苯酚与异丙醇烷基化合成异丙基苯酚的热力学和动力学

基于Benson基团贡献法研究苯酚与异丙醇烷基化反应过程,确定了主、副反应的反应热、平衡常数及平衡转化率,得到反映热力学性质的反应方程式并建立反应的网络结构,为该体系的工艺设计提供热力学依据。在苯酚与异丙醇物质的量比为0.5~2.0、温度(513.15~573.15)K、空速8 h-1和催化剂颗粒(40~60)目[相当于粒径(0.45~0.30)mm]条件下进行本征动力学实验。选用幂数型动力学模型,对参数进行估值。用Runge-Kutta法进行数值积分,Simplex法对参数进行优化,F统计法对模型进行检验,最终得到能较好描述反应的本征动力学模型。     

C207铜基催化剂常压甲醇分解反应动力学(Ⅰ)本征动力学模型

在直流流动积分反应器中常压下研究了C207催化剂甲醇分解反应本征动力学。实验温度、气体组成与甲醇合成工业条件相接近。以实验測定数据应用改进高斯-牛顿法对动力学模型参数进行估值,获得甲醇分解反应本征动力学方程。     

FX-01催化剂上苯与丙烯烷基化反应过程研究(Ⅰ)——反应动力学

对FX-01沸石催化剂上苯与丙烯烷基化反应进行了研究,得出了气液固三相催化反应的本征动力学模型.动力学实验是在消除了内扩散、外扩散影响的条件下,在高压釜间歇反应器中进行的, 采用常微分方程的参数估值法进行参数估值,得到本征动力学方程.     

B-O2催化剂上丁烯氧化脱氢动力学研究

本文利用内循环无梯度反应器,在320～420℃及较宽的各组分分压范围内研究了B-02工业催化剂用于丁烯氧化脱氢反应的本征动力学.按照串-并联反应网络,依据Redox机理、L-H机理和幂函数型规律构想出28个动力学模型;应用模型参数的物理特征、参数估值中的残差平方和相对大小以及非本征参数法筛选模型;采用模式探测法和马垮特法相结合的综合方法进行模型参数估值,从而求得适宜的本征动力学模型.最后对所定动力学模型进行显著性检验,证明该模型对实验数据确有较好的表现力.文中还讨论了水/烯比值对模型参数的影响、丁二烯的阻碍作用及催化剂的选择性等问题.     

乙烯在银催化剂上氧化本征动力学的研究

采用固定床恒温积分反应器，对YS-6型银催化剂进行乙烯氧化本征动力学研究。选择与工业应用接近的条件进行动力学实验，根据建立的动力学模型。用动力学试验数据采用双响应Marquardt法，以转化率，选择性为目标函数进行待定参数估值。确定待定参数，得到本征动力学方程，根据数学统计检验，文中所建立的模型残差分布合理。参数回归显著，能够反映YS-6型催化剂的反应特性。     

铁系无铬型高温变换催化剂本征动力学研究

本文采用等温管式微分反应器,研究了常压下在NBC-1型铁系无铬催化剂上CO变换反应的本征动力学。运用参数估值序贯实验设计的原理优选实验点,用非线性最小二乘法进行幂函数型本征动力学方程的参数估值,获得本征动力学模型。并经F检验、相关指数检验及应用该数学模型进行某厂变换炉催化剂用量的计算,证明了实验数据及数学模型的准确性。     

CoMo/Al2O3-TiO2催化剂上加氢深度脱硫反应及其宏观动力学

采用气液固三相滴流床反应器,在反应温度(493~558) K,氢压(1.5~3.0) MPa和氢油体积比为200~800条件下,研究了苯并噻吩和二苯并噻吩模型化合物在钴钼基催化剂上加氢脱硫反应及其宏观动力学。根据幂函数型动力学方程,以全局通用算法结合马夸特算法对动力学参数进行估值,建立了与实验数据相吻合的柴油中含硫模型化合物的深度加氢脱硫反应动力学模型。其中,苯并噻吩的一级方程活化能为3.985×104 J·mol^-1,二苯并噻吩的二级方程的活化能为3.130×104 J·mol^-1。残差检验和统计学考察表明,模型计算结果和实验数据吻合良好。     

