八碳芳烃临氢异构化反应网络的动力学研究

本文研究了一个更具普遍性的五元M~a(?)拟一级的八碳芳烃临氢异构化反应网络,并应用作者提出的试差矩阵法研究了该反应网络的双曲型动力学模型,求取了各模型参数及其表观活化能和指前因子.拟合结果与实验测定值相当吻合.     

试差矩阵熬及其在复杂反应动力学研究中的应用

本文提出了一种研究高维拟一级复杂反应动力学的新方法——试差矩阵法.该方法充分运用有效的数学方法和计算技术,以减少实验工作量,并能大大减少待定参数个数,提高估值精度.研究表明,该方法具有良好的方法统计特性,能耐受较大的实验误差。本文还提出了新的八碳芳烃临氢异构化和六碳组份重整体系的反应网络,应用试差矩阵法成功地研究了这两个体系的双曲型动力学模型,求取了各模型参数,模型拟合值与实验值能很好地吻合.     

对溴苯酚歧化异构化反应动力学

测定了在 15 0～ 180℃范围内对溴苯酚歧化异构化反应的动力学数据 ,提出了对溴苯酚的歧化异构化反应为一级不可逆平行反应 ,并选用 Powell法和定步长龙格库塔法相结合的数学方法拟合实验数据 ,估算了动力学模型参数 ,模型计算值与实验值拟合良好     

C_8芳烃在SKI-400-40催化剂上的临氢异构化反应动力学

利用固定床积分反应实验装置,在反应温度为365～410℃、空速为4～128 h~(-1)、氢烃物质的量比为3.8、反应压力为1.1 MPa条件下,对C_8芳烃在SKI-400-40催化剂上的临氢异构化宏观反应动力学进行了研究。采用六组分拟一级异构化反应网络,建立了C_8芳烃临氢异构化的宏观反应动力学模型,模型计算值与实验值吻合良好。得到的反应速率常数表明,二甲苯和乙苯间的转化可通过两种方式,一是两者之间的直接转化,二是两者通过C_8N+P的桥接转化,其中第二种方式的贡献更大。     

灵活多效催化裂化工艺反应动力学模型研究

根据催化裂化反应机理和灵活多效催化裂化(FDFCC)工艺特点,结合中试数据,分别确定了针对FDFCC工艺重油提升管的10集总和汽油提升管的7集总反应网络。将重油提升管中胶质沥青质向汽油、气体的裂化作为二级反应,其余(包括汽油提升管中全部反应)均作为一级不可逆反应,分别建立了10集总和7集总反应动力学模型。通过Runge-Kutta法与变尺度法(BFGS)相结合求取了模型的动力学参数。对动力学参数的分析表明,所求得的模型参数能够较好地反映催化裂化反应规律和FDFCC-Ⅲ工艺特点。模型对产品的计算值与实际值的相对偏差均小于5%,表明所开发的集总模型是可靠的。     

八碳芳烃临氢异构反应系统动力学模型——(Ⅰ)用特征向量法研究选择性动力学

八碳芳烃临氢异构化是工业生产对二甲苯的主要方法.本文研究了380℃,886kPa氢烃分子比为10和铂/沸石催化剂条件下这一复杂反应系统的选择性动力学,提出了将系统中八碳环烷作为一个集总组分的宏观化学反应模式,建立了具有拟一级形式的Hougen-Watson型数学模型,用特征向量法求取了相对速度常数矩阵.所得结果与文献报道的反应机理一致并能拟合实验数据.本文提供了在运用特征向量法过程中对组成数据进行清洗的方法和有助于简化计算的模态矩阵之逆矩阵的行向量表达式.     

