Abstract: The selective oligomerization of ethylene to prepare linear α-olefins has been highly valued in both academia and industry because of its high target product selectivity, easy product separation, and significant economic benefits. Chromium-based catalysts have good overall performance in catalyzing selective oligomerization of ethylene, and are a class of catalysts with broad application prospects. Recent studies have shown that the ligand structure has an important effect on the catalyst performance; the introduction of hydrogen in the reaction system can improve the distribution of oligomerization products and inhibit the formation of polymers; development of the catalyst without methylaluminoxane as a cocatalyst can reduce the costs of the catalyst; the ethylene selective oligomerization mechanism and the oxidation state of the central metal have important guiding significance to the design of the catalyst. Recent progress in the research of phosphoamine chromium and diphosphinoamine chromium complexes in the selective oligomerization of ethylene is reviewed from the above aspects, with the problems to be solved in the industrializaion of ethylene selective tetramerization and the further development in ethylene selective oligomerization.

Key words: Ethylene selective oligomerization, Linear α-olefin, Phosphoamine chromium, Diphosphinoamine chromium, Oligomerization mechanism