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Table of Content
18 December 2000, Volume 8 Issue 4
    RESEARCH PAPERS
    Adsorption Equilibria of n-Alkanes on Silicalite and ZSM-5
    CHEN Zhongxiu, LU Jiangang, LIU Xueyuan, DING Tongfu
    2000, 8(4):  283-286. 
    Abstract ( 646 )   PDF (1179KB) ( 284 )  
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    The adsorption equilibria of n-heptane, n-octane and n-nonane on silicalite and ZSM-5 have
    been measured in the temperature range of 373.15--473.15K under low pressure (0-5.332kPa).
    All the experimental data can be represented by a generalized characteristic curve of the
    extended adsorption potential theory utilizing the parameter of the initial heat of
    adsorption, which is estimated reasonably by a new approach.
    Determination of a Pore Structure Parameter of Porous Media by Analysis of Percolation
    Network Model
    XIN Feng, WANG Fumin, LI Shaofen
    2000, 8(4):  287-293. 
    Abstract ( 612 )   PDF (2039KB) ( 267 )  
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    According to the simulation of nitrogen sorption process in porous media with three-
    dimensional network model, and the analysis for such a process with percolation theory, a
    new method is proposed to determine a pore structure parameter-mean coordination number of
    pore network, which represents the connectivity among a great number of pores. Here the
    “chamber-throat” model and the Weibull distribution are used to describe the pore
    geometry and the pore size distribution respectively. This method is based on the scaling
    law of percolation theory after both effects of sorption thermodynamics and pore size on
    the sorption hysteresis loops are considered. The results show that it is an effective
    procedure to calculate the mean coordination number for micro- and meso-porous media.

    Process Design of Continuous-Flow Pervaporation Separa tion for Alcohol Dehydration
    CHEN Huanlin, ZHU Changle
    2000, 8(4):  294-299. 
    Abstract ( 603 )   PDF (1875KB) ( 271 )  
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    The separation characteristics of the PVA-CS (polyvinyl alcohol-chitosan) blended composite
    membrane for dehydration of ethanol-water mixture are examined. The relationships of flux
    and separation factor with the feed concentration and operation temperature are
    established. Using this correlated equation, the continuous-flow pervaporation process
    about 500 kilolitres/year dehydrated ethanol is designed. The numbers of stage and reheater
    are calculated by stage-by-stage method for two kinds of cascades: one with equal membrane
    area and the other with 10℃C of temperature decrement per section. The results show that
    when the numbers of stage and reheater are the same, the cascade with 10℃C of temperature
    decrement has more advantages than that with equal membrane area. The influences of feed
    concentration and flow rate on the numbers of stage and reheater in the cascades are
    discnssed.
    Distribution Behavior of Aminobenzoic Acid by Extraction with Di(2-ethylhexyl)phosphoric
    Acid
    ZHANG Jin, DAI Youyuan
    2000, 8(4):  300-303. 
    Abstract ( 597 )   PDF (1240KB) ( 286 )  
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    A series of extraction equilibrium experiments for aminobenzoic acid with di(2-ethylhexyl)
    phosphoric acid (D2EHPA) dissolved in n-octane or 1-octanol was carried out. The effects of
    aminobenzoic acid concentration, D2EHPA concentration and pH on the distribution ratio were
    discussed in detail. The infrared spectra of the organic phase loaded with solute
    illustrated that pH had little effect on the structure of the complex formed. There proceed
    ion association and cation-exchange reaction in the extraction. An expression of the
    equilibrium distribution was proposed.
    Neutral Complex Extraction and Synergistic Extraction of Macrolide Antibiotics
    LI Zhou, QIN Feng, GU Xueqiang, DAI Lingmei
    2000, 8(4):  304-309. 
    Abstract ( 786 )   PDF (1419KB) ( 223 )  
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    Based on the theory of reactive extraction, new solvent systems were developed to replace
    butylacetate for extraction of macrolide antibiotics (erythromycin, kitasamycin, spiramycin
    meleumycin etc.). A new neutral complex solvent extraction system, fatty alcohol-kerosene
    (marked by E1), was used for extraction of erythromycin, one of the macrolide antibiotics.
    The extraction equilibrium equation is obtained, and the extraction distribution is as
    follows The effects of several parameters on extraction equilibrium were investigated.
