Ethylene tetramerization is an attractive technology for the selective production of 1-octene which is commonly used as co-monomer in the production of linear low-density polyethylene (LLDPE). This catalysis, which originally employed a chromium catalyst with a bis(diphenylphosphino)isopropylamine (<i>i</i>Pr-PNP) ligand, was first reported in 2004, and improvements to this technology have been sought since its introduction. Most notably, maximizing selectivity for 1-octene and minimizing the formation of undesirable byproducts, especially high density polyethylene (HDPE) which is formed in low levels but can lead to reactor fouling, is desired. This presentation will describe the discovery of new chromium catalysts for ethylene tetramerization based on phospholane-containing ligand frameworks. Structure-property relationships among the prepared catalysts were investigated, and it was determined that the steric bulk of the ligand impacts reaction selectivity, with smaller ligands leading to the production of larger proportions of 1-octene. These new phospholane-containing catalysts were found to be significantly more active and lead to lower levels of HDPE than incumbent technology.

Discovery and development of novel chromium-based catalysts for ethylene tetramerization

255th National Meeting (2018)

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