Kinetics of ethylene polymerization over titanium-magnesium catalysts: The reasons for the observed second order of polymerization rate with respect to ethylene
Journal Title: Polyolefins Journal - Year 2015, Vol 2, Issue 1
Abstract
The data on the effect of ethylene concentration on polymerization rate for several modifications of modern highly active titanium–magnesium catalysts TiCl4/MgCl2 are presented. These catalysts differ in titanium content and conditions of support preparation, activities, and the shape of kinetic curves. It is found that the observed order of polymerization rate with respect to ethylene in the range of ethylene pressures of 0.5–6 bar is 1.8-2.1 for all catalysts used (polymerization at 80°C, AlEt3 used as a cocatalyst). When AlEt3 was replaced with Al(i-Bu)3, the reaction order decreased to 1.3-1.4. In order to elucidate the possible reasons for the observed high order with respect to ethylene, we analyzed the data on the effect of monomer concentration on the molecular weight of polyethylene. The results gave grounds for suggesting that the observed order with respect to monomer is attributable to the effect of ethylene concentration on the number of active sites. The possible reaction scheme explaining the nonlinear dependence of the polymerization rate on monomer concentration was proposed based on these data.
Authors and Affiliations
Mikhail A. Matsko, Vladimir Aleksandrovich Zakharov, Marina I. Nikolaeva, Tatiana B. Mikenas
Keywords
Related Articles
- EP ID EP283081
- DOI 10.22063/POJ.2015.1112
- Views 124
- Downloads 0
Addition of a second alcohol in magnesium ethoxide synthesis as a way to vary the pore architecture of Ziegler-Natta catalysts
In Ziegler-Natta olefin polymerization, the pore architecture of catalysts plays a crucial role in catalytic performances and polymer properties. While the type of preparation routes (such as chemical reaction and soluti...
Fouling mechanisms during protein microfiltration: The effects of protein structure and filtration pressure on polypropylene microporous membrane performance
A polypropylene microporous membrane (PPMM) was fabricated by thermally induced phase separation (TIPS) method. The effects of protein size and structure as well as filtration pressure on the membrane performance and fou...
In situ stabilization of polypropylene by lignin using a Ziegler-Natta catalyst
A fourth-generation Ziegler-Natta catalyst was prepared to synthesize polypropylene (PP), which was stabilized by in situ polymerization employing lignin as antioxidant. The antioxidant properties of lignin were compared...
Study of Ziegler-Natta/(2-PhInd)2ZrCl2 hybrid catalysts performance in slurry propylene polymerization
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)...
Effect of the synthesis conditions of titanium-magnesium catalysts on the composition, structure and performance in propylene polymerization
Supported catalysts synthesized via the interaction of Mg(OEt)2 with TiCl4 in the presence or absence of an internal stereoregulating donor (di-n-butyl phthalate), with different solvents (chlorobenzene, n-undecane, n-he...