ALKYLATION OF BENZENE WITH PROPYLENE OVER β ZEOLITE (Ⅰ) CHEMICAL REACTION KINETICS

对FX-01沸石催化剂上苯与丙烯烷基化反应进行了研究,得出了气液固三相催化反应的本征动力学模型.动力学实验是在消除了内扩散、外扩散影响的条件下,在高压釜间歇反应器中进行的, 采用常微分方程的参数估值法进行参数估值,得到本征动力学方程.     

乙酸光氯化制备氯乙酸的反应动力学

在环流反应器中实测了在光照下、不同氯化温度时乙酸、氯乙酸和二氯乙酸的浓度随反应时间的变化关系。建立了乙酸光氯化连串反应动力学模型 (Ⅰ )和平行 连串反应动力学模型 (Ⅱ ) ,得到了模型的解析解。通过参数估值 ,求得了表观反应速率常数。经模型检验 ,发现模型 (Ⅱ )与实验数据的吻合程度较好。计算了实验温度下的氯气在乙酸 氯乙酸混合液中的溶解度数据 ,结合表观反应速率常数 ,计算得到了本征反应速率常数     

TS-1催化环己酮氨氧化反应本征动力学模型

由TS-1催化环己酮氨氧化反应机理出发,分析了反应过程的特点及反应规律,根据推测的机理,建立了反应本征动力学模型.结合搅拌釜中测得的动力学数据,对动力学模型进行了参数估值及模型筛选.结果表明,假设反应合乎羟胺机理、双氧水吸附、表面反应为控制步骤时所导出的模型能较好地拟合实验数据,并满足统计检验.根据该动力学模型,通过模拟计算对部分操作条件进行了分析和优化.     

Electrocatalytic activity of copper alloys for \hbox{NO}_{3}^{-} reduction in a weakly alkaline solution Part 1: Copper–zinc

A comparative study of the influence of an addition of Zn to Cu as the basic cathode material on electrocatalytic activity for reduction was performed. Potentiodynamic measurements using a rotating ring-disk electrode were carried out in an artificial solution simulating solution after regeneration of the ion-exchange column for removal in drinking water treatment. The results were verified by batch electrolysis experiments. An enhancement of the electrocatalytic activity was observed. Unfortunately, NH₃ was found to be the main reduction product. The highest electrocatalytic activity was obtained using an electrode containing 41 wt.% Zn.     

Kinetics of the electrochemical deposition of sulfur from sulfide polluted brines

The kinetics of the electrochemical oxidation of sulfide ions in salt water were studied using rotating graphite disc electrodes, polarization techniques, Electrochemical Impedance Spectroscopy (EIS), X-ray Photoelectron Spectroscopy (XPS) and Electron Dispersion Spectroscopy (EDS). Elemental sulfur was shown to be the final product under various temperatures, potentials and times of electrolysis, in amounts that increased with increase in the above variables. The rate of the process is controlled by electron transfer across the interface, while diffusion in the electrolyte has only a modest effect. The apparent reaction orders with respect to the sulfide concentration and pH are 0.60 and 0, respectively. The proposed overall reaction is: while the rate determining step is: The charge transfer coefficient is α_a = 0.23 and the standard rate constant at the equilibrium potential is cm s⁻¹. The degree of coverage of the electrode with sulfur and the polarization resistance of the interface increase, while the current decreases, with the time of electrolysis as more sulfur is deposited on the electrode surface.     

Global kinetic models for the oxidation of NO on platinum under lean conditions

Different global kinetics for the oxidation of NO on platinum are compared in this work. The general form of the equation for the reaction rate is with . Furthermore steady-state and temperature-programmed experiments were performed. The best results of simulation coupled with parameter estimation were obtained using α = 0.28, β = 0.49, γ = 0 and δ = 1, along with an activation energy of 47.5 kJ mol⁻¹.     

