反应工程的工业实践

笔者以所了解的国内资料范围,论述了反应工程在工业应用方面所研究开发成果的种种事例,就其各具特色的研究开发的工作方法中,拟总结出一些经验,以作为后来者的借鉴,笔者尤其推崇以应用反应工程的理性认识,抓住主要关键,及半经验方法的做法,最终收到事半功倍之效。     

微分反应器中多相催化反应动态过程的模拟分析

动态响应方法可以为多相催化反应过程提供较多的反应机理的信息。与实验研究顺序相反,本文通过模拟微分反应器中多相催化反应的动态过程,分析了不同基元反应速率常数对 Eley-Riddeal 型机理和 Langmuir-Hinshelwood 型机理的动态响应曲线的影响。以利于阐述动态响应方法的基本思想。     

动态方法测定吸附和表面反应速率

本文较详细地综述了在近些年来刚刚发展起来的能用于分离测定非均相催化反应中的吸附和表面反应速率的三种动态分析方法:催化反应色谱技术,动态一稳态法和浆化反应器中的动态分析。文中不仅介绍了三种方法的基本理论和一些有代表性的实验结果,也指出了它们在研究催化反应动力学和机理以及催化剂制备变量对其影响方面的重要意义和前景。     

光化学反应工程

光化学反应工程是化学反应工程的一个分支，本文在概述光化学反应工程的发展基础上，对光化学反应速率方程的建立，光化学反应器的设计原理和特点进行了介绍。     

AN IMPROVED COMPUTATIONAL ALGORITHM FOR SINGULAR CONTROL PROBLEMS IN CHEMICAL REACTION ENGINEERING

A unidirectional method is developed to solve optimal singular control problems with bounded state variables. The computational algorithm utilizes the necessary conditions of optimality and an unidirectional scheme to reduce the iterations required in two-point boundary value problems. The advantage of the method is that it satisfies all the necessary conditions of optimality and results in a considerable reduction in computational effort. Three numerical examples illustrate the use of these algorithms for solving several chemical reaction engineering problems.     

MODELING MOISTURE TRANSPORT ACROSS PORCINE SKIN USING REACTION ENGINEERING APPROACH AND EXAMINATION OF FEASIBILITY OF THE TWO-PHASE APPROACH

The present study is an amendment to previous approaches to modeling moisture transport across porcine skin. The previous models were semi-empirical or based on the Fickian liquid diffusion equation. Effective liquid diffusivity was dependent on sample thickness, masking its dependence on temperature. From the modeling perspective, this can be a drawback. Therefore, use of two simultaneous equations to represent liquid and vapor transport would be fundamentally correct. A source term representing phase change has been introduced and their parameters established experimentally and correlated using the reaction engineering approach. The two-phase approach was implemented previously to model moisture transport for drying of porous biological materials. The current study checks the feasibility of this approach for modeling moisture transport across skin. A comprehensive model for moisture transport across skin could be of significance to researchers working in the areas of transdermal drug delivery, toxicology, and process applications such as leather drying.     

氨磺酸催化合成丁酸异戊酯的研究

以氨磺酸为催化剂催化合成了丁酸异戊酯,确定了酯化优化条件。实验结果表明,醇酸摩尔比值为1．8;催化剂用量1．0g;带水剂甲苯15ml（丁酸用量为0．2mol的情况下）;反应温度为110－135℃;反应时间2．0h;是最佳反应条件,酯化率98．5％。     

CATALYZED REACTION OF CARBON DISULFIDE AND o-PHENYLENE DIAMINE BY QUATERNARY AMMONIUM HYDROXIDE

Tetrabutylammonium hydroxide (Bu₄NOH, or QOH) is employed as the catalyst to increase the conversion and to enhance the rate of reaction of o-phenylene diamine and carbon disulfide both in the homogeneous as well as the two-phase solution. The alkalinity of the catalyst is an important factor in affecting the reaction. The mechanism of the reaction, which takes place only in the organic phase, was verified by two steps. The reaction of CS₂ with QOH first takes place to form the intermediate QCS₂OH. Then this intermediate reacts with o-phenylene diamine to produce 2-mercaptobenzimidazole (MBI). A kinetic model based on the reaction is considered for the homogeneous-phase and the two-phase reaction. A pseudo-steady first order rate law is employed to simplify the kinetic model. A high reaction rate and a large conversion is observed when the reaction is carried out in a homogeneous-phase solution using protic or aprotic solvent. Nevertheless, the MBI product precipitates from the two-phase reaction solution. Simple separation processes are sufficient to remove the product from the mixed solution.     

