共查询到20条相似文献,搜索用时 11 毫秒
1.
Simulation of non-stationary electrodiffusion processes in charged membranes by the network approach
Single techniques of network approach have been used to obtain the numerical solution for a boundary value problem involving the Nernst-Planck and Poisson equations system. A network model has been proposed for a particular physical situation, namely, ionic transport in charged membranes including the Donnan equilibrium relations at the membrane/solution interfaces. With this network model and using the electrical circuit simulation program PSPICE, the ionic concentration profiles as well as electric potentials and ionic fluxes have been simulated as a function of time for the ternary systems HClKCl and NaClKCl. 相似文献
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A model of the composite membrane consisting of the catalytic layer (CL) and the nanofiltration layer (NFL) is presented. It has been found that applying NFL on the permeate side of CL it is possible to enhance substantially the conversion of substrate into the product. The best performance is obtained for high retention of substrate and low of product. At higher values of volume flow and/or longer catalytic path the retention degree of product becomes negligible. The presence of NFL enhances the influence of distribution of the reaction rate constant, k, on the conversion ratio. Comparing to k = constant the positive effect is obtained if k increases along the catalytic pore, whereas negative—if k decreases. 相似文献
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Mathematical homogenization theory as a multiscale modeling strategy for deriving macroscopic models is gaining relevance in modeling electrochemical energy storage systems (ESSs) for its ability to capture the detailed microstructural properties of a material. Stochastic modeling, on the other hand, captures molecular fluctuations and uncertainties associated with ESSs. In this short review, modeling ESSs using both tools is presented. Integrating mathematical homogenization theory and stochastic modeling provides an effective tool for deriving macroscopic models that accurately predict various macroscopic behavior and electrochemical properties of ESSs to enable optimization and manufacturing of high performance ESSs. 相似文献
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S. Zalamea M. P. Pina A. Villellas M. Menéndez J. Santamaría 《Reaction Kinetics and Catalysis Letters》1999,67(1):13-19
Catalytic membranes operating in a mixed permeation regime (i.e., with significant Knudsen and laminar contributions) have been developed. The membranes prepared had wide pores and presented
a low pressure drop. After the addition of γ-Al2O3 and Pt, the resulting catalytic membranes were active for the combustion of VOCs. Their performance was compared with that
of similar catalytic membranes operating under the Knudsen diffusion regime. 相似文献
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催化动力学测定痕量对苯二酚 总被引:2,自引:0,他引:2
研究了在pH7.3的KH2PO4 Na2HPO4缓冲介质中,痕量对苯二酚催化高碘酸钾氧化靛红褪色的新指示反应及其动力学条件,建立了动力学光度法测定痕量对苯二酚的新方法。该方法检出限为6.8×10-6g L,线性范围是0.04~0 18μg mL和0.28~0.54μg mL。可用于显影废液中对苯二酚的测定。 相似文献
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Potential energy surfaces for the process of phosphonylation of the catalytic triad of acetylcholinesterase by sarin have been explored at the B3LYP/6-311G(d,p) level of theory through a computational study. It is concluded that the phosphonylation process involves a critical addition-elimination mechanism. The first nucleophilic addition process is the rate-determining step. The following elimination process of the fluoride ion comprises a composite reaction that includes several steps, and it occurs rapidly by comparison with the rate-determining step. The mobility characteristics of histidine play an important role in the reaction. A double proton-transfer mechanism is proposed for the catalytic triad during the phosphonylation process of sarin on AChE. The effect of aqueous solvation has been considered via the polarizable continuum model (PCM). One concludes that the energy barriers are generally lowered in solvent, compared to the gas-phase reactions. 相似文献
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A new macrocyclic ligand H2L (H2L = 1,2-[bis(6′-pyridine-2′-carboxamido)-ethane]benzene) has been designed and synthesized by condensation of pyridine-carboxylic acid and diamine. Its Mn(III) and Fe(III) complexes, [Mn(L)Cl (DMF)] and [Fe(L)Cl], were prepared and respectively characterized by IR, UV-Vis, ESI-Mass, elemental analysis and X-ray single crystal diffraction. The catalytic abilities of them were examined, and up to 95% yield was achieved in epoxidation of styrene. The preliminary investigation of catalytic mechanism by manganese complex was carried out, suggesting the involvement of Mn(V) oxo species during catalysis. 相似文献
