TiO_2–SA–Arg nanoparticles stabilized Pickering emulsion for photocatalytic degradation of nitrobenzene in a rotating annular reactor

Pickering emulsions stabilized by salicylic acid and arginine modified titanium dioxide(Ti O2–SA–Arg) nanoparticles were prepared in this study for photocatalytic degradation of nitrobenzene in a rotating annular reactor,and the effects of various design parameters of the rotating annular reactor, initial nitrobenzene concentration,catalyst amount, and solution p H on the degradation rate of nitrobenzene were investigated. Meanwhile, the degradation mechanism of nitrobenzene was proposed. The results show that increasing the aeration rate, the rotational speed, and light intensity results in a higher photocatalytic degradation rate of nitrobenzene owing to the effective clearance of electrons and a high quantity of oxidative free radicals. The degradation of nitrobenzene in the rotating annular reactor follows the pseudo first-order kinetics, but it is not well described by the Langmuir–Hinshelwood equation. Aeration has a significant effect on the photocatalytic degradation pathway of nitrobenzene. Because nitrobenzene can undergo reduction reaction as electron acceptors and oxidative degradation initiated by hydroxyl free radicals, the photocatalytic degradation of nitrobenzene follows the reduction mechanism under no aeration, but the oxidation mechanism under aeration.     

Modeling of a SrCe_(0.95)Yb_(0.05)O_3-αHollow Fibre Membrane Reactor for Methane Coupling

Proton-hole mixed conductor, SrCeo.95Yb0.05O3-α(SCYb), has the potential to be used as a membrane for dehydrogenation reactions such as methane coupling due to its high C2-selectivity and its simplicity for fabricating reactor systems. In addition, the mixed conducting membrane in the hollow fibre geometry is capable of providing high surface area per unit volume. In this study, mechanism of methane coupling reaction on the SCYb membrane was proposed and the kinetic parameters were obtained by regression of experimental data. A mathematical model describing the methane coupling in the SCYb hollow fibre membrane reactor was also developed. With this mathematical model, various operating conditions such as the operation mode, operation pressure and feed concentrations affecting performance of the reactor were investigated. The simulation results show that the cocurrent flow in the reactor exhibits higher conversion of methane and higher yield of ethylene compared to the countercurrent flow. In order to a     

乙酸与甲醇的催化酯化

Esterification of methyl alcohol with acetic acid catalysed by Amberlyst-15 (cation-exchange resin) was carried out in a batch reactor in the temperature ranging between 318-338 K, at atmospheric pressure. The reaction rate increased with increase in catalyst concentration and reaction temperature, but decreased with an increase in water concentration. Stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a second-order kinetic model based on homogeneous reaction. The apparent activation energy was found to be 22.9kJmol-1 for the formation of methyl acetate. The methyl acetate production was carried out as batch and continuous in a packed bed reactive distillation column with high purity methyl acetate produced.     

甲烷的二氧化碳重整动力学研究

The kinetics of CO2 reforming of methane has been studied at 976-1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio > 2. The Hougen-Watson rate models were fitted to experimental data assuming the dissociative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.     

脉冲电晕结合Ca(OH)2吸收法脱硫脱硝

Removal of SO2 and NOx by pulsed corona combined with in situ alkali absorption was experimentally investigated.In the reactor,a plate-wire-plate combination is devised for generating pulsed corona and then alkaline absorbent slurries were introduced into the reactor by a continuous band conveying system to capture the gaseous reaction products.It was found that both SO2 and NO could be removed by corona combined with in situ alkali absorption.The removal of SO2 increased to 75%with the corona discharge,compared with 60%removal only with Ca(OH)2 absorption.About 40%removal of NO was reached by pulsed corona combined with in situ Ca(OH)2 absorption.It was found that SO2 and NO in the gas stream are oxidized to SO3 and NO2 by pulsed corona respectively,and then absorbed by the alkali in the reactor.The removals of SO2 as well as NO were higher with Ca(OH)2 as the absorbent,compared with using CaCO3 or ZnO.     