    Furthermore, a new synergistic extraction system (marked by E2) was developed, in which
    another solvent was used as synergistic agent to replace the diluent kerosene in the
    neutral complex extraction system. Based on these new extraction systems, an improved
    process for extraction of erythromycin was developed, showing remarkable advantages in
    technology and economics owing to its low solvent consumption of 3kg per billion unit
    compared with 9-10 for butylacetate. The recovery process of solvent from raffinate may be
    eliminated.
    Preparation of Iminodiacetic Acid-Polyethylene Glycol for Immobilized Metal Ion Affinity
    Partitioning
    LIN Dongqiang, YAO Shanjing, MEI Lehe, ZHU Ziqiang
    2000, 8(4):  310-314. 
    Abstract ( 675 )   PDF (1523KB) ( 257 )  
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    The synthesis route was investigated and optimized for the preparation of iminodiacetic
    acid polyethylene glycol (IDA-PEG) for immobilized metal ion affinity partitioning in
    aqueous two-phaze systems. IDA PEG was synthesized from PEG in two steps by the reaction of
    iminodiacetic acid with a monosubetituted derivative of epichlorohydrin-activated PEG. The
    Cu2+ content combined with IDA-PEG was determined by atomic absorp tion spectrometry as 0.5
    mol.mol-1 (PEG). Furthermore, the affinity partitioning behavior of lactate dehydrogenase
    in polyethylene glycol/hydroxypropyl starch aqueous two-phaze systems was studied to
    clarify the affinity effect of the Cu(Ⅱ)-IDA-PEG.
    Dynamic Kinetics of Methanol Synthesis over a Commercial Copper-Based Catalyst
    CHEN Xiaochun, RAO Guoying
    2000, 8(4):  315-320. 
    Abstract ( 604 )   PDF (1722KB) ( 267 )  
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    Adsorption, surface reaction and process dynamics on the surface of a commercial copper-
    based cata lyst for methanol synthesis from CO/CO2/H2 were systematically studied by means
    of temperature programmed desorption (TPD), tsmperature programmed surface reaction (TPSR),
    in-situ Fourier transform-inferred spec troscopy(FTIR) and stimulua-response techniques. As
    a part of results, an elementary step sequence was suggested and a group of ordinary
    differential equations (ODEs) for describing transient conversations relevant to all
    species on the catalyst surface and in the gas phase in a micro-fixed-bed reactor was
    derived. The values of the parameters referred to dynamic kinetics were estimated by
    fitting the solution of the ODEs with the transient response data obtained by the stimulus
    -response technique with a FTIR analyzer as an on-line detector.

    Decomposition of Cellulose by Continuous Near-Critical Water Reactions
    LU Xiuyang, SAKODA Akiyoshi, SUZUKI Motoyuki
    2000, 8(4):  321-325. 
    Abstract ( 596 )   PDF (1712KB) ( 283 )  
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    A pilot-scale apparatus for continuous supercritical and near-critical water reaction was
    set up. A high- pressure slurry supplying system was developed to feed the solid material-
    water slurries. The apparatus features temperature up to 600℃, pressure up to 40MPa,
    residence time from 24s to 15min, maximum amount of slurry supply of 2.4 L.h-1, maximum
    solid content of slurry up to 10%(by mass) for cellulose from Merck, and resistance to
    corrosion. Long-time runs of decomposition of cellulose were carried out and steady runs
    were confirmed. Kinetics of cellulose decomposition was studied. The apparent activation
    energy evaluated was 147kJ·mol-1. In addition, a new three-step pathway for cellulose
    hydrolysis was proposed. The derived kinetic equation is in good agreement with the
    experimental data.
    Neural Network Approach to Predict Melt Temperature in Injection Molding Processes
    WANG Baoguo, GAO Furong, YUE Polock
    2000, 8(4):  326-331. 
    Abstract ( 563 )   PDF (1905KB) ( 220 )  
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    Among the processing conditions of injection molding, temperature of the melt entering the
    mold plays a significant role in determining the quality of molded parts. In our previous
    research, a neural network was developed to predict, the melt temperature in the barrel
    during the plastication phase. In this paper, a neural network is proposed to predict the
    melt temperature at the nozzle exit during the injection phase. A typical two layer neural
    network with back propagation learning rules is used to model the relationship between
    input and output in the injection phase. The preliminary results show that the network
    works well and may be used for on-line optimization and control of injection molding
    processes.
