Shell higher olefin process
The Shell higher olefin process is a chemical process for the production of linear alpha olefins via ethylene oligomerization and olefin metathesis invented and exploited by Royal Dutch Shell.[1] The olefin products are converted to fatty aldehydes and then to fatty alcohols, which are precursors plasticizers and detergents.
Process
Ethylene reacts by the catalyst to give longer chains. 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. The fraction containing C6 to C18 olefins has commercial value and is removed. The remaining higher and lower olefins next undergo liquid-phase isomerization reactions using alkaline alumina catalyst leading to internal double bonds.
The internal olefins are reacted with an excess of ethylene with rhenium(VII) oxide supported on alumina as catalyst in a ethenolysis reaction, which causes the internal double bond to break up to form a mixture of α-olefins with odd and even carbon chain-lenght of the desired molecular weight.[2]
The C6 to C18 olefins subsequently are subjected to hydroformylation (oxo process) to give aldehydes. The aldehyde is hydrogenated to give fatty alcohols, which are suitable for manufacturing detergents.[2]
The process was commercialized in 1977 by Royal Dutch Shell and in 1993 global annual production capacity was ten million tons.[citation needed]
Catalytic cycle
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. Such catalysts are typically prepared from diarylphosphinoacetic acids, such as (C6H5)2PCH2CO2H.[3] The process and its mechanism was intensively studied by the group of Professor Wilhelm Keim at the RWTH Aachen, who is also regarded as one of the key figures in the development of the process.[4]
Alternative routes
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 is still in use at Shell Stanlow refinery.
References
- ^ Industrial Organic Chemistry, Klaus Weissermel, Hans-Jurgen Arpe John Wiley & Sons; 3rd 1997 ISBN 3-527-28838-4
- ^ a b Reuben, Bryan; Wittcoff, Harold (1988). "The SHOP process: An example of industrial creativity". J. Chem. Ed. 65 (7): 605. doi:10.1021/ed065p605.
- ^ Kuhn, P.; Semeril, D.; Matt, D.; Chetcuti, M. J.; Lutz, P. (2007). "Structure–reactivity relationships in SHOP-type complexes: tunable catalysts for the oligomerisation and polymerisation of ethylene". Dalton Trans.: 515–528. doi:10.1039/B615259G.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Gadi Rothenberg. Catalysis: Concepts and Green Applications (Google Books excerpt). p. 97.
