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Table of Content
25 September 1984, Volume 35 Issue 3
    化工学报
    Catalytically Active Components of Fe_2O_3-Sb_2O_4Mixed Oxide Catalysts and Their Role in Ammoxidation of Propylene
    Wang Yufu, Zhao Xinping and Wu Yue (Changchun Institute of Applied Chemistry, Academia Sinica)
    1984, 35(3):  189-195. 
    Abstract ( 596 )   PDF (210KB) ( 129 )  
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    The catalytically active components of a series of Fe2O3-Sb2O4 mixed oxide catalysts with different Sb/Fe ratios, calcined at elevated temperature, with or without support, have been investigated by X-ray diffraction, Mossbauer spectroscopy and XPS in order to elucidate their catalytic behavior in ammoxidation of propylene. X-ray diffraction measurement showed that FeSbO4 is present in all samples, and that the appearence of α-Fe2O3 or Sb2O4 depends upon the Sb/Fe ratio. All the Mossbauer spectra showed a doublet caused by paramagnetic Fe3+ in FeSbO4; only at Sb/Fe<1, an additional sextet appeared typically for α-Fe2O3. All catalysts with Sb/Fe>1 and calcined at 800℃ showed a superposed second doublet undoubtely arising from Fe2+ of a new active component, perhaps of FeSb2O6. Surface analysis by XPS confirmed this result through the appearence of a shoulder at BE = 709.3 eV for Sb-rich catalysts. The rate of conversion of propylene was shown to vary with the ratio of Fe3+/Fe2+. This fact shows that, the catalytic behavior of catalyst could not be attributed to one component only. Correlations of acrylonitrile yield with concentrations of Fe2+ and Fe3+ respectively showed that, FeSbO4 seems to be the basic active component of catalyst, upon which the formation of a new phase containing Fe2+ may be responsible for good selective oxidation.
    The Thermal Effect on the Diffusion of Gases in Zeolite
    Wu Pingdong and Yi-Hua Ma Zhejiang University Worcester Polytechnic Institute, U.S.A.
    1984, 35(3):  196-202. 
    Abstract ( 661 )   PDF (200KB) ( 121 )  
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    A new technique for measuring simultaneously adsorption rate and temperature variation in zeolites has been developed. The transient temperature process during the adsorption of a gas on zeolite was analyzed by means of a simple model. It was found that the diffusion of gases in zeolite crystals could be made almost isothermal if the experimental conditions were appro-priately designed. Thus the thermal effect on the determination of diffusion coefficient of gases in zeolite could be neglected.
    Investigations on Branched Pipe Distributorsfor Fluidized Beds(Ⅱ) Determination of Design Parameters for Branched Pipe Distributors
    Jin Yong, Yu Zhiqing, Sun Zhufan and Peng Binpu Department nf Chemistry and Chemical Engineering, Qinghau University
    1984, 35(3):  203-213. 
    Abstract ( 675 )   PDF (279KB) ( 171 )  
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    The following design methods for determining the major parameters of branched pipe distributors have been studied in gas-solid fluidized beds for uniform gas distribution. 1. To describe the effect of varying mass flow of gas, a momentum equation was introduced: where K is the momentum recovery factor. An empirical formula for factor K is suggested as follows: K=0. 6041-0. 1561 2. For the proper arrangement of the ejector tube diameters along the branched pipes so as to attain a uniform gas distribution, the resistance coefficient , of the side flow ejector tube was studied, yielding the following relations. where and (for q/d>3.8) where Re>2300 Re<2300 3. A design procedure for this type of gas distributor systems has been developed and was illustrated with an example.
    Thermodynamic Analysis of Ammonia Synthesis Reactors
    Sun Zhifa, He Yaowen and Jiang Chusheng Beijing Institute of Chemical Technology Central Institute of Scientific Research in Chemical Industry
    1984, 35(3):  214-224. 
