Slurry-Phase Ethylene Polymerization Using Pentafluorophenyl- and Pentafluorophenoxy-Modified Solid Polymethylaluminoxanes

Abstract

Post synthesis modification of solid polymethylaluminoxane (sMAO) with tris(pentafluorophenyl)borane or pentafluorophenol produces highly active metallocene supports "sMMAOs" for use in slurry-phase ethylene polymerization. Characterization of the sMMAOs using ICP-MS analysis, BET isotherm, SEM-EDX, diffuse FT-IR and solid state NMR spectroscopy reveals that the surface methyl groups are exchanged for C 6 F 5 and C 6 F 5 O moieties respectively, giving a material with reduced aluminum content and a lower specific surface area than sMAO. Rac-ethylenebis(1-indenyl) zirconium dichloride, {(EBI)ZrCl 2 } immobilized on B(C 6 F 5) 3 and C 6 F 5 OH modified sMAO displayed activity increases of 66 and 71% respectively for ethylene polymerization compared to the same zirconocene catalyst precursor on unmodified sMAO. In the case of B(C 6 F 5) 3 modified sMAO this enhanced polymerization activity is accompanied by excellent control of polymer particle size and morphology, and a small decrease in polymer molecular weight and polydispersities. Scheme 1. Schematic of the synthetic routes to (a) Lewis acid; (b) phenoxy modified MAO solutions; and (c) free TMA removal. A linear MAO formula is shown for simplicity.

Physicochemical surface-structure studies of highly active zirconocene polymerisation catalysts on solid polymethylaluminoxane activating supports

“…[12][13][14] Observed activities are significantly higher than for other supports; for example sMAO-rac-ethylenebis(1-permethylindenyl)zirconium dichloride is at least three times more active than its silicasupported MAO counterpart (5365 vs. 1649 kg PE mol Zr À1 h À1 bar À1 respectively). 15,16 Furthermore, we have shown that reaction of sMAO with tris(pentafluorophenyl)borane or pentafluorophenol produces highly active modified-sMAO supports which show enhanced polymerisation activity with both rac-ethylenebis(1-indenyl) zirconium dichloride, rac-(EBI)ZrCl 2 , 17 and a range of unsymmetrical ansa-bridged permethylindenyl complexes. 18 Characterisation of sMAO using multinuclear NMR spectroscopy in solution and in the solid state reveals an aluminoxane structure that features ''structural'' and ''free'' AlMe x units in addition to benzoate residues.…”

Synthesis of zirconocene complexes and their use in slurry-phase polymerisation of ethylene

“…This insoluble 'solid MAO' can act simultaneously as both co-catalyst and support in slurry phase ethylene polymerisation. 28,29 Results and discussion Synthesis of ( 3-R Ind # ) 2 ZrX 2 (R ¼ Me, Et or Ph; X¼ Cl, Br or CH 2 Ph)…”

Catalyst Deactivation Processes during 1-Hexene Polymerization

“…27 This additive has proven useful in monitoring both aging and oxidation of MAO, 28,29 features known to be important in affecting the efficacy of this elusive but important activator. [30][31][32] We have also studied the reaction of MAO-activated Cp 2 ZrMe 2 with ethylene in toluene solution at low ethylene pressures. 33 In that case, a hitherto undetected, but long-suspected process for catalyst deactivation 34 was revealed by ESI-MS -formation of inactive, dinuclear Zr 2 complexes arising from the reaction of active species (i.e.…”