Fast Pyrolysis of Biomass in a Spout-fluidized Bed Reactor--Analysis of Composition and Combustion Characteristics of Liquid Product from Biomass

In order to gain insight into the fast pyrolysis mechanism of biomass and the relationship between bio-oil composition and pyrolysis reaction conditions, to assess the possibility for the raw bio-oil to be used as fuel, and to evaluate the concept of spout-fluidized bed reactor as the reactor for fast pyrolysis of biomass to prepare fuel oil, the composition and combustion characteristics of bio-oil prepared in a spout-fluidized bed reactor with a designed maximum capacity 5 kg/h of sawdust as feeding material, were investigated by GC-MS and thermogravimetry. 14 aromatic series chemicals were identified. The thermogravimetric analysis indicated that the bio-oil was liable to combustion, the combustion temperature increased with the heating rate, and only minute ash was generated when it burned. The kinetics of the combustion reaction was studied and the kinetic parameters were calculated by both Ozawa-Flynn-Wall and Popsecu methods. The results agree well with each other. The most probable combustion mechanism functions determined by Popescu method are f(a)=k(1-a)2 (400~406℃), f(a)=1/2k(1-a)3 (406~416℃) and f(a)=2k(1-a)3/2 (416~430℃) respectively.     

A METHOD FOR CALCULATING THE EXTENT OF REACTION OF SOLID PARTICLES WITH FLUID IN COMPLETELY MIXED REACTORS CONNECTED IN SERIES

When solid particles react with a fluid,the overall rate is influened by the fraction of the solidunconverted as well as by the operating conditions such as temperature and pressure.Calculation of solidsconversion in the individual reactor of a multi-stage reactor system has therefore to be based upon thesolids residence time distribution (RTD) in the respective stages.By using either the Dirac function δ(0) or the probability density function of the sum of independentrandom variables,the solids RTD in any stage of completely mixed reactors connected in series with nointerstage backflow has been obtained.The latter method has also been used in deriving general formu-las for the calculation of solids conversion when the order of chemical reaction is simple.For complexchemical reaction rate equations a stagewise procedure for numerical computation is proposed,and twocases are discussed according to whether the rate equation is expressed in its integral or differential formrespectively.     

用于甲烷偶联的SrCe0.95Yb0.05O3-α中空纤维膜反应器建模

Proton-hole mixed conductor, SrCe0.95Yb0.05O3-α(SCYb), has the potential to be used as a membrane for dehydrogenation reactions such as methane coupling due to its high C2-selectivity and its simplicity for fabricating reactor systems. In addition, the mixed conducting membrane in the hollow fibre geometry is capable of providing high surface area per unit volume. In this study, mechanism of methane coupling reaction on the SCYb membrane was proposed and the kinetic parameters were obtained by regression of experimental data. A mathematical model describing the methane coupling in the SCYb hollow fibre membrane reactor was also developed.With this mathematical model, various operating conditions such as the operation mode, operation pressure and feed concentrations affecting performance of the reactor were investigated. The simulation results show that the cocurrent flow in the reactor exhibits higher conversion of methane and higher yield of ethylene compared to the countercurrent flow. In order to achieve the highest C2 yield, especially of ethylene, pure methane should be used as feed and the operating pressure be 300 kPa. Air can be used as the source of oxygen for the reaction and it soptimum feed velocity is twice of the methane feed velocity. The air pressure in the lumen side should be kept the same as or slightly lower than the vressure of shell side.     

Kinetics of water-isocyanate reaction in N,N-dimethylformamide

The uncatalyzed reaction of p-tolyl isocyanate (p-TI) with water in N,N-dimethylformamide (DMF) was investigated by high performance liquid chromatography (HPLC).The reactions were carried out at different temperatures from 293 K to 323 K,using various molar ratios of water to p-TI.DMF,as a special amide,was proved to be an efficient catalyst for water-isocyanate reaction.Under the reaction conditions in this study,substituted urea was the only final product observed.An appreciable amount of intermediate p-toluidine was detected.Concentrations of the isocyanate group as well as the amine and urea were determined as a function of time.New kinetic equations were deduced for each of the substance on the basis of a multistep mechanism,instead of a simple second order reaction as usual.Kinetic constants were calculated using the software MATLAB.Furthermore,the effects of temperature and concentrations of reactants on the reaction rate and amine content were discussed.The activation energy of each step was also determined.     

