Molecular weight distribution broadening of polypropylene by periodic switching of hydrogen and catalyst additions
Corresponding Author
M. Al-Haj Ali
Department of Chemical Engineering-King Saud University, Riyadh 11421, Saudi Arabia
Department of Chemical Engineering-King Saud University, Riyadh 11421, Saudi Arabia===Search for more papers by this authorJ. Stroomer
HoSt BV, P.O. Box 920, 7550 AX Hengelo, The Netherlands
Search for more papers by this authorB. Betlem
University of Twente, 7500 AE Enschede, The Netherlands
Search for more papers by this authorG. Weickert
Polymer Reactor Technology GmbH, Mühlenweg 31, D-48683 Ahaus, Germany
Search for more papers by this authorB. Roffel
University of Groningen, NL-9700 AV Groningen, The Netherlands
Search for more papers by this authorCorresponding Author
M. Al-Haj Ali
Department of Chemical Engineering-King Saud University, Riyadh 11421, Saudi Arabia
Department of Chemical Engineering-King Saud University, Riyadh 11421, Saudi Arabia===Search for more papers by this authorJ. Stroomer
HoSt BV, P.O. Box 920, 7550 AX Hengelo, The Netherlands
Search for more papers by this authorB. Betlem
University of Twente, 7500 AE Enschede, The Netherlands
Search for more papers by this authorG. Weickert
Polymer Reactor Technology GmbH, Mühlenweg 31, D-48683 Ahaus, Germany
Search for more papers by this authorB. Roffel
University of Groningen, NL-9700 AV Groningen, The Netherlands
Search for more papers by this authorAbstract
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
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