A kinetic mathematical model for heterogeneous Ziegler-Natta copolymerization

Abstract A kinetic model has been derived based upon multiple catalyst sites of differing reactivities for the Ziegler-Natta copolymerization of olefins. The kinetic scheme accounts for the formation, initiation and deactivation of active sites, as well as for spontaneous transfer and for transfer reactions to hydrogen, monomer and organometallics. The model predicts the rate of polymerization, the copolymer composition and the molecular-weight distribution of the polymer produced. The model accounts for the observed broad copolymer composition and molecular-weight distributions. A method for the estimation of the model parameters via temperature-rising elution fractionation, gel permeation chromatography and nuclear magnetic resonance is discussed. Some simple calculations are performed to demonstrate that the observed broad copolymer composition and molecular-weight distributions can be predicted by this model.

[1]  B. Grieveson,et al.  Kinetics of the polymerization of ethylene with a ziegler‐natta catalyst. I. Principal kinetic features , 1965 .

[2]  R. J. Waite,et al.  Continuous electron microscopic observation of the behavior of ziegler‐natta catalysts , 1973 .

[3]  J. Ross.  Copolymerization Kinetic Constants and Their Prediction from Dyad/Triad Distributions , 1984 .

[4]  M. Kakugo,et al.  Carbon-13 NMR determination of monomer sequence distribution in ethylene-propylene copolymers prepared with δ-titanium trichloride-diethylaluminum chloride , 1982 .

[5]  Y. Doi,et al.  Monomer sequence distribution in ethylene‐propylene copolymers prepared with a silica‐supported MgCl2/TiCl4 catalyst , 1983 .

[6]  T. Usami,et al.  Generation mechanism of short-chain branching distribution in linear low-density polyethylenes , 1986 .

[7]  R. Roe,et al.  Surface-chemical mechanism of heterogeneous polymerization and derivation of Tung's and Wesslau's molecular weight distribution , 1961 .

[8]  L. Böhm.  Zur copolymerisation von ethylen und α‐olefinen mit ziegler‐katalysatoren , 1981 .

[9]  W. Ray,et al.  Polymerization of olefins through heterogeneous catalysis—V. Gas‐liquid mass transfer limitations in liquid slurry reactors , 1986 .

[10]  V. A. Poluboyarov,et al.  Study of the state of titanium ions and the composition of the active component in titanium-magnesium catalysts for ethylene polymerization , 1984 .

[11]  Y. Kissin.  Isospecific Polymerization of Olefins: With Heterogeneous Ziegler-Natta Catalysts , 1985 .

[12]  T. Keii.  Kinetics of Ziegler Natta Polymerization , 1972 .

[13]  R. Spitz,et al.  Catalyseurs Zieger-Natta supportés sur MgCl2 pour la polymérisation stéréorégulée du propène. II. Système catalytique simple: Solide binaire MgCl2-TiCl4 et solution cocatalytique triéthylaluminium, benzoate d'ethyle , 1984 .

[14]  J. Ross.  Markovian Statistics of Nonhomogeneous Copolymer Systems , 1986 .

[15]  B. Grieveson.  Kinetics of the polymerization of ethylene with a ZIEGLER‐NATTA catalyst. II. Factors controlling molecular weight , 1965 .

[16]  J. Begley.  The role of diffusion in propylene polymerization , 1966 .

[17]  G. Ver Strate,et al.  Ethylene-Propylene Copolymers. Reactivity Ratios, Evaluation, and Significance , 1971 .

[18]  P. W. Wijga,et al.  The fractionation of polypropylene , 1960 .

[19]  J. Chien,et al.  Magnesium‐chloride‐supported high‐mileage catalysts for olefin polymerization. III. Electron paramagnetic resonance studies , 1982 .

[20]  W. Harmon Ray,et al.  PREDICTION OF MOLECULAR WEIGHT DISTRIBUTIONS FOR HIGH-DENSITY POLYOLEFINS , 1980 .