曝气生物滤池中含苦味酸废水的COD降解动力学特性

An empirical model for COD removal in a biological aerated filter (BAF) in the presence of 2,4,6-trinitrophenol (TNP) was developed, which related effluent COD to influent COD or hydraulic loading rate along the bed height. The overall reaction rate for substrate biodegradation could be described as pseudo first order. The experimental data of COD removal against reactor height were used to calculate the parameters in the empirical model. The COD concentration at different reactor height was expressed as a function of influent COD concentration and hydraulic loading rate, and , respectively, under the experimental condi-tion. The models may be used to predict the COD removal profiles along the reactor height at different hydraulic loading rates and influent COD concentration for design, selection and sizing of BAF.     

Kinetics and mass transfer in hydroformylation—bulk or film reaction?

The kinetics of a gas–liquid reaction, alkene hydroformylation was studied in the presence of a homogeneous catalyst in a pressurised laboratory‐scale semibatch reactor. Hydroformylation of propene to isobutyraldehyde and n‐butyraldehyde was carried out at 70–115°C and 1–15 bar pressure in 2,2,4‐trimethyl‐1,3‐pentanediol monoisobutyrate solvent with rhodium catalyst using the ligands cyclohexyl diphenylphosphine. In order to evaluate the influence of mass transfer, experiments were made using varied stirring rate from 100 to 1000 rpm at 100°C and 10 MPa syngas pressure. Only at higher stirrings rates, the reaction took place in the kinetic regime. A reactor model was developed comprising both complex kinetics and liquid‐phase mass transfer. The model was based on the theory of reactive films. The model is able to predict under which circumstances the hydroformylation process is affected by liquid‐phase diffusion of the reactants. Experimental data and model simulations are presented for the hydroformylation of propene in the presence of a homogeneous rhodium catalyst.     

Application of water vapor and hydrogen-permselective membranes in an industrial fixed-bed reactor for large scale methanol production

Coupling reaction and separation in a membrane reactor improves the reactor efficiency and reduces purification cost in the next stages. In this work a novel reactor consisting two membrane layers has been proposed for simultaneous hydrogen permeation to reaction zone and water vapor removal from reaction zone in the methanol synthesis reactor. In this configuration conventional methanol reactor is supported by a Pd/Ag membrane layer for hydrogen permeation and alumina-silica composite membrane layer for water vapor removal from reaction zone. In this reactor syngas is fed to the reaction zone that is surrounded with hydrogen-permselective membrane tube. The water vapor-permselective membrane tube is placed in the reaction zone. A steady state heterogeneous one-dimensional mathematical model is developed for simulation of the proposed reactor. To verify the accuracy of the model, simulation results of the conventional reactor is compared with the available plant data. The membrane fixed bed reactor benefits are higher methanol production rate, higher quality of outlet product and consequently lower cost in product purification stage. This configuration has enhanced the methanol yield by 10.02% compared with industrial reactor. Experimental proof-of-concept is needed to establish the safe operation of the proposed configuration.     

高碳烯烃氢甲酰化研究进展

水/有机两相催化体系被成功应用于低碳烯烃氢甲酰化反应.对于水溶性差的高碳烯烃,其氢甲酰化反应速度远远低于低碳烯烃.本文论述了近年来铑催化高碳烯烃氢甲酰化反应的研究和开发进展,其新型配体和新催化体系的研究开发一直是该领域的研究热点.主要涉及两相反应体系中的水溶性膦配体以及均相催化剂固相化、氟两相催化、非离子液体催化体系和超临界CO2中的氢甲酰化反应等几种新型反应体系.     

Application of membrane reactor for dehydrogenation of ethylbenzene

Two types of membrane reactors have been constructed in order to evaluate the influence of membrane reactor configuration on the performance of the dehydrogenation of ethylbenzene in a porous alumina membrane reactor. The type I construction combine reaction and separation in the same space. The type II configuration is comprised of three parts, i.e., reaction prior to separation, reaction and separation, and reaction after separation. The results showed that the overall yield of styrene in Type I is only 4% higher than that of the fixed bed reactor at 893 K, while 11 % enhancement in yield to styrene was obtained with Type II through optimizing the reaction conditions.     

Methanol production in an optimized dual-membrane fixed-bed reactor

Coupling reaction and separation in a membrane reactor improves the reactor efficiency and reduces purification cost in the following stages. This paper focuses on modeling and optimization of methanol production in a dual-membrane reactor. In this configuration, conventional methanol reactor is supported by Pd/Ag membrane tubes for hydrogen permeation and alumina–silica composite membrane tubes for water vapor removal from the reaction zone. A steady state heterogeneous one-dimensional mathematical model is developed to predict the performance of this novel configuration. In order to verify the accuracy of the model, simulation results of the conventional reactor is compared with available industrial plant data. The main advantages of the optimized dual-membrane reactor are: higher CO₂ conversion, the possibility of overcoming the limitation imposed by thermodynamic equilibrium, improvement of the methanol production rate and its purity. Genetic algorithm as an exceptionally simple evolution strategy is employed to maximize the methanol production as the objective function. This configuration has enhanced methanol production rate by 13.2% compared to industrial methanol synthesis reactor.     

