Polymerization of propylene with TiCl3–AlEt2Cl–trilauryltrithiophosphite catalyst

AlEt₃Cl was modified with TLTTP (trilauryltrithiophosphite) in the catalyst system consisting of TiCl₃ and AlEt₂Cl. The effects of TLTTP on the polymerization of propylene were studied in comparison with those of alkyl homologues of TLTTP. The catalytic behavior of the TiCl₃–AlEt₂Cl-TLTTP catalyst system in the polymerization of propylene was also studied in comparison with that of the TiCl₃–AlEt₂Cl catalyst system. In the study of the effect of various alkylthiophosphites added, it is found that the bulkiness of the alkyl group affects the rate of propylene polymerization and the stereoregularity of the resultant polymers. The TiCl₃–AlEt₂Cl–TLTTP catalyst system gave different catalytic behavior in the propylene polymerization from that of the unmodified conventional catalyst system (TiCl₃–AlEt₂Cl). These effects of TLTTP were considered to be due to the bulkiness of the alkyl groups attached to the phosphorous atom and the higher reactivity to TiCl₃ of the modified AlEt₂Cl than of the unmodified AlEt₂Cl.     

Polymerizations of α-olefins and styrene with MgCl2-supported titanium catalyst system: MgCl2/TiCl4/PhCO2Et with AlEt3PhCO2Et

Summary Kinetic analysis was performed in a short time polymerizations of 1-butene,4-methyl-1-pentene and styrene by using a catalyst system composed of MgCl₂/TiCl₄/PhCO₂Et with AlEt₃/PhCO₂Et which is known as a highly active and highly stereospecific catalyst system in olefin polymerization. The concentration of the active centers, [C ^*], the propagation rate constant, k _p, and the chain transfer rate, r _tr, were determined for each monomer. It was found that the values of [C ^*] were almost same for every monomer, but the values of k _p changes widely in the following order: propylene>1-butene>4-methyl-1-pentene>styrene.     

Copolymerization of ethylene with propylene by MgCl2-containing highly active Ti catalysts

Summary In the ethylene-propylene copolymerization, two catalyst systems were examined. The one(cat-[a]) was the solid MgCl₂-containing Ti treated with ethyl benzoate together with AlEt₃, and the other(cat-[c]) was based on a homogeneous mixture of MgCl₂ dissolved in 2-ethylhexanol/n-decane and TiCl₄, which was treated with AlEt₂Cl. Both catalyst systems exhibited very high activity in comparison with the conventional catalysts of TiCl₃-AlEt₂Cl and VOCl₃-AlEt₂Cl. These two new systems, however, are different from each other in micro structure of the product copolymer,i.e., the latter(cat-[c]) brings about more random distribution of the monomeric units and also the decreased regiospecificity concerning the arrangement of propylene unit.     

Kinetics of ethylene polymerization at high temperature with Ziegler–Natta catalysts

A kinetic technique is developed for the study of ethylene polymerization reaction at high temperature with Ziegler–Natta catalysts. The technique is based on the calculation of polymerization rate parameters from the data on ethylene consumption vs. time. It takes into account increase of reaction temperature at the beginning of the reaction. Kinetic data in coordinates “polymerization rate–time” are presented for several pseudohomogeneous catalysts (TiCl₄? AlEt₂Cl, Ti(OiC₃H₇)₄? AlEt₂Cl), heterogeneous catalysts (δ-TiCl₃? AlEt₃, δ-TiCl₃? AlEt₂Cl, TiCl₄/MgCl₂? AlEt₃, TiCl₄/MgCl₂? AlEt₂Cl) and solubilized catalysts (δ-TiCl₃? poly-1-hexene? AlEt₂Cl) at 180°C and reaction pressure 14.6 atm for first 10 min of the reaction. These data are useful for the selection of Ziegler–Natta catalysts for testing in ethylene polymerization reaction in continuous high pressure reactors at short residence times.     

