
r
C
i process, that is, the diffusion-limited transfer of the ions across the interface followed by the irreversible dediazoniation
in the DCE phase. Arene radicals formed in DCE can initiate the radical polymerization of styrene at the interface. The polystyrene
formed in the interfacial region significantly impedes the transfer of tetraethylammonium ions across the DCEIW interface.
Published in Russian in Elektrokhimiya, 2008, Vol. 44, No. 1, pp. 80–84.
The text was submitted by the authors in English. 相似文献
9.
10.
Stefanie Machunsky Philipp Grimm Hans-Joachim Schmid Urs A. Peuker 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):186-190
The study presents first experimental results of the transfer of magnetite nanoparticles from an aqueous to a second non-miscible non-aqueous liquid phase. The transfer is based on the adsorption of macromolecular surfactants onto the particle surface at the liquid–liquid interface. For a successful direct phase transfer, it is essential to have cations, like ammonium ions, present in the aqueous phase as well as a threshold concentration of surfactant in the organic liquid phase. While penetrating the liquid–liquid interface, the particles are covered with the surfactant and therefore a partial de-agglomeration is initiated. Based on literature and experimental data a mechanism of surfactant adsorption is proposed. The competing adsorption of the surfactant molecules at the liquid–liquid interface leads to the formation of emulsions and therefore to a hindrance for particles passing the interface. Nevertheless a high efficiency of 100% yield can be reached using optimized process parameters for the phase transfer process. 相似文献
11.
TengQIU LiMingTANG XinLinTUO DeShanLIU 《中国化学快报》2004,15(8):931-934
Hydrophilic hyperbranched poly(ester-amine) (HPEA) synthesized from diethanolamine and methyl acrylate was used as phase transfer agent for the first time to transfer methyl orange(MO) from water into chloroform. This process was quantified by UV-Vis spectra. A possible mechanism was put forward based on the formation of amphiphilic aggregates. 相似文献
12.
反胶团相转移法提纯酵母脂肪酶 总被引:1,自引:0,他引:1
反胶团相转移法是80年代兴起的一种新型分离技术,它利用表面活性剂分子在有机溶剂中自发形成的反向胶团(反胶团),在一定条件下将水溶性蛋白质分子增溶进反胶团的极性核(水池)中,再创造条件将蛋白质抽提至另一水相,实现蛋白质的相转移,达到分离和提纯蛋白质的目的[1].反胶团中的蛋白质分子受到周围水分子和表面活性剂极性头的保护,仍保持一定的活性,甚至表现出超活性[2].由于蛋白质增溶于反胶团与蛋白质所带电荷及反胶团内表面电荷间的静电作用及反胶团的大小有关[3~5],因而表面活性剂的种类、水溶液的PH值及离子强度等因素… 相似文献
13.
《Journal of membrane science》2001,190(1):69-77
Mass transfer process involved in the immersion precipitation of polyurethane/dimethylformamide (DMF)/water system was investigated. The set of diffusion equations describing the local composition of the membrane solution as a function of space coordinate and time were solved by numerical method, and the composition path in the phase diagram was obtained. Instead of boundary conditions based on the instantaneous equilibrium assumption between membrane solution and coagulation bath, new boundary conditions were set up by using mass transfer formalism at the interface which is especially valid in the condition that the mass transfer rate is extremely rapid. Phase separation phenomena during immersion precipitation were taken into account to continue the calculation after phase separation. The calculated results showed that the chance of phase separation via spinodal decomposition increases with the strength of nonsolvent, addition of nonsolvent to the dope solution, and the use of more hydrophobic polymer. The proposed model is the improvement of the previous works eliminating the equilibrium assumption at the interface and extending the calculation after phase separation. 相似文献
14.
This study contains mathematical modelling and numerical analysis of heat transfer in laser beam welding process. The temperature field was obtained on the basis of numerical solution into unsteady heat transfer equation with convective term and volumetric heat sources taken into account. Volumetric heat source model describing laser beam power distribution in combined truncated cone?Ccylinder volume was developed. Due to the wide range of temperatures appearing in the process latent heat of fusion, evaporation as well as latent heat of phase transformations in solid state were taken into account in the solution algorithm. On the basis of developed numerical algorithms an analysis of heat transfer in laser butt-welded steel sheets as a three-dimensional initial-boundary problem was performed. 相似文献
15.
