Highly active supported catalyst of Ziegler-Natta type was prepared by reaction of a Grignard reagent. The starting chemicals for preparing MgCl2, the support, were butyl magnesium chloride which mixed with AlCl3 and CH3Si(OC2H5)3, following to two steps treatment of the chemicals with TiCl4 in toluene. Ti  oncentration in the solid catalyst was 3.19%. Slurry polymerization of ethylene was carried out using the catalyst in dry heptane, while, triethylaluminium was used as cocatalyst. The cocatalyst effects, such as cocatalyst/catalyst molar ratio, polymerization time, temperature, H2 concentration and the monomer pressure on activity of the catalyst were studied. There was an optimum [Al]/[Ti] molar ratio and temperature to obtain the highest activity of the catalyst. The maximum activity was obtained at 60ºC, and [Al]/[Ti]=714:1. Productivity of 14700 g PE/mmol Ti.h was obtained at monomer pressure of 8 bar. Addition of hydrogen decreased the activity of catalyst and the viscosity average molecular weight (Mv) of the polymer obtained, while, increasing monomer pressure increased its activity. Density of the polymer obtained was 0.93- 0.95 g/cm3 which is in the range of high density polyethylene. Melting point of the polymer was in the range of 140-1440C.

The determination of Ti+4 in Ziegler–Natta catalysts is highly relevant for industrial plants that use Ziegler–Natta (ZN) catalysts based on TiCl4 as a source of titanium. The catalyst preparation step requires analytical monitoring during the dilution process for the morphological effect according to the relationship between the Ti+3 and Ti+4 concentrations in the polymerization process, which in turn depend on a variety of intended grades for different market applications. Spectrophotometry in the visible region was evaluated as a potential analytical technique for the quantification of Ti+4 in ZN catalysts. The present study proposes the use of an easily accessible, reliable and low-cost validated instrumental method for Ti+4 determination. Therefore, the technical details regarding sample preparation, instrumental analytical parameters and performance characteristics of the method were descriptively addressed. The quantitative evaluation of performance parameters (namely, specificity, linearity, detection and quantification limits, precision, accuracy and robustness) demonstrated successful results compared with the theoretical values of the studied reference sample. The precision of the method by visible spectrophotometry was estimated at 0.4% for the relative error, and the accuracy presented within an IC of 95% for the LOC ± 1.7 mmolTi/L for the average concentration of 339.5 mmolTi L-1 in reference to the Tyzor ® TnBT sample with a theoretical concentration of 337 mmol L-1 study solution from this work. The method was shown to be a supporting tool for quantitative Ti+4 species determination in the control of industrial processes.

Hydrogen in spite of having a chain transfer agent role is one of the most important factors which directly affecting on kinetic of propylene polymerization. Hydrogen causes to dramatically increase the percentage of activated sites in proportion to being total potential sites on the catalyst surface. On the other hand, the chain transfer agent role of hydrogen gives rise to changing some vital indices of final product properties. This study has attempted to present a validated mathematical model that able to predicting profile polymerization rate and also calculating some of the vital indices of the final product, properties to be derived from kinetic equations. Furthermore, in this paper, we present a developed model that calculates fraction activated sites catalyst via hydrogen concentration based on dormant site theory and determining the best process condition. The modeling approach is based on the polymer moment balance method, i. e. population balance technique and validated by experimental works. The main aim of this study is assigned to investigate the behavior change of polymerization rate to hydrogen. The experimental data and model outputs were compared and concluded that the global errors were in the acceptable range.

Several types of hybrid catalysts are made through mixing of 4th generation Ziegler-Natta (ZN) and (2-PhInd) 2ZrCl2 metallocene catalysts using triethylaluminum (TEA) as coupling agent. Response surface methodology (RSM) is used to evaluate the interactive effects of different parameters including amounts of metallocene and TEA and temperature on metallocene loading. Analyzing the amounts of Al and Zr elements in the hybrid catalysts through ICP-OES and EDXA reveals that temperature plays a crucial role on anchoring of the metallocene catalyst on ZN while TEA has the least determining effect. The ICP analysis shows that as the concentration of Al goes up in the hybrid catalyst the concentration of Zr passes a maximum, while EDXA shows a direct relationship between the Al and Zr contents. Using triisobutylaluminum (TIBA) and methylaluminoxane (MAO) as the coupling agents, almost similar metallocene loadings are observed. Finally, the performance of hybrid catalysts is investigated in propylene polymerization and the obtained polymers are characterized using DSC and DMTA through which the presence of two types of polymers in the final product are confirmed.

Different chemical components in traditional Ziegler–Natta catalytic system include: (1) titanium and vanadium containing compounds, mostly TiCl4, as an active centre, (2) trialkylaluminium-based Lewis acid compounds, especially triethylaluminium, as precatalyst and alkylating agent, and (3) inorganic compounds, specifically MgCl2 and silica, as catalyst supports. Besides these compounds, shortly after the first discovery of Ziegler-Natta catalysts, electron donors have been considered as the key components for MgCl2-supported Ziegler-Natta catalysts, as they improve the stereospecificity and activity of these types of catalysts. Most electron donor compounds have oxygen atom and only a few contain nitrogen atom in their structure. Starting from benzoate for third-generation Ziegler–Natta catalysts, the discovery of new donors has always updated the performance of Ziegler–Natta catalysts. Since the first discovery of these compounds numerous efforts have been devoted in both industry and academic laboratories, not only to discover new electron donors but also to understand their roles in Ziegler–Natta olefin polymerization and suitable MgCl2-alcohol adducts formation. This article reviews the history of such research and development efforts. The first part of the article describes the historical developments of catalyst, with a special focus on donors of industrial importance, followed by an account given on recent trends in the latest donors developed. The next part of the article covers the historical progress toward mechanistic understanding of how donors improve the performance of Ziegler–Natta catalysts and how they undergo decomposition by interaction with Lewis acidic species such as the AlEt3 and TiCl4.

Suspension polymerizations were carried out at 1 atm of propylene in pentamethyl heptane using Mg(OC2H5)/di-n-butylphthalate/TiCl4-AlEt3/diphenyldimethoxy silane catalyst system. Active centre concentration (C*) was determined by quenching and radio-tagging methods using tritiated methanol and carbon monoxide, respectively. Effect of external donor on the C* was studied. An investigation in the effect of temperature ( 50-80 ° C) on C*, and propagation rate coefficient, kp , was carried out using the catalyst system. The optimum values of C* were achieved at 65-70 ° C. The maximum rate of polymerization as well as the kp values increased steadily with increasing temperature. The preliminary investigation involved the time needed for the tritiated methanol and carbon monoxide to react with the active centres to stop the polymerization quickly and completely. The amount of carbon monoxide and alcohol which were able to stop the polymerization was also determined. In the present work a five-fold of tritiated alcohol concentration to alkylaluminium was used.