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The influence of temperature on the electrophoresis of a spherical, pH-regulated polyelectrolyte (PE) particle having both acidic and basic functional groups in an aqueous salt solution containing multiple ionic species is investigated theoretically. The type of particle considered simulates entities including proteins, biomolecules, and synthetic polymers. The applicability of the model proposed is verified by the experimental data of succinoglycan nanoparticles reported in the literature. Taking a glycin PE as an example, the variations of its mobility with the temperature, bulk salt concentration, and pH are examined through numerical simulation. Empirical relationships that correlate the mobility with these factors are obtained for temperature, bulk salt concentration, and pH ranging from 293 to 308 K, 10−4 to 10−2 M, and 2-10.5, respectively. Several interesting and important results for the PE mobility are observed. These results provide not only valuable information for interpreting experimental data but also for designing electrophoresis devices where temperature can play a role. 相似文献
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《Journal of Saudi Chemical Society》2020,24(10):733-741
The Cu/γ-Al2O3 catalysts with different Cu loadings were prepared by impregnation method. The physicochemical properties of these Cu/γ-Al2O3 catalysts were characterized by H2-TPR, XRD, and in-situ XPS. The catalytic hydrogenation performances of methyl laurate over Cu/γ-Al2O3 catalysts were studied. The results show that the hydrogenation performances of methyl laurate on Cu/γ-Al2O3 catalyst are related to the dispersion, crystallite size, and content of the active component Cu0. The 10CA catalyst has the best hydrogenation performances for methyl laurate to produce C12 alcohol. At 300 °C, the conversion of methyl laurate and the selectivity of C12 alcohol are 55.6% and 30.4%, respectively. 相似文献
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H2O2能够氧化偶氮染料刚果红使之褪色,而模拟酶—血红蛋白对其具有催化作用。据此建立了一种以刚果红为指示剂的H2O2-刚果红-血红蛋白酶催化反应体系测定痕量H2O2的新方法。确定了反应的最佳条件,体系的酸度为pH10.7的NH3-NH4Cl缓冲溶液,最大吸收波长为497 nm。该法的线性范围为8.0×10^-8-8.0×10^-5mol/L,检出限为1.97×10^-9mol/L,表观摩尔吸光系数为4.6×10^4L.mol-1.cm^-1。该方法可用于雨水及消毒水中H2O2的测定。 相似文献
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N-Arylation of carbazole has been achieved in high yields within 1 h using a microwave-assisted catalytic CuI reaction with no organic ligand. The N-arylation can be performed by various arylhalides, such as phenyl, pyridine, thiophene, and thiazole moieties. Specifically, N-arylated bromocarbazoles were converted into useful synthetic intermediates for functionalized carbazole materials. 相似文献
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A. Mohamadalizadeh J. Towfighi R. Karimzadeh 《Journal of Analytical and Applied Pyrolysis》2008,82(1):134-139
At the start-up period, the most important mechanism in the coke production with a clean reactor surface is the catalytic mechanism. The study of this mechanism can be very useful for the better comprehension of the coke production process. In this paper, a model was designed for such a production through the utilization of a catalytic mechanism and a kinetic model, capable of interpreting the catalytic coke production on the reactor surface. For the determination of the model reliability, the experimental data related to the naphtha feed, existing in literature, were used. In addition, the constant parameters of the model, the velocity and the activation energy constants, associated to the kinetic model, were calculated. The results of the developed model were in satisfactory agreement with the experimental data. Eventually, the catalytic coke amount in comparison with the total coke production on the reactor surface and its significance were under investigation. 相似文献
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Syed A. Ali Mohammed A. Siddiqui and Mohammed A. Ali 《Reaction Kinetics and Catalysis Letters》2005,87(1):199-206
Summary A parametric study of catalytic reforming process in a pilot plant was carried out by varying the pressure, H2/HC ratio, and space velocity. The results show that lower aromatics and higher hydrogen yields can be accomplished by increasing
the space velocity in existing reformers, which will also result in better C5+yield. 相似文献