[2] The process was commercialized in 1977 by Shell plc and following an expansion of the Geismar, Louisiana (USA) plant in 2002 global annual production capacity was 1.2 million tons.
Unlike the Ziegler–Natta process, which aims to produce very long polymers, the oligomer stops growing after addition of 1–10 repeating units of ethylene.
[4] The first step in this process is the ethylene oligomerization to a mixture of even-numbered α-olefins at 80 to 120 °C and 70 to 140 bar (7 to 14 MPa) catalyzed by a nickel-phosphine complex.
In another olefin application of Shell cyclododecatriene is partially hydrogenated to cyclododecene and then subjected to ethenolysis to the terminal linear open-chain diene.
The process was still in use at Essar Stanlow refinery until a serious explosion and following fire lead to the closure of the plant and the alcohols units it fed in 2018.