Selective Ethylene Oligomerization

Abstract

Ethylene oligomerization to produce 1-alkenes is a cornerstone of organometallic research. The original αolefin commercial catalyst system, triethylaluminum, has grown to become one of the highest volume organometallics. This tutorial covers the developmental arc of ethylene oligomerization research and explains the ongoing technological shift from full-range (C 4 −C 30 ) to selective (C 6 , C 8 ) catalytic systems. Catalyst design determines product selectivity, and the differing mechanisms underpinning catalyst performance, linear versus metallacyclic, are covered in detail. Despite the field's maturity, there are still significant opportunities for exploration and discovery which are discussed at the conclusion.

PNPN‐H in Comparison to other PNP, PNPN and NPNPN Ligands for the Chromium Catalyzed Selective Ethylene Oligomerization

“…In a very interesting tutorial Sydora recently summarized several aspects of the selective ethylene oligomerization. [36] In the chapter regarding the general oligomerization mechanism he wrote about the tetramerization: "The proposed general mechanism of ethylene tetramerization builds off the ethylene trimerization metallacycloheptane intermediate with ethylene coordination followed by insertion and 1-octene elimination. Agapie recently published an isotopic labeling study confirming that the ethylene trimerization and tetramerization pathways share a common monomeric chromacycloheptane intermediate.…”

Investigating the Active Species in a [(R‐SN(H)S‐R)CrCl3] Ethene Trimerization System: Mononuclear or Dinuclear?

“…[3] However, due to the growing market demand for shorter LAOs, several companies (e. g. Sasol and Chevron Phillips Chemical) have successfully commercialized chromium catalysts that are capable of selectively forming 1-hexene. [4,5] An early mechanistic proposal has suggested the involvement of metalacyclic intermediates to explain the observed product selectivity (Scheme 1) and this proposal has been validated via deuterium labeling experiments. [6,7] However, the oxidation state of chromium during the catalytic cycle is still subject to debate.…”

“…Traditionally, LAOs are produced by ethene oligomerization catalysts which generate a statistical product distribution, e. g. the nickel‐based SHOP catalyst . However, due to the growing market demand for shorter LAOs, several companies (e. g. Sasol and Chevron Phillips Chemical) have successfully commercialized chromium catalysts that are capable of selectively forming 1‐hexene …”

Zirconium Catalyzed Ethylene Oligomerization

“…In a few articles, it is exclusively discussed with the results collected using chromium based catalysts . Recent technological developments and some existing catalytic systems based on transition metals in the ethylene oligomerization from full range (C 4 ‐C 30 ) to selective olefins (C 6 , C 8 ) have been collected in the article by Orson L. Sydora . G. Belov et al have summarized the results of studies on oligomerization of ethylene with zirconium containing catalysts .…”