Abstract—Ziegler-Natta (Z-N) catalysts have been established as the catalysts of choice since the 1950s for low pressure production of polyethylene grades. These catalysts are mainly based on titanium with an organo-aluminium activator. The discovery of MgCl2 as a support for Z-N catalysts led to a greatly increased catalyst activity. The phenomenon of replication in industrial gas phase polyethylene reactors necessitated the search for a support with high structural strength and an ability to be made in precisely tailored particle size distribution and morphology. MgCl2, although excellent in its chemical reactivity, was found wanting in structural strength and morphology control. These dual advantages were achieved when silica was used as a carrier/support for growing MgCl2 supported Z-N catalysts. There are numerous patent references on the manufacture of highly active silica supported Z-N catalysts as well as a number of commercial standard silica supported Z-N catalysts as per specific needs. This paper describes the methodologies, basis and results of comparison of various standard silica-supported catalysts in a simple lab reactor set-up without the need for elaborate pilot plant trials. Three commonly available samples of silica supported catalyst were obtained and compared with benchmark Z-N catalyst. The catalysts were tested for their performance in both solvent phase polymerization reactor as well as gas phase fluidized bed reactor. The overall yield and quality of polymer were compared as well as the kinetic performance of each catalyst. A heat balance was generated around the gas phase reactor to arrive at kinetic profiles of catalyst activity. The prediction of scale-up behaviour of these catalysts based on lab reactor data and kinetic parameters has been discussed.
Index Terms—Fluidized bed reactor, scale-up, silica-supported Ziegler-Natta catalysts.
The authors are with the Polymer Technology Group, Reliance Industries Limited, 7B-GF, Reliance Corporate Park, Ghansoli, Navi Mumbai, 400701, India (e-mail: Sivalingam.gunasekaran@ril.com).
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Cite: Vinit D. Makwana, G. Sivalingam, and Suketu M. Vakil, "Catalyst Evaluation and Scale-up Studies for Polyethylene Production," International Journal of Chemical Engineering and Applications vol. 5, no. 1, pp. 6-12, 2014.
