Low-temperature oxidation of Victorian brown coal

A study has been made of low-temperature oxidation of Victorian brown coal at 35 °C and oxygen pressure of 0.1 M Pa and regression analysis of the experimental results shows that the reaction can best be described by the continuous reaction model. The reaction is subject to reaction product inhibition, apparently caused by product adsorption. Progressive conversion is obtained through a series of cycles consisting of a reaction step followed by evacuation of the coal. The rate equation developed from the continuous reaction model describes satisfactorily the progress of the reaction in each of these cycles. A study of earlier findings on the nature of Victorian brown coal oxidation products indicates that the product water may be significant in this reaction inhibition.     

羟基氯醋改性聚氨酯预聚体合成反应动力学研究

采用化学分析方法研究了羟基氯醋树脂微粉存在下的聚醚N-220、蓖麻油等聚醚多元醇混合物与甲苯二异氰酸酯（TDI-80）的预聚合反应动力学,获得了聚氨酯预聚体合成反应动力学参数及反应表观速率常数表达式k=0．049exp（-23．95／RT）,并通过反应初期的实验数据对反应级数进行了验证。结果表明,在该体系下的预聚体合成反应中,氨酯化反应的表观速率常数随反应温度的升高而增大,合成反应以氨酯化反应为主,总反应级数为1．74~1．88,为近二级反应。该合成反应机理具有一定的复杂性。实验结果对相关聚氨酯弹性体预聚物合成及改性反应具有一定的理论价值和指导意义。     

由月桂烯合成香叶基丙酮的研究

以月桂烯为原料,与氯化氢反应生成香叶基氯及其同分异构体,产物与乙酰乙酸乙酯发生取代反应,经水解脱羧制得香叶基丙酮。月桂烯的加成反应是整个反应过程的关键步骤,对合成香叶基丙酮有决定性影响;重点探讨了催化剂种类及用量、反应温度及原料配比对月桂烯与氯化氢加成反应的影响。得到最适宜反应条件:以CuCl和四丁基溴化铵为催化剂,用量为月桂烯摩尔分数的1%,温度为10 ℃,n(月桂烯):n(氯化氢)=1:1。该条件下,氯化物的产率可达92.86%,且香叶基氯和橙花基氯占氯化物总量的75.71%。氯化物经取代反应,水解脱羧后得到香叶基丙酮,产率为76.62%。     

Oxidation and reduction characteristics of oxygen carrier particles and reaction kinetics by unreacted core model

The reaction kinetics of the oxygen carrier particles, which are used as bed material for a fluidized bed chemical looping combustor (CLC), has been studied experimentally by a conventional thermal gravimetrical analysis technique. The weight percent of nickel and nickel oxide in oxygen carrier particles and reaction temperature were considered as experimental variables. After oxidation reaction, the pure nickel particle was sintered and unsuitable to use as fluidizing particles. The oxidation reaction rate increased with increasing weight percent of nickel in oxygen carrier particles and reaction temperature. The rate of reduction shows maximum point with weight percent of nickel oxide (57.8%) and reaction temperature (750 or 800 °C) increased. In this work, the reaction between air and Ni/ bentonite particle was described by a special case of unreacted core model in which the global reaction rate is controlled by product layer diffusion resistance. However, the reaction between CH₄ and NiO/bentonite particle was described by unreacted core model in which the global reaction rate is controlled by chemical reaction resistance. The temperature dependence of the effective diffusivity of oxidation reaction and reaction rate constant of reduction reaction could be calculated from experimental data and fitted to the Arrhenius equation. Presented at the Int’l Symp. on Chem. Eng. (Cheju, Feb. 8-10, 2001), dedicated to Prof. H. S. Chun on the occasion of his retirement from Korea University.     