化学反应工程对石油化工技术发展的影响

本文通过若干实例，阐明了化学反应工程对我国石化工业发展的作用，并对提高石化工业技术水平的一些技术要点，如提高反应的选择性、节能及新技术路线的开发等问题特别作了强调。     

DESIGN OF SOLIDS SEPARATION PROCESSES CONSISTING OF IDENTICAL STAGES

The separation of the constituent minerals of an ore is never achieved in one stage. It is carried out in multiple stages incorporating recycling of streams to increase the recovery of the required mineral. This paper outlines a methodology for designing a separation process system consisting of nonsharp separation stages and involving recycles and mixtures instead of pure component as products.

For given technical and economic criteria the regions of optimal configurations on the grade versus flowrate diagram have been recognised. This diagram is used for the selection of the optimal circuit configuration for given feed flow, feed composition and separation characteristics. The minimum economically processable grade of the feed has been identified. This allows a decision to be made about an ore deposit as to whether it carries potential value for further processing or not. The maximum economically achievable grade has also been identified. This places a limit on the upgrading of the product for maximum profit.

The paper reports a number of case studies from the view point of application perspective, using the grade-flowrate diagram, and compares this work with the work of Chan and Prince. This comparison provides essentially the same results as the work of Chan and Prince. Sensitivity analysis in regard to the use of parameter values is another key aspect of this paper. The effects of various technical and economical parameters on the grade-flowrate diagram have been studied in this particular paper.

Results obtained from different case studies show that the present study offers an effective means for design engineers to make an initial selection of a process configuration for stagewise separation processes prior to the detailed flowsheet design.     

Bronsted酸离子液体催化的醛、酮、胺三组分Mannich反应

研究了Bronsted酸离子液体催化下醛、酮、胺的三组分Mannich反应. 在所选取的离子液体体系3-丁基-1-甲基咪唑四氟硼酸盐(BMImBF₄)/3-丁基-1-甲基咪唑磷酸二氢盐(BMImH₂PO₄)及1-乙基咪唑三氟乙酸盐(HEImTA)中,不需要加入酸性催化剂,在室温(25 ℃)下即可高收率和高选择性地得到Mannich产物.离子液体体系经过简单的处理即可实现回收利用.对于上述体系所适用的反应底物范围亦进行了探讨.     

EXPERIMENTAL AND MODELING STUDIES OF STAGED COMBUSTION USING A REACTOR ENGINEERING APPROACH

Combustion research, long dominated by mechanical engineers, is becoming increasingly a chemical engineering application. It is therefore desirable to have a well defined reactor in which to conduct combustion chemistry studies. A two zone laboratory reactor emulating a perfectly stirred reactor + plug flow reactor (PSR + PFR) sequence has been constructed and validated for use in high temperature normal and staged combustion studies. A premixed fuel/eed enters the backmixed primary zone. The effluent mixes with additional injected oxidant and/or steam, and then enters the linear flow secondary zone. Extracted gas samples from cooled probes located in each zone are subjected to several dedicated on-line stack gas analyzers, and separation/analyses by on-line gas chromatography. Detailed reaction mechanisms from the literature are incorporated into a PSR + PFR reactor engineering model. The experimental feed rates and measured temperatures are also input to the model. Good comparisons between model predictions and experimental data have been obtained for normal and air-staged combustion studies. Rate-of-prod,uction calculations from the modeling offers helpful insight into the reaction pathways responsible for important species, especially pollutants.     

