Molecular weight distribution broadening of polypropylene by periodic switching of hydrogen and catalyst additions

M. Al-Haj Ali, J. Stoomer, Bernardus H.L. Betlem, G. Weickert, B. Roffel

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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.
Original languageUndefined
Pages (from-to)2446-2457
JournalJournal of applied polymer science
Issue number4
Publication statusPublished - 2008


  • IR-72578
  • Molecular weight distribution broadening
  • periodic operation
  • liquid pool polymerization
  • control vector parameterization

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