Parametric sensitivity of the ignition process to mass transfer in adiabatic tubular reactors with exothermic heterogeneous reactions

The alternative effects of reaction kinetics, mass, heat and momentum transport on mass conversion by chemical reactions are examined theoretically for a reacot tube with laminar flow. The reaction enthalpy is considered. A heterogeneous reaction between several gaseous components takes place at the inner surface of this reactor tube. Strongly exothermic reactions lead to self-acceleration of the reaction, unless reaction enthalpy is removed through the tube wall. Under certain conditions, there will be a sudden change from mass transfer controlled by the reaction to that controlled by diffusion. This phenomenon is known as ignition of the reaction. The effect of ignition and its sensitivity to reaction enthalpy, thermal conductivity and diffusivity of the fluid as well as activation energy of the first order heterogeneous wall reaction are investigated by a numerical solution of the transport equations. Axial conduction of heat and mass is neglected both in the fluid and in the tube wall. Non-stoichiometric wall reactions of first order, with temperature dependent reaction rates and equilibrium constants, are considered. The results are presented in graphical form, as plots of the local mass flux at the reacting wall as functions of the dimensionless tube length.     

Dynamics of irreversible uncoiling of a polymer chain

Using a simple dynamic model, the growth of rigidity and of the mean size of the polymer chain induced by a chemical reaction irreversibly fixing extended conformations of units has been investigated. When the reaction rate is controlled by the rotational diffusion of segments, the change in the mean length of a rigid segment and mean radius of gyration of the chain with time are described by power dependencies. For a macromolecule in a constant viscosity medium, the time needed to complete the reaction (i.e. to transform the coil into an extended rigid rod) is t_comp N³, where N is the initial number of segments in the chain. The cases of a kinetically controlled reaction and a mixed type of reaction have also been considered. The slowing down of the reaction caused by increasing the viscosity of the reaction medium has been evaluated, giving t_comp N⁷.     

简单计量系数反应方程

对反应路径综合问题提出了简单计量系数反应方程的概念,通过对反应原子矩阵的数学变换可以直接枚举出物理意义明确的所有简单计量系数反应方程,从中即可容易地筛选出所需的反应路径方案. 为进一步解决更为复杂的反应路径综合问题奠定了基础.     

Esterification of lauric acid with isopropyl alcohol by tricaprylylmethylammonium chloride as a catalyst in a liquid-liquid heterogeneous system

Experiments were performed on the esterification of lauric acid with isopropyl alcohol by tricaprylylmethylammonium chloride in a stirred vessel with a flat liquid-liquid interface. The observed initial rate of reaction was used to analyze the reaction mechanism combined with the catalyst, and to evaluate the several kinds of reaction rate constant, from which equilibrium constants were expressed as a function of reaction temperature. The analysis of reaction kinetics indicated that the reaction was between a very slow and slow reaction regime.     

粘度法研究RIM聚氨酯反应动力学

本文根据粘度法测定反应级断ｎ的理论依据，利用旋转粘度计在等温、无催化剂条件下研究ＲＩＭ聚氨酯的反应动力学，发现在异氰酸酯基／羟基（浓度比）等于１．５时，其反应级数为１．３５，这与份数时间法测定的结果相一致。     

Reaction of glycidyl benzoate with acid in the presence of tertiary amines as the catalyst

The reaction of epoxides with carboxylic acids catalysed by tertiary amines has been discussed. The mechanism of the reaction has been deduced and confirmed, using experimental results, on the example of the reaction of glycidyl benzoate with benzoic acid in xylene, catalysed by benzyldimethylamine. The reaction occurs via a combined ionic mechanism as well as via a complex formation, thus explaining the abnormal dependence of the reaction constant on the dielectric constant of the milieu and the found non-integer orders of reaction with respect to the amine and to the acid.     

