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Molecular weight distribution broadening of polypropylene by periodic switching of hydrogen and catalyst additions |
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| Authors: | M. Al‐Haj Ali J. Stroomer B. Betlem G. Weickert B. Roffel |
| Affiliation: | 1. Department of Chemical Engineering‐King Saud University, Riyadh 11421, Saudi Arabia;2. HoSt BV, P.O. Box 920, 7550 AX Hengelo, The Netherlands;3. University of Twente, 7500 AE Enschede, The Netherlands;4. Polymer Reactor Technology GmbH, Mühlenweg 31, D‐48683 Ahaus, Germany;5. University of Groningen, NL‐9700 AV Groningen, The Netherlands |
| Abstract: | This study presents a feasibility study of the broadening of the polypropylene molecular weight distribution produced using a multisite Ziegler‐Natta catalyst in a continuous liquid‐pool polymerization reactor. The broadening is achieved by operating the reactor under periodic forcing of both hydrogen and catalyst feed flows. Model‐based dynamic optimization is used to determine the cycle period and peak width for these inputs. Through simulation it is shown that limited widening (～ 30%) of the molecular weight distribution can be achieved in case of a limited removal of hydrogen from the reactor. The results also show that the forced removal of hydrogen from the reactor could potentially double the polydispersity index of the produced polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 |
| Keywords: | molecular weight distribution broadening liquid‐pool polymerization periodic operation control vector parameterization |