Polymerization of olefins through heterogeneous catalysis. II. Kinetics of gas phase propylene polymerization with Ziegler–Natta catalysts

Propylene was polymerized in gas phase over a \documentclass{article}\pagestyle{empty}\begin{document}${\rm TiCl}_3 \cdot \frac{1}{3}{\rm AlCl}_3$\end{document} (Stauffer Type AA) Catalyst with AlEt₂Cl cocatalyst both with and without H₂ present. The effects of polymerization temperature, monomer concentration, catalyst composition, and hydrogen were investigated. The experiments were carried out at operating conditions approaching industrial practice.     

Empirical correlation of flow properties of poly(vinyl chloride)

Empirical correlations of flow properties of poly(vinyl chloride) were made using data reported by a number of investigators. Correlation was made by plotting the reduced variable viscosity η/η₀ versus \documentclass{article}\pagestyle{empty}\begin{document}$ (\eta _0 \dot \gamma \bar M_w )/(_\rho RT) $\end{document} or \documentclass{article}\pagestyle{empty}\begin{document}$ (\eta _0 \dot \gamma \bar M_w ^{0.5} )/(_\rho RT) $\end{document} for unplasticized PVC and versus \documentclass{article}\pagestyle{empty}\begin{document}$ (\eta _0 \dot \gamma \bar M_w ^{0.5} )/(_\rho RTW_2 ^a ) $\end{document} with polymer concentration, W₂, for PVC containing plasticizer.     

Modified response surface methodology (MRSM) for phase equilibrium-application

Attempts are being made to predict multicomponent azeotropic mixtures from the physical property of pure component and compositions of the constituting binary combination pairs. A modified response surface methodology (MRSM) model has been proposed which correlates boiling temperatures of binary, ternary and quaternary mixtures directly with the compositions of vapor and liquid phases. The generalized MRSM-2 models for liquid and vapor phases are proposed as follows: (for liquid phase) (for vapor phase) These models require normal boiling point of the pure components, T, and group-group parameters A_ij B_ij & C_ij which can be estimated by the group-group concepts of the constituent components. Therefore, this methodology is applied for the system of three and four components by the computer simulation. No experimental data is required for seeking of composition and temperature of the multicomponent azeotropic mixtures. By means of this methodology, MRSM, it is possible to depict an isothermal line map, temperature contours of the individual phase of the constituting ternaries for each quaternary system. Furthermore, it is possible to predict the azeotropic behaviors, maximum, minimum, saddle or any other type of azeotropic mixtures by examining the graphic contours obtained by computer graphics in the triangular coordinate for ternary and tetrahedron for quaternary. The proposed methodology (MRSM model) has been tested and compared successfully with previously reported azeotropic data in various journals for several ternary and quaternary multicomponent systems. Two azeotropic mixtures are newly found for each of two different quaternary tetrahedrons. The composition, temperature and type of the newly found azeotropes are reported.     

The effect of electro-osmosis on the synthesis of lead and tin fluoroborates

Pronounced electro-osmosis phenomena were observed during the anodic dissolution of lead and tin in fluoroboric acid with an anionic exchange membrane separating the anode compartment from the cathode compartment. The consequent volumetric increment of anolyte was influenced by the current density and the initial volume and concentration of catholyte. The selectivities (S _i) of the given membrane were found to be $$\begin{gathered} 50\% Sn(BF_4 )_2 solution: S_{BF^{4 - } } = 0.952; S_{Sn^{2 + } } = 0.048 \hfill \\ 50\% Pb(BF_4 )_2 solution: S_{BF^{4 - } } = 0.887; S_{Pb^{2 + } } = 0.113 \hfill \\\end{gathered}$$      

Influence of electrolytes on the absorption of nitrogen oxide components N2O4 and N2O3 in aqueous absorbents

