Kinetic study of a highly active MgCl₂‐supported Ziegler–Natta catalyst in liquid pool propylene polymerization. II. The influence of alkyl aluminum and alkoxysilane on catalyst activation and deactivation

Abstract

ABSTRACT:The influence of alkyl aluminum and alkoxysilane on the kinetics in liquid pool propylene batch polymerization was investigated with a highly active ZieglerNatta catalyst system that consisted of MgCl 2 /TiCl 4 /diester-alkoxysilane/AlR 3 . In this study, diethyl phthalate and t-BuEtSi(OMe) 2 were used as a diester and an alkoxysilane, respectively. The catalyst activity depended on the concentration of the alkyl aluminum when it came into contact with the catalyst. In addition, alkoxysilane as an external donor had a role in activating the catalyst. With respect to activity decay, the overreduction of Ti did not seem to be the cause. Instead, the decay rate decreased with an increasing alkoxysilane/catalyst ratio. This implied that activity decay was caused by the formation of dormant sites after 2,1-misinsertion of propylene.

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“…This method was improved to be used as an isoperibolic calorimeter. Pater21 and Shimizu et al9 used this slightly improved calorimetric method to study the kinetics of liquid‐pool propylene polymerization with highly active Ziegler‐Natta catalysts.…”

Estimation of the Polymerization Rate of Liquid Propylene Using Adiabatic Reaction Calorimetry and Reaction Dilatometry

“…Determination of kinetic constants. [8][9][10] 5. Establishing safety limits for batch, semi-batch and continuous chemical reactions.…”

“…This method was improved to be used as an isoperibolic calorimeter. Pater [21] and Shimizu et al [9] used this slightly improved calorimetric method to study the kinetics of liquid-pool propylene polymerization with highly active Ziegler-Natta catalysts. Finally, Korber et al [22] studied the kinetics of liquidpool polymerization of propylene with a silica-supported metallocenes/MAO catalyst, implementing a commercial isothermal calorimeter, at different polymerization conditions.…”

“…[9,10,17,25] For intensive mixing, the reactor was equipped with a turbine stirrer operated at 2 000 rpm. The pneumatic injection system allows the introduction of liquids and slurries into the reactor, even at high reactor pressures.…”

Low‐Rate Propylene Slurry Polymerization: Morphology and Kinetics

“…Figure 1b shows the reaction rate and the yield of polymerization calculated from MFM data. The temperature rise (Figure 1a) corresponds to the MFM rate profile, also allowing a calculation of the polymerization rate by calorimetry similar to liquid propylene experiments (see Samson et al, [11] Pater et al, [12] and Shimizu et al [13] ). Both the mass flow meter operation and the temperature difference are not directly proportional to the correct polymerization rate during the first 20 s. Both variables show a dynamic ''non-equilibrium'' change within the first 20 s until a quasi-steady-state, QSS, is reached.…”