Chromium catalysts for selective ethylene oligomerization to 1-hexene and 1-octene: Recent results

The objective of this review is the analysis and comment of recent publication results (from July 2010 until February 2017) obtained for selective ethylene oligomerization toward 1-hexene and 1-octene catalyzed by chromium-based catalytic systems. Both the scientific and patent literature was taken into the consideration. The catalytic systems for ethylene oligomerization are classified on the basis of the ligand type employed. The activities and selectivities of the catalysts are provided throughout the text. Despite a big success in the field, there is still rather limited choice of catalysts affording simultaneously high activity, selectivity and low polymer proportion. This is especially true for ethylene to 1-octene tetramerization reaction. The results of the studies concerning oligomerization mechanisms obtained over the recent years are also included in this review.