Ethylene and propylene polymerization catalyzed by a model Ziegler-Natta catalyst prepared by gas phase deposition of magnesium chloride and titanium chloride thin films

Model Ziegler-Natta catalysts are prepared by gas phase deposition of ultra-thin TiCl₄/ MgCl₂ films in UHV conditions. A monolayer of TiCl₄ chemisorbed on a solid solution of titanium and magnesium chloride is formed in this way. The reduction and alkylation of TiCl₄ by its reaction with a liquid layer of AlEt₃ condensed on the halide film is monitored by XPS. Most of the TiCl₄ is reduced by AlEt₃ and is incorporated in the mixed titanium /magnesium chloride. The model catalyst is active in the polymerization of ethylene and propylene at 300 K, both in the absence and in the presence of AlEt₃ in the reaction cell. The polymers that form over the catalyst film have been characterized by Raman spectroscopy. The weak signals from methyl end groups and unsaturations suggest high molecular weight for both polymers. The polypropylene film has a high degree of isotacticity even without the use of any electron donor. For the propylene polymerization reaction the overall turnover frequency is in the range between 0.1 and 1 molecule/(site s).     

Kinetics study of slurry-phase propylene polymerization with highly active Mg(OEt)2/benzoyl chloride/TiCl4 catalyst

Propylene was polymerized in a slurry phase over superactive and stereospecific catalyst prepared by the reaction of Mg(OEt)₂ with benzoyl chloride and TiCl₄ in the presence of AlEt₃ with or without an external donor. A kinetic analysis of propylene polymerization was carried out. The polymerization rate was first order with respect to monomer concentration and the dependence of overall polymerization rate on the concentration of AlEt₃ can be explained by the Langmuir adsorption mechanism. Maximum activity was observed around an Al/Ti mole ratio of 20. The average rate over 90 min of polymerization as a function of temperature showed a maximum around 42°C and the overall activation energy was 8.5 kcal/mol at T < 42°C and ?4.0 kcal/mol at T > 42°C. The analysis of the phenomenon of an optimum temperature gave 2.2 kcal/mol for the activation energy of the rate-determining step, and 6.3 kcal/mol, for the adsorption energy of AlEt₃. The addition of small amount of p-ethoxyethyl benzoate (PEEB) as an external donor increased the percentage of isotactic polymer to 98% and slightly increased activity in spite of the decrease in the concentration of active centers due to the stabilizing effect of the active centers by the external donor. The temperature showing maximum yield was shifted to the higher temperature when AlEt₃ and PEEB ([AlEt₃]/[PEEB] = 5) was used as a cocatalyst. © 1994 John Wiley & Sons, Inc.     

A highly non-stereospecific catalyst for propene polymerization

Summary The MgCl₂-supported TiCl₃ catalyst containing a small amount of Ti(about 0.1 wt.%) was prepared by treating the mixture of MgCl₂ and TiCl₃ 3py with an excess amount of AlEt₂Cl. Propene polymerization was conducted at 40°C by using AlEt₃ as cocatalyst. The catalyst system was found to be highly active, which gave atactic polypropylene     

High activity mixed metal alkyl cocatalysts for α-olefin polymerization

High activity α-olefin polymerization catalysts are generally obtained by mixing MgCl₂-supported TiCl₄ (MgCl₂/TiCl₄) with an aluminum trialkyl cocatalyst. Surprisingly, AlEt₂Cl, which is the preferred cocatalyst in polymerizations employing nonsupported Ti compounds, is a poor cocatalyst when used with MgCl₂/TiCl₄. It was found that in propylene and 1-butene polymerizations, using different MgCl₂/TiCl₄ catalysts, the cocatalyst activity of AlEt₂Cl can be greatly improved by the addition of a magnesium or lithium alkyl. The mixed metal alkyl obtained from AlEt₂Cl and MgBu₂ is a particularly effective cocatalyst always yielding more polymer, of about the same stereospecificity, than the conventional aluminum trialkyls. The exact nature of the mixed metal alkyl cocatalysts is not known, but the available evidence argues against in situ aluminum trialkyl formation resulting from the alkylation of AlEt₂Cl by the second metal alkyl.     

