Effect of Water on the Supported Ziegler–Natta Catalysts: Optimization of the Operating Conditions by Response Surface Methodology

Abstract

In this study different water containing adducts, with MgCl 2 ÁnEtOHÁmH 2 O formula, were synthesized through melt quenching method. After characterization of support samples, the final catalysts were prepared by reaction of the samples with TiCl 4 and tested in slurry phase propylene polymerization. The prepared catalysts showed similar stereospecificities but different activities in polymerization experiments, so that, with increasing water amount from m = 0.0 to m = 0.4 wt%, the catalyst activity reached its maximum value of 4.62 kgPP/g Cat.h, and then by further water increase, from m = 0.4 to m = 1.0 wt%, the activity decreased. After optimizing water content, to reach the maximum efficiency of the catalytic system, optimization of the synthesis conditions was considered via response surface methodology. The studied operation conditions affecting the catalyst efficiency were volume ratio of TiCl 4 to toluene (V), initial TiCl 4 injection temperature (I) and TiCl 4 injection time (T). Results showed that catalytic performance is strongly dependent on its preparation conditions. Analysis of variance indicated that V and I are the most effecting parameters on the catalyst activity with F-value of 39.64, and 8.12, respectively. Indeed, it was found that TiCl 4 injection time had no enormous effect on the catalyst activity, but in combination with V, the injection time increment through the scrutinized range decreased the polymerization activity. The obtained model provided a promising tool for designing suitable catalysts for polypropylene production using MgCl 2 /TiCl 4 based Ziegler-Natta catalysts. Graphical Abstract The focus of the present study is to explore how the presence of water in the adduct synthesis step affects the final ZN catalyst performance in propylene polymerization. Besides water amount, effect of important catalyst synthesis parameters on the catalytic performance was studied as well through response surface methodology.

Different behaviors of metallocene and Ziegler–Natta catalysts in ethylene/1,5‐hexadiene copolymerization

“…Zirconocene (Cp 2 ZrCl 2 ) and hafnocene (Cp 2 HfCl 2 ) catalysts were commercially obtained from Aldrich Company (Munich, Germany). An MgCl 2 /TiCl 4 ‐based catalyst that was synthesized according to our previous work was used as the ZN catalyst precursor . It contained 3% Ti as the active center.…”

“…An MgCl 2 /TiCl 4 -based catalyst that was synthesized according to our previous work was used as the ZN catalyst precursor. 17 It contained 3% Ti as the active center. Ethylene and nitrogen were purchased from Bandar Imam Petrochemical Company (Mahshahr, Iran) and Roham Company (Tehran, Iran), respectively, and were purified by flowing through molecular sieves (3 and 4 Å) and CuO/Al 2 O 3 packed beds to remove oxygen and water residues.…”

Highly efficient FeCl3 doped Mg(OEt)2/TiCl4-based Ziegler–Natta catalysts for ethylene polymerization

“…Because the use of MgC1 2 as a support drastically enhanced the catalyst activity, a great deal of attention has been focused on the development of various effective supports, such as inorganic compounds. [4,5] Nowadays, as two kinds of major industrial materials of the carrier, MgCl 2 ·nROH and magnesium ethoxide, Mg(OEt) 2 , are widely known. [6,7] Although, Mg(OEt) 2 has a morphological subject regarding roundness and particle size distribution as compared with MgCl 2 ·nROH, the catalyst made by Mg(OEt) 2 shows a higher activity.…”

“…[15][16][17][18] Lately, investigations have shown that doping a suitable amount of Lewis acids in MgCl 2 or Mg(OEt) 2 supports would be an effective way to improve their catalytic performance in α-olefin polymerization. The mostly used doping agents were based on different metal halides such as MnCl 2 , [2] ZnCl 2 , [3] NaCl, [4] AlCl 3 [5,6,19], and the mixture of metal halide with metalloids like ZnCl 2 -SiCl 4 system. [7,8] These agents not only can have notable effect on catalyst activity but also have the ability to change catalyst efficiency toward higher α-olefins in LLDPE production as well as stereo-regularity of final polymer in propylene polymerization.…”

Effects of monomer length on α‐olefins polymerization using a conventional Ziegler–Natta catalyst

“…The Ziegler-Natta catalyst was prepared according to our previous paper. [13] It was based on MgCl 2 /ethanol adduct, in which 3.3% Ti was loaded in TiCl 4 form. Triethylaluminium (TEAL, 2.7 M, as cocatalyst) and cyclohexyl methyl dimethoxy silane (CMMS, as external donor) were purchased from Sigma-Aldrich and used as received.…”