    Abstract ( 607 )   PDF (274KB) ( 194 )  
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    Based on the concepts of irreversible thermodynamics, a model for ther-modynamic analysis of ammonia synthesis reactors has been proposed. This model was checked by availability analysis of classical thermodynamics and calculation showed that the model gave good accuracy. The method is characterized by its ability to classify various kinds of exergy losses and to correlate these losses to effects of kinetic factors. Various types of ammonia synthesis reactors were evaluated by means of the proposed model.
    Studies on the Polycondensation of Friedel-CraftsReaction for Aralkyl Ethers and Aromatics (Ⅱ) Kinetics and Mechanism of Polycondensation
    Wang Jiashu, Jiao Yangsen and Li Shijin East China Institute of Chemical Technology
    1984, 35(3):  225-235. 
    Abstract ( 525 )   PDF (294KB) ( 104 )  
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    The kinetics of polycondensation of aralkyl ethers such as p-di(methoxy) xylene and 4,4/-di(methoxymethyl) diphenyl ether with ten kinds of aro-matics has been studied in the presence of catalysts for Friedel-Crafts reaction. The kinetic expression was found to be V=k [catalyst]0[aromatics]. A series of rate constants and activation energies was calculated. With the nuclear magnetic resonance method, the intermediate product, the carbon-ium ion, was determined, and the following polycondensation mechanism of electrophilic substitution by the carbonium ion was suggested: It was found that the order of reactivity for aromatics reacting with aralkyl ethers is as follows: phenol > p-cresol > 4-tert-butyl-phenol >o-cresol > salicylic acid > acenaphthene > acenaphthylene > 1 , 2 , 4 , 5-tetramethyl-benzene > phenyl ether > naphthalene. The electrophobic group present on the rings of aromatics is favorable to the reactivity of the aromatics.
    Reactivity of Char in Gasification with Steam and Carbon Dioxide at High Temperatures
    Tong Chuliang Yusaku Sakata and Shigeaki Kasaoka Lintong Fertilizer Industry Institute, Shanxi School of Engineering, Okayama University, Japan
    1984, 35(3):  236-243. 
    Abstract ( 590 )   PDF (230KB) ( 228 )  
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    The reactivities of chars were investigated for gasification with steam and carbon dioxide by thermogravimetry in the temperature range of 1100 to 1400℃ and at atmospheric pressure, and the results were compared to those of the previous work at temperatures below 1000℃, where the gasification velocity was chemically controlled. The parent coals of the six char samples differed in rank from brown coal to anthracite and from non-caking coal to strongly caking coal. The rate equation, f=1- exp( -aθb), designated as the modified volume reaction model, was applied to evaluating gasification reactivities using an average rate constant k.
    Mechanism and Kinetics of SO_2 Oxidation on"K-V" and "K-Na-V" Catalyst Series (Ⅱ) Kinetics
    Guo Hanxian, Han Zhehai and Xie Kechang Department of Chemical Engineering, Taiyuan Institute of Technology
    1984, 35(3):  244-256. 
    Abstract ( 667 )   PDF (318KB) ( 156 )  
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    On the basis of the mechanism proposed in paper ( I ), a mathematical model of intrinsic kinetics for SO2 oxidation on "K-V" and "K-Na-V" catalysts has been obtained: The intrinsic kinetics of the reaction was studied using the internal recirculation reactor TG-1 developed by the authors over broad reactant concentrations and temperature ranges. By graphical, linear- and weighted-least square methods, ten types of competitive models with more accurate initial values of parameters were obtained from seventeen types of kinetic equations, including the authors model. Then, computing with Powells optimum program under the same conditions, we found that the authors model is optimal for both low and high temperature ranges for SO2 oxidation with the two catalyst series. The optimum rate equation was validated through analysis of ( 1 ) the results of the single variable experiments, ( 2 ) the physical meaning of the parameter values in the optimum model, and (3) the rate-data residual errors over a wide range of gas compositions and temperatures.