THE ENHANCEMENT OF GAS ABSORPTION BY A HETEROGENEOUSLY CATALYSED CHEMICAL REACTION IN A STAGNANT LIQUID: TEMPERATURE RISE AND EFFECTIVENESS OF THE CATALYST

In the present paper a model has been developed to calculate the enhancement efficiency e of the gas absorption and the effectiveness factor η of the catalyst for a chemically reacting system consisting of a sedimented catalyst particles-containing layer of thickness γ_k adhering to the surface of a gas bubble situated in a stagnant liquid. This model predicts that for a heterogeneously catalysed first-order chemical reaction an increase in the thickness γ_k of the catalyst particles-containing layer will result in an increase of ε and a decrease of η. It has been shown that the optimum value (γ_k)_opt of this layer can be obtained from the relation (γ_k) = (D_AB/k₁₃). Further, a model is derived to calculate the steady-state temperature profile in the catalyst particles-containing layer adhering to the gas bubble surface. Both models have been applied to experimental results published in some of our previous papers. These experimental results concern the enhancement of the gas-absorption rate from a single hydrogen-containing gas bubble to a stagnant aqueous hydroxylaminephosphate-containing solution when a layer of sedimented Pd/C catalyst particles was adhered to the surface of the gas bubble. The model and the experimental results mentioned may approximately be considered as representative of slurry reactors in which finely divided catalyst particles show considerable adhesion to rising gas bubbles.     

ADVANCED CHEMICAL OXIDATION OF 2,4,6 TRICHLOROPHENOL IN AQUEOUS PHASE BY FENTON'S REAGENT-PART II: EFFECTS OF VARIOUS REACTION PARAMETERS ON THE TREATMENT REACTION

Part I of this paper examined the effects of the amounts of oxidant and catalyst on the rates and extents of oxidation of 2,4,6-Trichlorophenol (TCP), in aqueous phase, by Fenton's Reagent. In this part the effects of various reaction parameters, e.g. temperature, pH, oxidation state of catalyst (ferrous versus ferric), mode of addition of oxidant to the reactor (single batch versus multiple increments), and the presence of dissolved oxygen (D.O.) have been examined. The progress of each reaction has been monitored by the rate and extent of release of free chloride ions in the aqueous solution. All the experiments were conducted using optimum molar ratios of the oxidant (hydrogen peroxide) to the substrate (TCP), and the catalyst (ferrous ions) to the oxidant of 5.5:1 and 0.10:1 respectively, as defined in Part I.     

REACTION KINETICS PARAMETERS DESCRIBING DISPLACEMENT BY ACIDS OF STRUCTURAL METALLIC IONS FROM CLAY MINERALS

Chemical kinetics parameters describing reactions of naturally-occurring clay minerals with acids were determined using batch reaction and analytical techniques. Clay minerals included sodium montmo-rillonite, kaolinite, and illite, reacting with hydrochloric acid, nitric acid, and sulfuric acid. Two acid concentrations were examined at 50 and 70^°C. Displacement by acids of aluminum and magnesium from clays was found to follow pseudo-first order kinetics. Data analysis verified the batch reaction technique for determining kinetics parameters of acid-clay reactions and demonstrated acid neutralization by naturally-occurring clays. For reactions of sodium montmorillonite with hydrochloric acid, nitric acid, and sulfuric acid, reaction rate coefficients for displacement of aluminum ranged from 1·73 × 10^-4 kg/mol-hr at 50^°C to 3·02 × 10^-3 kg/mol-hr at 70^°C. Displacement of magnesium from sodium montmorillonite by these acids occurred at rates ranging from 3·68 × 10^-4 kg/mol-hr at 50^°C to 1·12 × 10^-2 kg/mol-hr at 70^°C. Activation energies for displacement by acids of aluminum from sodium montmorillonite were calculated to range from 31,000J/mol to 112,000J/mol, while activalion energies for displacement of magnesium from sodium montmorillonite ranged from 36.000 J/mol to 103,000 J/mol. For reactions of illite with acids, reaction rate coefficients for displacement of aluminum were determined to be 1·45×10^-4Kg/mol-hr at 50^°C to 1·7×10^-3kg/mol-hr at 70^°C. Displacement of magneisum by acids from illite occurred at rates from 6·06 × 10^-4 kg/mol-hr at 50^°C to 5·97 × 10^-3 kg/mol-hr. Activation energies for reactions of acids with illite ranged from 33,000 J/mol to 62,000 J/mol for displacement of aluminum and from 9,400 J/mol to 29,000 J/mol for displacement of magnesium.     