    Stable MIMO Constrained Predictive Control with Steady state Objective Optimization
    HUANG Dexian, WANG Jingchun, JIN Yihui
    2000, 8(4):  332-338. 
    Abstract ( 1081 )   PDF (2140KB) ( 236 )  
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    A two-stage multi-objective optimization model-predictive control algorithms(MPC) strategy
    is pre sented. A domain MPC controller with input constraints is used to increase freedom
    for steady-state objective and enhance stabilization of the controller. A steady-state
    objective optimization algorithm oriented to transient process is adopted to realize
    optimization of objectives else than dynamic control. It is proved that .the stabilization
    for both dynamic control and steady-state objective optimization can be guaranteed. The
    theoretical results are demonstrated and discussed using a distillation tower as the model.
    Theoretical analysis and simulation results show that this control strategy is efficient
    and provides a good strategic solution to practical process control.
    Assessment of Control Configurations for a General Heat Integrated Distillation Column
    HUANG Kejin, QIAN Jixin, NAKAIWA Masaru, NAKANE Takashi, TAKAMATSU Takeichiro
    2000, 8(4):  339-346. 
    Abstract ( 610 )   PDF (2413KB) ( 266 )  
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    The assessment of control configurations for an ideal heat integrated distillation column
    incorporated with an overhead condenser and a bottom reboiler (general HIDiC) is addressed
    in this work. It is found that double ratio control configuration, (L/D, V/B), is still the
    best one among all the possibilities. The control configuration, (Pr - Ps, q), appears to
    be a feasible one for the general HIDiC and the pressure difference between the rectifying
    and the stripping sections and feed thermal condition are expected to be consistent
    manipulative variables for the process. The performance of the general HIDiC can be
    substantially improved by employing effective multivariable control algorithms.
    Numerical Simulation of Erosion-Corrosion in the Liquid Solid Two-Phase Flow
    ZHANG Zheng, CHENG Xuewen, ZHENG Yugui, KE Wei, YAO Zhiming
    2000, 8(4):  347-355. 
    Abstract ( 591 )   PDF (2482KB) ( 260 )  
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    Erosion-corrosion of liquid-solid two-phase flow occurring in a pipe with sudden expansion
    in cross section is numerically simulated in this paper. The global model for erosion-
    corrosion process includes three main components: the liquid-solid two-phase flow model,
    erosion model and corrosion model. The Euierian-Lagranglan approach is used to simulate
    liquid-solid two-phase flow, while the stochastic trajectory model was adopted to obtain
    properties of particle phase. Two-way coupling effect between the fluid and the particle
    phase is considered in the model. The accuracy of the models is tested by the data in the
    reference. The comparison shows that the model is basically correct and feasible.
    Notes on Stefan-Maxwell Equation versus Grahan’s Diffusion Law
    MAO Zaisha
    2000, 8(4):  356-360. 
    Abstract ( 1056 )   PDF (1718KB) ( 287 )  
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    Certain prerequisite information on the component fluxes is necessary for solution of the
    Stefan-Maxwell equation in multicomponent diffusion systems and the Graham’s law of
    diffusion and effusion is often resorted for this purpose. This article addresses solution
    of the Stefan-Maxwell equation in binary gas systems and explores the necessary conditions
    for definite solution of concentration profiles and pertinent component fluxes. It is found
    that there are multiple solutions for component fluxes in contradiction to what specified
    by the Graham’s law of diffusion. The theorem of minimum entropy production in the non-
    equilibrium thermodynamics is believed instructive in determining the stable steady state
    solution out of infinite multiple solutions possible under the specified conditions. It is
    suggested that only when the boundary condition of component concentration is symmetrical
    in an isothermal binary system, the counter-diffusion becomes equimolar. The Graham’s law
    of diffusion seems not generally valid for the case of isothermal ordinary diffusion.
    Necessary and Sufficient Conditions for Reactive Azeotropes in Multi-reaction Mixtures in
    Terms of Elemental Composition
    LIN Jinqing, LI Haoran, HAN Shijun
    2000, 8(4):  361-365. 