    Disengagement of Agglomerates in the Jet Zone of a Fluidized-Bed Ash-Agglomerating Coal Gasifier
    Zhang Jiyu, Mao Xiubin and Zhang Bijiang Institute of Coal Chemistry, Academia Sinica, Shanxi
    1984, 35(3):  257-266. 
    Abstract ( 599 )   PDF (282KB) ( 183 )  
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    When a jet spouts vertically into a fluidized bed with a conical distributor, a jet zone is formed. In this jet zone, agglomerates will be disengaged downward from the fluidized bed consisting mainly of ash particles and then discharged from the jet nozzle. In general, this disengagement process for the agglomerates can be divided into three stages: 1 ) Initial disengagement. 2 ) Stable disengagement. 3 ) Critical disengagement.In this paper the equation obtained for the initial disengagement velocity UIJ is as follows: The difference between experimental and calculated values is less than ±5%. In practice, the flow characteristics and agglomerate disengagement process in the fluidized bed are affected by the geometric configuration of the jet zone. Based on experimental results, a configuration-flow parameter C, is proposed, which may be used as an important criterion for selecting the optimum geometric configuration of nozzle and distributor. Finally, the effect of fine powders on improving the agglomerate disengagement process is examined.
    Effect of Baffles on Agitation Characteristics
    Weng Zhixue, Huang Zhiming, Chen Kailai and Xu Sanjun Department of Chemical Engineering, Zhejiang University
    1984, 35(3):  267-273. 
    Abstract ( 507 )   PDF (193KB) ( 105 )  
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    Power consumption, mixing time, radius of cylindrically rotating vortex and discharge times for the impellers were measured for different conditions of the baffles in a model agitation vessel with an inner diameter of 400mm. The effect of baffles on power, mixing and circulating characteristics was studied, and correlation among them have been proposed for the design of mixing equipment and for the improvement of agitated reactors.
    Measuring Thermal Conductivity of Liquids by Transient Method
    Wang Congyu, Guo Cangsheng, Yang Menlin, Ma Lu and Lu Xinzhong Thermochemical Laboratory, Northwest University
    1984, 35(3):  274-277. 
    Abstract ( 633 )   PDF (106KB) ( 139 )  
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    Using a small bead-in-glass thermistor probe as a heating element, an apparatus was developed for measuring thermal conductivity of liquids by the transient method. The apparatus was calibrated by using seven standard substances at 25℃, with an average deviation of measurements less than 2%. To check the reliability of this apparatus and the correlation proposed, the thermal conductivities of thirteen known liquids were determined. The experimental results showed that all deviations were within 2% except one which reached 5%. The precision of the apparatus is 0.2%. This paper expounds the principle of the proposed method and discusses the experimental results.
    A New Microscopic Method for Studying Phase Morphology of Thick Sample of Rubber Blends
    Wu Xianglong, Li Hao, Wang Mengjiao, Xie Qichang, Xu Chunhua and Lin Yizhen Beijing Research and Design Institute of Rubber Industry
    1984, 35(3):  278-285. 
    Abstract ( 546 )   PDF (270KB) ( 108 )  
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    A Method has been devised for staining with aqueous KMnO4 solution on one surface of any thick sample of rubber blends in which one or both consisting of unsaturated hydrocarbons for effective visualization of its morphology under the microscope. Experiments showed that the method is sensitive for incompatible blends such as NBR with EPDM, BR with LDPE or EVA/SBR/PE, and is applicable to compatible blends when mutual blending is not yet completed or dispersion is not satisfactory. The advantage of this method lies in its simple preparation, ease of operation, low cost and freedom from morphological distortion. The strongly contrasting pictures resulting from this method can be used for examining thick samples without the use of the phase-contrast microscope or the microtome. This method is thus expected to provide an effective means of quality control for mixing operations and of rapid measurement of homogeneity of dispersion.