研究了膜接触器法高压吸收混合气中CO2的过程,考察水作为吸收剂时,操作压力、气体和吸收剂流量对聚偏氟乙烯(PVDF)中空纤维膜脱除CO2效果的影响.通过物理传质模型得出气相、膜相和液相的传质方程式,构建了二维数学模型,并结合边界层条件和多物理场耦合分析软件(COMSOL MULTIPHYSICS)对膜接触器法高压物理吸收CO2的过程进行了模拟预测.结果表明,吸收过程中膜的润湿情况显著影响CO2传质效果;在数学模型中引入润湿率,可以较准确预测CO2的物理吸收效果. 相似文献
16.
Chengbo Zhang Dr. Keyan Li Dr. Shuyan Song Prof. Dongfeng Xue 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6329-6333
A facile and reversible phase‐transfer protocol for luminescent ZnO quantum dots (QDs) between methanol and hexane is presented. Oleylamine together with acetic acid trigger this reversible phase‐transfer process, during which the structure and optical properties of the ZnO QDs are well‐protected. ZnO QDs with a diameter of approximately 5 nm emit yellow light at 525 nm, while those with a diameter of approximately 4 nm emit green light at 510 nm. The positions of the emission peaks remain unchanged during the presented phase‐transfer process. The Pearson’s hard and soft (Lewis) acid and base principle, together with the principle that similar substances are more likely to be dissolved by each other, describes the current reversible phase‐transfer process. Herein, we circumvent the time‐consuming work required to synthesize ZnO QDs in different environments, making it possible to combine the advantages of ZnO QDs dispersed in polar and nonpolar solvents. 相似文献
17.
聚苯乙烯三乙醇胺树脂催化合成对硝基苯甲醚 总被引:2,自引:0,他引:2
:讨论了聚苯乙烯三乙醇胺树脂为相转移催化剂催化合成对硝基苯甲醚的方法 ,探讨了最佳反应条件 ,证实了催化剂的重复使用性能 相似文献
18.
Firing of atmospheric-pressure, electrolytic-cathode glow discharge leads to an effect that is similar to well-known cathode
sputtering. This process can be called nonequilibrium vaporization of the solution. Unlike quasi-equilibrium vaporization,
the nonequilibrium process entails the transfer of nonvolatile components of the solution to the gas phase. Previously, studying
glow discharge with calcium and barium chloride solutions as the cathode, we have shown that the transfer of cations and anions
via the nonequilibrium vaporization of the nonvolatile solutes is not necessarily stoichiometric [1]. 相似文献
19.
《Electrochemistry communications》2001,3(6):306-311
The carbon ceramic electrodes impregnated with hydrophobic organic solvent (toluene, hexadecane, nitrobenzene) containing redox probe (decamethylferrocene) were prepared. The electrode material was obtained by sol–gel process. It consists of graphite powder homogeneously dispersed in hydrophobic silica matrix. After gelation and drying it was filled with organic liquid. The electrochemical properties of the electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Approximately symmetric cyclic voltammograms were obtained with these electrodes immersed in aqueous electrolyte solution. Their shape and current magnitude and position on the potential scale depends on the organic solvent and the salt present in aqueous phase. It has been concluded that the mechanism of the electrode process involves electron transfer between graphite particle and the redox probe in organic phase, followed by anion transfer from the aqueous phase. 相似文献
20.
MacDonald SM Opallo M Klamt A Eckert F Marken F 《Physical chemistry chemical physics : PCCP》2008,10(26):3925-3933
Understanding liquid|liquid ion transfer processes is important in particular for naturally occurring species such as carboxylates. In this study electrochemically driven mono-, di-, and tri-carboxylate anion transfer at the 4-(3-phenylpropyl)pyridine|aqueous electrolyte interface is investigated experimentally for a triple phase boundary system at graphite electrodes. The tetraphenylporphyrinato-Mn(III/II) redox system (Mn(III/II)TPP) dissolved in the water-immiscible organic phase (4-(3-phenylpropyl)pyridine) is employed for the quantitative study of the structure-Gibbs transfer energy correlation and the effects of the solution pH on the carboxylate transfer process. For di- and tri-carboxylates the partially protonated anions are always transferred preferentially even at a pH higher than the corresponding pK(a). COSMO-RS computer simulations are shown to provide a quantitative rationalisation as well as a powerful tool for predicting Gibbs free energy of transfer data for more complex functionalised carboxylate anions. It is shown that the presence of water in the organic phase has a major effect on the calculated Gibbs free energies. 相似文献