Catalysis
Odilia Pérez-Camacho; Eduardo Cardozo-Villalba
Abstract
In this work, the interaction between a polystearylmethacrylate (Mn = 8,900 g mol-1, Xn = 26, Ð = 1.1) and modified methylaluminoxane 12 (MMAO-12) co-catalyst is studied using different spectroscopic methods. The effect of this oxygen-donor additive was measured by the changes in the bulk ...
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In this work, the interaction between a polystearylmethacrylate (Mn = 8,900 g mol-1, Xn = 26, Ð = 1.1) and modified methylaluminoxane 12 (MMAO-12) co-catalyst is studied using different spectroscopic methods. The effect of this oxygen-donor additive was measured by the changes in the bulk density of the raw polyethylene, which resulted increased respect to those obtained in blank reactions. A decrease in the activity was also observed as a penalty for the improvement of the bulk density, enhancing the possibility of reducing fouling. The coordination of the carbonyl oxygen groups of polystearylmethacrylate to aluminum (III) centers is confirmed by 1H-NMR and FTIR studies, and by a simple semi-empirical computational calculation. A method for obtaining a tri-component co-catalyst mixture is described using the methyl-bridging capacity of trimethylaluminum and its Lewis acidity to get the polystearylmethacrylate and MMAO-12 linked together. This robust adduct introduces a hierarchy over the PE chain growing, leading to higher bulk densities for PE beads (0.43 g cm-3) concerning blank reactions (0.26 g cm-3).
Catalysis
Takao Tayano; Takehiro Sagae; Takashi Atsumi; Hideshi Uchino; Masahide Murata; Tsutomu Sato
Abstract
Spray dry granulation of clay minerals was studied to obtain clay mineral base support material for metallocene supported olefin polymerization catalysts. The morphology of the granules was strongly influenced by the nature of the clay mineral itself. Because of swelling characteristics of montmorillonite, ...
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Spray dry granulation of clay minerals was studied to obtain clay mineral base support material for metallocene supported olefin polymerization catalysts. The morphology of the granules was strongly influenced by the nature of the clay mineral itself. Because of swelling characteristics of montmorillonite, its water dispersion was highly viscous even in the low slurry concentration (< 4 wt %). Therefore, it was very difficult to control the granule characteristics such as size, shape, and inside structure by the spray dry with the clay mineral slurry. Then we examined some methods in order to change the clay mineral surface properties for getting less viscous dispersion. It was found that the milling of montmorillonite increased the amount of surface OH groups. This surface characteristic change should promote the interaction between the edges and basal planes of the primary particles of milled montmorillonite, resulting in the lowering the slurry viscosity. The milling is effective for overcoming difficulty in use of high concentration montmorillonite slurry in spray dry granulation which is indispensable for producing granules in the wide range of size (10–50 μm). The spray-dried montmorillonite granules are useful as a "Support-Activator" for an olefin polymerization catalyst combined with metallocenes.
