1. Highly active chromium-based selective ethylene tri-/tetramerization catalysts supported by PNPO phosphazane ligands.
- Author
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Zhou, Yusheng, Wu, Hongfei, Xu, Sheng, Zhang, Xuejun, Shi, Min, and Zhang, Jun
- Subjects
CHROMIUM catalysts ,PHOSPHAZANES ,OLIGOMERIZATION ,CATALYTIC activity ,LIGANDS (Chemistry) ,SUBSTITUENTS (Chemistry) - Abstract
Novel Cr(iii) catalysts supported by PNPO phosphazane ligands of the type Ph
2 PN(R)P(Ph)OAr have been prepared, all of which, upon activation with MMAO-3A, are highly active in ethylene tri-/tetramerization with considerable selectivity. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the PNPO phosphazane ligand with an N-cyclohexyl achieved high activity of 316.7 kg (g Cr h−1 )−1 and a high total selectivity of 85.1% towards valuable 1-hexene (45.7%) and 1-octene (39.4%) using chlorobenzene as the solvent at 35 bar and 40 °C. In methylcyclohexane, the precatalyst supported by [Ph2 PN(i Pr)P(Ph)OPh] exhibited a higher 1-octene selectivity (54.0%) with a considerable activity of 73.3 kg (g Cr h−1 )−1 at 35 bar and 40 °C. With the fine-tuned ligand backbone, such a PNPO phosphazane-based catalyst system provides a mode for precise understanding of the impact of ligand variations on catalytic performance. [ABSTRACT FROM AUTHOR]- Published
- 2015
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