4,4′,4″-三氨基三苯胺的合成

本文从对氯硝基苯和对硝基苯胺出发,经过两步反应合成了三偶氮类光导材料的重要中间体4,4′,4″-三氨基三 苯胺,其中第一反应采用KF/季铵盐催化法,收率48.4％,第二步反应采用钯碳催化加氢法,收率91.4％。     

Study on the reaction rate of sulfite oxidation with cobalt ion catalyst

Wet limestone scrubbing is the most common flue gas desulfurization process for control of sulfur dioxide emissions from the combustion of fossil fuels, and forced oxidation is a key past of the reaction. In the present work the oxidation rate was experimentally studied by contacting pure oxygen with a sodium sulfite solution. The sulfite oxidation reaction rate was then measured photographically for various sodium sulfite and Co²⁺ concentrations. The sulfite oxidation reaction rate was affected by the mass transfer characteristics of the gas-liquid absorbers with the cobalt ion catalyst as well as the reaction kinetics. The sulfite oxidation reaction rate controlled by the reaction kinetics was first order with respect to the sulfite. When the sulfite oxidation reaction rate was controlled by the gas-liquid rate of mass transfer characteristics, the reaction was zeroth order with respect to the sulfite.     

Performance simulation of a wall-type reactor in which exothermic and endothermic reactions proceed simultaneously, comparing with that of a fixed-bed reactor

By combining endothermic and exothermic reactions in one reactor, a mutual utilization of thermal energy involved in reactions is expected to produce a saving energy and a cost-down for running in industrial reaction process. In this case, a wall-type reaction system is thought to be suitable because such reaction system is good at exchangeability of thermal energy by conductive heat transfer. This study supposed a wall-type reaction system consisting of endothermic and exothermic reaction channels stacked up and a fixed-bed reaction system of the same configuration, and compared them by numerical simulation in the case where endothermic and exothermic reactions progress simultaneously.

In the fixed-bed reaction system, heat transfer in the catalyst bed takes place by convection, and this transfer becomes the rate-limiting process. Accordingly, occurrence of hot spot in the exothermic channel and shortage of thermal energy in the endothermic channel were predicted. This trend became distinct by making the feed gas directions flowing in the two channels countercurrent and by stacking the channels in multiple tiers. In the wall-type reaction system, however, the temperature distributions in the exothermic and endothermic channels almost conformed to the set temperatures, and the temperature difference between channels was small. Even if the feed gases flowed in countercurrent and even if the channels were stacked several deep, this trend did not change. In the wall-type reaction system, the exchange of thermal energy would take place efficiently by conductive heat transfer between the endothermic and exothermic channels. Furthermore, it was inferred that the wall-type reaction system would provide a stable operation in mutual utilization of thermal energy.     

Conversion of polyester into heat‐resistant polyamide by reacting with aromatic diamine compound II. Semibatch reaction by nitrogen gas sweeping process

The conversion of poly(ethylene terephthalate) (PET) into heat‐resistant polyamide was carried out in the solid state polycondensation by applying a nitrogen gas sweeping process. The reaction product obtained by the catalyzed and uncatalyzed batch reaction with the specified reaction condition was used as the starting material in the semibatch reaction process. Nitrogen gas was introduced into the reactor to remove a volatile reaction byproduct from the reaction mixture. Effect of the semibatch reaction variables such as temperature, time, and nitrogen gas sweeping rate on the extent of reaction and the heat‐resistant property of polyamide obtained was investigated. A comparison of the extent of reaction in the semibatch reaction process was made between the catalyzed starting material and the uncatalyzed one. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2223–2232, 2004     

碱性离子液体［BMIM］OH催化间二异丙苯氧化反应动力学研究

采用2 L搅拌反应釜，在（80~95） ℃和空气流量300 L·h^-1条件下，以离子液体［BMIM］OH为催化剂，进行间二异丙苯液相空气氧化反应动力学研究。通过热力学分析，提出氧化反应体系的反应网络，确定反应体系的主反应与副反应。根据氧化反应机理，对幂函数的速率方程进行修正，得到动力学模型方程。基于动力学实验数据，对模型方程中的动力学参数进行估值，并对其进行相应的模型检验，建立可描述间二异丙苯氧化过程的反应动力学模型。     

多种复杂化学反应动力学统一的数值模拟

研究各种经典复杂化学反应动力学方程如简单级次反应、平行反应、连续反应和对峙反应等的求解方法时,可以发现它们之间存在共同点,并得到统一的求解形式.文中给出了将多种复杂化学反应动力学的求解统一起来的方法,并用C++程序语言,编制了可以求解物理化学教学中各种经典复杂化学反应动力学方程的数值模拟程序.使用该程序,只要根据具体情...     