一级反应网络动力学模拟软件及其在教学中的应用

在化学动力学和物理化学等相关课程的教学过程中,通常会涉及一级复合反应或一级反应网络,其规律复杂,比较难以理解。通过使用可视化的Visual Basic语言编写的一级反应网络动力学模拟程序,反应组分数和反应条件可以随意输入,可以直观地模仿实验条件的改变对反应各组分浓度随时间的变化规律。通过教学实践表明,学生更容易掌握化学动力学的相关规律。     

5429双马来酰亚胺树脂的固化动力学研究

通过差示扫描量热法(DSC)研究了5429双马树脂的固化过程。分别使用Kissinger模型和Flynn-Wall-Ozawa模型计算得到了5429双马树脂动力学参数。结果表明Kissinger模型与FWO模型计算得到的动力学参数较为接近,验证了两个动力学模型的有效性。由于5429双马树脂的固化反应为一级反应,因此代入相应的固化动力学参数可得到其固化动力学方程。此外,通过T-β外推法可计算得到5429双马树脂凝胶化温度、固化温度和后处理温度等特征温度。     

光热双重固化胶粘剂的热固反应动力学研究

采用非等温示差扫描量热法对光热双重固化胶粘剂的热固化性能以及固化动力学进行了研究。根据Kissinger,Ozawa及Crane方程结合n级反应模型和自催化反应模型计算得到固化反应动力学参数。结果表明,紫外光处理后胶粘剂体系的特征固化温度下降。n级反应动力学模型与实验值相比存在较大差别,而自催化反应模型能够较好地与实验值吻合,并能较好地描述紫外光处理前后胶粘剂体系的热固反应过程,解释了紫外光处理降低固化反应温度的机理。     

臭氧氧化对甲基苯磺酸的动力学模型

选用典型制药中间体对甲基苯磺酸(p-TSA)作为模型污染物,研究了臭氧氧化技术对p-TSA的直接氧化和间接氧化效果。结果表明,在pH为2～13、臭氧流量16～64 mg·min^-1和污染物浓度100～5000 mg·L^-1条件下,臭氧氧化p-TSA均符合拟一级动力学降解规律,且pH、臭氧投加量的增大都有利于拟一级动力学常数的提高,而初始污染物浓度的提高则抑制拟一级动力学常数的增大。建立了表征臭氧氧化过程中直接反应和间接反应各相对贡献率的动力学模型,定量研究了臭氧流量、相似文献   

Assessment of kinetic modeling procedures of TAP experiments

Transient experiments can provide more information than steady-state experiments and are particularly useful in unraveling complex reaction networks. Modeling of the data allows to obtain quantitative information, e.g., sorption and rate constants as well as diffusion coefficients. To ensure correct estimation of the model parameters operating conditions that aim at eliminating diffusion resistances have to be defined as well as identification of the accessible parameters. Moreover, a statistical analysis of the model and its parameters after regression has to be performed. These issues are discussed here for temporal analysis of products (TAP) experiments as an example of a transient technique.     

Analysis of mass transfer effects in ethyl cellulose manufacture

A theoretical analysis of mass transfer effects in ethyl cellulose manufacture has been reported. This is the first model to describe a complex fluid–solid reaction in the presence of two immiscible liquids. The model derived here can be used to evaluate the dependency of the overall rate on different parameters incorporating the multiphase mass transfer effects.     

An Unreacted Shrinking Core Model for Calcination and Similar Solid-to-Gas Reactions

A variation on the unreacted shrinking core model has been developed for calcination and similar non-catalytic solid-to-gas decomposition reactions in which no gaseous reactant is involved and the reaction rate decreases with increasing product gas concentration. The numerical solution of the model has been validated against an analytical solution for the isothermal case. The model parameters have been tuned using literature data for the thermal dehydration (calcination) of gibbsite to alumina over a wide range of temperatures, from 490 to 923 K. The model results for gibbsite conversion agreed well with the published experimental data. A reaction order with respect to water vapor concentration of n = ?1 was found to give a good fit to the data and yield activation energies consistent with literature values. Predictions of the non-isothermal unreacted shrinking core model compare well with a more complex distributed model developed previously by the authors.     