[21]  G. D. Bukatov,et al.  Propylene polymerization on titanium‐magnesium catalysts determination of the number of active centers and propagation rate constants , 1982 .

[22]  R. V. Orye.  Prediction and Correlation of Phase Equilibria and Thermal Properties with the BWR Equation of State , 1969 .

[23]  N. Kashiwa,et al.  Kinetic study on propylene polymerization with MgCl2/TiCl4-AlEt3/PhCO2Et System — the role of ethyl benzoate , 1984 .

[24]  C. Mussa.  Molecular weight distribution and polymerization kinetics in some new catalytic processes , 1959 .

[25]  J. Crabtree,et al.  The role of diffusion in the Ziegler polymerization of ethylene , 1973 .

[26]  L. L Böhm,et al.  Reaction model for Ziegler-Natta polymerization processes , 1978 .

[27]  Y. Doi,et al.  Propene polymerization with a magnesium chloride‐supported ziegler catalyst, 1. Principal kinetics , 1982 .

[28]  R. Roe.  A test between rival theories for molecular weight distributions in heterogeneous polymerization: The effect of added terminating agent , 1961 .

[29]  V. W. Buls,et al.  A uniform site theory of ziegler catalysis , 1970 .

[30]  I. R. Peat,et al.  Determination of branching distributions in polyethylene and ethylene copolymers , 1982 .

[31]  P. Kamath,et al.  Fractional crystallization of polypropylene , 1966 .

[32]  J. Chien,et al.  Supported catalysts for stereospecific polymerization of propylene , 1976 .

[33]  P. Barbe,et al.  Microscopic analysis of polyolefin initial formation on TiCl4/MgCl2 supported catalysts , 1983 .

[34]  J. Chien,et al.  Magnesium chloride supported high mileage catalyst for olefin polymerization. VI. Definitive evidence against diffusion limitation , 1985 .

[35]  A. Nakajima,et al.  The Fractionation of Polypropylene by Extraction with Boiling Hydrocarbons with Increasing Boiling Points , 1964 .

[36]  C. Booth,et al.  Polypropylene oxide II — Dilute solution properties and tacticity☆ , 1964 .

[37]  Seikou Nakano,et al.  Development of automatic cross fractionation: Combination of crystallizability fractionation and molecular weight fractionation , 1981 .

[38]  D. R. Burfield.  Active centre determination in ziegler‐natta polymerization. An examination of the allene inhibition method , 1983 .

[39]  G. D. Bukatov,et al.  Propylene polymerization on titanium‐magnesium catalysts, 3. Influence of the products resulting from the interaction of trialkylaluminium with aromatic esters on the activity and stereospecificity , 1984 .

[40]  Y. Doi,et al.  Propene polymerization with a magnesium chloride‐supported Ziegler catalyst, 2. Molecular weight distribution , 1984 .

[41]  W. Ray,et al.  Polymerization of olefins through heterogeneous catalysis, I. Low pressure propylene polymerization in slurry with Ziegler–Natta catalyst , 1982 .

[42]  H. Meyer,et al.  Einfluß des stofftransportes bei der polymerisation von äthylen und 1‐okten mit Ziegler‐Katalysatoren , 1977 .

[43]  Paul E. Johnson,et al.  Carbon-13 Nuclear Magnetic Resonance Determination of Monomer Composition and Sequence Distribution in Ethylene-Propylene Copolymers Prepared with a Stereoregular Catalyst System , 1977 .

[44]  Daljit Singh,et al.  MOLECULAR WEIGHT DISTRIBUTION OF POLYETHYLENE PRODUCED BY ZIEGLER-NATTA CATALYSTS , 1971 .

[45]  C. Cozewith.  Interpretation of carbon-13 NMR sequence distribution for ethylene-propylene copolymers made with heterogeneous catalysts , 1987 .

[46]  J. Boor,et al.  Ziegler-Natta catalysts and polymerizations , 1979 .