乙酰丙酮铬(Ⅲ)催化合成己酸环氧酯的影响因素及其动力学研究

采用乙酰丙酮铬(Ⅲ)为催化剂,催化环氧树脂与己酸的加成酯化反应,探讨了反应温度和催化剂质量分数对酯化反应的影响,以及催化剂的活性,并研究了其动力学行为。实验结果表明,乙酰丙酮铬(Ⅲ)的催化能力高于叔胺和季铵盐催化剂,当其用量为原料总质量的0.4%时,于120℃反应200 min后酯化率可达86.2%。通过积分反应速率方程,对该反应的实验数据进行了动力学计算,确定乙酰丙酮铬(Ⅲ)催化环氧树脂与己酸的加成酯化反应级数为二级,反应表观活化能Ea为139.476 kJ/mol。用IR和1HNMR对产物进行了表征,证实合成了目标产物。     

A kinetic study of hydrothermal reaction in γ-C2S-quartz system II. Influence of the granulometry of quartz and of the treatment of samples

The kinetics and mechanism of hydrothermal reaction in the γ-C₂S-SiO₂ system at 200°C for initial CaO/SiO₂ molar ratio 1 was studied. The analysis of the reaction kinetics was carried out by a method assuming that at given reaction intervals the reaction rate can be simultaneously contorlled by nucleation and growth of the reaction product, phase-boundary interaction and diffusion through the layer of reaction product. According to the obtained results, at initial reaction stages the reaction rate is determined by all the three processes simultaneously; at later stages it is determined by nucleation and growth as well as fast diffusion if the reactants are powdered mixtures, and by very slow diffusion in case of compacted mixture. While the period of value increase of the diffusion rate constant coincides with the period of xonotlite crystallisation in the reactions of powdered mixtures, in the reaction of compacted mixture a slight lowering in the value of the diffusion rate constant was observed in the period of 3.01 Å phase crystalisation.     

搅拌床中甲基氯化铝法甲基三氯硅烷转化反应

针对“直接法”合成二甲基二氯硅烷过程中产生的副产物甲基三氯硅烷（M₁）,在搅拌床反应器中,对甲基氯化铝法甲基三氯硅烷气固相转化反应进行了系统研究.结果表明,该反应经历了约100 min的诱导期后,产物组成趋于稳定.机械搅拌促进了铝粉表面氧化膜的去除和表面更新,使得转化反应无须外加催化剂.提高搅拌速度和反应温度有利于转化反应程度的提高,但存在一个最佳值.原料组成MeCl/M₁摩尔比（m）对转化反应的进行程度和产物组成影响较大,当m＜2.0时,M₁转化率较低,转化产物主要为二甲基二氯硅烷（M₂）和三甲基氯硅烷（M₃）;当m＝2.0时,产物主要为M₃;当m＞2.0时,M₁转化率较高,主要产物为四甲基硅烷（M₄）.采用SEM对反应前后Al粉粒子表面形态进行了表征,探讨了该气固相转化反应的机理和历程.     

COMBINED EFFECT OF FREQUENCY OF MIXING AND FREQUENCY OF CHEMICAL REACTION ON THE RATE OF MASS TRANSFER AT A FREE LIQUID INTERFACE

The combined effect of mixing and chemical reaction on mass transfer at a free liquid interface subjected to a quasi-periodic motion is studied, taking as an example the wave motion in a thin liquid film flowing down a vertical wall. The equation of convective-diffusion with first-order reaction is solved in the small penetration approximation by using a method of successive transformations which contracts it to a pure-diffusion type equation. It is found that the amplification factor due to the wave motion diminishes as the reaction rate constant increases, and approaches unity in the limit of very rapid reaction. However, in the case of instantaneous bimolecular reaction, it is found that the amplification factor due to wave motion is not affected by the occurrence of reaction.