BATCH REACTION WITH REGULAR PARTIAL REPLACEMENT—A FORM OF SEMICONTINUOUS OPERATION

A mathematical model is derived to describe the semicontinuous process of first-order batch reaction with regular partial replacement and the steady-state performance of such a system is shown to depend on the frequency and degree of replacement. A useful analogy is also shown to exist between the system and a recycle plug flow reactor. The practical significance of this mode of operation is then briefly discussed.     

ANALYSIS OF COAL DISSOLUTION REACTION ENGINEERING

A phenomenological approach was developed for conversion of coal to pyridine soluble materials with the object of shedding additional light on the reactions taking place during short contact times. The approach was based on a theoretical analysis of many parallel reactions in a complex reacting mixture. The analysis used the concept of lumped species and weighted activation energies to improve on coal liquefaction models. i.e. to remove insensitivity problems for parameters in coal liquefaction models and to answer questions about behaviour of liquefaction reactions in different vessels.     

ACCELERATION OF THE WET OXIDATION REACTION OF PIPERAZINE BY HETEROGENEOUS Ru/TiO2 CATALYST

Wet air oxidation is a candidate technique for the effective treatment of wastewater contaminated by nitrogenous organic pollutants. Piperazine (PZ) is a cyclic diamine representing this class of compounds. In the present work, the wet oxidation reaction of PZ was studied for the first time. It was found that, in the studied range of temperatures of 180°–230°C and O₂ partial pressures of 0.69–2.07 MPa, the oxidation process was slow. Total organic carbon (TOC) conversion at 230°C and 0.69 MPa O₂ partial pressure was just 52% after 2 h. The investigated reaction was accelerated by a heterogeneous Ru/TiO₂ catalyst. Maximum TOC conversion (91%) was achieved during catalytic wet oxidation at 210°C and 1.38 MPa O₂ pressure. Kinetic data were collected over the range of temperatures 180°–210°C, O₂ partial pressures 0.34–1.38 MPa, and catalyst loading 0.11–0.66 kg/m³. The lumped TOC concentration decay was a two-step first-order process.     

BENZYL ACETATE FROM PHASE TRANSFER CATALYZED ACETATE DISPLACEMENT OF BENZYL CHLORIDE

The overall production rate equation of benzyl acetate by L-L phase transfer catalyzed acetate displacement of benzyl chloride were derived. The experimental results of the effects of stirring speed, structure and amount of catalyst, reaction temperature, amount of sodium acetate, and phase volume-ratio on the production rate of benzyl acetate are elucidated with the rate equation. Benzyltributylammonium chloride is the recommended catalyst. The apparent activation energy of the displacement of benzyl chloride with the ion pairs of benzyltributylammonium acetate is 8.13kcal/mol. Sodium sulfate is a suitable salt to improve the partition coefficient of the phase transfer catalyst. The cocatalyst, sodium iodide, can greatly improve the production rate of benzyl acetate when its amount do not exceed 3 mol% of the substrate, benzyl chloride. Under the conditions of 5mol% benzyltributylammonium chloride, phase volume-ratio 0.429, stirring speed 520 rpm, reaction temperature 70°C, and 50% aqueous sodium acetate, about 80% yield of benzyl acetate can be obtained within 2 hrs. of reaction time.     

反应精馏工艺流程的合成

反应精馏工艺是近年来倍受重视的研究领域之一,但反应精馏工艺流程的选择目前仍然靠人们的经验和实验探索．本文通过对传统化工工艺流程的理论分析,阐明了传统工艺流程与反应精馏工艺流程的相互关系,从而提出了一种反应精馏工艺流程的构成方法．