Optimization of a new catalyst composition for trimerization of ethylene

Document Type : Original research

Authors

1 Department of Chemical Engineering, Faculty of Engineering, Arak University, Arak 38156-8-8349, Iran

2 R&D Center, Shazand Petrochemical Company (ARPC), Arak 575, Iran

Abstract

The performance of the catalyst system [chromium(III)/pyrrole/co-catalyst/halide] on the trimerization of ethylene has been studied using the combined experimental and response surface method (RSM). The chromium(III) tris(2-ethylhexanoate) was synthesized and characterized by FTIR, 1HNMR and 13CNMR, to study chemical properties and identify molecular structures. The effect of four variables Al/Cr molar ratio, halide/Cr molar ratio, reaction temperature and catalyst dosage have been considered on catalyst activity, 1-hexene selectivity and polymer content. The central composite design (CCD) model with three main parameters in three response levels for each factor was applied to analyze the effects of the parameters. The comparative studies showed that carbon-tetra-chloride (CCl4) and tri-n-octyl-aluminum (TNOA) were the best candidates for this catalyst system, demonstrating high selectivity of 1-hexene formation, higher catalytic activity and lower polymer content. Based on the RSM results, the best trimerization condition for ethylene at 25 bar and 91.2°C was obtained at the catalytic system [Cr(2-EH)3/2,5-DMP/CCl4/TNOA] molar ratio of 1:6:10.8:201.5, which showed the activity of 105328 (g 1-C6/(g Cr.hr)), 99.21% selectivity for 1-hexene and no polymer was formed. The predicted process parameters were also verified by actual experiments at the optimized conditions.

Keywords

Main Subjects

References

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Polyolefins Journal
Volume 11, Issue 4 - Serial Number 26
December 2024
Pages 219-233

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History

  • Receive Date: 07 September 2024
  • Revise Date: 16 October 2024
  • Accept Date: 19 October 2024
  • First Publish Date: 23 October 2024

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