The influence of electrolytes, which are dissolved in the aqueous absorbent and do not react with nitrogen oxides, on the absorption kinetics of both these components was investigated experimentally. In addition to demineralized water, various salt solutions of different concentrations as well as sodium hydroxide solution were used as absorbents. The term H \documentclass{article}\pagestyle{empty}\begin{document}$ H\sqrt {k_1 D} $\end{document} for N₂O₄ and N₂O₃, which is important for the design of industrial absorbers, was determined as a function of composition and concentration of the absorbents. In the case of N₂O₄, the chosen measuring and evaluation methods permitted a separate determination of the rate constant k of the pseudo first order reaction and of the solubility H. The diffusion coefficient D of the gas in the absorbent can be obtained only by calculation. Experimental results showed that \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 4} } $\end{document} decreases with increasing ionic strength I, however, without a clear indication of any ion-specific effects. This decrease does not appear to be caused simply by a reduction in solubility (salting out effect), or in diffusion coefficient, but at least, to the same extent, through a decrease of the rate constant k with increasing electrolyte content in the absorbent. The measurements permitted the determination of the gas-based salting out parameter for N₂O₄. The investigations on the absorption of N₂O₃ in water and in an Na₂SO₄ solution showed no experimentally detectable influence of dissolved salts on \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 3} } $\end{document}. The numerical value of \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 3} } $\end{document} is six times that of \documentclass{article}\pagestyle{empty}\begin{document}$(H\sqrt {k_1 D} )\,_{{\rm N}_{\rm 2} {\rm O}_{\rm 4} } $\end{document}.     

Conduction in Bi2O3-based oxide ion conductor under low oxygen pressure. II. Determination of the partial electronic conductivity

In order to investigate the partial electronic conduction in the high oxide ion conductor of the system Bi₂O₃-Y₂O₃ under low oxygen pressure, e.m.f. and polarization methods were employed. Although the electrolyte was decomposed when the \(P_{{\text{O}}_{\text{2}} }\) was lower than the equilibrium \(P_{{\text{O}}_{\text{2}} }\) of Bi, Bi₂O₃ mixture at each temperature, the ionic transport number was found to be close to unity above that \(P_{{\text{O}}_{\text{2}} }\) . The hole conductivity (σ _p) and the electron conductivity (σ _p) could be expressed as follows, $$\begin{gathered} \sigma _p \Omega cm = 5 \cdot 0 \times 10^2 \left( {P_{O_2 } atm^{ - 1} } \right)^{{1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 106 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \sigma _p \Omega cm = 3 \cdot 4 \times 10^5 \left( {P_{O_2 } atm^{ - 1} } \right)^{ - {1 \mathord{\left/ {\vphantom {1 4}} \right. \kern-\nulldelimiterspace} 4}} \exp \left[ { - 213 kJ\left( {RT mol} \right)^{ - 1} } \right] \hfill \\ \end{gathered} $$ These values were much lower than the oxide ion conductivity under ordinary oxygen pressure.     

Promotional effects on a PtRu/C catalyst-electrode interfaced with aqueous electrolytes: electrochemical metal support interaction (EMSI) and electrochemical promotion of catalysis (EPOC)

The kinetics of the catalytic oxidation of H₂ on PtRu/C gas diffusion electrode (GDE) was studied by interfacing the electrode with aqueous electrolytes at different pH values. The conducting electrolytes were aqueous solutions of varying concentrations of KOH and HClO₄ so that the pH was ranging between 2 and 13. The open circuit catalytic reaction rates exhibit the lowest value at pH = 13, while the catalytic activity is progressively increasing with decreasing pH values. The enhancement of the open circuit catalytic reaction rate can be even an order of magnitude higher in the acidic solution with respect to the alkaline electrolyte. It is shown that the nature of the aqueous electrolyte plays the role of an active catalyst support for the PtRu/C electrode, which drastically affects its catalytic properties. This is substantiated through the electrochemical equilibrium charge transfer reactions at the catalyst-electrode/electrolyte interface: