化学反应活性指标与基元反应动力学参数的关系及链烷烃热裂解过程模型

本文采用广义休克尔法(EHMO)与全略微分重叠法(CNDO/2)计算了链烷烃及其自由基的反应活性指标.通过分析已知的基元反应动力学参数与这些指标间的关系,提出一种预测基元反应速率常数的方法.对链烷烃热裂解速度常数的预测,证明该法是可靠的.在此基础上,采用平推流反应器(PFR)模型及拟稳态假设描述C_4~-烃类热裂解过程,模拟了c_4~-单一烃及混合烃的热裂解过程.模拟结果与文献中的总包反应实验数据吻合良好,证明所建模型是正确、可靠的.     

氯化锂催化下硼酸和甲醇酯化反应动力学研究

以氯化锂为催化剂,采用间歇法研究了硼酸和甲醇酯化可逆反应动力学.对可逆反应动力学方程进行线性化处理,确定了积分法拟合可逆反应动力学参数的一种简便方法.测定了不同催化剂用量和反应温度下硼酸转化率随时间的变化,采用线性拟合得到了反应的动力学方程式.实验结果表明:在氯化锂用量为4%(质量分数)、硼酸和甲醇初始浓度分别为0.924 2 mol/L和24.99 mol/L、反应温度为303～333 K条件下,正、逆反应的活化能分别为49.5 kJ/mol和23.6 kJ/mol,指前因子分别为6.71×105 L/(mol·min)和68.4 L/(mol·min).     

硅酸二钙烧成过程动力学参数测定

对硅酸二钙(C2S)形成过程的各项动力学参数进行了测定计算,得到了不同温度下SiO2转化率G与时间t的关系.采用了金斯特林格(Ginstling)方程作为固相反应模型,对C2S的形成过程进行描述;计算了不同煅烧温度下固相反应的反应速率常数K、钙离子的扩散系数D;得到C2S形成的表观活化能Ea为167.4 kJ·mol-1,指前因子A为20.94.     

在工业催化剂上水煤气变换反应宏观动力学

用内循环式无梯度反应器,在不同的反应条件下,测定了B106及B109两种型号的原粒度工业变换催化剂的宏观反应速率.根据实验数据关联出两种催化剂都适用的宏观动力学方程,求定了相应的模型参数.该式可用以模拟工业变换反应器.此外,并由实验数据计算了各种情况下的有效因子.整个实验及计算结果表明,这两种催化剂对气体的内扩散阻力都是相当大的.     

水泥基材料的水化动力学模型

介绍了水泥基材料的水化动力学模型.根据实验测定的水化放热数据,采用模型给出的积分和微分方程,对水泥基材料的水化反应中的3个基本过程即结晶成核与晶体生长(NG)、相边界反应(I)和扩散(D)进行了表征,得到反应速率常数K、反应级数n和表观活化能Ea等动力学参数以及各反应阶段的反应速率与反应度的关系.计算得到的各阶段的反应速率曲线能较好地分段模拟由量热实验得到的胶凝材料实际水化速率dα/dt曲线.观察3个阶段的相互关系,可对水泥基材料复杂的水化机理进行解释.水泥基材料的水化反应存在两种不同的历程:NG-I-D或NG-D.在水化初期NG是控制因素,随着水化程度提高,逐渐转由I或D控制反应.     

膜反应器的数学模型

膜反应器是一种新型的反应装置,具有反应功能和分离功能。以化学反应工程的观点,建立了一级可逆反应的膜反应器的数学模型,通过反应速率和分离速率偶合的联立动力学方程求解方法,使用BASIC语言编制程序,采用IBM微机计算,最后得出关于膜反应器的几个基本结论。通过计算,在一定设计和操作条件下,这些关系对于研究膜反应器是有益的。     

明胶的酸水解反应动力学研究 Ⅱ.动力学规律和机理

根据文献的实验数据,计算了明胶的柠檬酸水解反应的反应级数、表观反应速率常数、表观活化能和指前因子等动力学参数,得到了反应速率方程式。并求得实验温度范围内的反应速率常数与温度的关系,符合Arrhenius公式。对明胶的酸催化反应机理进行了探讨,推得的机理动力学方程和实验结果相符合。     

球形钻相变换催化剂宏观活性评价方法

本文以B303Q型钻钥耐硫变换催化剂为例,研究了有关反应器材质、活性评价基准以及颗粒直径的影响。认为以二级反应速率常数作为催化剂宏观特性,不受反应组成的影响,并具有计算过程简捷的优点。求得了不同粒径的反应速率常数之 比以及同颗粒直径和温度的关系式。     

臭氧氧化对有机物降解的构效关系

臭氧氧化作为一种高级氧化技术,普遍应用于水处理工艺中。以靛蓝、甲基蓝、铬黑T、橙黄G、皂黄、萘酚绿B为研究对象,根据试验数据分析不同温度下臭氧氧化降解六种有机物的TOC去除率和TOC去除速率常数的变化趋势,分析结果表明温度升高对臭氧氧化降解有机物具有促进作用。根据阿伦尼乌斯公式建立了有机物TOC去除速率常数和温度的关系,估算出臭氧氧化有机物反应活化能,利用量子化学软件Gaussian 09软件计算了六种有机物的15个量子化学参数,进行臭氧氧化有机物的反应活化能与量子化学参数之间的相关性分析,结果表明臭氧氧化六种有机物的反应活化能主要与E_(HOMO)、E_(LUMO)和q(C-)_(min)相关。     

非平衡级速率模型用于催化精馏过程的模拟计算

采用非平衡级速率模型对醋酸甲酯水解的催化精馏中试过程进行了模拟计算,反应精馏段催化剂填料层的气相和液相传质系数用自行测定的经验关联式计算,提馏段的填料层传质系数用Onta的关联式,反应速率根据所测定的宏观反应动力学方程结合催化剂包的效率因子进行计算,得到令人满意的结果．     

D4/APAEDMS本体开环共聚反应机理及调控基元反应

Monte Carlo方法首次用来揭示八甲基环四硅氧烷（D₄）与N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷（APAEDMS）的本体开环共聚反应机理的关键调控基元反应.基于已提出的该体系本体共聚反应机理,并兼顾模拟精度与计算经济性,Monte Carlo模拟模型采用自由体积理论简化扩散效应并与本征反应动力学方程耦合.其中,本征动力学速率常数通过模拟主要共聚基元反应得到.基于优化的动力学速率常数通过模拟从分子水平上揭示：D₄/APAEDMS本体共聚机理为一伴有逐步特征的阴离子连锁聚合.其中,链引发及其逆反应对D₄/APAEDMS的本体共聚反应没有直接调控作用,而链缩合及其逆反应是本体系反应机理不同于纯活性阴离子聚合或逐步聚合反应机理的关键原因.     

ORTHOGONAL COLLOCATION SOLUTION FOR THE FREE RADICAL POLYMERIZATION WITH DIFFUSIONAL LIMITATIONS†

Free radical polymerizations in bulk as well as in concentrated solutions exhibit an autoacceleration of the rate of polymerization known as the gel effect. This phenomenon is believed to be caused by a decrease in the rate of termination due to diffusional limitations, In this work, we develop a method for simulating the polymerization when the reaction rate constants depend on the size of the species involved in each reaction. From the mass balances, an infinite system of integro-differential equations is obtained; this system is reduced to a set of algebraic equations using orthogonal collocation with Laguerre polynomials and Gauss-La guerre quadratures     

吸附反应器动态特性的研究

针对反应速率方程为γ_A=k_1c_A~m-k_2c_B~n的非瞬时可逆均相反应A(?)vB、液相反应或浓度很稀的气相反应和反应物A或产物B瞬时非线性Langmuir吸附的情况,研究了反应和吸附相结合的吸附反应器之动态特性.建立了平推流固定床吸附反应器的动态模型,通过数值解法获得了反应物阶跃和方波输入时,吸附反应器出口的动态响应曲线.研究结果表明,吸附反应器无需附加净化步骤就能获得高纯度的产物;吸附反应物时,反应转化率降低,吸附产物时,反应转化率提高.并讨论了吸附平衡常数和反应速率常数对吸附反应器性能的影响.     

A Study of the Kinetics of Dye Transfer in the Rub-fastness Testing of a Vat Dye

?Faculty of Science and Technology Keio University Hiyoshi Yokohama Japan The kinetics of the crocking (rub fastness) behaviour of a vat dye ha ve been investigated in dry and wet conditions. It is suggested that the dye removal process can be treated as a reversible first-order reaction. A measure of the kinetic properties of the rubbing process can be given by the rate constant (k,j and/or the equilibrium constant (K) of the reaction. The effects of the force applied during rubbing on these constants were also studied.     

Absorption of carbon monoxide with reversible reaction in cualcl4-toluene-complex solutions

The absorption of CO in CuAlCl₄-toluene-complex solutions was studied in a stirred reactor. The reaction was found to occur in a fast reaction regime. The effect of CO partial pressure, CuAlCl₄-toluene-complex concentration and temperature on the rate of absorption was studied. The results have been interpreted using a theoretical model for mass transfer with reversible chemical reaction and the rate parameters were determined. The equilibrium constants were also determined experimentally. An interesting observation showing a decrease in the rate with an increase in temperature was made for this system. This is explained on the basis of a higher activation energy for the reverse reaction. The activation energies evaluated for the forward and reverse reactions are 32.93 and 97.42 kJ/mol, respectively.     

D4/APAEDMS本体开环共聚反应的Monte Carlo模拟

Monte Carlo方法模拟八甲基环四硅氧烷与N-β-氨乙基-γ-氨丙基甲基二甲氧基硅烷（D₄/APAEDMS）的本体开环共聚动力学.在兼顾模拟精度与计算经济性基础上,模拟过程采用自由体积理论简化处理扩散效应并与本征反应动力学耦合.本征动力学常数通过模拟主要共聚基元反应得到,基于优化的动力学常数通过模拟从分子水平揭示：（1）D₄/APAEDMS本体开环共聚存在总活性基团的“稳态”行为;（2）D₄/APAEDMS本体开环共聚反应过程的重均分子量与数均分子量以及分子量分布系数存在“突变”特性.     

CONSECUTIVE ESTERIFICATION OF 1,4-BUTANEDIOL WITH ACRYLIC ACID BY HOMOGENEOUS CATALYSIS

The esterification of 1,4-butanediol with acrylic acid catalyzed by sulfuric acid in the absence of solvent was studied in a batch stirred reactor. Experiments were carried out with different acid/ alcohol mole ratios and different amounts of sulfuric acid in the temperature range 70 to 90°C and 1 atm. It was found that the esterification of 1.4-butanediol with acrylic acid is a two-step consecutive, reversible reaction and each esterification step follows a first-order rate expression with respect to each component. A kinetic model was proposed to describe such a consecutive, reversible esterification reaction catalyzed by sulfuric acid. The equilibrium constants were determined from the equilibrium concentrations of each component while the rate constants in each reaction step were calculated by correlating the experimental data with the developed kinetic model.     

The effect of dye particles on the rub fastness of naphthol dyes

The effect of dye particles on the rub fastness of naphthol dyes has been investigated from the kinetic viewpoint. A measure of the rub fastness properties can be given by the rate constant and/or the equilibrium constant of a reversible first-order reaction. The presence of granular dye particles increases these constants and lowers the rub fastness. On the other hand, needle-shaped dye particles have little effect on these constants and do not lower the rub fastness.     

The use of spin traps for the kinetic investigation of elementary events of pseudoliving radical reversible addition-fragmentation chain-transfer polymerization

The spin-trapping technique is used for the first time to study the kinetics and mechanism of addition and fragmentation elementary events in reversible addition-fragmentation chain-transfer pseudoliving radical polymerization. As shown by the example of the spin-trap-reversible addition-fragmentation chaintransfer agent model system, the constants of addition (substitution) of the model tert-butyl radical to polymeric reversible addition-fragmentation chain-transfer agents (poly(styrene dithiobenzoate), poly(n-butyl acrylate) dithiobenzoate, etc.) are one to two orders of magnitude higher than the constants of addition reactions involving low-molecular-mass reversible addition-fragmentation chain-transfer agents (tert-butyl dithiobenzoate, benzyl dithiobenzoate, di-tert-butyl trithiocarbonate, and dibenzyl trithiocarbonate). This circumstance makes it possible to significantly widen the synthetic possibilities of reversible addition-fragmentation chain-transfer polymerization. Rate constants of the fragmentation reaction for a number of intermediates are estimated, and the relationship between their structure and stability is ascertained. For the model reaction of the interaction (addition and fragmentation) of the tert-butyl radical with low-molecular-mass reversible addition-fragmentation chain-transfer agents, equilibrium constants are calculated via the methods of computational chemistry.     

Dynamic behavior of trickle-bed reactors

An analysis is given for the transient behavior of a trickle-bed reactor in which gas and liquid streams flow downwards through a bed of catalyst particles. Equations are given for the zero and first moments of the response, in either the gas or liquid effluent, to a pulse input of concentration in either the liquid or gas feed. First-order, reversible adsorption, and adsorption plus first-order irreversible reaction are considered.Procedures are discussed and illustrated for evaluating equilibrium, mass transfer, and reaction rate constants from the moment equations. Also, the dependency of the moments on the rate and equilibrium constants are summarized for various reactor arrangements and chemical processes. This information is useful in designing experiments to give data suitable for evaluating such constants.