Alkene polymerization reactions with catalysts based on acetylacetonate complexes of vanadium and titanium: effect of cocatalyst

Abstract

Alkene polymerization reactions were studied with three catalyst systems containing complexes of vanadium and titanium with the acetylacetonate ligand (V(acac)3, VO(acac)2, Ti(acac)2Cl2) and a binary activator, a combination of Al(C2H5)2Cl and Mg(C4H9)2 at an [Al]:[Mg] molar ratio of ca 3. All three catalysts are highly active in ethylene homopolymerization reactions. They copolymerize ethylene and 1‐hexene to random, compositionally uniform products with 1‐hexene content of up to 20–25%. The Ti(acac)2Cl2–Al(C2H5)2Cl/Mg(C4H9)2 combination is also an effective catalyst for propylene polymerization to an essentially atactic product. Gel permeation chromatography analysis showed that all the studied M(acac)n–Al(C2H5)2Cl/Mg(C4H9)2 catalysts contain several types of active centers which differ in the average molecular weight of polymer material they produce. © 2021 Society of Industrial Chemistry.

The role of alkoxysilanes in propylene polymerization catalysis. A study of model Ti(Oi‐C3H7)4‐Al(C2H5)2Cl/Mg(C4H9)2 catalyst system

“…Our earlier research showed that combinations of two types of organometallic compounds, AlR 2 Cl (R = CH 3 , C 2 H 5 , i-C 4 H 9 ) and MgR 0 2 (R 0 = n-and i-C 4 H 9 ), at an [Al]/[Mg] molar ratio of over 2 are universal activators for various types of transition metal polymerization catalysts, including TiCl 4 , 37,38 Ti 3+ -and Ti 4+ -based heterogeneous and supported catalysts, 39 Ti(OR) 4 , 22,40 metallocene complexes 41 and numerous pre-and post-metallocene catalysts. 39,[41][42][43][44][45] The Ti(Oi-C 3 H 7 ) 4 -Al(C 2 H 5 ) 2 Cl/Mg(C 4 H 9 ) 2 catalyst used in this research is a pseudo-homogeneous catalytic system. All its components are soluble in aliphatic and aromatic hydrocarbons but combining Al(C 2 H 5 ) 2 Cl and Mg(C 4 H 9 ) 2 generates finely dispersed MgCl 2 crystals with a Lewis-acidic surface: [37][38][39]46 Mg C…”

“…Our earlier research showed that combinations of two types of organometallic compounds, AlR 2 Cl (R = CH 3 , C 2 H 5 , i ‐C 4 H 9 ) and MgR′ 2 ( R ′ = n ‐ and i ‐C 4 H 9 ), at an [Al]/[Mg] molar ratio of over 2 are universal activators for various types of transition metal polymerization catalysts, including TiCl 4 , 37, 38 Ti 3+ ‐ and Ti 4+ ‐based heterogeneous and supported catalysts, 39 Ti(OR) 4 , 22, 40 metallocene complexes 41 and numerous pre‐ and post‐metallocene catalysts 39, 41–45 …”