M. Nele et Jc. Pinto, Retrofitting of industrial olefin polymerization plants: Producing broad MWDs through multiobjective periodic operation, J APPL POLY, 77(2), 2000, pp. 437-452
The drop-in of metallocene catalysts (MCs) in existing industrial polymeriz
ation plants is the current goal of most polymer producers. However, the na
rrow molecular weight distribution (MWD) of the polymers produced by NICs p
revent them of moving into commodities market dominated by conventional Zie
gler-Natta catalysts, where ease of processing is an essential property. Br
oader MWDs may be obtained through mixing of different iMCs or blending of
different resins, but resin-compatibility problems and complex undesirable
catalyst interactions pose technological problems that have yet to be solve
d. For these reasons, modern olefin polymerization plants have to work with
both catalysts to respond to market demands, resulting in costly operation
s of grade/catalyst change. In this article, we describe how periodic contr
ol of short residence-time reactors operating with an MC (Me2Si(2-Me-Benz[e
]Ind)(2)ZrCl2/MAO) can lead to polymers with broad MWD and, consequently, t
o high processability. (C) 2000 John Wiley & Sons, Inc.