钴膦催化剂丙烯低压醛化制丁醇数学模型的研究

本文报导丙烯低压醛化制丁醇气液并流填料鼓泡反应器的数学模型的研究.在实验室模型级装置上验证了该数学模型的结果,表明带有接触效率系数的本征动力学方程式可以作为丙烯低压醛化制丁醇的反应器数学模型,为放大设计提供参考.     

Application of hydrogen-permselective Pd-based membrane in an industrial single-type methanol reactor in the presence of catalyst deactivation

This work presents application of palladium-based membranes in a conventional single-type methanol reactor. A novel reactor configuration with hydrogen-permselective Pd and Pd–Ag membrane are proposed. In this configuration the reacting synthesis gas is fed to the shell side of reactor while the high pressure product is routed from recycle stream through tubes of the reactor in a co-current mode with reacting gas. The reacting gas is cooled simultaneously with recycle gas in tube and saturated water in outer shell. The permselective palladium layer on inner tube allows hydrogen to penetrate from the tube side to the reaction side. In this work, the results of two types of novel membrane reactors are compared with a conventional methanol synthesis reactor at identical process conditions. Also the effect of key parameters such as membrane thickness, reaction and tube side pressure, ratio of tube side flow rate to reaction side flow rate on performance of reactor are investigated. The steady-state and quasi-steady-state simulations results show that there are favorable profiles of temperature and methanol mole fraction along the reactor in proposed reactor relative to conventional reactor system. Therefore using this novel configuration in industrial single-type methanol reactor improves methanol production rate.     

三苯基膦和亚磷酸酯类配体在双环戊二烯氢甲酰化反应中的对比研究

以具有不同取代基的三苯基膦和亚磷酸酯为配体,铁磁性的钴铑双金属为催化剂,考察双环戊二烯氢甲酰化合成三环癸烷不饱和单醛的反应。结果表明,反应存在一定的诱导期,诱导期越短,反应速率越快;配体上的取代基对反应活性和产物选择性具有显著影响,吸电子取代基催化活性较高,诱导期较短,反应速率较快,但选择性较低。亚磷酸酯配体中以亚磷酸三苯酯效果最好,与三苯基膦相比,转化率和选择性均相对较低。在考察的配体中,三苯基膦作为配体,三环癸烷不饱和单醛选择性最高,达97%。     

Hydrothermal flames in supercritical water oxidation: investigation in a pilot scale continuous reactor

Hydrothermal flames at 25 MPa supercritical water environment were investigated using a 4800 ml reaction tower, in which the sapphire windows were fitted for optical access. Down flowing hydrothermal flames were observed for oxidation of 2-propanol when the reactor was fed with inlet organic concentration higher than 2 vol% and air ratio higher than 1.8. Flame temperature, as high as 1100 °C, was measured by means of a thermocouple and the temperature was found to be strongly influenced by air ratio. Effective and stable oxidation of organics with TOC removal rate of 99.9% was achieved. Dioxins were also decomposed with a ratio higher than 99.9%, within 1 min reaction time in this reactor configuration.     

Theoretical Investigation of a Pd‐membrane Reactor for Methanol Synthesis

A numerical study is performed in order to evaluate the performance and optimal operating conditions of a palladium membrane reactor for methanol synthesis. A novel reactor configuration with a Pd wall, which is perm‐selective to hydrogen, has been proposed. In this configuration the reactants are added to the tube side while pure hydrogen is added to the shell side, as a result, the hydrogen diffuses across the membrane from the shell side to the tube side. In this membrane reactor, hydrogen penetrates to the reaction side in order to maintain a suitable hydrogen level in the whole length of the reactor and shift the equilibrium reaction. The effects of different parameters on the methanol output mole fraction were investigated in the co‐current mode. These parameters were membrane thickness, reaction side flow rate, reaction side pressure, shell side pressure and H₂/CO₂ ratio in the feed.