Effect of immobilization of titanocene catalyst in aralkyl imidazolium chloroaluminate media on performance of biphasic ethylene polymerization and polyethylene properties

1-(2-Phenylethyl)-3-methylimidazolium and 1-benzyl-3-methylimidazolium chloroaluminates, [Ph-C₂mim][AlCl₄] and [Bzlmim][AlCl₄], were applied as media of the Cp₂TiCl₂ catalyst for biphasic ethylene polymerization. The studied aralkyl ionic liquids ensure greater stability of the catalyst at higher temperatures and more regular morphology of the produced polyethylene than analogous 1-n-alkyl-3-methylimidazolium chloroaluminates. The alkylaluminium compound participates in the termination reaction of the polymer chain. The catalyst is stable and enables recycling of the ionic liquid phase in the consecutive polymerization reactions. The [Ph-C₂mim][AlCl₄] ionic liquid and AlEt₂Cl alkylaluminium compound turned out to be the most suitable for the biphasic process. The influence of the kind of ionic liquid, alkylaluminium compound (AlEt₂Cl and AlEtCl₂), activator/catalyst molar ratio, reaction temperature, reaction time and catalyst recycling on the polymerization performance as well as polyethylene properties such as molecular weight (M _w ), polydispersity, melting temperature, crystallinity degree, bulk density and particle size is presented.     

Preparation of highly active supported catalysts for producing polypropylene with less content of chloride

Summary Highly active supported catalysts for propylene polymerization have been prepared by treating the complexes of TiCl₃· 3C₅H₅N and MgCl₂·(THF) with AlEt₂Cl in the presence of MgO, Mg(OH) ₂ ^x or SiO₂. Polypropylene with less content or chloride was produced over these catalysts combined with AlEt₃.     

Polymerization of propylene by highly active catalysts synthesized with Mg(OEt)2/benzoyl chloride/TiCl4

Summary Active centers have been studied in the polymerization of propylene using highly active Mg(OEt)₂/Benzoyl chloride/TiCl₄ catalysts activated with AlEt₃. The method for the measurement of active centers is based on the inhibiting effect of CO on polymerization. The activity of the present catalysts, which is higher than that of TiCl₃ or MgCl₂-supported catalyst, is mainly due to the higher concentration of active centers by one order of magnitude. In order to investigate the stability of active centers during polymerization the number of active centers are compared at various polymerization times.     

Interaction of α-TiCl3 with organoaluminium compounds and its correlation with propylene polymerization

Summary The kinetics of the interaction between the catalyst components of a Ziegler-Natta sterospecific system formed by TiCl₃ and AlEt₃ in heptane was studied. The experimental results show that the rate of propylene polymerization is influenced by the rate of the interaction, activation energy, and the efficiency of interaction.     

Polymerisation of dec-1-ene. III. The nature of the catalyst species using triethylaluminium and titanium tetrachloride under cationic conditions

The polymerisation of dec-1-ene, using several combinations of aluminium alkyls and titanium halides, has been studied to try to elucidate the nature of the active catalyst species in the system triethylaluminium/titanium tetrachloride at a molar ratio (AlEt₃:TiCl₄) of 0.3:1. Polymers similar to those formed by the AlEt₃/TiCl₄ system have been obtained using ethylaluminium dichloride in combination with titanium trichloride and titanium tetrachloride. The complexes formed from these combinations are the most likely catalyst in the AlEt₃/TiCl₄ (0.3:1) system.     