    Abstract ( 699 )   PDF (1456KB) ( 226 )  
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    Necessary and sufficient conditions for azeotropy in reactive mixtures are derived in terms
    of elemental composition, which shows that in the space of elemental compositions, they
    take the same functional form as the conditions for azeotropy in non-reactive mixtures. The
    production of methyl tert-butyl ether (MTBE) is taken as an example. It is found that there
    are a “pseudo” intermediate-boiling ternary reactive azeotrope at p = 101.325 kPa and two
    “real” ternary reactive azeotropas at p = 101.325 Pa. The introduced elemental
    compositions also reduce the dimensionality of the phase diagrams and provide a natural set
    of variables for visualization of phase behavior.
    Novel Fluorescent Dyes Based on Coumarin System
    ZHAO Defeng, LI Zhuoshu, XIU Jinghai
    2000, 8(4):  366-373. 
    Abstract ( 663 )   PDF (2202KB) ( 258 )  
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    Seven novel fluorescent coumarin derivatives were synthesized from 7-diethylamino-4-chloro
    -3-formyl coumarin. The spectra of absorption, excitation and emission were dependent not
    only on the structures and also on the concentration of dyes. The PPP-MO predictions can
    only be consistent with the spectra in dilute solutions.
    RESEARCH NOTES
    Oxidative Dehydrogenation of Butane to Butadiene and Butene Using a Novel Inert Membrane
    Reactor
    GE Shanhai, LIU Changhou, FAN Yu, WANG Lianjun
    2000, 8(4):  374-378. 
    Abstract ( 640 )   PDF (1427KB) ( 292 )  
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    The oxidative dehydrogenation of butane to butadiene and butene was studied using a
    conventional fixed-bed ractor (FBR), inert membrane reactor (IMR) and mixed inert membrane
    reactor (MIMR). When IMR and MIMR were employed, a ceramic membrane modified by partially
    coating with glaze was used to distribute oxygen to a fixed-bed of 24-V-Mg-O catalyst. The
    oxygen partial pressure in the catalyst bed could be decreased. The effect of feeding modes
    and operation conditions were investigated. The selectivity of C4 dehydrogenation products
    (butene and butadiene) was found to be higher in IMR than in FBR. The feeding mode with 20%
    of air mixing with butane in MIMR was found to be more efficient than the feeding mode with
    all air permeating through ceramic membrane. The MIMR gave the most smooth temperature
    profile along the bed.
    Kinetics of the Double Carbonylation of Benzylchloride
    OUYANG Pingkai, FAN Weiping, ZHANG Shi
    2000, 8(4):  379-384. 
    Abstract ( 596 )   PDF (1651KB) ( 216 )  
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    It is a multi-phase-catalyzed reaction to produce calcium phenylpyruvate by double
    carbonylation of benzylchloride. Based on the analysis of the reaction mechanism, a kinetic
    model of the carbonylation reaction was obtained. The model was verified through
    experiments in which the diffusion effect was neglected with the appropriate operation
    manner. But it is inevitable that the carbonylation process is controlled by diffusion as
    the autoclave scaling up.
    A New Model for Prediction of Mean Liquid Circulating Velocity in Bubble Columns
    CHEN Qiming, WU Yuanxin
    2000, 8(4):  385-387. 
    Abstract ( 640 )   PDF (734KB) ( 298 )  
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    A new model without any fitting parameter for estimating the mean liquid recirculating
    velocity has been derived from previous work directly. The prediction agrees with
    experimental data reasonably well. Accurency of prediction from the new model is comparable
    with the models reported in the literature. However, the new model has a potential
    capability to predict the average liquid recirculation velocity at elevated pressure bubble
    columns since n and c is developed under pressure. However this needs to be further tested
    experimentally.
    Pressure Drop of Non-Newtonian Liquid Flow Through Elbows
    T. K. Banerjee, S. K. DAS
    2000, 8(4):  388-390. 
    Abstract ( 598 )   PDF (809KB) ( 312 )  
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    Experimental data on the pressure drop across different types of elbow for non-Newtonian
    pseudoplastic liquid flow in laminar condition have been presented. A generalized
    correlation has been developed for predicting the frictional pressure drop across the
    elbows in the horizontal plane.