MATHEMATICAL MODELING OF NON-CATALYTIC LIQUID-SOLID REACTION AND ITS SOLUTION BY ORTHOGONAL COLLOCATION

The mathematical model of non-catalytic liquid-solid diffusion reactions discussed in this paper can be applied to quite different cases. The models in the literature such as unreacted shrinking core model, two stage model and homogeneous model can be considered as special cases of the above model which has been derived for leaching vanadium from steel slag with sodium carbonate and]or sodium bicarbonate solution reacting with two components in the slag simultaneously. The vanadium leaching reaction is inhibited by the solid product formed during the reaction. The power law equation can be used to represent the kinetic experimental data of leaching reaction. The model equations have been solved by orthogonal collocation and semi-implicit Runge-Kutta method. The parameters of the model have been estimated by the complex method. The calculated results based on this model is in good agreement with experimental data.     

基于交叉迭代BLSTM网络的乙烯裂解炉建模

数据驱动的乙烯裂解炉模型通常忽视了裂解炉结构和反应机理，存在预测误差偏大的缺点，为此提出基于知识和数据融合驱动的乙烯裂解炉乙烯收率等关键参数的双向长短时间记忆网络(BLSTM)预测模型。为了解决BLSTM建模缺少可用数据的问题，提出了一种采用交叉迭代的BLSTM(CIBLSTM)模型。所提CIBLSTM模型采用了正反向交叉迭代方法，逐步逼近所缺数据的真实值，进而建立乙烯裂解炉的预测模型。为了验证所提CIBLSTM模型的有效性，选取9种工业实际原料与分析数据进行仿真测试，仿真结果验证了所提的CIBLSTM模型的有效性与实用性，所提方法也可应用于其他复杂化工过程建模。     

Fortschritte bei der Modellierung von Festbettreaktoren

Progress in the modeling of fixed bed reactors. Recent work on the modeling of catalytic fixed bed reactors have led to more realistic mathematical models and to a better understanding of problems connected with modeling. Nowadays standard routine computer programs are available for use in the design (and analysis) of catalytic fixed bed reactors for very complex reaction systems. The influence of bed structure on transport parameters was illustrated by experimental determination of axial and radial concentration and temperature distribution. Moreover the problem of multicomponent diffusion coupled with complex reactions in porous catalysts has been solved and can be included in the reactor model. However, the practical application of possible reactor models is limited by the availability of transport parameters for fixed beds.     

基于时间序列的多岛遗传算法在水泥窑中的应用

研究时间序列在水泥回转窑中的建模问题,水泥回转窑熟料的煅烧是一个涉及物理、化学反应的复杂多变量、多扰动非线性过程.针对最小二乘在多参数高阶时间序列模型中难以寻找到较好的系数组,从而不能建立较精确的时间序列模型的情况,采用传统遗传算法也很难寻找出最优参数组,当利用多岛遗传算法对其进行参数寻优时,只要适当地设置算法里的一些关键参数即能得出满意的组解.实验结果表明：经过多岛遗传算法寻优得出的参数建立的时间序列模型,其拟合度满足模型曲线的精度要求.     

Development of a thermodynamically consistent kinetic model for reactions in the solid oxide fuel cell

The parameter estimation using the traditional kinetic modeling of complex reaction systems will give incorrect results if the reaction mechanism contains a loop. In this work, a thermodynamically consistent kinetic model of the anodic electrochemical hydrogen oxidation reaction mechanism of a solid oxide fuel cell (SOFC) is formulated. An iterative algorithm for estimating the reaction rate constants using the thermodynamically consistent model formulation is developed. The kinetic parameters estimated using the proposed method gives a better fit to the experimental data. Using the concept of ‘Degree of rate control’ it is found that the surface reactions may have a greater role in deciding the overall rate. The proposed iterative parameter estimation algorithm developed in this work can also be adapted to other complex chemical and biochemical reaction networks for which the reaction rate constants need to be estimated using the experimental data.