Propylene polymerization with δ-TiCl3/AlClEt2 and δ-TiCl3/AlEt3 catalyst systems

Summary Some parameters of propylene polymerization using -TiCl₃/AlClEt₂ and -TiCl₃/AlEt₃ catalyst systems were evaluated. The catalyst was prepared through the reduction of TiCl₄ complexed with di-n-butyl ether (DBE) (mole ratio DBE/TiCl₄=0.67) by AlClEt₂. Propylene polymerizations were carried out at different Al/Ti ratios, using AlEt₃ or AlClEt₂ as cocatalysts and different polymerization temperatures. The effects of these parameters on catalyst activity, stereo-specificity and polymer molecular weight were investigated. The results indicate that these parameters strongly affect catalyst performance.     

Kinetic study on propylene polymerization by a high activity catalyst system: MgCl2/TiCl4/PhCO2Et-AlEt3/PhCO2Et

Summary Kinetic study was performed in short time propylene polymerization with a high activity-high stereospecificity catalyst system composed of MgCl₂/TiCl₄/PhCO₂Et with AlEt₃/PhCO₂Et. The concentration of the active centers, [C ^*], the propagation rate constant, k _p, and the chain transfer rate, r _tr, were determined. The change of these values by the change of polymerization conditions, the concentration of monomer, AlEt₃, and the temperature, were studied.     

Interaction of α-TiCl3 with organoaluminium compounds and its correlation with propylene polymerization

Summary The characterization of polymer system by means of interaction reaction between the catalyst components of a Ziegler-Natta stereospecific system formed by TiCl₃ and AlEt₃ in heptane was carried out. The experimental results show that the formation and decay of the active centers are interdependent. The interaction of the catalyst components, which causes a destruction of the solid phase, influences the rate of polymerization.     

Polymerization of propylene over metal oxides-supported TiCl3 catalysts

Summary Several metal oxides-supported TiCl₃ catalysts were prepared and propylene polymerization was conducted over them without cocatalysts. It was found that isotactic polymerization of propylene took place effectively over them.     

Kinetics of 1-hexene polymerization

Kinetics of 1-hexene polymerization was studied by following the amount of unreacted monomer using gas chromatography. The Ziegler-Natta catalyst system used was comprised of TiCl₄-AlEt₃ with Al: Ti ratio of 0.85. The sampling and monomer analysis techniques developed can be applied to study the kinetics of higher α-olefins polymerizations, in general. Also, with minor modifications in this technique, a precise profile of molecular weight can be obtained during polymerization.     

Interaction of α-TiCl3 with organoaluminium compounds and its correlation with propylene polymerization

Summary The interaction between the catalytic components of a Ziegler-Natta sterospecific system formed by TiCl₃ and AlEt₃ in heptane was studied. The extent of interaction was monitored by following the rate of chlorine exchange between the solid and liquid phase and by the development of gaseous hydrocarbons. The experimental results show that interaction between the catalytic components is a necessary but not the only condition for the formation of active centers of sterospecific polymerization.     

Investigation of polymerizability of ω-alkenyldioxolanes with α-olefins and alkyl vinyl ethers by modified ziegler-natta catalysts

Results are presented of an investigation on the polymerizability of functional olefins, such as allylisopropylidene glycerol (AIPG) and undecenylisopropylidene glycerol (UIPG), in the presence of conventional and modified Ziegler-Natta catalysts based on TiCl₄ or MgCl₂-supported titanium and triisobutylaluminum, hexaisobutyltetraalumoxane, or bisdiethyl-aluminum sulfate. Homopolymerization experiments were performed on AIGP at temperatures of -78, 25, and 50°C; only these at 50°C provided appreciable amounts of polymeric materials insoluble in methanol, whose structures comprise monomeric units derived from opening both dioxolane rings and vinyl double bonds. In spite of all attempts and precautions, polymerization experiments carried out on mixtures of the functional olefins AIPG and UIPG with either 4-methyl-1-pentene or isopropyl vinyl ether gave rise to the homopolymers of the nonfunctional α-olefin and of the vinyl ether, without any appreciable amount of either copolymers or homopolymers of the dioxolane containing monomers. © 1996 John Wiley & Sons, Inc.